Amateur Radio (Ham) Glossary

Compiled by Dick Oakes

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I'm really new to amateur radio. In fact, I don't have an amateur radio Technician Class License yet and am just listening to repeaters on a borrowed Realistic PRO-39 scanner.

I became very frustrated at having to go to so many sources to find the terms for which I was looking that I started putting together my own list. So, here is an amateur radio glossary collected, collated, and expanded from many sources.

NOTE that abbreviations, acronyms, contractions, initialisms, symbols, and synonyms (such as ARRL meaning "American Radio Relay League") follow the meaning instead of preceding it.

ANOTHER NOTE: If, while looking for an initialism, for instance ARRL, and you find there are too many references, you may want to click and jump to the SUPPLEMENT version to find the translation!

Here are a few suggestions for site searches:

Should you find a term or a definition that is a bit screwy or mispelled, contact me and let me know the correction so I can fix it!


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To the top! = "Top of page"


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Ø - zero with a stroke - A Ø distinguishes a 0 (zero) from the letter O and resolves ambiguity in call signs. On a Macintosh keyboard, press the caps lock key, then press option-O. On a general personal computer keyboard's numeric keypad, press Alt-O-216. For hyper-text markup language web pages, use Ø or Ø.
10-code - ten code - A series of abbreviations (originally 10-1 through 10-29) created by United States Association of Public-Safety Communications Officials-International (APCO) officers for use on 1950s-era police radio. As many localities extended the series with their own non-standard codes, the same codes may have different meanings in different agencies, even between police and fire services in the same town. Ten-codes are never used in amateur, marine, or aviation radio as Q-symbols already are in long-established international use but they may be heard in the unlicensed CB radio service and on local public-service frequencies.
10 log - A logarithmic unit of measurement, it is based on the common logarithm of ratios: 10 times the common logarithm of a power ratio or 20 times the common logarithm of a voltage ratio. The bel is the logarithm of a power ratio. It is 10 times the log of the ratio of the output voltage to the input voltage. Since 1 bel represents a large power ratio (10), the decibel was introduced as a matter of convenience. One bel equals 10 decibels and corresponds to a power ration of 10 to 1.
1929-type - (Archaic) Stations, transmitters, and receivers that were designed specifically to adhere to the bands and signal characteristics dictated by the 1927 International Radio Convention, whose specifications went into effect on January 1, 1929.
20 log - (See 10log)
5/8 wave antenna - A 5/8 λ vertical radiator antenna that is fed at its base. A matching device of some sort must be added between the antenna and the feed line to feed it with coax. Adding a coil in series with the antenna at the base is one such method of matching. The λ is a Greek small lambda.
5x5 - (Archaic) Five-by-five is an older term used to assess radio signals, as in 5 out of 5 units for signal strength and for readability. Other terms similar to 5-by-5 are "Loud and clear" and "Lima and Charlie."
7O Yemen - For DXers, a most unattainable contact or a non-existent station. The rarest call sign prefix as one of two countries worldwide (the other is P5 North Korea) to have had no licensed radio amateur service at all since 2002.
73 - A radiotelegraph code meaning "Best regards." Used in both CW, from where it came, and phone toward the end of a contact.
73 Magazine - (Archaic) A United States-based amateur-radio magazine that was published from 1960 to 200(3) It was known for its strong emphasis on technical articles and for the lengthy editorials in each issue. Also known as 73 Amateur Radio Today
88 - A radiotelegraph code meaning "Love and kisses." Used in both Morse code (CW), from where it came, and phone toward the end of a contact.
92-code - (CW Term) A series of telegraphic abbreviations, devised by Western Union in 1859, as numbers 1 to 91. The later Philips Code added abbreviations for news wire service. While many of the codes are long forgotten, 19 and 31 (absolute and permissive) continue as orders for trains in railroad use.


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A-index - An index of the conditions of the Earth's magnetic field as measured at Boulder, Colorado. Propagation generally improves with lower measurement numbers.
A battery - (Archaic) In early radio, batteries were the prime source of power. The A battery provided the filament voltage in a vacuum tube, the B battery furnished the B+ or the voltage to the plates of the vacuum tube, and the C-battery provided the grid-bias voltage for the vacuum tube.
above ground level (AGL) - Intended for antenna installations, AGL has relatively little direct bearing on the broadcast range of a station.
above sea level (ASL) - The vertical height in feet (ft) or meters (m) above sea level.
absorption - The reduction in a radio signal strength due to refraction in the ionosphere.
accessory (ACC) - (Archaic) A socket in the back of a radio.
accessory power outlet (APO) - A cigarette light socket in an automobile that is typically fused at 15 amperes. It should not be used to power any amateur radio device.
access code - (Repeater Term) A code to activate a repeater function, for example, auto patch, link, etc. One or more numbers and/or symbols are keyed in with a telephone key pad and transmitted to the repeater.
active antenna - A physically short or small antenna with a high-gain preamplifier that is designed for use indoors or in limited-space areas.
active filter - (See filter)
active noise control (ANC) - A method for reducing unwanted sound.
active noise reduction (ANR) - A method for reducing unwanted sound. (See active noise control)
adapter - A device for connecting pieces of equipment that cannot be connected directly.
adjacent-channel interference (ACI) - A condition that occurs when a receiver is tuned to a specific frequency and interference is received on a nearby frequency.
admittance - The reciprocal of impedance of a component in a series or parallel tuned circuit. (See parallel tuned circuit)
address - The information in a packet specifying the intended receiving station.
Advanced - (Archaic) The Advanced Class operator license for intermediate-level amateur radio operators, whose privileges included 275 kilohertz (kHz) of additional spectrum in the high-frequency (HF) bands over and above that allocated to General Class licensees. It was deprecated by the restructuring in 2000.
advanced digital network (ADN) - A 56-kilocycle-bps dedicated leased line.
aerial - (Archaic) An antenna; an electrical device that converts electric power into radio waves, and vice versa. The term was used in the early days of radio. The term is still used in the United Kingdom. Also known as outdoor antenna.
aeronautical station - A radio station aboard an airplane or a ground station that communicates with aircraft.
Affiliated Club Coordinator (AC) - An appointee of the American Radio Relay League (ARRL) who specializes in motivating, providing assistance to, and coordinating joint activities of radio clubs.
agw packet engine (AGWPE) - Personal computer software written by George Rossopoulos SV2AGW that allows a computer sound card to emulate a terminal node controller (TNC) for packet operation.
air link - That portion of a data and/or voice transmission that takes place using radio signals with no wires involved. A good example is a microwave link between two towers.
airwaves - The radio frequencies used for broadcasting.
alligator - (1) (Repeater Term) A repeater that transmits further than it can receive. (2) (Repeater Term) Used in reference to a repeater timer timeout. If you talk on the repeater too long, an internal timer will cut you off, and jargon for this is "The alligator got you!" (3) Used in contesting circles to refer to a station whose transmit signal is greater than the receive capability which is usually running high power and under noisy receive conditions.
allocation - A frequency authorized for a particular Federal Communications Commission (FCC) telecommunications service.
Alpha - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter A. Used in radio communication, particularly when spelling out a call sign.
alternating-current hum (AC hum) - Unwanted 60- or 120-Hz modulation of an audio radio frequency (RF) signal due to inadequate filtering in a power supply or improper grounding.
alternating current (AC) - Electrical current that flows first in one direction and then in the other in a wire, reversing polarity at regular intervals. Sometimes written as ac.
amateur - A person licensed to operate a radio in the amateur radio bands.
Amateur's Code - A code of conduct for amateur radio operators written in 1928 by Paul M. Segal W9EEA.

THE AMATEUR'S CODE
The radio amateur is:
CONSIDERATE . . .
     never knowingly operates in such a way as to lessen the pleasure of others.
LOYAL . . .
     offers loyalty, encouragement, and support to other amateurs, local clubs, and the ARRL through which amateur radio in the Unites States is represented nationally and internationally.
PROGRESSIVE . . .
     with knowledge abreast of science, a well-built and efficient station, and operation above reproach.
FRIENDLY . . .
     slow and patient when requested; friendly advice and counsel to the beginner; kindly assistance, cooperation, and consideration for the interests of others. These are the hallmarks of the amateur spirit.
BALANCED . . .
     radio is an avocation, never interfering with duties owed to family, job, school, or community.
PATRIOTIC . . .
     station and skill always ready for service to country and community.

amateur communications - Non-commercial radio communication by or among amateur stations solely with a personal aim and without personal or business interest.
Amateur Data Interchange Format (ADIF) - A standard specification for format of exported logbook files.
Amateur Extra Class - The top United States license class is Amateur Extra Class. This license requires the same tests as the General Class license plus a 50-question multiple-choice theory exam. Those with Amateur Extra Class licenses are granted all privileges on all United States amateur bands. It does not require familiarity with Morse code (CW).
amateur operator - A person holding a written authorization to be the control operator of an amateur radio station.
amateur radio - A non-commercial radio service as set by a recognized cognizant government agency. A synonum is ham radio. In the United States, amateur radio is defined under part 97 of the Federal Communications Commission (FCC) Rules and Regulations. (See ham radio)
Amateur Radio Association (ARA) - A club of amateur radio enthusiasts. This term is usually prefixed by the name of the community or region served.
Amateur Radio Club (ARC) - A club of amateur radio enthusiasts. This term is usually prefixed by the name of the community or region served.
amateur radio direction finding (ARDF) - An amateur radio racing sport that combines radio direction finding with the map and compass skills of orienteering. It is a timed race in which individual competitors use a topographic map, a magnetic compass, and radio-direction finding apparatus to navigate through diverse wooded terrain while searching for a radio transmitter (the "fox" or "bunny"). Also known as radio orienteering, radiosport, fox hunt or foxhunt, and bunny hunt.
Amateur Radio Disaster Services (ARDS) - An organization of licensed amateurs who have voluntarily registered their qualifications and equipment for communication duty in the public service when disaster strikes.
Amateur Radio Emergency Service (ARES) - A public service organization of the Amateur Radio Relay League (ARRL) in which licensed amateurs have voluntarily registered their qualifications and equipment for communication duty in the public service when disaster strikes.
Amateur Radio on the International Space Station (ARISS) - A cooperative venture of the National Aeronautics and Space Administration (NASA), the American Radio Relay League (ARRL), and the Radio Amateur Satellite Corporation (AMSAT), and other international space agencies that organizes scheduled contacts by way of amateur radio between spacecraft personnel aboard the International Space Station and classrooms or communities.
amateur radio operator - (See amateur operator)
Amateur Satellite (AMSAT) - In particular, the Radio Amateur Satallite Corporation, with headquarters at Silver Spring, Maryland, near Washington DC. (2) Organizations that design, build, arrange launches for, and then operate or command satellites carrying amateur radio payloads, including the Orbiting Satellite Carrying Amateur Radio (OSCAR) series of satellites.
Amateur Radio Society (ARS) - A club of amateur radio enthusiasts. This term is usually prefixed by the name of the community or region served.
amateur service - A radio communication service for the purpose of self-training, intercommunication, and technical investigations carried out by amateurs, for example, duly authorized persons interested in radio technique solely with a personal aim and without pecuniary interest. Also known as amateur radio service.
amateur station - A radio station licensed in the amateur service, including necessary equipment, used for amateur communication.
amateur teleprinting over radio (AMTOR) - A version of radioteletype (RTTY). Also used commercially as simplex teletype over radio (SITOR).
amateur television (ATV) - The transmission of broadcast-quality video and audio over the wide range of frequencies of radio waves allocated for amateur radio use. Also known as fast-scan television.
American Radio Relay League (ARRL) - The national association for amateur radio in the United States whose public service mission is based on five core areas or pillars: Public Service, Advocacy, Education, Technology, and Membership.
American Standard Code for Information Interchange (ASCII) - A seven-unit digital code that represents 128 characters, including 32 control characters, for the transmission of teleprinter data made up of 0s & 1s.
American wire gauge (AWG) - A standard for describing the diameter of wire by which the wire size increases as the gauge number decreases.
ammeter - A test instrument that measures current.
ampere (A, Amp) - An abbreviation for the basic unit of electrical current which is a measure of the electron flow through a circuit. Ampere is represented by the symbol A and also is written as Amp.
ampere hour - A term frequently used in measurements of electrochemical systems such as electrical batteries.
amplification - The process of increasing the strength of a radio signal.
amplifier - A device connected between the transmitter and antenna that amplifies the radio frequency (RF) power output, often to the full legal amateur power limit of 1500 watts (W) peak envelope power (PEP), without changing the signal's characteristics. Also known as linear amplifier or power amplifier.
amplify - To increase the strength or amplitude of a signal.
amplitude - The strength or amplitude of a signal, it is the height of a wave from the average or median position.
amplitude-compandored sideband (ACSB) - (Archaic) A narrow-band modulation using a single sideband with a pilot tone, allowing an expander in the receiver to restore the amplitude that was severely compressed by the transmitter.
amplitude modulated phone - An amplitude modulation (AM) transmission in which voice signals, or phone are used to modulate the carrier.
amplitude modulation (AM) - (1) A modulation technique that varies the power output of a transmitter in accordance with the variations in the modulating audio signal. (2) A method of combining an information signal and a radio frequency (RF) carrier.
analog - Any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, that is, analogous to another time varying signal.
analog-to-digital (ADC) - A converter that samples an analog wave and converts it into a digital signal, in which a series of numbers is used to represent the amplitude of the original wave. Also known as A/D and A-to-D.
analog data - Continuous waves that vary or fluctuate infinitely within a range. In comparison, digital data consists of discrete, discontinuous binary digits.
analog signal - A linear signal, usually electrical, that can have any amplitude (voltage or current) value, and whose amplitude can vary smoothly over time. (See digital signal)
anode - An electrode through which electric current flows into a polarized electrical device. (See cathode and electrode)
ante meridian (a.m.) - Before noon.
antenna (ANT) - A rod, wire, or other device used to transmit or receive radio frequency energy or television signals. Also known as skyhook.
antenna-matching device - (See antenna tuner)
antenna-matching network - (See antenna tuner)
antenna-tuning unit, impedance-matching device, matchbox, and transmatch.
antenna analyzer - A portable instrument that combines a low-power signal source, a frequency counter, and a standing-wave ratio (SWR) meter.
antenna direction - The direction to which an antenna is pointed.
antenna farm - A ham's dream; lots of room for big, high, long, antennas.
antenna gain - The ratio of the power required at the input of a loss-free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength at the same distance.
antenna ground system (AGS) - A radio frequency (RF) reference potential for some types of antennas. Most unbalanced or asymmetrical antennas need a good RF ground.
antenna impedance - The impedance of an antenna at its resonance. Although an antenna's impedance fluctuates with the frequency of operation, an antenna should be 50 Ohms for most transceivers.
antenna matching - When the antenna's impedance at resonance is at optimum performance for a transmitter output circuit.
antenna party - A long-standing tradition where several ham operators gather to assist a fellow ham in mounting antennas and/or towers.
antenna pattern (AP) - (1) The relative power density of the wave transmitted by the antenna in a given direction. (2) The response of an antenna to a plane wave incident from a given direction.
antenna relay - An electromechanical device that can be used to switch an antenna remotely, typically from transmitter to receiver.
antenna tuner - A device that matches the antenna system input impedence to the transmitter, receiver, or transceiver output impedance. Also called antenna-matching device, antenna-matching network, antenna switch - A device used to connect one transmitter, receiver, or transceiver to several different antennas.
anti-voice operated (anti-VOX) - A transceiver circuit used in VOX stations to prevent audio from the receiver's speaker from actuating the voice-operated transmitter.
antipode - (Archaic) One of two locations directly opposite one another on the Earth's surface, believed in the early days to favor propagation because of a re-convergence of signals from multiple paths around the globe.
apogee - A point in a satellite's orbit at which it is farthest from the Earth. (See perigee)
appliance operator - Amateur radio operators who neither build nor experiment with radio equipment, but only operate commercial equipment.
acquisition of signal (AQS) - A condition that occurs when a satellite becomes visible to an antenna as the satellite comes up from the horizon.
armchair copy - Easily copied.
Army-Amateur Radio System (AARS) - (Archaic) The precursor to Military Affiliate Radio System (MARS).
array antenna - An antenna with more than one element. In a driven array, all elements are driven elements. In a parasitic array, some elements are parasitic elements.
Association of North America radio Clubs (ANARC) - An umbrella organization of radio hobby clubs in North America.
Association of Public-Safety Communications Officials-International (APCO) - An independent United States communications consultancy with more than 600 employees in 29 worldwide locations, it is the second largest independently-owned PR firm in the United States. Known as APCO Worldwide.
asymmetrical antenna - (See unbalanced antenna)
atmosphere - The layer of air surrounding the Earth.
attended operation - Operation of a radio station with a human operator at the control point.
attenuator (ATT) - A resistive device or network to reduce the amplitude or power of a signal, often expressed in decibels (dB) of reduction. The types of attenuator circuits are the π pads (Greek small pi) and T pads. These may be required to be balanced or unbalanced networks depending on whether the line geometry with which they are to be used is balanced or unbalanced. For instance, attenuators used with coaxial lines would be the unbalanced form while attenuators for use with twisted pair are required to be the balanced form. The pi pad is formed in the shape of the Greek letter π. T pads are formed in the shape of a T. π pads and T pads are easily converted back and forth.
audibility - (Archaic) A measure of signal strength, usually based on audio strength.
audio - An electrical or other representation of sound.
audio-frequency gain (AF-gain) - (1) Receiver output volume. (See gain) (2) The volume control on a radio.
audio-frequency shift keying (AFSK) - As opposed to frequency-shift keying, it is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. (See frequency-shift keying)
audio-frequency signal (AF signal) - An alternating current (AC) electrical signal in the frequency range of 20 to 20,000 hertz (Hz). This is called an audio signal because human hearing responds to sound waves in the same frequency range.
audio frequency (AF) - The range of 20 to 20,000 hertz (Hz), the human hearing range.
audio mixer - A circuit or device that adds miltiple signals together into a single signal.
audio rectification - Interference to electronic devices caused by a strong radio frequency (RF) field that is rectified and amplified in the device.
audion - (Archaic) A three-electrode vacuum tube, the name was coined in 1906 by Lee de Forest of the DeForest Radio Telephone and Telegraph Co. It is widely believed, however, that a Canadian inventor, Reginald Fessenden, actually came up with the idea, but Fessenden didn't seem to make it into the history books for that invention. (See vacuum tube)
auroral propagation - Propagation above 30 megahertz (MHz) by means of refraction of highly ionized regions around the Earth's poles. (See propagation)
authorized bandwidth - The allowed frequency band, specified in kilohertz (kHz), and centered on the carrier frequency.
auto patch - (Repeater Term) A device that interconnects a radio system to commercial phone lines and allows repeater users to make telephone calls from a distant station to be completed to anyone within range. Also known as phone patch or patch.
auto tuner - An antenna tuner that automatically senses the mismatch between the transmitter and antenna and does the necessary matching with minimal user intervention.
automatic control - The use of devices and procedures for control of an amateur radio station when it is transmitting so that compliance with the Federal Communications Commission (FCC) Rules is achieved without the control operator being present at a control point.
automatic frequency control (AFC) - A method or circuit to automatically keep a resonant circuit tuned to the frequency of an incoming radio signal.
automatic gain control (AGC) - A feedback voltage in the receiver circuit to prevent fading, it automatically optimizes receiver gain by adjusting the gain for different input signal levels to maintain a constant output.
automatic level control (ALC) - A circuit that limits radio frequency (RF) drive level to the power amplifier during transmit to prevent distortion. A feedback voltage in the transmitter's output amplifier used to prevent amplifier overload. Also used as feedback from a linear amplifier back to the exciter to prevent overdriving.
automatic noise limiter (ANL) - A device that eliminates impulse and static noise peaks.
automatic notch filter (ANF) - A device that quickly locates and suppresses interfering carriers, such as those caused by other stations tuning up nearby.
automatic packet reporting system (APS) An amateur radio-based system for real time tactical digital communication of information of immediate value in the local area.
automatic position reporting system (APRS) - A term used in conjunction with a global positioning system (GPS) and a terminal node controller (TNC) to provide position reporting.
automatic power control (APC) - Current limiting of a power amplifier to prevent damage to the finals in high standing-wave ratio (SWR) conditions.
automatic repeat query (ARQ) - An error-control method for data transmission that uses acknowledgements, or messages sent by the receiver, indicating that it has correctly received a data frame (packet) and timeouts (specified periods of time allowed to elapse before an acknowledgment is to be received) to achieve reliable data transmission over an unreliable service. Used in amateur teleprinting over radio (AMTOR). Also known as automatic repeat request.
automatic repeat request - (See automatic repeat query)
automatic send-receive (ASR) - A radioteletype (RTTY) terminal mode that allows message composition while receiving text from the another station.
automatic transfer switch (ATS) - A switch that changes equipment to a backup power supply in event of power failure.
automatic volume control (AVC) - A feedback scheme to level out the receiver audio volume.
auxiliary station - A radio system that is part of a radio frequency (RF) control link, often used for control of a remote repeater station.
average power - Power measured on a standard power meter.
aviation headset - Combination earphones and attached boom-mounted microphone.
AX.25 - Amateur version of the X.25 communication protocol. X.25 supports store and forward messaging and insures delivery of American Standard Code for Infomation Interchange (ASCII) text by retransmitting packets in the event an acknowledgment is not received from the destination.
azimuth - A horizontal direction or angle measured clockwise from north.
azimuth/elevation (Az/El) - Used to describe an antenna rotator that can change both the azimuth (horizontal) and the elevation (vertical) direction of the antenna.
azimuth pattern - Graphical description of the power intensity of radiation from an antenna as a function of the horizontal angle at a specified elevation angle around an antenna.
azimuth plot - Graphical representation of signal strength from an antenna as a function of horizontal angle around the antenna center. It is made of a particular elevation angle, often the angle with the maximum response.
azmuthal pattern - A graph showing how an antenna radiates and receives in horizontal directions. (See radiation pattern)


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B battery - (Archaic) In early radio, batteries were the prime source of power. The A-battery provided the filament voltage, the B battery furnished the B+ or the voltage to the plates of the vacuum tubes, and the C battery provided the grid-bias voltage to the tubes.
backbone - A high-speed communications line/link or series of lines/links that form a major pathway in which devices can communicate within a network. The term is relative to a single smaller backbone in a group network and that of a larger multi-linked backbone in enterprise networks. A backbone can be wired, fiber optic, or air link.
backscatter - A form of ionospheric propagation by way of the E- and F-layers of the atmosphere allowing stations to hear other stations within the skip zones.
balanced-to-unbalanced (balun) - A simple transformer used to change an unbalanced input to a balanced output. It is part of an antenna system that provides the transition between a balanced antenna such as as center fed dipole and an unbalanced transmission line such as coaxial cable, or dipole to coax.
balanced line - A feed line with two conductors having equal but opposite voltages, with neither conductor at ground potential.
balanced load - A termination in which each of the two terminals is at the same potential above ground.
balanced modulator - A mixer or modulator in which at least one of the input signals is canceled at the output following generation of the desired modulation or mixing products. The original carrier signal and the audio signal are suppressed.
ballmount - An antenna mount with a built-in adjustable swivel allowing an antenna to be mounted on a surface that is not exactly horizontal or vertical.
band - A range of frequencies allocated for a particular use. Some of the allocations are:

BAND FREQUENCY RANGES
FrequencyBand
10 kHz to 30 kHzVery Low Frequency (VLF)
30 kHz to 300 kHzLow Frequency (LF)
300 kHz to 3 MHzMedium Frequency (MF)
3 MHz to 30 MHzHigh Frequency (HF)
30 MHz to 144 MHz
144 MHz to 174 MHz
174 MHz to 328.6 MHz
Very High Frequency (VHF)
328.6 MHz to 450 MHz
450 MHz to 470 MHz
470 MHz to 806 MHz
806 MHz to 960 MHz
960 MHz to 2.3 GHz
2.3 GHz to 2.9 GHz
Ultra High Frequency (UHF)
2.9 GHz to 30 GHzSuper High Frequency (SHF)
30 GHz and aboveExtremely High Frequency (EHF)

band-pass filter (BPF) - A circuit that allows signals to go through it only if they are within a certain range of frequencies and attenuates signals above and below that range.
band pass - A range of frequencies permitted to pass through a filter or receiver circuit.
band plan - Agreements between operators about how to use the amateur bands, rather than Federal Communications Commission (FCC) regulations. Portions of each ham band are dedicated to certain modes of operation.
band spread - A receiver quality used to describe how far apart stations on different nearby frequencies will seem to be, usually expressed as the number of kilohertz (kHz) that the frequency changes per tuning-knob rotation.
bandwidth - The width of a frequency band outside of which the mean power is attenuated at least 26 decibels (dB) below the mean power of the total emission, including allowances for transmitter drift or Doppler shift. Bandwidth describes the range of frequencies that a radio transmission occupies.
bank - (See memory bank)
barefoot - A synonym for transmitting with a transceiver alone with no linear amplifier.
base - (1) A radio station located at a fixed location as opposed to a mobile station. It is used to identify the control location in a network of radio stations. (2) (See transistor)
baseloading - Shortening the physical length of a vertical antenna by substituting a loading coil for inductance at the base for part of the lower section of the antenna. Also known as base loading. (See center-loading coil.
battery - (1) A device that converts chemical energy into electrical energy. (2) (Archaic) In early radio, batteries were the prime source of power. The A-battery provided the filament voltage, the B-battery furnished the B+ or the voltage to the plates of the vacuum tubes, and the C-battery provided the grid-bias voltage to the tubes.
battery pack - Several battery cells connected together to act as a single, larger battery.
baud (Bd) - The unit of digital-signal speed. It is the unit used to express the speed of transmission of electronic signals, corresponding to one information unit or event per second. The baud unit is named after Émile Baudot.
Baudot code - (Archaic) A five-digit character set predating extended binary coded decimal interchange code (EBCDIC) and American Standard Code for Information Exchange (ASCII) and was the predecessor to the International Telegraph Alphabet Number 2 (ITA2), the teleprinter code in use until the advent of ASCII. It was invented by Émile Baudot for whom it was named.
bayonet Neill-Concelman (BNC) - A type of antenna connector commonly used on a hand-held transmitter, receiver, or transceiver for radio frequency (RF) signals. Built like an N-type connector, but smaller, and named after its inventors, Paul Neill and Carl Concelman.
bazooka antenna - A type of wire antenna.
beacon - An amateur radio station transmitting communications for the purposes of observation of propagation and reception or other related experimental activities.
beam antenna - A directional antenna, a beam antenna must be rotated to provide coverage in different directions. Also known as parasitic beam antenna.
beam transmission - (Archaic) A term first used in the mid-1920s to refer to a directional signal, especially at very short wavelengths around 1 meter (m) and below.
beat frequency oscillator (BFO) - (CW Term) A receiver circuit that provides a signal to the detector. The BFO signal mixes with the incoming signal to produce an audio tone for Morse code (CW) reception. A BFO is needed to copy Morse code (CW) and single sideband (SSB) signals.
bel (B) - A logarithmic unit of measurement named after Alexander Graham Bell. One bel is defined as a power ratio of ten, or ten times the power. (See decibel)
bent-double antenna - A dipole antenna installed with its wires bent so a longer antenna fits into a shorter space.
Benton Harbor Lunchbox - A portable transceiver made by Heathkit Company. Operational band choices were 2, 6, or 10 meters (m).
bias supply - (Archaic) A power supply designed to provide the usually low-current negative-direct current voltage required by the control grid of a vacuum tube.
big gun - An amateur radio operator with a lot of money who can afford to purchase a boatload of expensive equipment and has a whopping one- or two-thousand watts for DXing and contesting.
binary-coded decimal (BCD) - Decimal numbers represented in binary code by 0s and 1s.
binary phase shift keying (BPSK) - Digital double sideband (DSB) suppressed carrier modulation.
binocular core - A dual-ferrite core structure often used in radio frequency (RF) transformers.
bipolar-junction transistor (BJT) - A semiconductor device made from a pair of back-to-back positive/negative (P/N) junctions that are controlled by a current. (See transistor)
bird - (1) The nickname for a satellite. (2) A brand name of a high-end, high quality directional wattmeter.
birdie - Spurious signals produced in a receiver which are usually a product of mixed intermediate frequencies within the radio.
bit error rate (BER) - The rate at which bit-level errors occur in a stream of digital data.
bits per second (bps) - The number of bits that are conveyed or processed per unit of time.
blanker - (See noise blanker)
bleed over - Interference caused by a station operating on an adjacent channel.
bleeder resistor - A large-value resistor placed across the filter capacitors in a power supply so that they will have a discharge path when equipment is turned off. This prevents lethal voltages from lurking in an otherwise non-operating power supply.
block diagram - A drawing using boxes to represent sections of a complicated device or process. The block diagram shows the connections between sections without the detail of a schematic diagram.
Bluetooth - A wireless communication system intended to replace the cables connecting many different types of devices, from mobile phones and headsets to heart monitors and medical equipment.
boat anchor - Antique ham equipment so named because of weight and size.
bonding - Interconnecting by way of low-resistance conductors, particularly of separate ground points to avoid potential between them. (Also known as strapping)
bonding - The installation of grounding straps between the frame or unibody and all bolted on hardware. Doors, hood, trunk, and exhaust system are examples. Although bonding may help in reducing egressed noise, its primary function is to improve what little ground plane a vehicle offers.
boom - Structure that forms the support for multiple individual elements on a beam antenna.
boomset - (See headphones)
bootlegger - Someone, usually not an amateur radio operator but a wannabe, making up a call sign, one usually not in the callbook, and getting on the air. Sometimes it is someone who already bought a radio, took the test and flunked, and then gets on the air anyway. Also called a pirate.
bounce - Reflections of a radio wave off of an object, for example, the ionosphere or the moon.
brass pounder - (CW Term) Someone who sends telegraphy by old fashioned straight key without any paddles.
Brass Pounders League (BPL) - An American Radio Relay League (ARRL) Club for Morse code (CW) traffic net operators.
Bravo - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter B. Used in radio communication, particularly when spelling out a call sign.
breadboard - (1) An experimental layout of circuits on whatever media, such as printed circuit boards. Also known as bread board. (See printed circuit board) (2) (Archaic) Early experimenters used a wooden board to lay out circuits.
break - (Repeater Term) A term used to interrupt a conversation on a repeater to indicate that there is an emergency or urgent message. If non-urgent, an operator simply interjects his call sign. Also known as breaking in.
break break - (Repeater Term) A term used to intercede in an existing conversation with emergency communication.
breaker - A radio amateur operator who wants to join a contact that is already in progress.
breakin - (CW Term) Switching between transmit and receive during Morse code (CW) operation so that one can listen to the operating frequency between Morse elements (full break in) or during short pauses in one's transmissions (semi-break-in).
British Broadcasting Corporation (BBC) - A public corporation for radio and television broadcasting in Britain.
broadband - A system or an antenna that can operate over a wide band of frequencies.
broadband over power lines - Provides Internet access over power lines.
broadcast band (BCB) - An initialism for the amplitude modulation (AM) broadcast band running from 540 to 1700 kilohertz (kHz).
broadcast listener (BCL) - (Archaic) A term used to refer to listeners in the early 1920s to distinguish them from amateurs. The term novice was also used at this time to refer to such a listener.
broadcast radio interference (BCI) - The term refers to a time when sunspot activity is low during the nighttime causing heavy interference.
broadcasting - Transmissions intended to be received by the general public, either direct or relayed. Broadcasting is prohibited on the amateur radio bands, other than QSTs (general call preceding a message) that are of interest to all amateur radio stations.
buffer amplifier - An amplifier usually attached to an oscillator so as to reduce the drain on the oscillator output.
bug - (1) (CW Term) A semi-automatic telegraph or code key that mechanically forms dots while sending Morse code (CW) but is no longer in common use. (2) (Archaic) When used alone, an early term for ham, as in radio bug.
bulb - (Archaic) (See vacuum tube)
bulletin board system (BBS) - A combination of software and personal computer hardware that accepts packet messages for use by multiple users to receive messages at a later time by request.
bunny hunt - (See amateur radio direction finding)
bus - An electrical conductor for distributing power or to provide a common connection.
business communications - Any transmission or communication the purpose of which is to facilitate the regular business or commercial affairs of any party. Business communications are prohibited in the amateur service.
Bustands - (Archaic) A contraction for the Bureau of Standards, the precursor of the the National Institute of Standards and Technology (NIST). Also known as Bustand.
busted call - An incorrectly logged call sign.
busy lockout - A circuit that inhibits transmit on a frequency in use.


To the top!   C

C battery - (Archaic) In early radio, batteries were the prime source of power. The A battery provided the filament voltage, the B battery furnished the B+ or the voltage to the plates of the vacuum tubes, and the C battery provided the grid-bias voltage to the tubes.
cable television (CATV) - A system of distributing television programs to subscribers by way of radio frequency (RF) signals transmitted through coaxial cables or light pulses through fiber-optic cables. (2) (Archaic) Originally called community television.
cable television interface (CATVI) - A device working directly with cable television (CATV) to provide digital video recorder functions.
cage-dipole antenna - A dipole antenna built for broader standing-wave ratio (SWR) bandwidth than a standard dipole antenna by using multiple wires spaced apart with circular spreaders to create a thick radiator.
California kilowatt - A power setting above the legal limit.
call - (1) Attempt to make contact. (2) Abbreviated form of the words call sign.
call-sign assignment - A primary call sign systematically assigned each amateur station by the Federal Communications Commission (FCC). The types of selection are sequential, vanity, and special event.
call-sign system - The method used to select a call sign for amateur station over-the-air identification purposes.
call district - One of the ten administrative areas of the United States established by the Federal Communications Commission (FCC).
call letters - (See call sign)
call name - (See call sign)
call sign - A sequence of letters and numbers that identify a person who has earned a specific amateur radio license and the country in which the license was granted. Also may be spelled out by using the North Atlantic Treaty Organization (NATO) phonetic alplhabet. Abbreviated as call, it is also known as call letters, call name, and historically as call signal.
call signal - (See call sign)
callbook - A publication or compact disc (CD) read-only memory (ROM) that lists licensed amateur radio operators.
callbook address (CBA) - A list of the names and call signs of licensed amateur radio operators.
calling frequency - A defacto standard frequency where stations attempt to contact each other. For example, 146.52 is the United States National frequency modulation (FM) simplex calling frequency.
calling frequency - A frequency on which amateur radio operators establish contact with one another before moving to a different frequency. It is usually used by hams with a common activity or interest.
candy store - A ham term for the local amateur radio dealer.
cans - headphones. (Archaic) A pair of earphones typically joined by a band placed over the head, for listening to audio signals such as voice or music.
capacitance - A measure of the ability of a capacitor to store energy in an electric field.
cap hat - A means of increasing the capacitance of that portion of the antenna above the loading coil, thus raising the current node, and radiation efficiency.
capacitive hat - A system of wires, or at very-high frequency (VHF) and above a solid metal disk, added to the top of a vertical antenna to reduce its inductance and increase its bandwidth. Also known as capacity hat.
capacitive reactance - The opposition to current that a capacitor creates in an alternating current (AC) circuit. Reactance is measured in Ohms. (See reactance)
capacitor. (1) A passive two-terminal electrical component usually formed by separating two conductive plates with an insulating material that stores energy in an electric field. Capacitors are made from a pair of conductive surfaces called electrodes that are separated by an insulator called the dielectric. Also known as cap. (2) (Archaic) (See condenser)
capacity hat - (See capicitive hat)
carbon microphone - A microphone element in which a diaphragm is pushed against a cup of carbon granules by acoustic pressure from speech. Also known as carbon mic.
carrier - An unmodulated transmitted radio frequency (RF) signal. It is a pure continuous radio emission at a fixed frequency, without modulation, and without interruption. Several types of modulation can be applied to the carrier by which information is added.
carrier-operated relay (COR) - (Repeater Term) Circuitry that causes a repeater to transmit in response to a received signal.
carrier deviation - (See deviation)
carrier frequency - The center frequency of a radio signal.
carrier frequency offset - The distance between a mark frequency condition and a space frequency condition of the radioteletype (RTTY) or similar transmissions. The digital logic levels are +5 volts (a logical 1) or mark frequency and 0 volts (a logical 0) or space frequency. Also known as carrier shift.
carrier power - The average power supplied to an antenna when no modulation is taking place.
carrier shift - (See carrier frequency offset)
carrier wave - (CW Term) A waveform, usually sinusoidal, that is modulated or modified with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal. The purpose of the carrier is usually either to transmit the information through space as an electromagnetic wave, as in radio communication, or to allow several carriers at different frequencies to share a common physical transmission medium by frequency-division multiplexing, as, for example, a cable television system. The term is also used for an unmodulated emission in the absence of any modulating signal.
cathode - An electrode through which electric current flows out of a polarized electrical device. (See anode and electrode)
cathode-ray tube (CRT) - A high-vacuum tube in which cathode rays produce a luminous image on a fluorescent screen, used chiefly in televisions and computer terminals.
cavity filter - (Repeater Term) A very narrow radio frequency (RF) filter used to pass one single frequency, common in repeater operations where the receiver must be protected from overload by a transmitter on the same band on the same antenna tower.
cell - An electrochemical cell is a combination of chemicals and electrodes that convert chemical energy into electrical energy. (See battery)
center-fed Zepp antenna - A common name for a balanced antenna in a dipole configuration and fed with low-loss open wire or window line to allow operation on multiple bands. Zepp stands for Zeppelin. (See Zepp antenna)
center-loading coil - A loading coil at the center of an antenna to achieve a lower resonant frequency.
center frequency - The unmodulated carrier frequency of a frequency modulation (FM) transmitter.
centi- (c-) - One hundredth, or the metric prefix for 10-2, or divide by 100.
centimeter (cm) - The unit of length in the metric system equal to one hundredth of a meter (m), which is the International System of Units (SI) base unit of length.
central processing unit (CPU) - The hardware within a computer that carries out the instructions of a computer program by performing the basic arithmetical, logical, and input/output (I/O) operations of the system.
Certificate of Successful Completion of Examination (CSCE) - A document certifying that a person has successfully passed one or more of the amateur radio license examination elements. The term is used in the United States, is good for 365 days, and may be used as evidence of having passed an element at any other amateur license exam session.
channel - (1) The communications channel connecting the source and drain of a field-effect transistor (FET) and through which current flows. (2) The fixed frequency sequence of memory positions where a frequency and related information is stored. It is represented by the abbreviation ch.
Channel Guard (CG) - General Electric's trademarked name for continuous tone coded squelch system (CTCSS). Radio Corporation of America (RCA) called it QC (Quiet Channel).
channel spacing - The difference in frequency from one channel to the next.
characteristic impedance - The ratio of radio frequency (RF) voltage and current for a given power level in a transmission line.
characters per minute (cpm) - Morse code (CW) speed is measured in characters per minute (cpm) or words per minute (wpm).
charge - To store energy in a battery by reversing the chemical reaction in its cells.
charger - A device for storing energy in a battery.
Charlie - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter C. Used in radio communication, particularly when spelling out a call sign.
chassis ground - The common connection for all parts of a circuit that connect to the metal enclosure or chassis of the circuit. Chassis ground is usually connected to the negative terminal of the power supply.
check in - To register one's station's presence on a net with a net control station.
checksum - A method of detecting errors in digital data by including a calculated value with the data.
chief engineer (CE) - The person at a broadcasting station responsible for proper and legal operation of a station and maintenance of all required records.
chip - (See integrated circuit)
chirp - (CW Term) A slight shift in transmitter frequency each time one keys a transmitter that results in a chirping sound.
choke filter - A type of low-pass filter that blocks radio frequency (RF) current.
chopper - (Archaic) (CW Term) A rotary device used to modulate a Morse code (CW) signal to produce interrupted Morse code (ICW).
circuit - A conductive path through which current can flow.
circuit breaker - A protective component that opens or trips a circuit when an excessive current flow occurs.
circuit common - (See common)
circuit design - The process of circuit design can cover systems ranging from complex electronic systems all the way down to the individual transistors within an integrated circuit. For simple circuits, the design process can often be done by one person without needing a planned or structured design process, but for more complex designs, teams of designers following a systematic approach with intelligently guided computer simulation have become common.
circular polarization - an electromagnetic propagation mode in which the polarization, rather than being vertical or horizontal linear polarization, rotates as the wave moves from the source.
Citizen's Band (CB) - A United States radio service having 40 assigned channels in the former amateur 11-meter (m) band (near 27 MHz). Available to United States citizens for personal or business use under strict power and antenna limitations over a few miles.
Civil Air Patrol (CAP) - A volunteer affiliate of the United States Air Force. The CAP operates a national radio network of high frequency single sideband and very-high frequency radio repeaters.
clamp - (See limiter)
clarifier (CLAR) - A control on a transceiver to allow the receive frequency to be shifted from the transmit frequency by a small amount. On some radios it is called RIT. (See receiver incremental tuning)
clear - A term used to indicate that a radio station has finished transmitting.
clockwise (CW). A curve corresponding in direction to the movement of the hands of an analog clock.
cloning - Duplicating the memory contents of a radio into another radio.
closed circuit - An electrical circuit with an uninterrupted path for the current to flow. Turning a switch on, for example, closes or completes the circuit and allows current to flow. Also known as complete circuit.
closed repeater - (Repeater Term) A repeater that restricts access to those who know a special code. (See open repeater)
closing - (1) When a station ends its operations and shuts down. (2) When a frequency can no longer support propagation to a desired station or location.
cloud warmer - An antenna that radiates most of the transmitted energy nearly straight up.
clover - A phase shift keying (PSK) mode that allows full duplex communication. (See phase shift keying version 31)
club station - In the United States, special call signs may be made available for clubs, and are frequently used at a club station established for use by the club's members.
co-channel interference - Interference from stations on frequencies adjacent to the desired signal.
coax - (See coaxial cable)
coaxial cable - A type of transmission or feed line with one conductor inside the other used for radio and data transmission. Coaxial cable consists of a single center conductor surrounded by a dielectric, often polyethylene or foam polyethylene, but sometimes air. The dielectric is then enclosed by a tubular conductor which is then covered by a plastic jacket. The word coax is pronounced kó-aks. Also known as coax.
code - (See Morse code)
Code of Federal Regulations (CFR) - A code that covers the operating rules and regulations for the amateur radio service in the United States.
coded access - (Repeater Term) A method of restricting access to a repeater station to amateur radio stations that begin their transmission with a special sequence of tones.
code practice oscillator (CPO) - (CW Term) An oscillator used with a key and either headphones or a loudspeaker to practice sending and receiving Morse code (CW).
coherent continuous wave (CCW) - (CW Term) A Morse code (CW) technique that employs stable and precisely calibrated transmitters keyed at a known clock rate. This allows receivers to use extremely narrow band filtering that increases the signal-to-noise ratio (SNR) to a usable point, even if the sending rate is very slow.
coil - A conductor wound into a series of loops. (See inductor)
coil-choke balun - A multi-turn coil in a length of coaxial cable intended to provide an inductive reactance and thus reduce currents flowing on the outside of the shield. (See balun)
collector - (See transistor)
collision - A condition that exists when two or more packet radio stations simultaneously attempt to transmit on the same frequency.
color code - A system of numerical values that are assigned to various colors. Colored stripes are painted on the body of resistors and sometimes other components to show their values.
Colpitts oscillator - An oscillator circuit in which the feedback is provided by a signal from a portion of the tuned circuit set by a voltage divider. Invented in 1918 and patented 1927 by American engineer Edwin H. Colpitts.
Commission Registration System (CORES) - An agency-wide registration system for anyone filing applications with or making payments to the Federal Communications Commission (FCC).
common - The term for the shared reference for all voltages in a circuit. Also known as circuit common.
common mode - Currents that flow equally on all conductors of a multi-conductor cable, such as speaker wires or telephone cables. This type of connection is sometimes intentionally used for signaling on a balanced telephone line, but is generally undesired in amateur radio systems.
communications - The means of connection between people or places. In particular, the means of sending or receiving information, such as by amateur radio, over telephone lines, or by computers.
communications emergency - A situation in which communication is required for immediate safety of human life or protection of property.
community television - (Archaic) The precursor to cable television. (See cable television)
compact disc (CD) - An optical disk used to store digital data.
complementary-symmetry metal-oxide semiconductor (CMOS) - A technology or a chip built using such technology for making low-power integrated circuits.
complete circuit - (See closed circuit)
component - An electrical device that has a specific quantity of an electrical property, such as resistance, or that has a specific electrical function.
component signal - One of the signals that makes up a composite signal. (See composite signal)
composite signal - A signal made up of several individual component signals.
compression - (See speech compression)
computer interface version five (CI-V) - A device allowing multiple radio control simultaneously that was developed by Icom.
condenser - (Archaic) An old term for a capacitor. (See capacitor)
conditions (CNDX) - The prevailing state of the weather, ground, sea, or atmosphere at a particular time.
conductor - A material that has a loose grip on its electrons in response to an applied voltage so that an electrical current can pass through it.
Conference of Postal and Telecommunications Administrations (CEPT) - CEPT was established in 1959 by 19 countries of Europe, that expanded to 26 during its first ten years and issues amateur radio licenses. CEPT's activities include co-operation on commercial, operational, regulatory, and technical standardization issues.
connection - (Archaic) An early term for a circuit design. (See circuit design)
connected - The condition in which two packet-radio stations are sending information to each other. Each is acknowledging when the data has been received correctly.
contesting - A competitive activity pursued by amateur radio operators. In a contest, an amateur radio station, that may be operated by an individual or a team, seeks to contact as many other amateur radio stations as possible in a given period of time and exchange information. Rules for each competition define the amateur radio bands, the mode of communication that may be used, and the kind of information that must be exchanged. The contacts made during the contest contribute to a score by which stations are ranked. Contest sponsors publish the results in magazines and on web sites.
continuous-tone coded squelch system (CTCSS) - (Repeater Term) A continuous sub-audible low frequency tone that is added to a transmitted carrier to access many repeaters. Receivers set to the same low frequency tone can decode the signal. (See private line)
continuous wave (CW) - A continuous wave is an unmodulated, uninterrupted radio frequency (RF) wave. However in common usage the term refers to international Morse code (CW) emissions or messages that are an interrupted wave. The name was given to an early method of radio transmission, in which a carrier wave was switched on and off. Information was carried in the varying duration of the on and off periods of the signal, for example by Morse code (CW) in early radio. (See carrier)
continuous wave filter (CW filter) - (CW Term) A device used to narrow passband to improve reception of Morse code (CW) in crowded band conditions.
control code - Information in the form of data or tones used to adjust a station under remote control.
control link - The means by which a control operator can make adjustments to a station under remote control.
control operator - An amateur radio operator responsible for the proper operation of a licensed radio station. The control operator has broad authority to take any action deemed necessary to insure that the station is being operated within Federal Communications Commission (FCC) regulations per the terms of the license.
control point - The locations at which the control operator function is performed.
controlled environment - Any area in which a radio frequency (RF) signal may cause radiation exposure to people who are aware of the radiated electric and magnetic fields and who can exercise some control over their exposure to these fields. The Federal Communications Commission (FCC) generally considers amateur radio operators and their families to be in a controlled radio frequency (RF) exposure environment to determine the maximum permissible exposure levels. (See uncontrolled environment)
controller - (Repeater Term) The control system within a repeater. It usually includes turning the repeater on and off, timing transmissions, sending the identification signal, controlling the auto patch, and continuous tone coded squelch system (CTCSS) encoder/decoder.
conventional current - (See current)
conversion - The number of intermediate frequency (IF) circuits in a receiver. (See superheterodyne)
coordinator - A non-governmental group that works to voluntarily assign frequencies to users in order to prevent interference, especially for repeater stations.
copy - (1) A term used as a question, as in "Did you understand all?" (2) A term used as a statement as in "I understood all." (3) An indication of how well communications are received, as in "I have a good copy on you."
copying - A term used to indicate one is monitoring as in "I was copying the mail," meaning "I was listening in on the conversation."
core - In an inductor, it is the material or space used in the center of an inductor coil, where the magnetic field is concentrated.
corona ball - A round ball placed at the top of a whip antenna to minimize static discharge. Its use, purpose, and importance is often over-looked.
coulomb (C) - The basic unit of electrical charge. A coulomb is 1 ampere second, or 6.25 x 1012 electrons, thus 1 ampere equals the flow of 1 coulomb of electrons per second.
counterclockwise (CCW) - In the opposite direction to the way in which the hands of an analog clock move.
counterpoise - One or more wires in a network insulated from the ground to reduce loss resistances that might occur when a quarter-wave antenna is connected to poorly conducting earth. It acts as a condenser plate with high capacity to earth, with the result of lower loss in the antenna system. (See radials)
country code - A short alphabetic or numeric geographical code (geocodes) developed to represent a country and its dependent areas, for use in data processing and communications. (See grid square)
courtesy beep - (See courtesy tone)
courtesy tone - (Repeater Term) A tone or beep transmitted by a repeater to indicate that it is okay for the next station to begin transmitting. The courtesy tone is designed to allow a pause between transmissions on a repeater, so other stations can call. It also indicates that the time-out timer has been reset. Also known as courtesy beep.
covenents, conditions, and restrictions (CC&Rs) - An extensive set of rules drawn up by homeowner's associations and their lawyers that, among other things, typically restrict or completely prohibit a homeowner from having most forms of antennas on his or her property. Such regulations are formed and placed upon the property before the home is initially sold, and typically remains in effect for the life of the home.
coverage - (Repeater Term) The geographic area for which the repeater provides communication.
CQ - seek you - A radiotelegraph code meaning "Calling any amateur radio station," the general call when requesting a conversation with anyone. The call may be sent in Morse code (CW), phone, or in some digital modes. The term also refers to the etiquette on high-frequency (HF) bands where you'll talk with anyone. It is, however, frowned upon on very-high frequency (VHF) and ultra-high frequency (UHF) where efficiency (minimum communication) is the goal.
CQ Amateur Radio Magazine - A quarterly magazine for active amateur radio operators that focuses on all aspects of very-high frequency (VHF) and ultra-high frequency (UHF) amateur radio.
CQ DX - seek you foreign country - A radio communications term used for "Calling any amateur radio station," the general call when requesting a conversation only with someone in a foreign country.
CQ VHF Magazine - A quarterly magazine that serves ham radio operators whose operational and technical interests lie above 50 megahertz (MHz). The magazine focuses on radio technology, products, and activities that exist on 6 meters, 2 meters, 440 megahertz (MHz) and above.
critical angle - The angle at which a radio signal is refracted in the ionosphere. Lower angles generally result in greater distance transmissions.
critical frequency - The highest frequency at which a vertically incident radio wave will return from the ionosphere. Above the critical frequency, radio signals pass through the ionosphere instead of returning to Earth.
cross-band repeater (CBR) - (Repeater Term) A repeater that receives incoming signals and re-transmits them on different bands.
cross band - The process of transmitting on one band and receiving on another. For example, a repeater might receive a signal on 70 centimeters (cm) and retransmit it at 2 meters (m).
cross modulation - Distortion caused by two or more carriers interfering with each other.
crystal (XTAL) - A piezoelectric device that tends to resonate at a frequency dependent on its material, dimensions, and temperature. (See piezoelectric)
crystal-controlled transmitter - A type of transmitter that consists of a crystal oscillator followed by driver and power amplifier stages.
crystal filter - A network of piezoelectric crystals used to obtain high rejection of unwanted signals. (See piezoelectric)
crystal oscillator - A device that uses a quartz crystal to keep the frequency of a transmitter constant.
cubical-quad antenna - An antenna built with its elements in the shape of four-sided loops. In 1957 James Sherriff McCaig patented the cubical two-element multi-band quad antenna.
current - A flow of electrons in an electrical circuit. Also known as conventional current. (See electric current)
current balun - A transformer or choke designed to force the currents on the two leads of a transmission line to be equal and opposite.
cut numbers - A system of sending numbers by way of Morse code (CW) by substituting shorter letter characters for the longer number characters.
cutoff frequency - The frequency at which a filter's output power is reduced to one-half the input power.
cycle - One complete repetition of a repeating waveform, such as the sine wave.
cycles per second (CPS) - (Archaic) (See hertz)


To the top!   D

D-layer - The lowest region of the ionosphere. The D-layer contributes very little to short-wave radio propagation and acts mainly to absorb energy from radio waves as they pass through it. This absorption has a significant effect on signals below about 7.5 megahertz (MHz) during daylight. Also known as D-region.
damped oscillations - (Archaic) Radio frequency pulses such as those produced by a spark transmitter which typically are a series of short bursts of radio frequency energy that decay in amplitude with time. Also known as damped waves.
damped waves - (See damped oscillations)
data - Computer-based communication modes, such as packet radio, that can be used to transmit and receive computer files or digital information.
data communications - The transfer of data between two or more locations.
data mode - A digital computer-to-computer communication, such as by packet radio or radioteletype (RTTY), in which information is exchanged as data characters or digital information.
datagram - A basic transfer unit associated with a packet-switched network in which the delivery, arrival time, and order of arrival are not guaranteed by the network service.
dead end - (Archaic) The unused part of a tapped inductor beyond the tap in use. Letting unused turns float was a source of various problems in early radio frequency (RF) circuit design. (See tap)
dead full quieting (DFQ) - (Repeater Term) A condition where there is no noise behind the signal.
dead zone - A region where a radio signal cannot be received due to propagation difficulties.
deca- (da-) - (See deka-)
decameter band - (See high frequency)
decameter wave - (See high frequency)
deci- (d-) - One tenth, or the metric prefix for 10-1, or divide by 10.
deceptive signals - Transmissions that are intended to mislead or confuse those who may receive the transmissions. For example, distress calls transmitted when there is no actual emergency are deceptive signals. Also known as false signals.
decibel (dB) - A unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale. One decibel (dB) equals 10log (power ratio) or 20log (voltage or current ratio). The term dB comes from a logarithmic unit of measurement, called a bel (B), that was invented by Bell Labs and named after Alexander Graham Bell. One bel is defined as a power ratio of ten, or ten times the power. Although the dB is defined with respect to power, it has become common practice to also use it to express voltage or current ratios, in which case it is defined as 20log.
decibels above a dipole antenna (dBd) - A unit of radio frequency (RF) power in decibels compared to a dipole antenna.
decibels above an isotropic antenna (dBi) - A unit of radio frequency (RF) power in decibels compared to an isotropic antenna.
decibels of the measured power (dBm) - A decibel measure, 1 mW with a load impedance of 600 Ohms (0dBm equals 1 mW). It is used for low-power transmissions.
decibels microvolt (dBμV) - A decibel measure relative to 1 microvolt (μV).
decibels optical gain (dBo) - A decibel measure relative to light transmission and is an unofficial term used by some amateurs working with transmission of data using light.
decibels to a carrier (dBc) - In terms of radio frequency (RF) signals, dBc is the power ratio of a signal to a carrier signal, expressed in decibels.
decoding - The process of returning the signal to its original form. (See encoding)
decrement - (Archaic) A parameter of a spark- or damped-wave transmitter that denotes how rapidly the amplitude of the radio frequency (RF) wave decreases. If damping is too quick, you get a series of very short pulses that are very broad.
decryption - The process of reversing the enconding process. (See encryption)
degree - A measure of angle or phase. There are 360 degrees in a circle or cycle. (See cycle)
deka- (da-) - One ten, or the metric prefix for 10, or times 10. Also known as deca-
delay - The time a scanner radio pauses on a channel to await another transmission.
Delta - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter D. Used in radio communication, particularly when spelling out a call sign.
delta loop antenna - A loop antenna shaped as a triangle.
demodulate - To recover information from a modulated signal by reversing the process of modulation. (See modulate)
deprecated - Not supported or diminished in value.
desensitization - The reduction of receiver sensitivity due to overload from a nearby transmitter. Also known as desense.
desense - (See desensitization)
designator - Letters or numbers used to identify a specific electronic component.
detect - (1) To determine the presence of a signal. (2) To recover the information directly from a modulated signal.
detector - The stage in a receiver in which the modulation, voice, or other information is recovered from a modulated radio frequency (RF) signal.
deviation - The change in frequency of a frequency modulation (FM) carrier because of a modulating signal. Also called carrier deviation.
deviation ratio - The ratio between the maximum change in radio frequency (RF) carrier frequency and the highest modulating frequency used in a frequency modulation (FM) transmitter. (See modulation index)
dielectric - (1) The insulating material in which a capacitor stores electrical energy. (2) A non-conductive material used to separate the center conductor and shield (conductor) in coaxial cable that is typically made of foam or plastic and that can be polarized by an applied electric field.
differential phase shift keying (DPSK) - A form of binary phase shift keying (BPSK) where only data transitions are transmitted.
differential mode circuit - The circuit formed by two conductors in which the current leaves on one and returns on the other, the typical desired circuit.
diffract - To alter the direction of a radio wave as it passes by edges of or through openings in obstructions, such as buildings or hills.
digipeater - (Repeater Term) A type of repeater station that retransmits or forwards digital messages.
digital-coded squelch (DCS) - A selective calling system, it is a digital form of continuous tone coded squelch system (CTCSS). Instead of sending a continuous audio tone however, it transmits a low level digital signal. Also known as Digital Private Line (DPL), A Motorola trademark..
digital-message device - See electronic-message unit
digital-to-analog converter (DAC) - A device that converts digital signals into analog signals. Also known as D/A and D-to-A.
digital communication - A computer-based communication mode. This can include data modes, such as packet radio, and text-only modes, such as radioteletype (RTTY).
digital data - Discrete, discontinuous binary digits. In comparison, analog data consists of continuous waves that vary or fluctuate infinitely within a range.
digital filter - (See filter)
digital message unit - (See electronic message unit)
digital mode - (See data mode)
digital multimeter (DMM) - (See multimeter)
digital radio mondiale (DRM) - High-definition digital transmission system used by commercial shortwave broadcast stations.
digital signal - (1) A signal, usually electrical, that can only have certain specific amplitude values, or steps, such as 0 and 1 or ON and OFF. (2) On the air, a digital signal is the same as a data mode signal. (See data mode)
digital signal processing (DSP) - The process of converting an analog signal to digital form and using a microprocessor to process the signal in some way, such as filtering or reducing noise. The mathematical manipulation of an information signal to modify or improve it in some way, it is characterized by the representation of discrete time, discrete frequency, or other discrete domain signals by a sequence of numbers or symbols and the processing of these signals. It is used to improve the signal-to-noise ratio for cleaner and more legible communications.
digital tone coded squelch (DTCS) - (See digital-coded squelch)
digital voltmeter (DVM) - (See multimeter)
diode - An electronic component that allows electric current to flow in only one direction.
dip meter - A device used to determine the resonant frequency of an electronic circuit. Also known as grid-dip meter.
diplex - Circuitry that can process two signals without combining them. (See half-wave dipole)
diplexer A frequency splitting and isolation device, typically used to couple two transceivers to a single or dual-band antenna, thus allowing one to receive on one transceiver and transmit on the other transceiver. A typical application is to put 2 meter (m) and 440 megahertz (MHz) transceivers into a dual band antenna for satellite work. Thus, it allows a dual-band radio to use a single dual-band antenna.
dipole antenna - A simple common type of wire antenna, usually center fed with coaxial cable. (See half-wave dipole)
direct conversion - A type of receiver that recovers the modulating signal directly form the modulated radio frequency (RF) signal.
direct current (DC) - An electric current flowing in one direction only in a wire. Sometimes written as dc.
direct current ground (DC ground) - A connection point directly to a chassis or battery ground to prevent build-up of hazardous DC voltage.
direct current voltage (DC voltage) - A voltage with a constant polarity.
direct detection - A device acting as an unintentional receiver by converting a strong radio frequency (RF) signal directly to voltages and currents internally, usually resulting in RF interference to the receiving data.
direct path - The route that a transmitting antenna's signal takes directly to a receiving antenna without interference. (See reflected path)
direct wave - A radio signal propagated by way of line of sight.
direction finding (DF) - (See amateur radio direction finding)
directional antenna - An antenna that radiates greater power in one or more directions allowing for increased performance on transmit and receive and reduced interference from unwanted sources.
directional wattmeter - (See wattmeter)
directivity - A measure of how much of the energy from an antenna is radiated in a particular direction.
director - A parasitic element on a Yagi antenna and some other antennas in front of the driven element that focuses the radiated signal in the forward direction. (See Yagi)
discharge - To extract energy from a battery or cell.
discriminator - (See frequency discriminator)
dish antenna - A highly directional antenna, parabolic in shape, often used at microwave frequencies, that uses reflections to focus radio frequency (RF) signals.
distant station (DX) - (1) On high-frequency (HF) radio, it is normally used to refer to a station on another continent or in an exotic location. (2) To contact a distant station. (3) (Archaic) Distant Station Century Club (DXCC) - An American Radio Relay League (ARRL) award for verified contacts with 100 countries or more.
distant station expedition (DXpedition) - Radio expedition to remote, unusual, and rare locations.
distant station operator (DXer) - An amateur radio operator who actively pursues contacting distant and rare amateur radio stations. The term is also applied to short wave listeners.
distress call - A transmission that signals a life-threatening situation. Most commonly referred to as an SOS or mayday call. (See SOS and mayday)
distress frequency - A frequency or channel specified for use in distress calling. The radiotelephone distress frequencies are 2.182 megahertz (MHz) and 156.8 megahertz (MHz). The survival craft and maritime distress frequency is 243 megahertz. The general aviation distress frequency is 121.5 megahertz.
District - (Archaic) An American Radio Relay League (ARRL) organizational unit in the 1920s just below the division level and administered by a District Supervisor.
District Emergency Coordinator (DEC) - An appointee of the American Radio Relay League (ARRL) who supervises the efforts of local Emergency Coordinators in a defined district.
DominoEX - A digital mode that uses a variant of multi-frequency-shift keying (MFSK) known as incremental frequency keying (IFK) for transmission of information. It works by sending short transmissions of 18 different tones, called symbols, one at a time, each carrying four bits of data. DominoEX is twice as fast as phase shift keying version 31 (PSK31), as well as more sensitive. It was designed by Murray Greenman ZL1BPU and means Domino from scratch. (See frequency-shift keying)
dope - To add an impurity to a semiconductor to produce a desired electrical characteristic. An N-type material is created if adding the impurity results in more electrons being available to flow as current. A P-type material results of fewer electrons are available.
Doppler shift - The change in frequency of a wave, or other periodic event, for an observer moving relative to its source or a source moving relative to an observer. It was named for the Austrian physicist Christian Doppler, who proposed it in 1842 in Prague. Also known as Doppler effect.
double-extended Zepp antenna - A 1-1/4 wavelength long dipole. It provides about 3 decibels (dB) gain over a half wavelength dipole by narrowing the main beam perpendicular to the dipole wires. Zepp stands for Zeppelin. (See Zepp antenna)
double-bazooka antenna - A dipole antenna that uses two quarter-wavelength coaxial cable stubs as part of the dipole wires. The stubs provide some small standing-wave ratio (SWR) bandwidth improvement.
double-pole, double-throw (DPDT) - A switch that has six contacts. The DPDT switch has two center contacts which can be connected to one of two other contacts.
double-pole, single-throw (DPST) - A switch that connects two contacts to another set of contacts. A DPST switch turns two circuits on or off at the same time.
double-bazooka - An extremely broad-banded half-wave antenna that can operate efficiently across an entire amateur radio band with little change to the standing-wave ratio (SWR). The design eliminates the need for antenna matching baluns and can be fed directly with 50 Ohm coaxial cable.
double sideband (DSB) - In conventional amplitude modulation (AM) transmission, the carrier and both sidebands are present, sometimes called double-sideband amplitude modulation (DSB-AM). In some forms of amplitude modulation (AM), the carrier may be removed, producing double sideband with suppressed carrier (DSB-SC). An example is the stereophonic difference (L-R) information transmitted in stereo frequency modulation (FM) broadcasting on a 38 kilohertz (kHz) subcarrier.
doubling - (Repeater Term) On a repeater, if two stations transmit simultaneously, the signals mix in the repeater's receiver and results in a raspy signal. Frequency modulation (FM) has a characteristic whereby the stronger signal captures and overrides the weaker one.
downlink - Transmitted signals or the range of frequencies that a repeater or satellite transmits to a user. It is the opposite of uplink. (See uplink)
drain - (See transistor)
drift - Slow, gradual change in the frequency of a transmitter or receiver.
driven element - The part of an antenna that connects directly to the feed line. (See Yagi)
driver - The amplifier stage immediately preceding a power amplifier in a transmitter.
dropping out - (Repeater Term) A repeater requires a minimum signal in order to transmit so when a signal does not have enough strength to keep the repeater transmitting, it drops out.
dry contacts - A switch or relay whose contacts are isolated from both power and ground.
dual-band antenna - An antenna designed for use on two different amateur radio bands.
dual-tone multi-frequency (DTMF) - Used to transmit/receive numeric information such as a touch-tone phone number, a PIN, and remote radio control commands.
dual bander - The term can be applied to either an antenna or transceiver, usually a combination of 2 meters (m) and 70 centimeters (cm).
dualwatch - To receive two signals simultaneously.
dummy antenna- A station accessory that allows testing or adjusting transmitting equipment without sending a signal out over the air. It is a device that allows a dual-band radio to use a single dual-band antenna. A non-radiating 50 Ohm load connected to a transmitter replaces an antenna for testing purposes. Also known as dummy load and phantom antenna.
dummy load - (See dummy antenna)
dupe - A duplicate contact, such as happens in radio contesting.
duplex - (1) (Repeater Term) A mode of operation in which the transmit and receive frequencies are different. (2) A mode of communication in which a user transmits on one frequency and receives on another frequency simultaneously. This is in contrast to half-duplex transmission in which the user transmits at one time and receives at another time. Also known as full duplex. (See half-duplex and simplex)
duplexer - (Repeater Term) A device that allows the transmitter and receiver to share a single antenna.
duty cycle - A measure as a percent of the amount of time a transmitter is operating at full output power during a single transmission. A lower duty cycle means less radio frequency (RF) radiation exposure for the same peak envelope power (PEP) output. (See duty factor)
duty factor - A measure as a fraction of the amount of time a transmitter is operating at full output power during a single transmission. A lower duty factor means less radio frequency (RF) radiation exposure for the same peak envelope power (PEP) output. (See duty cycle)
DX Century Club (DXCC) - A sponsored club of the American Radio Relay League (ARRL) by which membership is allowed only after showing proof of having made contact with at least 100 different countries.
dynamic host configuration protocol (DCHP) - A protocol by which a machine can obtain an Internet Protocol (IP) number and other network configuration information from a server on a local network.
dynamic microphone - A microphone element in which the diaphragm is tied to a coil of wire surrounding a permanent magnet. Also abbreviated dynamic mic.
dynamic range - The ratio of the strongest to the weakest signal that a system can respond to within a specified level of distortion.
dyne (dyn) - A unit of force that, acting on a mass of one gram, increases its velocity by one centimeter (cm) per second every second along the direction that it acts. (See newton)


To the top!   E

E-layer - The region of the ionosphere found approximately 55 to 90 miles above Earth, the second lowest ionospheric layer. This region fades away a few hours after sunset. The main impact of the E-layer on radio propagation is to absorb energy from signals passing through it. Although sporadic, E propagation makes possible distant communication on frequencies above 30 megahertz (MHz). Also known as E-region.
e-mail - (See email)
E-skip - Sporadic E-layer ionospheric propagation.
earth-moon-earth (EME) - A method of communicating with other stations by reflecting radio signals off the Moon's surface. Also known as moonbounce.
earth ground - (See ground)
earth grounding system - A set of usually buried conductors often arranged radially and in combination with metal ground rods driven into the soil. Designed to provide a low-resistance ground connection for systems or equipment. (See ground)
earth station - An amateur radio station located on, or within 50 km of, the Earth's surface and intended for communication with space stations or with other Earth stations by means of one or more other objects in space.
Echo - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter E. Used in radio communication, particularly when spelling out a call sign.
EchoLink - A softward program that uses a network protocol called voice over Internet Protocol (VoIP) that allows worldwide connections to be made between stations, from computer to station, or from computer to computer. There are more than 100,000 registered users in more than 125 countries worldwide.
Edison effect - (Archaic) Thomas A. Edison discovered the electron flow from a glowing cathode to an anode in an evacuated glass bulb that was called the Edison-effect. This led to the development of the vacuum tube.
effective radiated power (ERP) - Station output, including the transmitter, antenna, and everything in between, when considering transmitter power and system gains and losses.
egress - The leakage of radio-frequency interference (RFI) and audio-frequency interference (AFI) out of the vehicle's various electrical circuits into some other electrical circuit where it is unwanted.
Electronic Industries Association 232 (EIA232) A standard of the Electronic Industries Association (EIA) defining a serial computer connection arrangement. The standard specifies pin-outs for a 25-pin (DB25) and 9-pin (DB9) subset, signal relations, voltage levels, and maximum cable lengths. The EIA changed the name from RS-232 to EIA232 and some signal lines were renamed and various new ones were defined, including a shield conductor. The EIA ceased operation in February of 2011 and their standards are now managed by the Electronic Components Industry Association (ECIA).
electric field - An electric field exists in a region of space if an electrically charged object placed in the region is subjected to an electrical force; it is an invisible force of nature.
electrical current A flow of electric charge. Electric charge flows when there is voltage present across a conductor. It is the opposite of current, or conventional current. (See current)
electrically erasable programmable read-only memory (EEPROM) - A type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, for example, calibration tables or device configuration.
electrically programmable read-only memory (EPROM) - A type of non-volatile memory chip that retains its data when its power supply is switched off.
electrode - (1) An electrical conductor used to make contact with a nonmetallic part of a circuit, such as a semiconductor, an electrolyte, or a vacuum. (See anode and cathode) (2) An electrical contact or connection point.
electrolysis - An electrochemical process in which a current passed through a solution between electrodes of different metals results in the transfer of molecules of one material into the solution and then often to the other electrode. This is the process by which electroplating is performed. It also can happen if two dissimilar metals are in contact in the presence of water.
electrolytic capacitor - A high-capacitance capacitor used in power supply filters and other applications. Unlike many capacitors, the positive terminal is marked and must be connected to the positive terminal. (See electrolyte)
electromagnetic force - The fundamental force that is associated with electric and magnetic fields and is responsible for atomic structure, chemical reactions, the attractive and repulsive forces associated with electrical charge and magnetism, and all other electromagnetic phenomena. It is carried by the photon.
electromagnetic interference (EMI) - A disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. Also known as radio-frequency interference (RFI).
electromagnetic pulse (EMP) - An extremely high-energy magnetic field, such as the current flow caused by a lightning strike or nuclear explosion.
electromagnetic spectrum - A graphic representation of a range of frequencies from 60 hertz (Hz) electrical current, through radio waves, visible light, ultra violet light, X-rays, and Gamma rays.
electromagnetic wave - The electric field and magnetic field moving through space or a transmission line.
electrolyte - A liquid or semi-liquid paste material used in high-capacitance capacitors.
electromagnetic interference sleeves (EMI sleeves) - Ferrite beads or tubes slipped over wires to insert inductance with the intent of attenuating unwanted high-frequency signals. They are usually enclosed in a snap-on plastic cover so they can be easily placed over existing wiring without the need to splice into the wiring and act like chokes. When properly applied, reduce or eliminate radio-frequency interference (RFI) ingress and egress. Also called split beads.
electromotive force (emf) - The energy per unit of charge, measured in volts, that pushes a current through a circuit.
electron - A negatively-charged particle, normally found in an area surrounding the nucleus of an atom. Moving electrons make up an electrical current.
electron tube - (Archaic) (See vacuum tube)
electronic-message unit (EMU) - (Archaic) Used in combination with an existing radio set, it allowed secure messages to be sent between Special Operations units of the British Army and was usually contained in a special slot but could also be used stand-alone, powered by a simple 9V-volt battery. It had a 20-button numeric key pad and used two digits to represent letters and other characters. Also known as digital-message device.
Electronic Code of Federal Regulations (e-FCR) - A regularly updated, editorial compilation of Code of Federal Regulations (CFR) material and Federal Register amendments produced by the National Archives and Records Administration's Office of the Federal Register (OFR) and the Government Printing Office (GPO).
Electronic Components Industry Association (ECIA) - The organization that manages the maintenance of all existing interconnect, passive, and electro-mechanical (IP&E) standards for the Electronic Industries Association (EIA) as of February 2011.
electronic current - In electronic circuits, the reference current directions are often chosen so that all currents are toward ground. This often matches conventional current direction, because in many circuits the power supply voltage is positive with respect to ground. It is the opposite of conventional current. (See current)
Electronic Industries Association (EIA) - (Archaic) An organization that assigned maintenance of all existing interconnect, passive, electro-mechanical (IP&E) standards. The EIA ceased operation in February of 2011 and their standards are now managed by the Electronic Components Industry Association (ECIA).
electronic keyer - (See keyer)
Electronic QSL Card Centre (eQSL.cc) - A website for sending and receiving QSL cards online.
electronic mail (email) - A method of exchanging digital messages from an author to one or more recipients. Also called e-mail.
Electronics Illustrated Magazine - (Archaic) An American magazine started in May 1958 by Fawcett Publications, the publishers of Mechanix Illustrated. The magazine was published monthly from 1959 to 1961 then bi-monthly until November 1972.
element - (1) An arrangement of metallic conductors of an antenna, electrically connected to a receiver, transmitter, or transceiver, to radiate or receive radio waves. (2) A pool of questions for an amateur radio exam. (3) A dot or dash in Morse code (CW).
elephant - (Repeater Term) A repeater that receives further than it can transmit.
elevation - (1) The angle that an antenna, often a beam antenna, makes with the horizon. (2) How high an object or place or station is above sea level. (See above sea level)
elevation pattern - A graph showing how an antenna radiates and receives at different vertical angles. (See radiation pattern)
eleven meters - (CW Term) Currently the Citizen's Band (CB), a United States radio service having 40 assigned channels that once was an amateur radio band. (See Citizen's Band)
elmer - A mentor or teacher who is an experienced operator who tutors newer operators. The term first appeared in QST Magazine in a March 1971 "How's DX" column by Rod Newkirk.
emergency - A situation where there is a danger to lives or property.
Emergency Alert System (EAS) - A system where at first an alert tone is transmitted, followed by specific instructions regarding the receivable frequency in case of a national or local emergency. The EAS superseded the Emergency Broadcast System (EBS) in 1994.
Emergency Broadcast System (EBS) - (Archaic) A system where at first an alert tone is transmitted, followed by specific instructions regarding the receivable frequency in case of a national or local emergency. Superseded by the Emergency Alert System (EAS) in 1994. (See Emergency Alert System)
emergency communications (emcomm) - In times of crisis and natural disasters, amateur radio is often used as a means of emergency communication when wireline, cell phones, and other conventional means of communication fail.
Emergency Coordinator (EC) - An appointee of the American Radio Relay League (ARRL) who prepares for, and engages in management of communications needs in disasters.
Emergency Operation Center (EOC) - A central command and control facility responsible for carrying out the principles of emergency preparedness and emergency management (disaster management functions at a strategic level in an emergency situation) and ensuring the continuity of operation of a company, political subdivision, or other organization.
emergency traffic - Messages with life and death urgency or requests for medical help and supplies that leave an area shortly after an emergency.
emission - Transmission of a signal from an amateur radio station.
emission mode - (See mode)
emission privilege - Permission to use a particular emission type, such as Morse code (CW) or voice.
emission types - The different modes authorized for use on the amateur radio bands. Examples are frequency modulation (FM), Morse code (CW), radioteletype (RTTY), and single sideband (SSB).
emitter - (See transistor)
enameled copper wire - Wire in which the insulation is a thin coating of enamel. Often used for inductors, transformers, or electromagnets.
encoding - Changing the form of a signal into one suitable for storage or transmission. (See decoding)
encryption - The transmitting of a cryptic form so that only certain people understand what has been sent. (See decryption)
energy - The ability to do work or the ability to exert a force to move an object.
envelope - The outline of a radio frequency (RF) signal formed by the peaks of the individual RF cycles.
ether - An old theory for the medium once believed to conduct radio waves. The existence of the ionosphere was first discovered by the English physicist, Appelton in 1924.
exalted-carrier reception - A reception technique where the carrier produced by a receiver's beat frequency oscillator (BFO) circuit or product detector is used to replace the carrier of an amplitude modulation (AM) signal for better reception.
exalted-carrier single sideband (ECSS) - A method of using single sideband to tune amplitude modulation (AM) broadcasts. Also known as ECSSB.
exchange - The passing of all necessary information between two stations during a contact.
exciter - The oscillator and modulator in large transmitters.
Experimenters' Section (X Section) - (Archaic) A QST magazine department in the 1920s.
extended binary coded decimal interchange code (EBCDIC) - An 8-bit character encoding used mainly on International Business Machines Corporation (IBM) mainframes and their midrange computer operating systems.
extended-coverage receiver - A receiver that tunes frequencies from around 30 megahertz (MHz) to several hundred megahertz or into the gigahertz (GHz) range. Also known as wide-range receiver.
extremely high frequency (EHF) - A frequency in the range of 300 to 30,000 megahertz (mHz) or 30 to 300 gigahertz (GHz).
extremely low frequency (ELF) - Radio waves of electromagnetic radiation with frequencies from 3 to 300 hertz (Hz), and corresponding wavelengths from 100,000 to 1000 kilometers (km).
eyeball - A face-to-face meeting between two ham radio operators. Also known as eyeball QSO.
ezine - A magazine on the world wid web (WWW), usually in Portable Document Format (PDF). Also called e-zine. (See Portable Document Format)


To the top!   F

F-layer - The region of the ionosphere found approximately 90 to 400 miles above Earth and which is responsible for most long distance propagation on frequencies below 30 megahertz (MHz). The F-layer refracts radio waves and returns them to Earth. During the daytime, especially in the summer, solar heating can cause the F-layer to split into two separate layers, the F1-layer and the F2-layer. Also known as F-region.
facsimile (fax) - A digital mode for transmitting text and images.
fading - Signal reduction due to atmospherics. Also known as freak.
Fahnstock clip - (Archaic) A metal spring clip shaped like the letter R with a small loop at the center. Often used for the connection of antenna and ground leads in early radio equipment.
false signals - (See deceptive signals)
Family Radio Service (FRS) - A walkie-talkie radio system authorized in the United States since 1996 and intended for short-range communication by family members. Short-range handheld radios can be used in this system without a license. The service uses channelized frequencies around 462 and 467 megahertz (MHz) in the ultra-high frequency (UHF) band. It does not suffer the interference effects found on Citizen's Band (CB) at 27 megahertz (MHz), or the 49 megahertz (MHz) band also used by cordless phones, toys, and baby monitors. FRS uses frequency modulation (FM) instead of amplitude modulation (AM).
fan antenna - (Archaic) A popular antenna in the 1920s, it is multiple vertical wires that spread out as they are strung up from ground level, fed at the common point at the bottom, insulated and supported by a horizontal wire at the top.
far field of an antenna - That region of the electromagnetic field surrounding an antenna where the field strength as a function of angle (the antenna pattern) is essentially independent of the distance from the antenna. In this region, also known as the free-space region, the field has a predominantly plane-wave character, locally uniform distributions of electric field strength, and magnetic field strength are in a plane perpendicular to the direction of propagation.
farad (F) - The basic unit of capacitance, it is the charge in coulombs that a capacitor will accept for the potential across it to change 1 volt. The term was coined by Josiah Latimer Clark in the year 1861 in honor of Michael Faraday. (See coulomb)
Farnsworth - (CW Term) A method of sending Morse code (CW) characters when learning. Example characters are sent at 13 words per minute but the spacing is adjusted so that the overall code speed is 5 words per minute.
fast-scan television (FSTV) - (See amateur television)
fast blow - (See fuse)
fast Fourier transform (FFT) - A digital technique to interchange frequency and time domain data. Named after the first man to work on the technique, Joseph Fourier.
Federal Communications Commission (FCC) - The governmental body that regulates wireless communications in the United States, including amateur radio.
Federal Radio Commission (FRC) - (Archaic) The precursor to the Federal Communications Commission (FCC) created by the Radio Act of 1927.
Federal Registration Number (FRN) - An identification number assigned to an individual by the Federal Communications Commission (FCC) to use when performing license modification or renewal.
feed impedance - The resistance and sometimes reactance as seen at the connection point of an antenna.
feed-line loss - (See transmission-line loss)
feed line - (See transmission line)
feed point - The part of an antenna at which connections are made. The connections are usually to a transmission line that runs from the antenna to the radio equipment.
feed point impedance - The ratio of radio frequency (RF) voltage to current at the feed point of an antenna.
ferrite - A ceramic material with magnetic properties used in inductors. Ferrite is often formed into beads or cores so that it may be placed on cables, forming an electronic radio frequency (RF) choke.
fiber optics - The field of applied science and engineering concerned with the design and application of optical fibers. (See optical fiber)
Field Day - An annual American Radio Relay League (ARRL) sponsored event in which temporary amateur radio stations are set up, usually in a public place, to communicate with as many stations as possible.
field-effect transistor (FET) - A transistor that uses an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material. An FET has three electrodes, a gate, a drain, and a source. (See transistor)
field-strength meter - A test instrument used to show the presence of radio frequency (RF) energy and the relative strength of the RF field.
filter - A circuit or device that will allow some signals to pass through it but will greatly reduce the strength of others. An active filter uses amplifier circuits or components. A passive filter is constructed entirely from resistors, capacitors, and inductors. A digital filter performs the filtering functions on digital data.
final - (1) The final transistor(s), or in the early days, vacuum tubes, in an amplifier. (2) The last transmission in a contact before singing off.
fire bottle - (Archaic) (See vacuum tube)
firmware - Operating instructions for microprocessors that are stored in non-volatile memory. It remains even when power is turned off.
First Class CW Operators Club (FOC) - A club in the United Kingdom that promotes good Morse code (CW) operating, activity, friendship, and socializing by way of its worldwide membership of approximately 500.
fist - (1) (CW Term) Early spark transmitters showered the operator with sparks so Marconi's key lever was lengthened and the padded end was beaten with the fist of the operator to send dots and dashes. (2) (CW Term) A Morse code (CW) operator's reference to another operator's keying characteristic.
FISTS - A club founded by Geo Longden G3ZQS in 1987 to promote the use of Morse code (CW) transmission mode. FISTS refers to an individual's sending style to send Morse code (CW) dots and dashes.
fixed resistor - An electronic component specifically designed to oppose or control current through a circuit. The resistance value of a fixed resistor cannot be changed or adjusted.
fixed station - A station that always operates from a constant, specified land location.
flat topping - Over-modulating so as to distort a waveform.
flutter - The rapid variation in the signal strength of a station, usually due to propagation variations.
folded dipole antenna - A dipole antenna utilizes two parallel and end connected half-wavelength wires. The feed line connects to only one of the wires. Because of the antenna's current distribution, the feed impedance is increased, typically by a factor of four. This antenna is used to provide a low standing-wave ratio (SWR) match to an open wire feed line at the dipole's resonant frequency.
for example (e.g.) - An abbreviation for the Latin phrase exempli gratia. Form 605 - An Federal Communications Commission (FCC) form that serves as the application for the amateur radio license, or for modifications to an existing license.
formal traffic - (See traffic)
forward error correction (FEC) - A mode that sends all data twice with an interleaving technique to reduce errors from impulse noise and static crashes.
forward power - Power in a transmission line traveling from a transmitter toward a load or antenna.
fox hunt - (See amateur radio direction finding)
Foxtrot - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter F. Used in radio communication, particularly when spelling out a call sign.
freak - (See fading)
free-space region - (See far field of an antenna)
frequency - The number of complete cycles of an alternating current that occur per second. The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency.
frequency-division multiplexing (FDM) - A technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency sub-bands, each of which is used to carry a separate signal. This allows a single transmission medium, such as a cable or optical fiber, to be shared by many signals. An example of a system using FDM is cable television, in which many television channels are carried simultaneously on a single cable.
frequency-modulation capture effect - The ability of a frequency modulation (FM) signal that is stronger than others on the same channel to completely take over the channel to the exclusion of the weaker signals.
frequency bands - A group of frequencies where amateur radio communications are authorized. (See band)
frequency coordination - (Repeater Term) Allocating repeater input and output frequencies to minimize interference between repeaters and to other users of the band.
frequency coordinator - (Repeater Term) An elected individual or group that recommends repeater frequencies to reduce or eliminate interference between repeaters operating on or near the same frequency in the same geographical area.
frequency counter - A test instrument that measures and displays the frequency of signals or the repetition rate of pulses.
frequency discriminator - A circuit that delivers an output voltage that is proportional to the deviations of a signal from a predetermined frequency value. It is a type of detector used in some frequency modulation (FM) receivers.
frequency-shift keying (FSK) - A form of digital frequency modulation used especially in facsimile, data, and telegraph transmission in which the modulating wave shifts transmitter frequency to represent the bits of digital data.
frequency modulated phone - The type of frequency modulation (FM) signals used to communicate by voice (phone) over most repeaters. FM is a method of combining a radio frequency (RF) carrier with an information signal, such as voice. The voice information, or data, changes the RF carrier frequency in the modulation process. FM broadcast stations and most professional communications (fire, police, taxi) use FM. FM phone is the most popular amateur mode on very-high frequency (VHF) and other frequency bands.
frequency modulation (FM) - The process of adding information to a radio frequency (RF) signal or carrier by varying its frequency.
frequency privilege - The permission to use a particular group of frequencies.
frequency response - Radio spectrum frequency response can refer to measurements of antenna systems, coaxial cable, twisted-pair cable, video switching equipment, and wireless communications devices.
frequency synthesis - A tuning method in transmitters and receivers that uses a few piezoelectric crystals to generate a wide range of frequencies.
Friendship Award (FA) - (Archaic) An award given by the American Radio Relay League (ARRL) whose purpose was to encourage friendly contact between radio amateurs (hams) and thereby discover new friends through personal communication with others. It was discontinued in 2004.
front-end overload - Interference to a receiver caused by a strong signal that overpowers the receiver radio frequency (RF) amplifier, or front end. Front-end overload results in distortion of the desired signal and the generation of unwanted spurious signals within the receiver. (See receiver overload)
front-to-back ratio (F/B) - The ratio of an antenna's gain in the forward direction to that in the opposite direction. (See front-to-side ratio)
front-to-side ratio (F/S) - The ratio of an antenna's gain in the forward direction to that at right angles to the forward direction. (See front-to-back ratio)
full break-in - (CW Term) Allows a station to break into the communication without waiting for the transmitting station to finish.
full duplex - (See duplex)
full gallon - (See gallon)
full quieting - (Repeater Term) A phenomenon of frequency modulation (FM) transmissions where the incoming signal is sufficient to engage the receiver limiters, thus eliminating the noise due to amplitude fluctuations.
full-wave bridge rectifier - A circuit that converts alternating current (AC) to direct current (DC) and that uses four diodes that do not require a center-tapped transformer. (See tap)
fundamental - The lowest frequency to which a harmonic is related. (See harmonic)
fundamental overload - Radio frequency (RF) interference caused when a strong RF signal exceeds a receiver's ability to reject it.
fuse - A thin metal strip mounted in a holder. When too much current passes through the fuse, the metal strip melts and opens the circuit. Fuses are rated in amperes and voltage and time to activate such as fast blow or slow blow.


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G5RV antenna - A simple 20-meter (m) dipole antenna that is 102 feet long and uses a short length of open-wire transmission line to provide a match to 50-ohm coaxial cable. It is also popular as a multi-band antenna but suffers high loss in the 50-Ohm cable on some bands. It was invented in 1946 by Louis Varney G5RV.
gain - (1) An increase in the effective power radiated by an antenna in a certain desired or forward direction, or an increase in received signal strength from a certain direction. This is at the expense of power radiated in, or signal strength received from, other directions. (2) The ability of a component, circuit, or piece of equipment to amplify a signal.
gallium arsenide (GaAs) - A compound of the elements gallium and arsenic. It is a high-speed semiconductor and is used in the manufacture of devices such as microwave frequency integrated circuits, monolithic microwave integrated circuits, infrared light-emitting diodes, laser diodes, solar cells, and optical windows.
gallon - (1) Fifteen-hundred watts peak envelope power (PEP). (2) One thousand watts Morse code (CW). (3) A slang word for transmitter output power.
gamma match - A kind of impedance matching arrangement in which a rod is used to tap into one side of a dipole-antenna element to allow attachment of coaxial cable to the appropriate impedance point of the antenna. Often used in directional array antennas such as Yagis. (See tap)
gate - (See transistor)
gateway - (1) A station that serves to connect one network of stations with the Internet or another network of stations. (2) A hardware or software setup that translates between two dissimilar protocols.
gel cell - A small sealed lead-acid rechargeable battery that uses a gel instead of a liquid electrolyte. It is often used as backup power in applications.
general-coverage receiver - A receiver used to listen to a wide range of frequencies. Most general-coverage receivers tune from frequencies below 550 to 1700 kilohertz (kHz), the standard-broadcast amplitude modulation (AM) band, to at least 30 megahertz (MHz). They are capable of operation in several different modes, including amplitude modulation (AM), Morse code (CW), and single sideband (SSB). These frequencies include the shortwave-broadcast bands and the amateur radio bands from 160 to 10 meters (m). (See extended-coverage receiver)
General Certification Rule (GCR) - Most award sponsors allow GCR in lieu of actually wanting to see one's cards and usually means getting the signatures of two witnesses who certify that the holder possesses the cards and that the information stated on the application is correct.
General Class - The most common level of amateur radio license, it allows for cross-country and worldwide communication. In addition to the Technician privileges, General Class operators are authorized to operate on any frequency in the 160-, 30-, 17-, 12-, and 10-meter (m) bands. They may also use significant segments of the 80-, 40-, 20-, and 15-meter bands. The General Class license does not require familiarity with Morse code (CW).
General Conference on Weights and Measures (CGPM) - The senior of the three Inter-governmental organizations established in 1875 under the terms of the Metre Convention to represent the interests of member states. The treaty, which also set up two further bodies, the International Committee for Weights and Measures (CIPM) and the International Bureau of Weights and Measures (BIPM), was drawn up to coordinate international metrology and to coordinate the development of the metric system.
General Mobile Radio Service (GMRS) - A licensed North American land-mobile frequency modulation (FM) ultra-high frequency (UHF) radio service designed for short-distance two-way communication for family use within a city or region. It requires a license in United States but can be used license-free in Canada.
generator - A device that uses a motor to convert mechanical energy into alternating current (AC) or direct current (DC) electrical energy.
geographical codes (geocodes) - A code to identify a point or area on the surface of the Earth. (See country code)
Get on the Air (GOTA) - A category in the annual American Radio Relay League (ARRL) Field Day event. The GOTA station may be operated by a Technician and generally inactive amateur radio operators under their existing operating privileges, or under the direction of a control operator with appropriate privileges, as necessary. Non-licensed persons may participate under the direct supervision of an appropriate control operator.
giga- (G-) - One billion, the metric prefix for 109, or times 1,000,000,000.
gigahertz (GHz) - One billion (1,000,000,000) hertz (Hz).
Global Positioning System (GPS) - An accurate worldwide navigational and surveying facility based on the reception of signals from an array of orbiting satellites.
go-kit - A pre-packaged collection of equipment or supplies kept at hand to allow a radio operator to quickly report where needed in time of need.
go ahead - (See over)
>Golay-teleprinting over radio (G-TOR) - A digital frequency-shift keying mode that offers faster data transfer rate than PACTOR (Latin for the mediator). G-TOR is a trademark of Kantronics, Inc. and was devised by M. Golay. It is rarely used by amateur radio operators.
Golf - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter G. Used in radio communication, particularly when spelling out a call sign.
Government Printing Office (GFO) - An agency of the legislative branch of the United States federal government, the office prints documents produced by and for the federal government, including the Supreme Court, the Congress, the Executive Office of the President, executive departments, and independent agencies.
grace period - The time Federal Communications Commission (FCC) allows following the expiration of an amateur radio license to renew that license without having to retake an examination. Those who hold an expired license may not operate an amateur radio station until the license is reinstated.
grant - Authorization given by the Federal Communications Commission (FCC).
gray line - A band around the Earth that separates daylight from darkness. It is a transition region between day and night. One of the many types of propagation paths. Also known as grey line.
great-circle route - The shortest path by radio between any two points on Earth.
green stamp - A United States dollar bill sent along with a QSL card instead of an International Reply Coupon (IRC) to offset postage costs of the return card.
Greenwich Mean Time (GMT) - (See Universal Time Coordinate)
grid-dip meter - (See dip meter)
grid square - A locator in the Maidenhead Locator System, named after the town outside London where it was first conceived by a meeting of European very-high frequency (VHF) managers in 1980. It is a shorthand means of describing the operator's general location anywhere on the Earth in a manner that is easy to communicate over the air. The entire globe is divided into grid rectangles. Each subsquare is designated by the addition of two letters after the grid square and measure 2.5 minutes latitude by 5 minutes longitude, roughly corresponding to 3 by 4 miles in the continental United States. For example, Meadow Hills, Aurora, Colorado 80014 is located in grid DM79op.
ground - To connect an electrical device with the earth, it is a common zero-voltage reference point. Grounds fulfill three distinct functions: (a) A safety ground to protect from a shock hazard if one of the mains or high voltage power supply wires contacts the chassis due to some kind of fault. (b) A lightning ground for lightning protection. (c) a radio frequency (RF) ground, required only for certain types of antennas that require current flow to ground to complete the antenna circuit. Also known as earth ground or ground potential.
ground-fault interrupter (GFI) - A breaker that opens a circuit when an imbalance of current flow is detected between the hot and neutral wires of an alternating current (AC) sending current flowing along an unintended path, possibly through water or through a person. Also known as ground-fault circuit interrupter (GFCI) (See circuit breaker)
ground-plane antenna - (1) An omni-directional vertical antenna built with the central radiating element one-quarter-wavelength long and several radials extending horizontally from the base. The radials are slightly longer than one-quarter wave, and may droop toward the ground. Groud-plane antennas require a ground plane in order to operate properly. (2) A flat or nearly flat horizontal conducting surface that acts as an electrical mirror and serves as part of an antenna, to reflect the radio waves from the other antenna elements. The plane does not necessarily have to be connected to ground. Ground planes are particularly used with monopole antennas.
ground connection - A connection made to the earth for electrical safety. This connection can be made inside to a metal cold-water pipe or outside to a ground rod.
ground potential - (See ground)
ground rod - A copper or copper-clad steel rod that is driven into the earth to create a ground to electrical equipment. A heavy copper wire from the ham shack connects all station equipment to the ground rod.
ground-wave propagation - The method by which radio waves travel along the Earth's surface, even beyond the horizon.
ground wave - An electrical wave traveling directly from the transmitter to the receiving station without bouncing off the ionosphere. Also known as surface wave.
group frequency method - (Archaic) Using a tuning capacitor in the headphone circuit to select a specific spark tone.
guy rope - A rope used to support a tower or mast.
guy wire - A wire used to support a tower or mast.


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half-duplex (HDX) - (Repeater Term) A communication mode in which a radio transmits and receives on two different frequencies but performs only one of these operations at any given time. (See duplex and full duplex).
half-wave dipole antenna - A basic half-λ is a dipole antenna approximately a half wavelength long, usually fed by connections to each side of the center with a ladder-type open feeder. It is often used as an antenna itself, it is also a reference standard for other antennas. It is a popular antenna with amateur radio operators. The λ is a Greek small lambda. (See dipole)
ham - An informal term for an amateur radio operator licensed to operate an amateur radio station. By extension, ham radio refers to amateur radio in general. (See ham radio)
ham-band receiver - A receiver designed to cover only the bands used by amateur radio operators. Usually refers to the bands from 80 to 10 meters (m), sometimes including 160 meters. Also known as ham-bands-only receiver.
ham bands - The Federal Communications Commission (FCC)-authorizes amateur radio bands used in the United States. There are 27 in all with the most popular being the 70-centimeter (cm) and 2-meter (m) amateur radio bands.
ham radio - The use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication. A synonym is amateur radio. In the United Kingdom, the term ham radio was deprecated in the 1970s because amateurs were self-conscious and a bit offended by the image of them created by Tony Hancock in his famous Radio Ham episode. In the United States, there used to be a magazine called Ham Radio but they had never heard of Tony Hancock so they were much less stuffy about it. The term ham radio started as a pejorative, mocking amateur radio operators with a 19th century term for being bad at something, like ham actor or ham-handed. It had already been used for bad wired telegraph operators, who (like a ham-fisted boxer) presumably was seen with hands as clumsy as if they were hams. Subsequently, it was coopted by the community itself, which adopted it as a welcome moniker. Other, more entertaining explanations have grown up throughout the years, but are apocryphal. Amateurs increasingly adopted the word ham to describe their hobby and themselves after 1919. (See amateur radio)
Ham Radio Magazine - (Archaic) A monthly amateur radio enthusiast magazine published in the United States from February 1968 to June 1990. At the 1990 Dayton Hamvention it was announced that Ham Radio had been sold to the publishers of CQ Amateur Radio. The June 1990 issue was the 268th and final issue published where subscribers were told of the sale and that they would receive CQ in the future.
hamfest - An informal flea market for a scheduled gathering of amateur radio operators. Often includes presentations, workshops, exam sessions, and sellers of computer equipment, electronic equipment, ham radio equipment, and all the accessories.
hand-held transceiver - (Repeater Term) A small, lightweight portable transceiver that operates in the 70 centimeter (cm) and 2 meter (m) amateur radio bands. Self-contained hand-held radios include an antenna and battery and transmit at low power.
Handie-Talkie - A hand-held radio used in lieu of a walkie-talkie to distinguish licensed amateur radio operators from CBers. It is a Motorola trademark.
Handy's Handbook - (Archaic) The first edition of The Radio Amateur's Handbook, edited by the American Radio Relay League (ARRL) Communications Department Manager F. E. Handy and published in 1926. It was commonly referred to as Handy's Handbook in the late 1920s.
handy talky - Transceivers that operate in the 70-centimeter (cm) and 2-meter (m) amateur radio bands. (See hand-held)
hang time - (Repeater Term) The short period following a transmission that allows others who want to access the repeater a chance to do so. A courtesy tone sounds when the repeater is ready to accept another transmission.
harmful interference - Malicious nterference that seriously degrades, obstructs, or repeatedly interrupts a radio communication service operating in accordance with the Radio Regulations. (See malicious interference)
harmonic - (1) A multiple of a fundamental frequency. These signals from a transmitter or oscillator occur on whole-number multiples, such as 2×, 3×, 4×, etc., of the desired operating frequency. (2) Slang for the child of a ham.
header - The first part of a digital message containing routing and control information about the message. (See preamble)
headphones - A pair of speakers held against or inserted into each ear. A headset or boomset combines headphones with a microphone for additional convenience.
headset - (See headphones)
health and welfare traffic - Messages about the well being of individuals in a disaster area. Such messages must wait for emergency and priority traffic to clear, and results in advisories to those outside the disaster area awaiting news from family and friends.
hecto- (h-) - One hundred, or the metric prefix for 102, or times 100. Also known as hecta- (h-).
height above average terrain (HAAT) - A measure of how high an antenna site is above the surrounding landscape. It is officially measured in meters (m), even by the Federal Communications Commission (FCC) in the United States because Canada and Mexico, both of which use metric, have extensive border zones where international stations can be received on either side of the international boundaries.
height above sea level (HASL) - A measurement of how high an antenna site is above sea level, often used for mountaintop stations such as repeaters and portable operations to describe their elevation. Measured in either feet (ft) or meters (m) depending on the country.
Hellschreiber (Hell) - light, bright, or clear writer - A digital mode for sending and receiving text using facsimile technology. Named for the inventor, a German engineer named Rudolph Hell, who patented this early method of facsimile sending in 1929. Also known as Feldhellschreiber and Feld-Hell
henry (H) - The International System of Units (SI) derived unit of inductance named in honor of Joseph Henry, the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday in England.
hertz (Hz) - The International System of Units (SI) unit of frequency defined as the number of cycles per second of a periodic phenomenon. One hertz equals one complete cycle per second. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications. It is named for Heinrich Rudolf Hertz, who was the first to conclusively prove the existence of electromagnetic waves.
heterodyne - Signals at the output of a mixing or modulating process.
hi hi - ha ha - The Morse code (CW) equivalent of a laugh. In Morse code, hi hi sounds like someone chuckling, that is, dot dot dot dot   dot dot. Although used in Morse code, it actually has carried over to phone as well, although absolutely no one knows why someone must say "hi hi" or even spell it out as "aich-eye-aich-eye;" why not just laugh!
high-definition television (HDTV) - When transmitted at two megapixels per frame, HDTV provides about five times as many pixels as standard-definition (SD) television.
high frequency (HF) - The frequency range of 3 to 30 megahertz (MHz). Normally, the 1.8 MHz or 160-meter (m) band is also included. Also known as the decameter band, the decameter wave, and short wave.
high-frequency bands (HF bands) - Amateur radio bands in the region of the radio frequency (RF) spectrum from 3 to 30 megahertz (MHz). There are bands at approximately 80, 30, 20, 17, 15, 12 and 10 meters (m) in this region.
high-pass filter (HPF) - An electronic filter that passes high-frequency signals but attenuates or reduces the amplitude of signals with frequencies lower than the cutoff frequency.
high-speed meteor scatter (HSMS) - A software program for meteor scatter communication. (See meteor scatter)
High Speed Multimedia (HSMM) - An American Radio Relay League (ARRL) working group and individual amateur effort as well. Primary to high-speed voice, video, and data transmission on the amateur allocations within the 2.4 gigahertz (GHz) and 5.8 gigahertz (GHz) bands using commonly available WiFi equipment with high-gain directional antennas. Also known as hinternet.
high tension (HT) - Voltage levels over 500 volts.
hinternet - (See high-speed multimedia)
hollow state - (Archaic) A slang term for equipment that uses vacuum tubes.
Home Call Area - Of the 10 Federal Communications Commission (FCC) Regions in the United States, the one in which you resided upon issuance of your amateur radio license. For years, the Federal Communications Commission (FCC) required licensees to change call signs when they moved to a different call area, a requirement that is no longer in effect.
homebrew - Home-built, noncommercial radio equipment.
honeycomb coil - (Archaic) An inductor wound with turns that weave in and out radially so that adjacent windings are never parallel and thus minimizes the distributed capacitance of the coil.
hop - Communication between stations by reflecting the radio waves off of the ionosphere. (See sky-wave propagation)
horizontally polarized antenna - An antenna in which the electric field lines are horizontal. This is generally the case for dipole or Yagi antennas with horizontal elements.
horizontally polarized wave - An electromagnetic wave with its electric lines of force parallel to the ground.
hot-wire ammeter (HWA) - (Archaic) A device for measuring feed-line current and therefore antenna current. It was the common way of specifying radiation (rather than power in watts).
Hotel - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter H. Used in radio communication, particularly when spelling out a call sign.
hyperscan - A very high scanning rate in a scanner receiver. Also known as turboscan.


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iambic - (CW Term) A method of Morse code (CW) keying where the operator holds both paddles at same time and sends alternating dots and dashes.
identification (ID) - The identification of an amateur radio operator that announces the station's call sign every 10 minutes as and at the end of a conversation as specified by Part 97 of the Federal Communications Commission (FCC) Rules and Regulations. Conversations need not come to a halt when one identifies.
image - A false signal produced in a superheterodyne receiver's circuitry.
impedance - The opposition of both the electrical alternating current (AC) and direct current (DC) in a circuit. Impedance includes factors other than resistance, and applies to alternating currents. Ideally, the characteristic impedance of a feed line is the same as the transmitter output impedance and the antenna input impedance.
impedance-matching device - Also called impedance matching unit. (See antenna tuner)
impedance match - To adjust impedances to be equal or the case in which two impedances are equal. The term usually refers to the point at which a feed line is connected to an antenna or to transmitting equipment. If the impedances are different, that is a mismatch. (See mismatch)
impedance transformation - Changing the voltage to the current ratio of a signal in a circuit. It can be done with a transformer or by making use of the transformational property of mismatched transmission lines.
increment steps - The discrete frequency steps tuned by a receiver using frequency synthesis.
incremental frequency keying (IFK) - A shift keying variant of multi-frequency-shift keying (MFSK) used for transmission of information. (See DominoEX and multi-frequency-shift keying)
India - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter I. Used in radio communication, particularly when spelling out a call sign.
indicator - Used to signal status audibly or visually, it is words, letters, or numerals appended to and separated from the call sign during station identification.
indirect frequency modulation (indirect FM) - (See phase modulation)
inductance - A measure of the ability of a coil to store energy in a magnetic field.
inductive reactance - The opposition to current that an inductor creates in an alternating current (AC) circuit. Reactance is measured in Ohms. (See reactance)
inductor - An electrical component, usually composed of a coil of wire wound on a central core. An inductor stores energy in a magnetic field and is usually composed of a coil of wire wound around a central core.
informal traffic - Messages handled informally on behalf of others without the benefit of a preamble. (See traffic and preamble)
information bulletin - A message directed only to amateur operators consisting solely of subject matter of direct interest to the amateur service.
infrared - Having a wavelength just greater than that of the red end of the visible light spectrum but less than that of microwaves. Infrared radiation has a wavelength from about 800 nanometers (n) to 1 milimeter (m), and is emitted particularly by heated objects.
ingress - The absorption of radio-frequence interference (RFI) and audio-frequency interference (AFI( into a vehicle's or radio's electrical circuitry where it is unwanted.
input/output (I/O) - The communication between an information processing system, such as a computer, and the outside world — possibly a human or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it.
input frequency - (Repeater Term) A repeater's receiving frequency. To use a repeater, one transmits on the input frequency and receives on the output frequency.
insulation-displacement connector (IDC) - A connector intended for use on flat ribbon-type cables.
insulator - A material whose internal electric charges do not flow freely, and which therefore does not conduct an electric current under the influence of an electric field.
integrated circuit (IC) - A single structure, such as a chip, containing multiple active devices that perform a function such as an op-amp, a number of logic gates, or a microprocessor.
intensity (I) - The symbol for current in an electric circuit, measured in amperes.
interconnect, passive and electro-mechanical (IP&E) - The non-active components in an electronic system. Interconnects are plugs and sockets. Passive components refer to resistors, capacitors, potentiometers, transformers, and inductors. Electromechanical covers mechanical relays and switches, as well as fans and power supplies.
intermediate - (Archaic) The separator between a called and a calling station's call signs which in the 1920s was proposed to change depending on the countries involved during a contact. Also known as interval sign.
intermediate-frequency shift (IF shift) - A function that electronically shifts intermediate frequency (IF) frequency from a center frequency, usually to eliminate interference.
intermediate frequency (IF) - A frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. The IF is created by mixing the carrier signal with a local oscillator signal in a process called heterodyning, resulting in a signal at the difference or beat frequency. These frequencies are used in superheterodyne radio receivers, in which an incoming signal is shifted to an IF for amplification before final detection is finished. Most of the receiver's gain and selectivity are achieved at the IF stages. (See heterodyne)
intermodulation (intermod) - A problem caused in the receiver of a radio by a nearby transmitter's spurious emissions that may fall on or very near to the receiver's receive frequency. In some cases, a perfectly clean transmitter (i.e., no spurious signals) can produce intermod if it overloads a receiver or if there is some other point for 3rd-order intercept. Intermod, which is close, but not necessarily right on, the receiver's frequency can cause the receiver to become less sensitive. Also known as desense and intermodulation distortion. (See desensitization)
intermodulation distortion (IMD) - (See intermodulation)
International Amateur Radio Permit (IARP) - A document that allows foreign operation within North and South American treaty countries, other than the United States, without the need to obtain a license or permit.
International Amateur Radio Union (IARU) - An association of national amateur radio organizations created to represent amateur radio before the International Telecommunications Union (ITU). (See International Telecommunications Union)
International Civil Aviation Organization (ICAO) - An organization that promotes understanding and security through cooperative aviation regulation.
International Civil Aviation Organization spelling alphabet (ICAO spelling alphabet) - (See North Atlantic Treaty Organization (NATO) phonetic alphabet)
International Bureau of Weights and Measures (BIPM) - An international standards organization, one of three such organizations established to maintain the International System of Units (SI) under the terms of the Metre Convention.
International Committee for Weights and Measures (CIPM) - The eighteen persons from Member States of the Metre Convention appointed by the General Conference on Weights and Measures (CGPM) whose principal task is to ensure world-wide uniformity in units of measurement by direct action or by submitting proposals to the CGPM.
International Prototype Kilogram (IPK) - Commissioned by the General Conference on Weights and Measures under the authority of the Metre Convention (1875), the IPK is in the custody of the International Bureau of Weights and Measures (BIPM).
International Reply Coupon (IRC) - A coupon available at the post office and widely accepted worldwide, although not universally, as return postage for QSL cards.
International Space Station (ISS) - A habitable artificial satellite in low Earth orbit.
International System of Units (SI) - The modern form of the metric system.
International Telecommunications Union (ITU) - The organization of the United Nations (UN) that specifies worldwide guidelines concerning the use of the electromagnetic spectrum for communication purposes.
International Telecommunications Union phonetic alphabet (ITU phonetic alphabet) - (See North Atlantic Treaty Organization phonetic alphabet)
International Telegraph Alphabet number 2 (ITA2) - A system in which characters are expressed using five bits that was used until the advent of the American Standard Code for Information Exchange (ASCII).
Internet - A global system of interconnected computer networks that use the standard Internet protocol suite, Transmission Control Protocol (TCP) and Internet Protocol (IP) to serve billions of users worldwide.
Internet Protocol (IP) - The principal communication protocol in the Internet protocol suite for relaying datagrams across network boundaries. (See Transmission Control Protocol)
Internet protocol suite (TCP/IP) - The set of communications protocols used for the Internet and similar networks, and generally the most popular protocol stack for wide area networks. (See Internet Protocol and Transmission Control Protocol)
Internet Radio Linking Project (IRLP) - (Repeater Term) A system that uses a network protocol called voice over Internet Protocol (VoIP) to link repeaters. There are now over 1,000 repeaters around the world connected by the Internet through the amateur radio Internet radio linking project, 24 hours a day, 7 days a week.
Internet remote base - The control an amateur radio station remotely through a computer.
interrupted Morse code (ICW) - (Archaic) (CW Term) A modulated Morse code (CW) signal using a chopper to pulse it. (See chopper)
interval sign - (Archaic) (See intermediate)
inverted V antenna - A dipole wire antenna in which the center is higher than the two ends. This is probably the most common way dipoles are installed today.
inverter - A device that converts direct current (DC) power typically into 60Hz alternating current (AC) power.
ion - An electrically-charged atom or molecule in which the total number of electrons is not equal to the total number of protons, giving the atom a net positive or negative electrical charge.
ionosphere - A region of electrically charged or ionized gases high in the atmosphere. The ionosphere bends radio waves as they travel through it, returning them to Earth. Also known as sky-wave propagation.
ionospheric storm - A disturbed condition in the ionosphere caused by release of charged particles by the sun that results in high absorption and poor radio propagation on most frequencies.
ionizing radiation - Electromagnetic radiation that has sufficient energy to knock electrons free from their atoms, producing positive and negative ions. X-rays, Gamma rays, and ultraviolet radiation are examples of ionizing radiation. (See radiation)
Islands On The Air (IOTA) - A popular Radio Society of Great Britain (RSGB) award for amateur radio operators, where the objective is to contact amateur radio operators transmitting from offshore islands throughout the world.


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J-antenna - (See J-pole antenna)
J-pole antenna - A mechanically modified version of the Zepp (Zeppelin) antenna. It consists of a half-wavelength radiator fed by a quarter-wave matching stub. This antenna does not require the ground plane that 1/4-wave antennas do to work properly. Also known as J-antenna.
jack - A female electrical connector designed to have a mating assembly inserted into it.
jam - To cause intentional interference.
Jamboree On The Air (JOTA) - An annual event in which about 500,000 Scouts and Guides all over the world make contact with each other by means of amateur radio.
Joe Taylor 65 (JT65) - A weak-signal digital mode developed for use in the very-high frequency (VHF) and ultra-high frequency (UHF) bands for earth-moon-earth (EME) and other reflected path modes. It is so labeled because it sends 65 tones. The software for this mode (WSJT) was written by Joe Taylor K1JT, the 1993 winner of the Nobel Prize in physics.
Joe Taylor 65-High Frequency (JT65-HF) - An adaptation of Joe Taylor 65 (JT65) for use on the high-frequency (HF) bands.
joule (J) - The International System of Units (SI) unit of work or energy, equal to the work done by a force of one newton when its point of application moves one meter (m) in the direction of action of the force, equivalent to one 3600th of a watt-hour. Named for the British physicist James Prescott Joule.
jug - (Archaic) A synonym for a large transmitting vacuum tube. Also known as klystron, magnetron, or valve. (See vacuum tube)
juice - (Archaic) An early common slang term for electric power service.
Juliet - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter J. Used in radio communication, particularly when spelling out a call sign.
jumper - A small piece of wire used to connect two parts of a circuit. In computers and other devices, a jumper may take the form of a smaller plastic piece with an internal conductor that fits over two circuit board posts.
junction diode - An electrical component formed by placing a layer of N-type semiconductor material next to a layer of P-type material. Diodes allow current to flow in only one direction.
junction field-effect transistor (JFET) - A field-effect transistor that can be used as an electronically-controlled switch or as a voltage-controlled resistance. Electric charge flows through a semiconducting channel between source and drain terminals and by applying a reversed-bias voltage to a gate terminal. The channel had reached the pinch-off voltage, so that the electric current is impeded or switched off completely. (See varactor)
junkbox - A slang word for the collection of spare parts and miscellaneous items kept by an amateur radio operator or hobbyist.
jury rig To fix in an unorthodox manner.


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K-index - A measure of the Earth's magnetic field as measured at Boulder, Colorado. Propagation conditions improve with lower measurement numbers.
K9YA Telegraph Magazine - A magazine offering the amateur radio community a no-cost, high-concept publication covering a number of topics unavailable elsewhere and in providing a welcoming venue and readership to first-time writers. It is an ezine first published in January 2004.
Keplerian elements - Numeric parameters describing a satellite's orbit that can be used to compute the position of the satellite at any point in time. Named for Johannes Kepler and his six laws of planetary motion.
kerchunk - (Repeater Term) The sound made when a brief transmission activates a repeater.
kerchunker - (Repeater Term) An operator that activates a repeater station by transmitting on its input frequency without speaking.
kerchunking - (Repeater Term) Activating a repeater without identifying or modulating the carrier.
key - (1) (CW Term) A manually operated switch device that turns a transmitter on and off to send Morse code (CW). Also called a straight key or telegraph key. (2) To press a key or button.
key click - A spurious signal generated when a transmitter is turned on or off that is heard as a click by stations on nearby frequencies.
key up - (1) To activate a transmitter. (2) (Repeater Term) To turn on a repeater by transmitting on its input frequency.
keyboard-to-keyboard - A digital mode intended for operators to exchange text messages as characters are entered.
keyer - (1) (CW Term) A device used to send Morse code (CW) semi-automatically and more accurately. It connects to a key and forms a continuous string of dots and dashes, depending on which lever of a connected paddle is pressed. Also known as electronic keyer. (2) (CW Term) A person who sends Morse code.
kilo- (k-) - One thousand, or the metric prefix for 103, or times 1,000.
Kilo - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter K. Used in radio communication, particularly when spelling out a call sign.
kilocycle (kc) (Archaic) A thousand cycles per second. Replaced by kilohertz (kHz). (See kilohertz)
kilogram (kg) - The base unit of mass in the International System of Units (SI) defined as being equal to the mass of the International Prototype of the Kilogram (IPK).
kilohertz (kHz) - One thousand (1,000) cycles per second. (See hertz)
kilometer (km) - A unit of length in the metric system, equal to one thousand meters (m). Also known as kilometre.
kilowatt (KW) - One thousand (1,000) watts.
kilowatt-hour meter (kWh meter) - A device used to measure electrical consumption over time. Often used by power companies to establish usage for billing purposes.
knife-edge - The result of the alteration of radio waves if the dimensions of a diffraction edge is small in terms of a wave's wavelength. (See diffract)


To the top!   L

L network - A two-element, generally passive network, with one series element and one shunt element. The circuit diagram resembles the letter L.
ladder line - (See open-wire line)
lag - The waveform in which positive chnge occurs last in comparing two waveforms.
landline - A dedicated leased or dial-up telephone line, often used to provide control connectivity to a remote repeater station.
lead - (1) A wires or connection point on an electrical component or a probe and cable that is used to connect test instruments to the devices being measured. (2) The waveform in which change in the positive direction occurs first when comparing two waveforms.
lead acid - The oldest type of rechargeable battery most commonly used in automobiles and marine applications. As some batteries can deliver large amounts of current instantaneously and contain sulphuric acid, these must be handled with caution.
least significant bit (lsb) - The bit in a binary number that is of the lowest numerical value.
lid - (CW Term) A synonym for an inept radio operator — one who does not follow proper procedures, sends sloppy Morse code (CW), has very poor practices, and has bad manners.
light-emitting diode (LED) - A semiconductor light source, LEDs are used as indicator lamps in many devices and are increasingly used for other lighting.
lightning arrestor - A device used on buildings, electrical power systems, and telecommunications systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a ground terminal. When a lightning surge (or switching surge, which is very similar) travels along the power line to the lightning arrester, the current from the surge is diverted through the arrestor, in most cases to earth.
lightning protection - Methods to prevent lightning damage to one's house and equipment, such as unplugging the equipment, disconnecting the antenna feed lines, and using a lightning arrestor that is placed where wires enter a structure, preventing damage to electronic instruments within and ensuring the safety of individuals near them.
liquid-crystal display (LCD) - A device for displaying graphics or characters by passing light through a liquid crystal between patterns of electrodes. The light transmission is changed from transparent to opaque with the application of voltage.
Lima - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter L. Used in radio communication, particularly when spelling out a call sign.
limiter - (1) An amplifier in a frequency modulation (FM) receiver that makes the receiver less sensitive to amplitude variations and pulse noise. (2) A type of circuit that prevents a signal's amplitude from exceeding a fixed limit. Also known as clamp.
line-of-sight propagation - The term used to describe very-high frequency (VHF) and ultra-high frequency (UHF) propagation in a straight line directly from one station to another.
linear - To act on a signal such that the result is a replica of the original signal at a different scale.
linear amplifier - (See amplifier)
ling distance (LD) - (Archaic) A precursor to distant station (DX). (See distant station)
lithium ion (Li-ion) - A type of rechargeable battery that has better capacity than Ni-Cad (Nickel-Cadmium), Ni-MH (Nickel-Metal Hydride), etc., with no memory effect after repeated non-full charge/discharge cycles.
Litzendraht wire (Litz wire) - (Archaic) A bundle of stranded wire with each strand insulated from one another to reduce alternating current (AC) resistance due to skin effect by increasing surface area. The term comes from Litzendraht, German for braided, stranded, or woven wire.
load - (1) A device or system to which elelctrical power is delivered, such as an antenna or a heating element. (2) The amount of power consumed or that can be safely dissipated, such as a 50-watt load.
loaded dipole antenna - An electrical half-wavelength antenna shortened by the substitution of series inductance or shunt capacitance in place of antenna length.
loading coil - An inductance inserted into an antenna that lowers its resonant frequency allowing for a shorter antenna. Also known as inductor and resonator.
lobe - An area in the radiation pattern of an antenna where the radiation is at maximum. The main or major lobe has the greatest strength for the entire pattern. The side lobes of the far field radiation pattern of an antenna are located at an angle to the main lobe.
local area network (LAN) - A small computer network generally limited to a small geographical area. This is usually within the same building or a single floor of a building.
local control - A control operator who directly manipulates the operating adjustments in a station to achieve compliance with Federal Communications Commission (FCC) rules.
Local Government Liaison (LGL) - An appointee of the American Radio Relay League (ARRL) who monitors local government dockets consistently, offers local, organized support quickly when necessary, and is known in the local amateur community as the point man for local government problems.
local oscillator (LO) - A receiver circuit that generates a stable, pure signal used to mix with the received radio frequency (RF) to produce a signal at the receiver intermediate frequency (IF).
log - (1) The documents of an amateur radio station that detail operation of the station. They can be used as supporting evidence and for troubleshooting interference-related problems or complaints. (2) The recording of amateur radio contacts. Although it is no longer mandatory by Federal Communications Commission (FCC), it is required for contesting.
log-period dipole array (LPDA) A broadband, multi-element, directional, narrow-beam antenna that has impedance and radiation characteristics that are regularly repetitive as a logarithmic function of the excitation frequency.
logger - A person who assists the operator of a contest or event by recording the contact details.
lollipop - A ham radio term for an Astatic D-104 microphone.
long-range navigation (LORAN) - Originally developed for navigation over the Atlantic, the original LORAN system used longer wavelengths for longer range.
long wave (LW) - The frequency range of 150 to 300 kilohertz (kHz), although this term is often used to mean any radio signal lower than 540 kilohertz (kHz).
loop antenna - (1) A small receiving antenna usually designed for indoor use and tuning frequencies below 5 megahertz (MHz). It is constructed with elements that are continuous lengths of wire or tubing. (2) A point of maximum voltage of current on an antenna.
loss of signal (LOS) - A condition that occurs when a satellite becomes invisible to the antenna as it goes below the horizon.
loudspeaker - (See speaker)
low-pass filter (LPF) - A filter that allows signals below the cutoff frequency to pass through and attenuates signals above the cutoff frequency. (See cutoff frequency)
low frequency (LF) - The frequency range of 30 to 300 kilohertz (kHz).
lower sideband (LSB) - (1) In an amplitude modulation (AM) signal the sideband located below the carrier frequency. (2) The common single-sideband operating mode on the 40-, 80- and 160-meter (m) amateur radio bands. (See sideband)
lowest usable frequency (LUF) - The lowest frequency that can support propagation between two points.
lowfer - A synonym for one who experiments at very low frequencies, typically on 1750 meters (m), which is 160 to 190 kilohertz (kHz) and can be used under Federal Communications Commission (FCC) Part 15 which covers radio-frequency devices.


To the top!   M

machine - (Repeater Term) Slang term for repeater.
magic band - A synonym for the 6-meter (m) band, or 50 to 54 megahertz (MHz), due to its unpredictable propagation. During band openings you can work the world with just 10 watts or less.
magnetic field - A mathematical description of the magnetic influence of electric currents and magnetic materials. A magnetic field exists in a region of space if a magnet or an electrical current is subjected to a magnetic force.
magnetic mount (mag mount) - (Repeater Term) A magnetic base that permits quick installation and removal of an antenna from a motor vehicle or other metal surface. Also known as mag-mount.
magnetron - (See vacuum tube)
Maidenhead Locator System - A geographic coordinate system of grid squares drawn on maps of the Earth and used by amateur radio operators. It was named after the town outside London where it was first conceived by a meeting of European very-high frequency (VHF) managers in 1980. (See grid square)
main lobe - (See lobe)
mains electricity - The general-purpose alternating-current (AC) electric power supply.
malicious interference - Harmful nterference that seriously degrades, obstructs, or repeatedly interrupts a radio communication service operating in accordance with the Radio Regulations. (See harmful interference)
marine high-frequency radio channels - Channels assigned by international agreement for use by recreational or commercial vessels beyond the range of coastal very-high frequency (VHF) operation. There are channels assigned near 2, 4, 6, 8, 11, 13, 17 and 22 megahertz (MHz).
maritime station - A two-way radio unit aboard a ship or a station on land that communicates with ships.
mark frequency - In frequency-shift keying, the higher of the two frequencies used. (See space frequency)
mass-produced rig (MPR) - A radio that is produced in large quantities. The term is often used to describe radios that are not originally purchased in kit form.
mast - The bottom section of a center-loaded antenna. Common mast materials include aluminum, stainless steel, copper plated steel, and fiberglass covered copper.
master oscillator, power amplifier (MOPA) - A configuration that inserts an amplifier stage between the oscillator and the antenna which prevents changes in the loading presented by the antenna from altering the frequency of the oscillator.
matchbox - (See antenna tuner)
matching coil - A small coil attached at the base of a mobile high-frequency (HF) antenna. It uses capacitive reactance from the antenna to form an inductor/capacitor (LC) network which transforms the antenna's input impedance to that of the feed line.
maximum permissible exposure (MPE) - The highest power or energy density that is considered safe, that is, that has a negligible probability for creating damage in the human body. Limits are based on whole-body specific absorption rate (SAR) values. The Federal Communications Commission (FCC) Rules establish maximum permissible exposure values for humans to radio frequency (RF) radiation. (See specific absorption rate)
maximum useable frequency (MUF) - The highest-frequency radio signal that will reach a particular destination using sky-wave propagation, or skip. The MUF may vary for radio signals sent to different destinations.
mayday - From the French m'aidez for help me, mayday is used when calling for emergency assistance in voice modes. (See distress call)
mechanical filter - A filter that uses a network of mechanical piezoelectric elements to obtain high rejection of unwanted signals. (See piezoelectric)
medium frequency (MF) - The frequency range of 300 to 3,000 kilohertz (kHz).
medium-wave-frequency experimental radio (medfer) - Experiments with radio communications at low frequencies such as those on the edges of the amplitude modulation (AM) broadcast band.
medium wave (MW) - The frequency range of 300 to 3,000 kilohertz (kHz). Also used for the amplitude modulation (AM) broadcast band from 530 to 1710 kilohertz (kHz). This range includes the 160-meter (m) amateur band, the AM broadcast band, and the 2182 kilohertz (kHz) marine radiotelephone band.
mega- (M-) - One million, the metric prefix for 106, or times 1,000,000.
megacycles (Mc) - (Archaic) This terminology has been replaced by megahertz (MHz). (See megahertz)
megahertz (MHz) - One million (1,000,000) cycles per second.
megawatt (MW) - One million (1,000,000) watts of transmitter power.
memory bank (bank) - A set of memory channels organized into a group.
memory channel - Frequency and mode information stored by a radio and referenced by a number or alphanumeric designator.
memory effect - A situation in which rechargeable batteries such as Ni-Cad and Ni-MH types may be temporarily getting less capacity as a result of repeated non-full charge/discharge cycles.
menu - A list of selectable control or configuration functions or options.
message forwarding system - A group of amateur stations participating in a voluntary, cooperative, interactive arrangement where communications are sent from the control operator of an originating station to the control operator of one or more destination stations by one or more forwarding stations.
meteor-scatter operator - One who uses the ionized trails produced by meteors to scatter and reflect radio signals.
meteor scatter - Ionized trails of meteors used as a radio reflecting media.
meter - An instrument that displays a numeric value as a number or as the position of an indicator on a numeric scale.
meter (m) - The International System of Units (SI) symbol m, it is the fundamental unit of length. Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole (at sea level), its definition has been periodically refined to reflect growing knowledge of metrology. Since 1983, it has been defined as the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second. Also known as metre.
Metre Convention - An international treaty, signed in Paris on 20 May 1875 by representatives of seventeen nations that set up an institute for the purpose of coordinating international metrology and for coordinating the development of the metric system.
metric prefixes - A series of terms used in the metric system of measurement. Metric prefixes are used to describe a quantity as compared to a basic unit. The metric prefixes are indicated by multiples of 10.
metric system - A system of measurement developed by scientists and used in most countries of the world that use a set of prefixes that are multiples of 10 to indicate quantities larger or smaller than the basic unit. (See General Conference on Weights and Measures and Metre Convention)
mic - An abbreviation for microphone. (See microphone)
mic fright - Being reluctant to make one's first radio contact.
micro- (μ-) - One millionth, or the metric prefix for 10-6, or divide by 1,000,000. The μ is a Greek small mu.
microfarad (μF) - One millionth (10-6) of a farad. The μ is a Greek small mu. (See farad)
microphone (mic, mike) - An acoustic-to-electric transducer or sensor that converts sound into an electrical signal. Abbreviated as mic or mike.
microphone gain (mic gain) - Sensitivity of a microphone amplifier circuit.
microphone to you - (See over)
microsecond (μs) - An International System of Units (SI) unit of time equal to one millionth of a second, or 10−6, or 1/1,000,000.
microwave - The region of the radio spectrum above 1,000 megahertz (MHz), or 1 GHz.
microwave bands - A division of the range of frequencies above 1,000 megahertz (MHz), or 1 GHz, into a series of bands.
mike - An abbreviation for microphone. (See microphone)
Mike - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter M. Used in radio communication, particularly when spelling out a call sign.
mil - One thousandth (1/1,000) of an inch.
Military Affiliate Radio System (MARS) - A system for military-affiliated amateur radio operators who provide free communication for overseas G.I.s and other federal services. And, for those who would like to know, the letters G.I. were used to denote equipment made from galvanized iron during World War I. In that same war, G.I. started being interpreted as Government Issue, and it was used from then on as an adjective for anything having to do with the Army.
mill - A special typewriter used by radio operators to copy messages.
milli- (m-) - One thousandth, or the metric prefix for 10-3, or divide by 1,000.
milliampere (mA) - One thousandth (1/1,000) of an ampere.
milliampere hour (mAh) - One-thousandth (1/1,000) of an ampere hour, commonly used to describe the energy charge that a battery will hold and how long a device will run before the battery needs recharging.
milliwatt (mW). One thousandth (1/1,000) of a watt. A derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt. The unit, defined as one joule (J) per second, measures the rate of energy conversion or transfer. (See watt)
mismatch - A condition that happens when a feed line is connected to an antenna or to transmitting equipment and the impedances are different. (See impedance match)
mixer - A circuit that takes two or more input signals, and produces an output that includes the sum and difference of those signal frequencies.
mnemonic - A pattern of letters, ideas, or associations that assists in remembering something.
mobile - Operating an amateur radio from a vehicle.
mobile device - (See mobile station)
mobile flutter - (Repeater Term) A synonym for a condition experienced on very-high frequency (VHF) and above where a signal rapidly fluctuates in amplitude experiencing multi-path interference causing a sound akin to rubbing a stick on a picket fence. If a repeater user's signal isn't strong enough to maintain solid access to the machine's input, such as when operating from a vehicle passing beneath underpasses or through hilly terrain, the signal would be hard to copy because of a pronounced, rapid fluttery or choppy characteristic. Also called picket fencing.
mobile station - A radio transmitting device designed to be mounted in a vehicle or in a boat, plane, motorcycle, truck, recreational vehicle, etc., that can be used while the vehicle is in motion or at various stops. A push-to-talk (PTT) switch activates the transmitter. As a class of transceiver, mobile units fall between hand-held (5 watts or less) and base stations in both physical size and transmitted power. These units typically operate from the vehicle's battery and often transmit 50 watts or more using a vertical antenna mounted to use the metal vehicle body as a ground plane.
mode - (1) The combination of a type of information and a method of transmission. For exmple, frequency modulation (FM) radiotelephony or frequency modulation (FM) phone consists of using FM modulation to carry voice information. (2) A form of a radio emission, such as amplitude modulation (AM), frequency modulation (FM), or single sideband (SSB). (3) The combination of a satellite's uplink and downlink bands.
mode-restricted - Portions of the amateur radio bands in which only ceertain emission types are allowed.
modulator/demodulator (modem) - A device that modulates a radio signal to transmit data and demodulates a received radio signal to recover transmitted data.
Modern Electrics Magazine - (Archaic) A technical magazine for the amateur radio experimenter that was created by Hugo Gernsback and began publication in April 1908. The magazine was initially intended to provide mail-order information for radio parts and to promote the amateur radio hobby. The magazine was sold in 1913, and ceased publication with the December 1913 issue.
modulate - The process of adding information to a radio frequency (RF) signal or carrier by varying its amplitude, frequency, or phase. (See demodulate)
modulated continuous wave (MCW) - (CW Term) Sending Morse code (CW) over an amplitude modulation (AM) transmitter using an audio tone.
modulation - The process of varying a radio frequency (RF) carrier in some way, for example, the amplitude or the frequency, to add an information signal to be transmitted.
modulation index - (Repeater Term) The ratio between the maximum carrier-frequency deviation and the audio-modulating frequency at a given instant in a frequency modulation (FM) transmitter.
Molex connector - A nylon-supported two-pin (or more) connector often used for power connections. The connector was pioneered by the Molex Connector Company.
monitor mode - One type of packet radio receiving mode. In monitor mode, everything transmitted on a packet frequency is displayed by the monitoring terminal node controller (TNC). This occurs whether or not the transmissions are addressed to the monitoring station.
monitoring - (1) To listen to radio voice or Morse code (CW) signals without transmitting. (2) To disable a radio's squelch to listen for weak signals.
monoband antenna - An antenna suitable for operation on just one band of frequencies.
monopole antenna - A vertical antenna that is typically connected to the inner conductor of a coaxial transmission line (or a matching network) and the shield of the transmission line is connected to ground.
moonbounce - (See earth-moon-earth)
Morse code (CW) - (CW Term) In 1836, Samuel F.B. Morse developed the forerunner to modern International Morse code (CW), a method of transmitting text information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment. In amateur radio and military communications, the terms CW and Morse code are used interchangeably, despite the distinctions between the two. Also known as code. (See continuous wave)
metal-oxide semiconductor field-effect transistor (MOSFET) - A type of active solid-state device often used as an amplifier or switch.
motorboating - An undesirable low-frequency feedback resulting in a motorboat sound on the audio.
mount - A method of attaching an antenna to a vehicle, such as with magnets, to the trunk, hood, or mirror.
MP73-N - A digital narrow band slow-scan television (SSTV) program mode.
multi-band antenna - An antenna suitable for operation on several different bands of frequencies, usually using a single transmission line.
multi-band trap antenna - An antenna in which parallel resonant circuits, called traps, are used to isolate certain sections to operate only on some frequencies. This results in an antenna that can operate on multiple bands. (See trap)
multi-frequency-shift keying (MFSK) - A technique for transmitting digital data using multiple tones, extending the radioteletype (RTTY) two-tone technique to many tones, usually, but not always, one tone at a time. (See frequency-shift keying)
multi-hop - A radio signal refracted more than one time between the transmitting and receiving stations.
multi-mode transceiver - A transceiver capable of amplitude modulation (AM), Morse code (CW), frequency modulation (FM), and single sideband (SSB) operation. Also known as multi-mode radio.
multi-path interference - A condition when reflected propagation signals partially cancel. (See mobile flutter)
multi-path propagation - Propagation by means of multiple reflections. When the reflected signals partially cancel, it is referred to as multi-path interference. (See mobile flutter)
multimeter - An electronic test instrument used to measure current, voltage, and resistance in a circuit. The term describes all meters capable of making these measurements. Also known as volt-ohm-milliammeter and vacuum-tube voltmeter. If the numeric display is digital, the instrument may also be called a digital multimeter or digital voltmeter.
multiple-dipole antenna - Two or more separate dipole antennas connected to the same feed point to provide multi-band operation on the same feed line.
multiple-protocol controller (MPC) - A device that can act as a terminal node controller (TNC) for several protocols.


To the top!   N

N-doped - An N-type junction that is doped with electrons. A P-N junction (or N-P junction) is formed by creating two substrate materials of P-type and N-type on a semiconductor. A diode is formed with a P-N junction. (See P-doped)
N-type - When a doped semiconductor contains excess free electrons it is known as N-type. (See dope)
N connector - A Type N connector is a coaxial cable connector family particularly suited for ultra-high frequency (UHF) operation up to full legal amateur radio power levels, featuring low loss, constant impedance, and waterproof operation. It was one of the first connectors capable of carrying microwave-frequency signals, and was invented in the 1940s by Paul Neill of Bell Labs, after whom the connector is named.
nano- (n-) - One billionth, or the metric prefix for 10-9, or divide by 1,000,000,000.
nanofarad (nF) - A farad is the charge in coulombs that a capacitor will accept for the potential across it to change 1 volt. One nanofarad (nF) is equal to one billionth (10−9) of a farad. (See farad)
narrow band (NB) - A channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth.
narrow band frequency modulation (NBFM) - A term used for when the significant energy in frequency modulation (FM) occupies the same bandwidth as ordinary amplitude modulation (AM) with the same modulating signal.
narrow frequency modulation (NFM) - A receive mode that gives good results in congested frequency ranges.
National Aeronautics and Space Administration (NASA) - An independent agency of the United States government responsible for aviation and spaceflight.
National Archives and Records Administration (NARA) - An independent agency of the United States government charged with preserving and documenting government and historical records and with increasing public access to those documents, which comprise the National Archives.
National Bureau of Standards (NBS) - (Archaic) The precursor to the National Institute of Standards and Technology (NIST). (See National Institute of Standards and Technology)
National Contest Journal Magazine (NCJ) - A bimonthly magazine published by the American Radio Relay League (ARRL), with an independent volunteer editor. The magazine covers topics related to amateur radio contesting, is published in English, and draws its subscription base primarily from the United States and Canada.
National Electrical Code (NEC) - A set of guidelines governing electrical safety that includes antennas.
National Incident Management System (NIMS) - A system that identifies concepts and principles that answer how to manage emergencies from preparedness to recovery regardless of their cause, size, location, or complexity.
National Institute of Standards and Technology (NIST) - The United States government standards body for time, frequency, measures, and weights. Formerly known as the National Bureau of Standards.
National Oceanic and Atmospheric Administration (NOAA) - A scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere.
National Radio Quiet Zone (NRQZ) - The area in Maryland, Virginia, and West Virginia bounded by 39° 15' N on the north, 78° 30' W on the east, 37° 30' S on the south, and 80° 30' W on the west. This area is home of a number of high-sensitivity radio telescopes and equipment run by the National Aeronautics and Space Administration (NASA), National Security Agency (NSA), and others. There are restrictions on amateur radio beacons in this area; transmissions of any kind near certain facilities must be coordinated with the area frequency coordinator.
National Traffic System (NTS) - An American Radio Relay League (ARRL) organized structure of local, regional, and national networks designed to deliver formal written message traffic, or radiograms, anywhere in the United States.
National Weather Service (NWS) - A service that provides weather, water, climate data, forecasts, and warnings for the protection of life and property and enhancement of the national economy.
natural wave - (Archaic) The resonant length of an antenna, usually one full wave.
Naval Communication Reserve (NCR) - (Archaic) A United States service for hams to serve in reserve duty in the 1920s and 1930s.
near-vertical-incidence-skywave (NVIS) - A propagation mode where signals are reflected back down from directly overhead. Useful for relatively short-distances, overcoming the limitations of the usual skip-zone distance. (See skip)
near field - The region of the electromagnetic field immediately surrounding an antenna where the reactive field dominates and where the field strength as a function of angle, or antenna pattern, depends upon the distance from the antenna. It is a region in which the electric and magnetic fields do not have a substantial plane-wave character, but vary considerably from point to point. (See plane-wave character)
negative - (1) The part of an electric circuit that is at a lower electrical potential than another part designated as having zero electrical potential. (2) No; wrong; incorrect.
negative-positive-negative (NPN) - A transistor that has a layer of P-type semiconductor material sandwiched between layers of N-type semiconductor material.
negative copy - Reporting an unsuccessful transmission.
negative feedback - The process in which a portion of the amplifier output is returned to the input, 180 degrees out of phase with the input signal, that improves linearity and reduces distortion.
negative offset - (Repeater Term) (See offset)
negative resistance characteristic - Action of a material or device in which increased current results in reduced voltage drop. Often found in materials in the plasma state, such as within a lightning arc.
net - A group of stations that meet on a specified frequency at a certain time. The net is organized and directed by a net control station operator, who calls the net to order, recognizes stations entering and leaving the net, and authorizes stations to transmit.
net control station (NCS) - A formal or directed net that manages its operation for a given session. The NCS operator calls the net to order at its designated start time, periodically calls for participants to join, listens for them to answer or check in, keeps track of the roster of stations for that particular net session, and generally orchestrates the operation of the net. (See net)
Net Manager (NM) - An appointee of the American Radio Relay League (ARRL) who is responsible for coordinating and supervising traffic handling activities in a section of the ARRL.
network - Several digital stations linked together to transmit data over long distances.
new Motorola mount (NMO) - A kind of screw-on mobile antenna mounting arrangement that provides a coaxial connection. It is the preferred mount for any very-high frequency (VHF) and ultra-high frequency (UHF) antenna. It is waterproof with or without the antenna attached, and can be installed from the outside. It is the mount of choice if maximum efficiency is to be maintained.
newton (N) - The International System of Units (SI) unit of force. It is equal to the force that would give a mass of one kilogram an acceleration of one meter (m) per second per second, and is equivalent to 100,000 dynes (dyn). It is named after Isaac Newton in recognition of his work on classical mechanics, specifically Newton's second law of motion. (See dyne and joule)
nickel-cadmium (NiCad) - A type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes. The term is derived from the chemical symbols of nickel (Ni) and cadmium (Cd) or NiCd. The term NiCad is a registered trademark of the Saft company, although this brand name is commonly used to describe all NiCd batteries.
nickel-metal hydride (NiMH) - A type of rechargeable battery. It is very similar to the nickel–cadmium cell. NiMH batteries use positive electrodes of nickel oxyhydroxide (NiOOH), like the NiCd, but the negative electrodes use a hydrogen-absorbing alloy instead of cadmium, being in essence a practical application of nickel–hydrogen battery chemistry. An NiMH battery can have two to three times the capacity of an equivalent size NiCad, and their energy density approaches that of a lithium-ion cell.
nickels - A synonym used on distant station (DX) nets as a signal report of 5-by-5.
node - (1) A point of minimum voltage or current on an antenna. (2) A remotely controlled terminal node controller/digipeater that is used as a connect point in packet radio.
noise - Unwanted elecromagnetic energy that can interfere with signal transmission or reception.
noise blanker - A circuit that provides noise reduction for impulse noise. Also known as blanker.
noise bridge - A test instrument used to determine the impedance of an antenna system.
noise figure - The ratio in decibels (dB) of noise added to a signal by a device to the noise that would be in the signal if none were added. It especially applies to amplifiers.
noise floor - The average power of the sum noise from all noise sources. A weak signal must be above the noise floor to be discernible.
noise reduction (NR) - A digital signal processing (DSP) feature that reduces unwanted signal noise.
non-ionizing radiation - Electromagnetic radiation that does not have sufficient energy to knock electrons free from their atoms. Radio frequency radiation is nonionizing. (See radiation)
North American Low-power Morse-code Club (NAQCC) - A club promoting and encouraging Morse code (CW) proficiency on the amateur radio bands. Life membership is free.
North Atlantic Treaty Organization (NATO) - An intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The organization constitutes a system of collective defence whereby its member states agree to mutual defense in response to an attack by any external party.
North Atlantic Treaty Organization phonetic alphabet (NATO phonetic alphabet) - More accurately known as the International Radiotelephony Spelling Alphabet, it is code words assigned to the letters of the English alphabet so that critical combinations of letters and numbers can be pronounced and understood by those who transmit and receive voice messages by radio or telephone regardless of their native language or the presence of transmission static. The NATO phonetic alphabet is the most widely used spelling alphabet. Also known as ICAO phonetic alphabet, ICAO spelling alphabet, and ITU phonetic alphabet.

THE NATO PHONETIC ALPHABET
AAlfa (AL fah)
BBravo (BRAH voh)
CCharlie (CHAR lee — SHAR lee)
DDelta (DELL tah)
EEcho (ECK oh)
FFoxtrot (FOKS trot)
GGolf (GOLF)
HHotel (hoh TELL)
IIndia (IN dee ah)
JJuliet (JEW lee et)
KKilo (KEY loh)
LLima (LEE mah)
MMike (MIKE)
NNovember (no VEM ber
OOscar (OSS kah)*
PPapa (pah PAH)
QQuebec (keh BECK)
RRomeo (ROW mee oh)
SSierra (see AIR ah)
TTango (TANG go)
UUniform (YOU nee form — OO nee form)
VVictor (VIK tah)*
WWhiskey (WISS key)
XX-ray (EKS ray)
YYankee (YANG key)
ZZulu (ZOO loo)
* NOTE: The pronunciations for Oscar and Victor were
designed for speakers from all international languages.

notch filter - A filter that passes all frequencies except those in a stopband centered on a center frequency. (See stopband)
November - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter N. Used in radio communication, particularly when spelling out a call sign.
Novice - (1) (Archaic) The Novice Class operator license was for persons who had passed a 5-word-per-minute Morse code (CW) examination and a basic theory exam. After the 1987 restructuring, privileges included four bands in the high-frequency (HF) range, or 3 to 30 megahertz (MHz), one band in the very-high frequency (VHF) range, or 30 to 300 megahertz (MHz), and one band in the ultra-high frequency (UHF) range, or 300 to 3,000 megahertz (MHz). This class was deprecated by the restructuring in the year 2000. (2) (Archaic) An early 1920s term for a broadcast listener, as distinguished from a radio amateur.
null - (1) To tune or adjust for a minimum response. (2) A position in the radiation pattern of an antenna where the radiation is zero or approaches zero.
number - Issue, as in this month's number of QST magazine.


To the top!   O

odd split - The unconventional frequency separation between input and output (I/O) frequencies. Also known as odball split. (See split)
oddball split - (See odd split)
off-center-fed antenna (OFC) - A dipole wire antenna in which the feed wire is not attached in the middle. Also known as windom.
off wave - (Archaic) A term mostly used in the late 1920s and 1930s meaning operation outside the legal limits of an amateur band.
Office of the Federal Register (OFR) - An office of the National Archives and Records Administration, it provides access to the official text of Federal Laws, Presidential Documents, and Administrative Regulations and Notices.
Official Emergency Station (OES) - An appointee of the American Radio Relay League (ARRL) who is responsible for specific, pre-determined operational assignments during drills or actual emergency situations.
Official Observer (OO) - An appointee of the American Radio Relay League (ARRL) who monitors the amateur radio bands for infractions. The OO keeps watch for such things as frequency instability, harmonics, hum, key clicks, broad signals, distorted audio, over deviation, out-of-band operation, and other potential problems.
Official Observer Coordinator (OOC) - An appointee of the American Radio Relay League (ARRL) who supervises the maintenance monitoring work of the section Official Observers, and coordinates special Amateur Auxiliary efforts with ARRL Headquarters.
Official Relay Station (ORS) - An appointee of the American Radio Relay League (ARRL) who functions in the community interest in case of emergency.
Official Traffic Station (OTS) - A position of the American Radio Relay League (ARRL) charged with maintaining communication with served agency shelters and with health and welfare traffic.
offset - (Repeater Term) The difference between the receive and transmit frequencies of a radio channel. On the 2-meter (m) amateur radio band these frequencies are 600 kilohertz (kHz) apart. In order to listen and transmit at the same time, repeaters use two different frequencies. If the output is above 147 megahertz (MHz) then the input is 600 kilohertz (kHz) above and is referred to as a positive offset. As a general rule, if the output frequency, or transmit of the repeater is below 147 megahertz (MHz) then the input frequency, or listening is 600 kilohertz (kHz) lower and is referred to as a negative offset.
offset frequency - (Repeater Term) Frequency difference between a repeater's receive and transmit frequencies. Also known as split.
Ohm (Ω) - The basic unit of electrical resistance, used to describe the amount of opposition to current. One Ohm is the resistance offered when a potential of one volt results in a current of one ampere. The Ω is a Greek capital omega.
Ohm's law - A formula for basic electronic calculation that gives a relationship between voltage (E), current (I) and resistance (R). The voltage applied to a circuit is equal to the current through the circuit times the resistance of the circuit (E = IxR, or I = E/R, or R = E/I). The law was named for George Simon Ohm, a German physicist and mathematician.
ohmeter - A device used to measure electrical resistance.
Olivia - A digital-mode software package using multiple frequency-shift keying carriers and intended for operation under weak-signal conditions.
old man (OM) - A friendship term for a friend, pal, or buddy, or any male operator.
old timer (OT) - A ham who has been around ham radio for a long, long time.
Old Timer's Club (OTC) - (Archaic) An American Radio Relay League (ARRL) club that recognized ham radio activity that had spanned 20 years or more. The club was discontinued in 2004.
omnidirectional antenna - An antenna that radiates and receives well in all horizontal directions.
one-way communication - A transmission that is not intended to be answered. The Federal Communications Commission (FCC) strictly limits the types of one-way communication allowed on the amateur radio bands.
open-sleeve dipole antenna - An antenna with one or more additional closely spaced wires placed parallel with but with no electrical to a simple dipole to create multiple resonant frequencies.
open-wire line - A type of feed line constructed of two wires held at a constant distance apart, either incased in plastic or constructed with insulating spacers placed at intervals along the line. Also known as ladder line, parallel-conductor line, or twin-lead line.
open circuit - An electrical circuit that does not have a complete path, so current cannot flow through the circuit.
open repeater - (Repeater Term) A repeater that can be used by all amateur radio operators who have licenses that authorize operation on the repeater frequencies. (See closed repeater)
opening - A condition that occurs when radio propagation is possible between two stations on the same frequency.
operational amplifier (op-amp) - A direct current (DC)-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output.
operator/primary station license - The operator portion of an amateur radio license gives permission to operate an amateur radio station. The primary portion of an amateur radio license authorizes an amateur radio station at a specific location and also lists the call sign of that station. Only one operator/primary station license grant may be held by any one person.
optical fiber - A flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair. It functions as a waveguide, or light pipe, to transmit light between the two ends of the fiber.
Orbiting Satellite Carrying Amateur Radio (OSCAR) - The sattelite use of amateur radio frequency allocations to facilitate communication between amateur radio stations. These satellites can be used for free by licensed amateur radio operators for voice and data communication. Fully-operational satellites in orbit act as repeaters or linear transponders, or store and forward digital relays.
orthogonal frequency division multiplexing (OFDM) - A common modulation type used in high-speed multimedia (HSMM) work.
Oscar - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter O. Used in radio communication, particularly when spelling out a call sign.
oscillate - To vibrate or generate a signal at a single frequency.
oscillator (OSC) - A device or circuit that generates oscillating electric currents or voltages by nonmechanical means at a single frequency.
oscillation transformer – (Archaic) A transformer that forms the resonant circuit in a spark transmitter and couples to the antenna.
oscilloscope - An electronic test instrument used to observe wave forms and voltages on a cathode-ray tube (CRT). The tube displays time on the X-axis, amplitude on the Y-axis, and intensity of the CRT spot on the Z-axis.
outdoor antena - (Archaic) (See aerial)
output frequency - A repeater's transmitting frequency. To use a repeater, one must transmit on an input frequency, and receive on an output frequency.
over - A term used during a two-way communication to alert the other station that you are returning the communication back to them (although, not used on all frequencies or on repeaters). Other terms are go ahead, "microphone to you," and in Morse code (CW) the letter K is used as an invitation to transmit. The term is not actually necessary on 2-meter (m) frequency modulation (FM) repeaters, as the courtesy tone serves this function. Also known as over and out.
overload - A signal so strong that circuits begin to operate improperly creating false ghost signals on various frequencies in the frequency range.


To the top!   P

π pad - pi pad - One of the possible configurations used in attenuators. (See attenuator)
P-doped - A P-type junction that is doped with free holes or electron depletion. A diode is formed with a P-N junction. (See N-doped)
P-type - When a doped semiconductor contains excess holes it is called P-type.
P/N junction - A P/N junction (or N/P junction) is formed by creating two substrate materials of P-type and N-type inside a single crystal of semiconductor.
P5 North Korea - For distant station operators (DXers), a most unattainable contact or a non-existent station. The rarest call sign prefix as one of two countries worldwide (the other is 7O Yemen) to have had no licensed radio amateur service at all since 2002.
packet - An amateur digital-data system that communicates using very-high frequency (VHF) and ultra-high frequency (UHF) frequencies.
Packet Bulletin Board System (PBBS) - A system that offers the ability to send and receive personal messages or bulletins intended for people around the world.
packet cluster - A network of automated packet radio stations for disseminating distant station (DX) and contest reports.
packet radio (PKT) - A form of packet-switching technology used to transmit digital data by way of radio or wireless communications links. For instance, with the AX.25 protocol, information is broken into short bursts, or packets, that also contain addressing and error-detection information.
PACTOR - An evolution of amateur teleprinting over radio (AMTOR) and packet radio, it is a radio modulation mode used by amateur radio operators, marine radio stations, and radio stations in isolated areas to send and receive digital information by way of radio. The word pactor is Latin for the mediator.
paddle - (CW Term) A device used to send Morse code (CW) with an electronic keyer.
panadapter - An oscilloscope for monitoring a band of frequencies.
Papa - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter P. Used in radio communication, particularly when spelling out a call sign.
parabola - A symmetrical open-plane curve formed by the intersection of a cone with a plane parallel to its side.
parabolic antenna - An antenna in the shape of a dish with a parabolic cross section.
parallel-conductor line - (See open-wire line)
parallel-tuned circuit - A circuit in which the capacitor and inductor are in parallel, and therefore have the same voltage.
parallel circuit - An electrical circuit in which the electrons follow more than one path in going from the negative supply terminal to the positive terminal.
parasitic - Oscillations in a transmitter on frequencies other than the desired one that can produce spurious signals from the transmitter.
parasitic-element antenna - An antenna element that affects the antenna performance by receiving and re-radiating energy from a driven element. Parasitic elements are not connected directly to the feed line.
parasitic beam antenna - (See beam antenna)
parasitic oscillation - An undesirable oscillation caused by feedback.
parasitic suppressor - A suppressor, designed to absorb sufficient energy to suppress unwanted very-high frequency (VHF) parasitic oscillations in a high-voltage high-frequency (HF) amplifier.
parawatch - (See dualwatch)
parity - An error detection method for digital data that counts the number of 1 bits in each data character. One bit added to each character, the parity bit, is used to indicate whether the correct number of 1 bits is odd or even.
Part 15 - The section of the Federal Communications Commission (FCC) rules that permits operation of low-power transmitting devices likely to transmit or receive radio frequency (RF) signals without a license.
Part 97 - The section of the Federal Communications Commission (FCC) rules that regulates amateur radio service. The fundamental purposes are expressed in the following principles: (a) Recognition and enhancement of the value of the amateur service to the public as a voluntary noncommercial communication service, particularly with respect to providing emergency communications. (b) Continuation and extension of the amateur's proven ability to contribute to the advancement of the radio art. (c) Encouragement and improvement of the amateur service through rules which provide for advancing skills in both the communication and technical phases of the art. (d) Expansion of the existing reservoir within the amateur radio service of trained operators, technicians, and electronics experts. (e) Continuation and extension of the amateur's unique ability to enhance international goodwill.
pass - The period during which signals from an orbiting satellite can be heard at a ground location.
passband - The range of frequencies or wavelengths that can pass through a filter without being attenuated.
passband tuner - A receiver circuit that permits adjusting the bandpass for best reception under different interference conditions. (See bandpass)
passband tuning (PBT) - A function to electronically reduce receiver interference by narrowing the intermediate frequency (IF) bandwidth.
passive filter - (See filter)
patch - (See auto patch)
path - The route taken by a signal from the transmitting station to the receiving station.
path noise - (Repeater Term) The signal is so weak that the limiters have not engaged thus noise on the signal will be heard. This is sometimes referred to incorrectly as white noise. (See white noise)
peak envelope power (PEP) - The average power of a radio frequency (RF) signal at the crest of the waveform which can be calculated by multiplying peak envelope voltage (PEV) by 0.707.
peak inverse voltage (PIV) - The maximum voltage a diode can withstand when it is reverse biased or not conducting.
peak-to-peak (P-P) - The distance measured between the greatest peaks of a periodically varying quantity, as in peak-to-peak voltage.
peak envelope voltage (PEV) - The maximum voltage on a transmission line during transmission.
pecuniary - Payment of any type, whether money or other goods. Amateur radio operators may not operate their stations in return for any type of payment.
perigee - A point in the orbit of a satellite at which it is closest to the Earth. (See apogee)
period (Τ) - The length of time in seconds taken by one cycle of a repeating waveform to pass a reference point. It is the reciprocal of frequency. The Τ is a Greek capital tau. (See frequency)
permeability-tuned oscillator (PTO) - A variable-frequency oscillator (VFO) in which the frequency change is accomplished by way of an inductor with a movable slug rather than by way of a variable capacitor. Used with temperature compensated components, this oscillator provides a low-drift operation. Usually much more linear than a VFO.
personal computer (PC) - A computer designed for use by one person at a time.
phantom antenna - (Archaic) (See dummy antenna)
phase - A measure of position in time within a repeating waveform, such as a sine wave. Phase is measured in degrees or radians.
phase-locked loop (PLL) - An electronic circuit consisting of a variable frequency oscillator and a phase detector that can generate a wide range of frequencies in discrete steps such as 10 hertz (Hz).
phase alteration line (PAL) - A television standard used in parts of Europe.
phase modulation (PM) - Similar to frequency modulation (FM), it is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave. Modification in phase according to low frequency will give phase modulation.
phase shift keying (PSK) - (See phase shift keying version 31)
phase shift keying version 31 (PSK31) - A method of digital modulation that shifts the transmitted signal's phase to represent the bits of digital data. It is a popular computer-generated radioteletype mode, used primarily by amateur radio operators to conduct real-time keyboard-to-keyboard informal text chat over the air. PSK31 occurs at 31.25 hertz (Hz) bandwidth. (See radioteletype (RTTY))
phone - Another name for voice communication or voice modulation, it is an abbreviation for radiotelephone. (See radiotelephone)
phone emission - The Federal Communications Commission's (FCC) name for voice or other sound transmissions.
phone patch - (See auto patch)
phonetic alphabet - North Atlantic Treaty Organization (NATO) standard words used in voice modes to make it easier to understand letters of the alphabet, such as those in call signs. For instance, the call sign of the Aurora Repeater Association, Inc. (Aurora, Colorado) is NØARA, stated phonetically as November-Zero-Alpha-Romeo-Alpha.
photodetector - A sensor of light or other electromagnetic energy.
photodiode - A type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation. The common solar cell used to generate electric solar power is a large area photodiode.
picket fencing - (See mobile flutter)
pico- (p-) - One trillionth, or the metric prefix for 10-12, or divide by 1,000,000,000,000.
picofarad (pF) - One trillionth (10−12) of a farad. A farad is the charge in coulombs that a capacitor will accept for the potential across it to change 1 volt. (See farad)
piezoelectric - Substances that are able to convert mechanical signals, such as sound waves, into electrical signals, and vice versa. They are therefore widely used in microphones, phonograph pickups, and earphones, and also to generate a spark for igniting gas.
piezoelectric effect - The ability of a substance to produce an electric charge when it is deformed physically.
pileup - The situation in which a large number of stations are trying to call the same distant station (DX) on the same frequency.
pilot streamer - A column of ionized air that progresses downward at speeds of about 100 mph and establishes a path for a return lightning strike.
pilot tone - A 19 kilohertz (kHz) pilot tone added to a stereo broadcast to allow receivers to detect the presence of a stereo-encoded signal.
pinch-off voltage (VPO) - A condition in which the drain-source terminals of a field-effect transistor (FET) start to look like an open circuit, and no appreciable current flows even at high drain-source potentials. In practice there is always some residual current and the actual VPO measurement must make an allowance for this.
ping - A brief reception of a radio signal by way of meteor scatter radio wave propagation.
ping jockey - A nickname for meteor-scatter operator. (See meteor-scatter operator)
pirate - A station using an existing call sign and illegally operating on the air. (See bootlegger)
PL-259 - plug-259 - Female antenna connector used on most high-frequency (HF) radios, it is a World War II threaded radio frequency (RF) connector design from an era when ultra-high frequency (UHF) referred to frequencies over 30 megahertz (MHz). Originally intended for use as a video connector in radar applications, the connector was later used for radio frequency (RF) applications. The term is often used for any compatible UHF cable plug and thus misnamed UHF. It mates the SO-239 socket. (See SO-239)
plane-wave character - A locally uniform distribution of electric field strength and magnetic field strength in a plane perpendicular to the direction of propagation.
plate tank - (Archaic) A resonant circuit at a vacuum tube amplifier's output frequency that is used to couple energy from the high-impedance plate or anode circuit to an antenna load.
plate transformer - (Archaic) A voltage step-up device that provides the high voltage to be rectified and filtered to supply a vacuum tube amplifier's plate circuit.
plug - An male electrical connector designed to be inserted into a jack. (See jack)
pocket beep - A beeping function, usually of a hand-held transceiver, when a specific signal is received.
polar orbit - A satellite orbit that passes over the North and South poles.
polarity - The orientation of an object or comparison of a value to some standard or convention that assigns the positive and negative. For example, a voltage can have a positive or negative value depending on what value of voltage is used as a reference.
polarization - The electrical-field characteristic of a radio wave. A radio wave can be horizontally, vertically, or circularly polarized. An antenna that is parallel to the surface of the earth, such as a dipole, produces horizontally polarized waves. One that is perpendicular to the earth's surface, such as a quarter-wave vertical antenna, produces vertically polarized waves. An antenna that has both horizontal and vertical polarization is said to be circularly polarized.
pole - A controlled current path or circuit in a switch.
pole-pig - A step-down transformer used by power transmission companies. Some surplus units can be reverse wired and used as the transformers in amateur radio high voltage supplies.
portable designator - Additional identifying information added to a call sign specifying the station's location.
portable device - A radio transmitting device designed to be transported easily and to be set up for operation independently of normal infrastructure. For purposes of radio frequency (RF) exposure regulations, a portable device is one designed to have a transmitting antenna that is generally within 20 centimeters (cm) of a human body.
Portable Document Format (PDF) - A file format used to represent documents in a manner independent of application software, hardware, and operating systems.
portable station - An amateur radio station that is designed to be easily moved from place to place but can only be used while stopped. In Morse code (CW), portable operators may identify using /P. Portable stations differ from mobile stations in that large antennas or other structures must be folded or stowed away in order to move the station to a new location. While well-suited to field day or emergency/disaster operations, portable stations normally do not have a mobile station's ability to continue transmission while in motion.
positive - (1) The part of an electric circuit that is at a higher electrical potential than another point designated as having zero electrical potential. (2) Yes; right; correct.
positive-intrinsic-negative (PIN) - A photodiode with a large, neutrally doped intrinsic region sandwiched between P-doped and N-doped semiconducting regions. A PIN diode exhibits an increase in its electrical conductivity as a function of the intensity, wavelength, and modulation rate of the incident radiation.
positive-negative-positive (PNP) A type of bi-polar junction transistor that has a layer of N-type semiconductor material sandwiched between two layers of P-type semiconductor material. A small current leaving the base is amplified in the collector output. That is, a PNP transistor is on when its base is pulled low relative to the emitter.
positive offset - (Repeater Term) (See offset)
post meridian (p.m.) - After noon.
potentiometer - An electrical device in which the total resistance remains constant while resistance between end points is varied. The value of a potentiometer can be changed over a range of values without removing it from a circuit. Also known as pot and variable resistor.
power (PWR) - The rate at which energy is consumed, transferred, transformed, or used. Power is calculated in an electrical circuit by multiplying the voltage applied to the circuit by the current through the circuit, or P = IxE.
power amplifier (PA) - An electronic amplifier used to convert a low-power radio-frequency signal into a larger signal of significant power, typically for driving the antenna of a transmitter. (See amplifier)
power density - The strength of a radio frequency (RF) field measured as power per unit of area.
power factor - (Archaic) The cosine of the angle between voltage and current, so in resonance, it equals 1.
power meter (PM) - (See wattmeter)
power supply (PS) - A device with a circuit that provides a direct current (DC) output at some desired voltage from an alternating current (AC) input voltage.
preamble - The header of a radiogram including message number, message type, originating station identification, time, and date originated.
preamplifier (preamp) - A receiving circuit that gives extra amplification to weak signals but at the cost of additional background noise and possible distortion. Preamplifier circuits are often included in a receiver and may be turned on or off.
prefix - In the United States, each call sign has a one-letter prefix (K, N, W), or a two-letter prefix (AA-AL, KA-KZ, NA-NZ, WA-WZ), and a one-, two-, or three-letter suffix separated by a numeral (0-9) indicating the geographic region. For example, WØ is a prefix for Colorado, while the call sign might have a suffix of ZYX for a call sign of WØZYX.
preselector - A circuit that tunes a receiver's signal amplifying circuitry for maximum sensitivity on a desired frequency range.
press-to-transmit - (See push-to-talk)
press release (PX) - (Archaic) An abbreviation used during the MacMillan polar expedition from 1923 to 1924.
primary service - For each International Telecommunications Union (ITU) region, each frequency band allocated to the amateur service is designated as either a secondary service or a primary service. A station in a secondary service must not cause harmful interference to, and must accept interference from, stations in a primary service.
primary station license - (See operator/primary station license)
printed circuit board (PCB) - A board used to mechanically support and electrically connect electronic components using conductive pathways, tracks, or signal traces etched from copper sheets laminated onto a non-conductive substrate.
priority channel - A channel a scanner will immediately switch to when a signal is present.
priority traffic - Emergency-related messages, but not as important as emergency traffic.
priority watch - A reception mode in which a selected frequency is periodically checked even when the radio is tuned to another frequency.
private line (PL) - (Repeater Term) A Motorola proprietary trademarked name for continuous-tone coded squelch system (CTCSS). (See continuous-tone coded squelch system)
Private Radio Bureau (PRB) - A group that administers the amateur radio services.
privileges - The frequencies and modes of communication that are permitted in an Federal Communications Commission (FCC) telecommunications service.
procedural signal - (CW Term) One or two letters sent as a single character that do not represent text per se, but have a special meaning in transmission. They are generally not copied down, but are a form of control character. Amateur radio operators use procedural signals in Morse code (CW) contacts as a short way to indicate the operator's intention. A couple of examples are K for "Go ahead" or AR for "End of message." A bar over the letters, such as AS for "Wait a second" indicates that the letters are sent as one character. Also known as proword and prosign.
product detector - A receiver circuit consisting of a beat frequency oscillator and additional circuitry for enhanced reception of Morse code (CW) and single sideband (SSB) signals.
programmable interface controller (PIC) - A family of Harvard architecture microcontrollers made by Microchip Technology, derived from the PIC1640 originally developed by General Instrument's Microelectronics Division.
programmable read-only memory (PROM) - A form of digital memory where the setting of each bit is locked by a fuse or antifuse. Such PROMs are used to permanently store programs.
propagation - the behavior of radio waves when they are transmitted, or propagated, from one point on the Earth to another, or into various parts of the atmosphere. Radio propagation is affected by the daily changes of water vapor in the troposphere and ionization in the upper atmosphere, because of the effects of the Sun.
prosign - (See procedural signal)
protocol - A method of encoding, packaging, exchanging, and decoding digital data.
proword - (See procedural signal)
Public Information Coordinator (PIC) - An appointee of the American Radio Relay League (ARRL) who is responsible for organizing, training, guiding, and coordinating the activities of each Public Information Officer (PIO) within an ARRL section.
Public Information Officer (PIO) - An appointee of the American Radio Relay League (ARRL) who establishes and maintains a list of media contacts in the local area, is a contact for local media, and carries out other duties as assigned by the ARRL.
pull the big switch - A synonym for going off the air.
pulse-code modulation (PCM) - A method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony, and other digital audio applications.
pulse modulation - A modulation method in which the timing, amplitude, and/or spacing of pulses of a transmitter's carrier are varied in order to convey information.
push-to-talk (PTT) A method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode using a thumb- or foot-activated switch. Also known as press-to-transmit.


To the top!   Q

Q-signals - (CW Term) Three-letter symbols specific to amateur radio beginning with Q to speed Morse code (CW) communication. They are similar to police 10 codes. Also known as Q-codes.
QEX Magazine - A bimonthly magazine published by the American Radio Relay League (ARRL) that covers topics related to amateur radio and radiocommunication experimentation. The magazine features advanced technical articles on the theory, design, and construction of radio antennas and equipment and is published in English with a worldwide subscription base.
QSL Bureau - A United States international amateur organization set up by American Radio Relay League (ARRL) to process QSL cards between countries that provides an inexpensive way to send and receive QSL cards. Canadian amateur radio operators use the Radio Amateurs of Canada's incoming QSL bureau. QSL is a radiotelegraph Q-signal for "Can you acknowledge receipt?" Also known as bureau, burro or buro.
QSL card - A postcard, usually 3.5 inches by 5 inches, sent to a station confirming a radio contact.
QSL manager - A person, usually an amateur radio operator, who manages the receiving and sending of QSL cards for a managed station. A QSL Manager is needed because the managed station either has difficulty handling the volume of incoming QSL cards, or the station is geographically located such that it is difficult or impossible for that station to accept and/or send QSL cards. It is very common for rare distant stations (DX) and DXpeditions to have a QSL Manager.
QSLL - reply card - (Archaic) (CW Term) A reply card to a received QSL card.
QST Magazine - A magazine for ham radio fans of the United States, it was first published in 1915 by the American Radio Relay League (ARRL).
quad antenna - A multi-element directional beam antenna with elements in the shape of a four-sided loop, approximately one wavelength in circumference.
quadrature amplitude modulation (QAM) - In single-sideband, the special case where one of the baseband waveforms is derived from the other, instead of being independent messages.
quadrature phase shift keying (QPSK) - A method of modulating a carrier in digital transmissions by changing its phase four times, with each change being represented by two binary digits. Also known as quadraphase phase shift keying.
quagi antenna - An antenna constructed with both quad and Yagi elements.
quality (Q) - A factor of a resonant circuit, it is the ratio of stored power to dissipated power in the reactance and resistance of the circuit. For antennas, the Q is inversely proportional to useable bandwidth, with reasonable standing-wave ratio (SWR). For example, an antenna with high Q will not provide a good SWR over a very wide range of frequencies.
quarter-wave antenna - quarter-wavelength antenna - A ground plane quarter-λ antenna constructed of a quarter-wavelength long radiating element placed perpendicular to the earth. The λ is a Greek small lambda. Also called quarter-wave vertical antenna and quarter-wave monopole antenna.
Quarter Century Wireless Association (QCWA) - An amateur radio club with local chapters in which membership is offered solely to operators who were first licensed twenty-five or more years ago.
quartz crystal - A crystal of silicon dioxide cut to vibrate at a particular frequency when an electric current is applied to it. Used in high stability oscillators.
Quebec - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter Q. Used in radio communication, particularly when spelling out a call sign.
question pool - The set of questions from which an amateur license exam is constructed. There is one pool for each license class.
question set - A series of examination questions on a given examination selected from the question pool.
Quiet Channel (QC) - A Radio Corporation of America (RCA) trademarked name for continuous tone coded squelch system (CTCSS). General Electric called it CG (Channel Guard).


To the top!   R

radial - A horizontal counterpoise element of a vertically polarized antenna, sometimes buried to act as a low resistance path to ground, and running away from the antenna. (See counterpoise)
radian - The standard unit of angular measure or phase, used in many areas of mathematics. An angle's measurement in radians is numerically equal to the length of a corresponding arc of a unit circle and equals 360/2π or 57.3 degrees. The π is a Greek small pi.
radiate - To emit energy in the form of waves as from an antenna.
radiation - The emission of energy, such as a radio wave. Ionizing radiation has sufficient energy to cause an electron to escape from an atom, creating a charged ion. Non-ionizing radiation is radiation that uses radio frequency (RF) energy for radio communication and is much less energetic.
radiation pattern - A graph showing how an antenna radiates and receives in different directions. An azimuthal pattern shows radiation in horizontal directions. An elevation pattern shows radiation at different vertical angles.
radiation resistance - That part of the total resistance of an antenna that results in radiation. The remainder generally results in loss of applied power as heat.
radio - An apparatus capable of receiving and transmitting messages between individuals, ships, planes, etc. over the airwaves. An Irish-Italian inventor, Guglielmo Marconi, is commonly credited for inventing radio in 1895. However, some eleven years earlier a dentist named Mahlon Loomis had actually gotten a patent for wireless telegraphy, and the electrical genius Nikola Tesla transmitted electrical energy though the electromagnetic spectrum before Marconi.
Radio-Television Manufacturers Association (RTMA) - A standards and trade organization for the consumer electronics industry in the United States. CEA works to influence public policy, hold events, conduct market research, and help its members and regulators to implement technical standards.
Radio Amateur Civil Emergency Service (RACES) - A part of the amateur radio service that provides radio communication for civil preparedness organizations during local, regional, or national civil emergencies.
Radio Amateurs of Canada (RAC) - A national amateur radio organization in Canada.
Radio Craft Magazine - (Archaic) The first issue of Radio-Craft was published in 1929 and by late 1943 it had dropped the hyphen from the title. In 1948 the title changed to Radio-Electronics. It was published under that title until 1992, changing at that point to Electronics Now and surviving until 1999.
radio control (R/C) - The use of radio signals to remotely control a device.
radio detection and ranging (radar) - An object detection system that uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio waves or microwaves which bounce off any object in their path. The object returns a tiny part of the wave's energy to a dish or antenna which is usually located at the same site as the transmitter.
radio direction finding (RDF) - The method of locating a transmitter by determining the bearings of received signals. This can refer to radio or other forms of wireless communication. By combining the direction information from two or more suitably spaced receivers or a single mobile receiver, the source of a transmission may be located in space by way of triangulation.
radio frequency (RF) - The rate of oscillation in the range of about 3 kilohertz (kHz) to 300 gigahertz (GHz), which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals. RF usually refers to electrical rather than mechanical oscillations. Mechanical RF systems, however, do exist. Although radio frequency is a rate of oscillation, the term radio frequency or its acronym RF are also used as synonyms for radio, that is, to describe the use of wireless communication, as opposed to communication by way of electric wires. Radio frequency energy is measured in watts.
radio frequency burn (RF burn) - A skin burn produced by coming in contact with exposed radio frequency (RF) voltages.
radio frequency carrier (RF carrier) - A steady radio frequency signal that is modulated to add an information signal to be transmitted. For example, a voice signal is added to the radio frequency (RF) carrier to produce a phone emission signal.
radio frequency choke (RF choke) - An inductor used to prevent or reduce the flow of radio frequency (RF) current.
radio frequence exposure (RF exposure) - Federal Communications Commission (FCC) rules estblish maximum permissible exposure (MPE) values for humans to radio frequency (RF) radiation. (See maximum permissible exposure)
radio frequency feedback (RF feedback) - Distortion of transmitted speech caused by radio frequency (RF) signals being picked up by the microphone input circuits.
radio frequency gain (RF gain) - (See gain)
radio frequency ground (RF ground) - The connection of radio equipment to earth ground to eliminate hazards from radio frequency (RF) exposure and to reduce radio frequency radiation (RFI).
radio frequency interference (RF interference) - A situation in which an inadvertent radiator (computer, power line, appliance, etc.) produces radio frequency (RF) energy that interferes with a receiver intended to receive RF energy. (See electromagnetic interference)
radio frequency radiation (RF radiation) - Waves of electric and magnetic energy. Such electromagnetic radiation with frequencies as low as 3 kilohertz (kHz) and as high as 300 gigahertz (GHz) are considered to be part of the radio frequency (RF) region.
radio frequency safety (RF safety) - Preventing injury or illness to humans from the effects of radio-frequency energy.
radio frequency signals (RF signals) - Any electrical signals with a frequency higher than 20,000 hertz (Hz), up to 300 gigahertz (GHz). Also known as radio signals.
radio frequency overload (RF overload) (See receiver overload)
radio guide (RG) - Guides, and there are many, to all things radio.
radio group - A group of ham radio afficionados as opposed to an electrical group or a telephone group. (3) A term as in RG-8 Coax, a thick cable with a velocity factor of 75.
radio horizon - The most distant point to which radio signals can be sent by line-of-sight propagation. (See line-of-sight propagation)
Radio Inspector (RI) - (Archaic) A government district level official.
radio message servers (RMS) - Mailbox stations that receive email transmissions using amateur radio for the connection to individual amateur radio operators.
Radio News Magazine - (Archaic) An American monthly technology magazine published from 1919 to 1971. The magazine was started by Hugo Gernsback as a magazine for amateur radio enthusiasts, but it evolved to cover all the technical aspects to radio and electronics. In 1929 a bankruptcy forced the sale of Gernsback's publishing company.
radio orienteering - (See amateur radio direction finding)
Radio Regulations - The latest International Telecommunication Union (ITU) regulations to which the United States is a party. Covering both legal and technical issues, it serves as an instrument for the optimal international management of the radio spectrum.
radio signals - (See radio frequency signals)
Radio Society of Great Britain (RSGB) - The British equivalent of the United States' American Radio Relay League (ARRL).
radio wave - radio waveform - An electromagnetic wave with a frequency greater than 20 kilohertz (kHz).
Radiocorp - (Archaic) Early shorthand for Radio Corporation of America (RCA).
radiogram - Formal written message traffic routed by a network of amateur radio operators through traffic nets.
radiosport - (See amateur radio direction finding)
radiotelephone - A communication system for transmission of speech over radio. (See phone)
radiotelephone distress frequency - An international distress and calling frequency for mobile radiotelephone stations, survival craft, and emergency position-indicating radio beacons. The radiotelephone distress frequencies are 2.182 megahertz (MHz) and 156.8 megahertz (MHz). The survival craft and maritime distress frequency is 243 megahertz (MHz) and the general aviation distress frequency is 121.5 megahertz (MHz).
radioteletype (RTTY) - (1) A telecommunications system consisting originally of two or more electromechanical teleprinters in different locations. (2) A mode that uses frequency-shift keying to form letters, numbers, and special characters for display on a printer or video monitor. (3) Keyboard-to-keyboard transmission mode originally conducted between special teletype machines. Now one of many modes that are frequently sent with a personal computer (PC) with a sound card.
Radiotron - (Archaic) A brand name for a Radio Corporation of America (RCA) vacuum tube. (See vacuum tube)
rag chew - Chatting informally by amateur radio. Also known as ragchew or rag chewing.
Rag Chewers Club (RCC) - (Archaic) Traditionally an introductory amateur radio award, it was issued by the American Radio Relay League (ARRL) to the operators of thousands of amateur radio stations and many long-time operators who could proudly claim to have received it as their first award in the 1950s and 1960s. Originally available to ARRL members for the price of a confirmed half-hour QSO and a self-addressed stamped envelope, and later for a fee, the award was issued by ARRL headquarters until 2004 when interest waned. The award was discontinued by the ARRL in 2004 and is now being offered through the Society for the Preservation of Amateur Radio (SPAR) organization.
random-length wire antenna - A multi-band antenna consisting of any convenient length of wire, connected directly to a transmitter or impedance matching network without the use of a feed line.
random access memory (RAM) - A form of computer data storage. A random-access device allows stored data to be accessed quickly in any random order. In contrast, other data storage media such as hard disks, CDs, DVDs, and magnetic tape, as well as early primary memory types such as drum memory, read and write data only in a predetermined order, consecutively, because of mechanical design limitations.
range - The longest distance over which radio communication can take place.
rat killing - Doing other things besides talking on the radio, such as, "Well, I'm going back to my rat killing."
reactance - The opposition to current that a capacitor or inductor creates in an alternating current (AC) circuit. Capacitors exhibit capacitive reactance and inductors exhibit inductive reactance. Reactance is measured in Ohms.
read-only memory (ROM) - A class of storage medium used in computers and other electronic devices that cannot be modified or only slowly or with difficulty.
readability, strength, tone (RST) - A system of numbers used for signal reports: Readability (1 to 5), Strength (1 to 9), Tone (1 to 9). On single-sideband phone, only R and S reports are used. The report is given as a series of three numbers, for example, 599, 579, 458. (See SINPO and S-meter)

RST REPORT
 
Readability (Voice and CW)
1Unreadable
2Barely readable, occasional words distiguishable
3Readable with considerable difficulty
4Readable with practically no difficulty
5Perfectly readable
 
Signal Strength (Voice and CW)
1Faint signals, barely perceptible
2Very weak signals
3Weak signals
4Fair signals
5Fairly good signals
6Good signals
7Moderately strong signals
8Strong signals
9Extremely strong signals
 
Tone (CW only)
1Sixty cycle AC or less; very rough and broad.
2Very rough AC; very harsh and broad
3Rough AC tone; rectified but not filtered
4Rough tone; some trace of filtering
5Filtered rectified AC; strongly ripple-modulated
6Filtered tone; definite trace of ripple modulation
7Near pure tone; trace of ripple modulation
8Near perfect tone; slight trace of ripple modulation
9Perfect tone; no trace of ripple modulation
 
Additions
If the signal has the characteristic steadiness of crystal control, add the letter X to the RST report.
If there is a chirp, add the letter C to the RST report.
If there is a click, add the letter K to the RST report.

reading the mail - (CW Term) To listen to a communication without participating.
real time - Communications that are taking place with no perceptible delay.
receive (RCV, RX) - To detect or pick up radio broadcast signals. (See receiver)
receiver (rcvr) - (1) A device that converts radio waves into signals that can be heard, seen or red by a computer. (2) (Archaic) When plural, an early synonym for headphones.
receiver incremental tuning (RIT) - A tranceiver control circuit that allows the receive frequency to be shifted from the transmit frequency by a small amount using frequency synthesis. On some radios it is called clarifier.
receiver overload - Interference to a receiver caused by a strong radio frequency (RF) signal that forces its way into the equipment. A signal that overloads the receiver RF amplifier (or front end) causes front-end overload. Also known as RF overload.
receiving converter - A device that shifts the frequency of incoming signals so that a receiver can be used on another band.
reception report - A letter written to a radio station supplying details about a station's signal and the programming heard in order to solicit a QSL card from the station.
recharge - To restore an electric charge to a battery or a battery-operated device by connecting it to a device that draws power from another source of electricity.
reciprocal - Bearing on or binding each of two parties equally
reciprocal operating authority - Permission for amateur radio operators from another country to operate in the United States using their home license. This permission is based on various treaties between the United States government and the government of other nations.
rectifier - A diode that allows current to pass through it in only one direction and is used in power supplies and power conversion circuits.
rectify - To convert alternating current (AC) to direct current (DC).
reflected path - The route that a transmitting antenna's signal takes to a receiving antenna when it is reflected by large objects such as buildings or terrain. (See direct path)
reflected power - Non-radiated power in a transmission line that is dissipated as heat when a transmitter is mismatched to the antenna or load.
reflection - Signals that travel by line-of-sight propagation that are reflected by large objects such as buildings or terrain.
reflector - (1) A parasitic element behind the driven element in a Yagi and some other directional antennas that focuses the radiated signal toward the forward direction. (See Yagi) (2) A server that allows multiple nodes or repeaters to be linked together at the same time. (3) A mail list that forwards news to the subscribers, for example, DX Reflector or Contest Reflector.
refract - To bend. Electromagnetic energy is refracted or bent when it passes through a boundary between different types of material much as light is refracted as it travels from air into water or from water into air. Radio waves refract as they travel through the ionosphere.
region - An administrative area of the United States as defined by the International Telecommunications Union (ITU).
regulation - The ability of a power supply to control output volatage.
regulator - A device that maintains a constant output voltage over a range of load currents and input voltages.
relay - A switch operated by an electromagnet.
remote base - A high-frequency (HF) amateur station set up to operate by remote control, usually by connecting to the Internet through a computer.
remote control - The use of a control operator who indirectly manipulates the operating adjustments in the station through a control link to achieve compliance with the Federal Communications Commission (FCC) Rules.
remote receiver - (Repeater Term) A receiver at a separate location from a repeater to extend the repeater's listening range.
remote tuned antenna - Includes the Scorpion, all motorized screwdriver antennas, and some base-loaded antennas. repeater - (Repeater Term) A receiver/transmitter that listens for a transmission on one frequency, usually a weak one, and re-transmits it, usually at higher power, on another frequency for extended communication. Repeaters are usually placed at high geographical locations for access by very-high frequency (VHF) and ultra-high frequency (UHF) hand-held and mobile transceivers to extend the range of a transmission. The separation between these two frequencies is referred to as the offset. (See offset)
Repeater Council - (Repeater Term) A voluntary regional amateur organization coordinating repeater frequency pair assignments to minimize interference. As no individual amateur group owns any given radio frequency, a council does not exercise legal authority to force individual repeater operators onto a specific frequency, height, location, power, or directional pattern. Nonetheless, amateurs are obligated by national laws to avoid interference to other amateur stations and official regulatory agencies will resolve interference complaints between repeater operators by forcing uncoordinated repeaters to move off frequencies where their operation interferes with any coordinated repeater.
Repeater Directory - (Repeater Term) An annual American Radio Relay League (ARRL) publication or software program that lists repeaters in the United States, Canada, and other areas.
repeater etiquette - (Repeater Term) The customary code of polite behavior in society or among members of a particular profession or group. The following are a few repeater etiquette hints:

REPEATER ETIQUETTE

repeater station - An amateur station that automatically retransmits the signals of other stations.
resistance - The ability to oppose an electric current.
resistive divider - A two-resistor circuit used to reduce an applied voltage.
resisitivity - The measure of how strongly a material, such as plastic, opposes the flow of electric current.
resistor - An electronic component with a specific value of resistance used to oppose or control current through a circuit.
resonance - In an electrical circuit or antenna, the frequency at which inductive reactance and capacitive reactance are absent or balanced such that their effects cancel. A resonant circuit will respond strongly to a particular frequency, and much less so to differing frequencies which allows the radio receiver to discriminate between multiple signals.
resonant circuit - A circuit in which the inductive and capacitive reactances are equal and cancel, leaving just the resistive part of the circuit, and that exhibits resonance at one or more frequencies.
resonant frequency - The desired operating frequency of a tuned circuit. In an antenna, the resonant frequency is one where the feed-point impedance contains only resistance.
resonator - A device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others.
rettysnitch - A fictional torture device for bad hams. (Also see Wouff Hong)
reverse biased - Not conducting.
rig - A wireless amateur-radio transmitter, receiver, or transceiver.
ripple - The residual alternating current (AC) left over after rectification and filtering when an AC supply has been converted to direct current (DC).
rock bound - A synonym for a crystal controlled oscillator used to stabilize frequencies in transmitters and receivers.
rock crusher - (Archaic) A slang term for a spark transmitter.
roger - (Archaic) The letter R has been used since the early days of Morse code (CW) to indicate that "The message has been received." The voice code equivalent for R is Roger. Wilco is radio slang for "Will Comply." So, Roger Wilco means "The message has been received and I will comply."
roger beep - A tone that sounds when a radio operator un-keys a microphone. The tone can be short, long, or even a combination of multiple tones, such as, a dit-dah-dit sent at the end of a transmission. The intention of the roger beep is to let the other operator in the conversation and any other people on the radio know when the person talking has finished.
Romeo - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter R. Used in radio communication, particularly when spelling out a call sign.
root mean square (RMS) - A statistical measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative, for example, in sinusoids. RMS is used in various fields, including electrical engineering.
root mean square voltmeter (RMS voltmeter) - An alternating current (AC) voltmeter to read the root mean square voltage level.
rotary inductor - A variable inductor in which a sliding contact is moved along the coil as it is rotated.
rotate - To take batteries in and out of service, preventing continuous use.
rotator - A motorized device to rotate a directional antenna. Years ago, this device was simply called a rotor.
rotor - (See rotator)
round table - A contact in which several stations take turns transmitting in a rotating format.
rover - A station that operates from several grid squares or counties during a contest.
RS-232 - (Archaic) A standard that defined a serial computer connection arrangement. The standard specified pin-outs for a 25-pin (DB25) and 9-pin (DB9) subset, signal relations, voltage levels, and maximum cable lengths. RS-232 was renamed EIA232 in the 1990s.
rubber duck antenna - A shortened flexible rubber-coated antenna used with hand-held very-high frequency (VHF) and ultra-high frequency (UHF) scanners, transmitters, receivers, and transceivers. Also known as rubber ducky antenna.
RW open protocol (RWOP) - (CW Term) A system based on the electronic message unit (EMU) of the British tactical radio that used standard frequency-shift keying to protect against reception errors. It was created by Paul R. Signorelli WØRW. (See electronic message unit)


To the top!   S

S-line - (Archaic) A line of transmitters, receivers, amplifiers, and other accessories offered by the Collins Radio Company from 1958 to 1975.
safety ground - A ground connection intended to prevent shock hazards.
safety interlock - A switch that automatically turns off alternating current (AC) power to a piece of equipment when the cover is removed.
scan - To continually sweep and monitor frequencies or a set of memory channels looking for active signals.
scan edge - The start or end frequencies for a scanning range.
scanner - A radio receiver that automatically tunes through a sequence of user-selected frequencies.
scanning - Rapidly switching between a list of frequencies to listen for an active channel. Tone scanning determines what sub-audible access tones are being used.
scatter - Radio wave propagation by way of random scattering of a signal directly off the ionosphere overhead or off an obstruction. Scatter signals are usually weak.
schedule 40 poly-vinyl chloride - A poly-vinal chloride plastic pipe with thicker walls than some other types and a popular material often used as antenna structural support or insulator.
schematic diagram - Semi-pictorial record of the circuits and electrical connections in a piece of electronic equipment by using symbols to repersent the electrical components.
schematic symbol - A standardized symbol used to represent an electrical or electronic component on a schematic diagram.
scope - (See oscilloscope)
scratch-pad memory - Temporary frequency memories for quick access.
screwdriver antenna - A motorized mobile multi-band high-frequency (HF) antenna invented by Don Johnson W6AAQ in 1991. A modified battery-powered screwdriver is used to move the loading coil in and out of the mast section. It is not as efficient as some claim because of the capacitive end affect caused by the requisite large diameter mast.
search - A feature in certain receivers that will scan a frequency range at certain increments (such as 1 kHz or 5 kHz) and pause on any frequency where a signal is present.
search and rescue (SAR, S&R) - The search for and provision of aid to people who are in distress or imminent danger. Amateur radio is used to communicate on a search and rescue.
secondary allocation - The attribute of a range of frequencies over which a radio user (amateur or otherwise) shares the band with users of a different license type. Secondary users must not interfere with primary users and must accept interference from primary users.
secondary circuit - (Archaic) An early synonym for the grid circuit of a vacuum tube circuit design. (See vacuum tube)
secondary coupling - In a lightning environment, it is a transformer-like electro-magnetic coupling between powerful cloud-to-earth lightning strikes and nearby above ground wires and cables. A secondary coupling typically creates above-ground surges in those wires.
secondary service - (See primary service)
Section Emergency Coordinator (SEC) - An appointee of the American Radio Relay League (ARRL) who takes care of all matters pertaining to emergency communications and the Amateur Radio Emergency Service (ARES) on an ARRL sectionwide basis. The SEC is the assistant to the Section Manager (SM) for emergency preparedness.
Section Manager (SM) - An American Radio Relay League (ARRL) position, the Section Manager is accountable for carrying out the duties of the office in accordance with ARRL policies established by the board of directors who act in the best interests of amateur radio.
Section Traffic Manager (STM) - An appointee of the American Radio Relay League (ARRL) who coordinates all radio traffic efforts within a section so that routings within the section and connections with other networks and digital traffic nodes will result in orderly and efficient traffic flow.
selectivity - The ability of a receiver to detect weak signals.
self-addressed stamped envelope (SASE) - An unused envelope sent to another amateur radio operator with the sender's address and with return postage affixed.
self-controlled oscillator - (Archaic) An oscillator that is variable in frequency, as opposed to one that is crystal controlled.
self-discharge - The internal loss of energy without an external circuit. (See discharge)
self supporting - Not requiring guy wires to remain vertical.
semi-break-in - (CW Term) A Morse code (CW) station using voice-activated dialing (VOX) or other means to automatically switch from transmit to receive during sending pauses. Such stations generally cannot hear received signals between code characters or words needing a somewhat longer cessation in sending for automatic switch over from transmit to receive. The switch to transmit automatically occurs when the key is depressed. This is common in single-sideband (SSB) transceivers being used for Morse code (CW).
semi-duplex - A mode of operation in which transmit and receive is accomplished on different frequencies alternatively.
semiconductor - (1) An element that is normally an insulator but which can, under certain physical conditions, be made to conduct. (2) An electrical component constructed from semiconductor material.
selectivity - The ability of a receiver to separate two closely spaced signals.
sensitivity - A receiver's ability to detect and receive weak signals.
separation - To split the difference in kilohertz (kHz) between a repeater's transmitter and receiver frequencies. Repeaters that use unusual separations, such as 1 megahertz (MHz) on 2 meters (m), are sometimes said to have odd splits. (See split)
sequential system - One of three methods used to select a call sign for amateur station over-the-air identification purposes. (See call-sign system)
series circuit - An electrical circuit in which all the electrons must flow through every part of the circuit and there is only one path for the electrons to follow.
series inductance - An inductance used to cancel a residual capacitance.
service - A set of regulations by the Federal Communications Commission (FCC) that defines a certain type of telecommunications activity.
service entrance panel - A device generally located immediately behind the killowatt-hour meter that provides mains electricity fusing for the electric service wires. It then distributes the electrical load to a number of separately fused electrical circuits for customer equipment.
set mode - An operational mode used for radios to set less-frequently used control features.
shack - The room where an amateur radio operator keeps his or her wireless station equipment, such as a closet, or space in a basement, living room, or corner of a bedroom, and from which the radio station is operated. The term dates from the very early days of radio when those that could afford it built a small shack in the back yard to house their often large (many pieces of equipment), noisy (crackling spark gaps and sometimes whining motors and generators), smelly (ozone from the arcing spark gap and sparking motor/generator brushes), dangerous (very high voltages on fully exposed wiring and equipment), sloppy (chemical rectifiers that routinely boiled over and batteries containing spillable acid which generated explosive gases while being recharged) amateur station. Also known as static room.
shadowing - Mounting an antenna too close to the body of a vehicle. Doing so increases shunt capacitance, thus lowering efficiency.
shape factor - A receiver's selectivity measured at the 6 and 60 decibels (dB) rejection points.
shared non-protected (SNP) - (Repeater Term) In repeater coordination, an input/output (I/O) frequency pair on which no fixed or permanent repeater stations have been deployed. These frequencies remain available for temporary use only within a very limited coverage area by portable public service, emergency, search and rescue operations, or short experiments. Individual temporary repeaters on these frequencies are not regionally-coordinated, so are not protected from mutual interference with other temporary repeaters on the same frequency. Also known as shared non-protected frequency.
shared non-protected frequency (SNPF) - (See shared non-protected)
shield - The conductor in a cable that is designed to be at ground potential.
shielding - A coating surrounding an electronic circuit with conductive material to block radio frequency (RF) signals from being radiated or received.
short circuit - An electrical circuit in which the current does not take the desired path, but finds a shortcut instead. Often the current goes directly from the negative power-supply terminal to the positive one, bypassing the rest of the circuit.
short skip - Propagation by way of the ionosphere over a distance of a few hundred miles or less.
shortwave (SW) - Radio communication using the upper medium frequency (MF) and all of the high-frequency (HF) portion of the radio spectrum between 1,800 and 30,000 kilohertz (kHz). (See high frequency)
shortwave listener (SWL) - One who listens to shortwave.
shortwave listening (SWL) - The hobby of listening to shortwave radio broadcasts located on frequencies between 1700 kilohertz (kHz) and 30 megahertz (MHz).
side load - Also known as sidelobe. (See lobe)
Side Winders On Two (SWOT) - A radio club promoting single sideband (SSB) transmissions on the 2-meter (m) band.
sideband - A radio frequency (RF) signal that results from modulating the amplitude or frequency of a carrier. An amplitude modulation (AM) sideband can be either higher in frequency (upper sideband or USB) or lower in frequency (lower sideband or LSB) than the carrier. Frequency modulation (FM) sidebands are produced on both sides of the carrier frequency. (See single sideband and double sideband)
sideband line (SB line) - (Archaic) A line of transceivers (SB10x), transmitters (SB40x), receivers (SB30x), amplifiers (SB2xx) and other accessories (SB6xx) offered by the Heathkit Radio Company in the 1960s and 1970s. They were considered the poor man's Collins because of the similarities and much lower cost.
sidewinder - A slang term for a single sideband (SSB) station.
Sierra - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter S. Used in radio communication, particularly when spelling out a call sign.
sign - (Archaic) An identifier for a specific operator at a station, usually two letters, used to distinguish one operator from another, and is a carry over from the days before government issued call signs when two-letter identifiers were used. Also archaically known as sine.
signal - A radio emission.
signal-strength meter (S-meter) - Originally used in the early 20th century as part of the readability, strength, tone (RST) reporting code, this was a subjective assessment of the received signal, based on a 9-point scale and reported in S-units. It is often provided on communication receivers, such as amateur radio receivers or shortwave broadcast receivers. The scale markings are derived from a subjective system of reporting signal strength from S1 (faint, barely perceptible signals) to S9 (very strong signals) as part of the RST code. There is often an additional scale above S-9 (S-9 + 10) calibrated in decibels (dB). (See readability, strength, tone)
signal-to-noise ratio (SNR, S/N) - (CW Term) A measure used to compare the level of a desired signal to the level of background noise. The better the SNR ratio, the better the quality of the signal and the easier it is to decode.
signal generator - A device that produces a low-level signal that can be set to a desired frequency.
signal report - An evaluation of the transmitting station's signal and reception quality.
signal to noise and distortion (SINAD) - A measure of the quality of a signal from a communication device.
signing off - Ending the work with a particular station.
Silent Key (SK) - A deceased amateur radio operator.
simplex - A communication operational mode in which transmit and receive frequencies are the same. Most often used when communicating directly, in other words, not used when operating by way of voice repeaters. Also called talk around. (See duplex)
simplex repeater - A radio that has a digital audio store-and-forward relay system that produces results similar to that of a conventional repeater.
simplex teletype over radio (SITOR) - (See amateur teleprinting over radio)
Simulated Emergency Test (SET) - A nationwide exercise in emergency communication, administered by American Radio Relay League (ARRL) Emergency Coordinators and Net Managers. Both the Amateur Radio Emergency Service (ARES) and the National Traffic System (NTS) are involved. The SET weekend gives communicators the opportunity to focus on the emergency communication capability within their community while interacting with NTS nets.
sine - A trigonometric function of an angle. The sine of an angle is defined in the context of a right triangle: it is the ratio of the length of the side opposite that angle to the length of the hypotenuse.
sine wave - A waveform with an amplitude equal to the sine of frequency times time.
single-pole, double-throw (SPDT) - A switch that connects one center contact to one of two other contacts.
single-pole, single-throw (SPST) - A switch that only connects one center contact to another contact.
single sideband (SSB) - A modulation mode of voice operation on the amateur radio bands in which one sideband and the carrier are removed. SSB is a form of amplitude modulation where the amplitude of the transmitted signal varies with the voice signal variations. SSB signals have a lower sideband (LSB), which is that part of the signal below the carrier, and an upper sideband (USB), which is that part of the signal above the carrier. SSB transceivers allow operation on either LSB or USB.
single-sideband suppressed-carrier (SSB-SC) - A refinement of amplitude modulation that more efficiently uses transmitter power and bandwidth.
single-signal receiver - (Archaic) A superheterodyne design in the 1930s using interstage filtering for added selectivity. Also known as S.S. receiver.
sinusoid - A mathematical curve that describes a smooth repetitive oscillation. It is named after the function sine, of which it is the graph.
Six Meter International Radio Klub (SMIRK) - A club that promotes the use of the 6-meter (m) band, organized in 1973 by a group of San Antonio, Texas-area amateurs active on the 50 to 54 megahertz (MHz) amateur band.
skip - A radio phenomenon in which signals are reflected or refracted by the atmosphere and return to earth in unexpected places, far away from the normal reception zones. In between transmitter and receiver there is a zone where no transmissions can be heard.
skip distance - The shortest distance, for a fixed frequency, between transmitter and receiver.
skip zone - The distance between the point of no reception and the closest point of reception. It is an area of poor radio communication, too distant for ground waves and too close for sky waves.
sky-wave propagation - The method by which radio waves travel through the ionosphere and back to Earth. Sky-wave propagation has a far greater range than line-of-sight and ground-wave propagation. Travel from the Earth's surface to the ionosphere and back is called a hop. Also known as skip. (See skip)
sky wave - (See sky-wave propagation)
skyhook - A slang word for an antenna. (See antenna)
SkyWarn - An organization of trained volunteer storm spotters for the National Weather Service (NWS). (See National Weather Service)
slash - Slang for the fractional bar (/ or –), a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight-fifths, or three-quarters. It may be either an inclined bar from bottom left to upper right or a horizontal bar. It is differentiated from a stroke, such as found in the numeral Ø.
slim - A synonym for someone pretending to be a distant station (DX), usually rare, that is supposed to be on the air. For example, someone in southern Argentina pretending to be on Heard Island.
slop jar - (Archaic) A synonym for an electrolytic rectifier. Electrolytic rectifiers were common in the late 1920s and early 1930s. One cell consisted of two strips of dissimilar metals in a caustic potash, or lye solution. Many cells were needed for a high voltage supply.
sloping dipole antenna - Any kind of dipole antenna installed so the dipole wires slope from one end to the other. Often created when one end of the dipole is attached high on a tower and the other to some lower support.
slow-scan television (SSTV) - Graphic communication in the bandwidth required for a voice signal, usually still images by way of radio in monochrome or in color.
slow blow - (See fuse)
slug - A short, cylindrical unit that is inserted into a wattmeter that allows the unit to read power (watts) for a particular frequency range. A slug always has a finite frequency range and a maximum power rating. By swapping out different slugs, the wattmeter can be used for many different frequencies and power ranges.
SO-239 - socket-239 - Female antenna connector used on most high-frequency (HF) radios, it is a World War II threaded radio frequency (RF) connector design from an era when ultra-high frequency (UHF) referred to frequencies over 30 megahertz (MHz). Originally intended for use as a video connector in radar applications, the connector was later used for radio frequency (RF) applications. It mates the PL-259 plug.
Society for the Preservation of Amateur Radio (SPAR) - A non-partisan group of concerned amateur radio operators working together to ensure the vitality of the amateur radio service by promoting technical abilities among amateur radio operators.
software-defined radio (SDR) - Radio system in which the majority of processing is performed in a personal computer (PC) using special software that defines the radio's functionality.
solar cycle - An 11 year cycle of intense sunspot activity. High activity equals good distant station (DX) propagation, low activity equals poor DX propagation.
Solar Flux Index (SFI) - A measure of the radio noise on 2800 megahertz (MHz) (2.8 GHz), it is a gauge of solar particles and magnetic fields reaching our atmosphere. Higher numbers mean more solar wind is reaching the earth thus better propagation.
solder lug - An electrical connector that has a toothed hole to fit under a machine screw or nut. It includes a protrusion with one or more holes designed as a place for wires to be soldered.
soldering copper - (Archaic) A soldering iron in the 1920s which were available electrically heated and stand-alone for heating over a flame.
solid state - Circuitry containing no vacuum tubes.
SOS or SOS - (CW Term) A Morse code (CW) call for emergency assistance. In popular usage, SOS became associated with such phrases as save our ship, save our souls, and send out succour. These may be regarded as mnemonics, but SOS does not stand for anything and is not an abbreviation, acronym, or initialism. (See distress call)
source - (See transistor)
Space Amateur Radio Experiment (SAREX) - (Archaic) SAREX has been superseded by the Amateur Radio on the International Space Station program. (See Amateur Radio on the International Space Station)
space frequency - In frequency-shift keying, the lower of the two frequencies used. (See mark frequency)
space station - An amateur radio station located more than 50 kilometers (km) above the Earth's surface. (See Amateur Radio on the International Space Station)
space telemetry - A one-way transmission from a space station of measurements made from the measuring instruments in a spacecraft, including those relating to the functioning of the spacecraft.
spark gap - (Archaic) An early transmitter design which used electrical sparks to generate radio frequency oscillations.
speaker (SP) - Short for loudspeaker, it is a device that converts electrical impulses into sound.
speaker microphone (speaker mic) - An optional accessory for a hand-held transceiver containing both a small speaker and a microphone.
special-event system - One of three methods used to select a call sign for amateur station over-the-air identification purposes. (See call-sign system)
special event - A radio operating event, usually on high-frequency (HF), in which a group or organization celebrates an event or holiday by making contacts and offering special QSL cards or certificates to confirm the contact. Ham radio magazines, such as QST, usually publish a monthly list of special events.
special license - (Archaic) A license granted for some stations to operate at wavelengths above 200 meters (m).
specific absorption rate (SAR) - The rate at which radio frequency (RF) energy is absorbed into the human body. Maximum permissible exposure (MPE) limits are based on whole-body SAR values.
spectrum - The range of electromagnetic signals. The radio spectrum includes signals between audio frequencies (AF) and infrared (IR) light.
speech compression - Increasing the average power of a voice signal by amplifying low-level components of the signal more than high-level components. Also called compression and speech processing.
speech processor - A circuit that increases the average level of the modulating signal applied to a transmitter.
splatter - Undesired emissions resulting from overdriving an amplifier or modulator, causing distortion.
split - (1) (Repeater Term) An operational mode in which the transmit and receive frequencies are different. Repeaters that use unusual separations, such as 1 megahertz (MHz) on 2 meters (m), are sometimes said to have odd splits or separation. (See offset) (2) Distant stations (DX) often operate split, that is, transmitting on one frequency and listening at a different frequency or range of frequencies. This avoids congestion on the DX transmit frequency.
split channel - A frequency located between standard frequency allocations, such as the 10 kilohertz (kHz) spacing of amplitude modulation (AM) broadcast band frequencies or coordinated repeater frequencies.
split beads - (See electromagnetic interference sleeves)
sporadic E-layer skip (sporadic E-skip) - Unexpected and unpredictable propagation using refraction in the atmospheric E-layer.
spot frequency net - (Archaic) A net where everyone is on the same frequency which was a novelty in the late 1920s and 1930s.
spread spectrum - A modulation method that spreads transmitter energy across a relatively wide frequency range according to a modulating code.
spurious emissions - Signals from a transmitter on frequencies other than the operating frequency. Also known as spurs.
spurs - (See spurious emissions)
squeak box - (Archaic) A spark coil, or spark coil-based transmitter.
squelch (SQL) - A circuit that mutes the receiver when no signal is present, thereby eliminating band noise.
squelch tail - (Repeater Term) A brief bit of noise heard between the end of a radio transmission and the reactivation of the receiver's squelch circuit.
spread-spectrum emissions (SS) - Emissions using bandwidth-expansion modulation having designators with A, C, D, F, G, H, J, or R as the first symbol; <X> as the second symbol; and <X> as the third symbol.
standard-definition television (SD) - A television system that uses a resolution that is not considered to be high-definition television (HDTV).
standard frequency (SF) - (Archaic) An initialism for standard frequency, used in the 1930s.
standing-wave ratio (SWR) - (1) The ratio of power sent down a feed line from the transmitter to the power reflected back through the feed line to the transmitter. A ratio of 1 to 1 is ideal; anything higher than 2 to 1 usually indicates a problem in the feed line or antenna. (2) A measure of how much radio energy sent into an antenna system is being reflected back to the transmitter.
standing-wave ratio meter (SWR meter) - A measuring instrument used to measure standing-wave ratio (SWR) that can indicate when an antenna system is working well. (See standing wave ratio)
standing wave - The vector sum of two waves, in ham radio this most usually refers to the forward and reflected waves in a feed line.
State Government Liaison (SGL) - An appointee of the American Radio Relay League (ARRL) who collects and promulgates information on state legislation and regulation affecting amateur radio; and guides, encourages and supports individual radio amateurs and clubs in representing the interests of the amateur radio service at all levels, including the federal level.
static - A random signal with a constant power spectral density. In other words, a signal that contains equal power within any frequency band with a fixed width. Also known as white noise.
static room - (Archaic) An early term for a ham shack.
station grounding - An electrical connection of a circuit or conductor eventually to the earth. Connecting all of one's station equipment to a good earth ground improves both safety and station performance.
station identification - The transmission of a transmitter's identifying information (usually the call sign), required by law at least every ten minutes during and at the end of a contact.
station license - An amateur radio license. In some countries, an amateur radio license is necessary in order to purchase or possess amateur radio equipment. (See operator/primary station license)
stinger antenna - (See whip antenna)
stopband - A band of frequencies, between specified limits, through which a circuit does not allow signals to pass, or the attenuation is above the required stopband attenuation level.
store and forward - A system for the receipt, storage, and later retransmission of packet radio messages.
straight key (SK) - (CW Term) A non-electronic Morse code (CW) key with one paddle. (See key)
Straight Key Century Club (SKCC) - A club promoting the use of hand keys for Morse code (CW) communication.
strapping - (See bonding)
strays - (Archaic) Another word for static.
strength, interference, noise, propogation, overall (SINPO) - A reporting system used by radio hobbyists to indicate how well a station was received: S equals Strength, I equals Interference, N equals Noise, P equals Propagation, O equals Overall. Reported as SINPO <4-digit number>. (See readability, strength, tone and S-meter)
strength unit (S-unit) - Unit of measure on S-meters (m). Each S-unit is intended to represent a factor of 2 in input voltage at the receiver antenna terminals. (See signal-strength meter)
stub - A length of transmission line that is open or shorted at one end. It is effectively a capacitor or inductor, depending on length, and can be used to achieve a match if connected at a selected point in the basic transmission line.
subminiature version A (SMA) - A connector for an antenna, usually used on hand-held scanners, transmitters, receivers, and transceivers.
suffix - In the United States, each call sign has a one-letter prefix (K, N, W), or a two-letter prefix (AA-AL, KA-KZ, NA-NZ, WA-WZ), and a one-, two-, or three-letter suffix separated by a numeral (0-9) indicating the geographic region. For example, WØ is a prefix for Colorado, while the call sign might have a suffix of ZYX for a call sign of WØZYX.
Summits On The Air (SOTA) - An amateur radio operating award program, it is an international event in which operators gain points from contacts to and from mountain summits over 500 meters (m).
sunspot - A dark storm spot on the sun's surface responsible for radiation that increases ionization level and consequently long distance propagation by way of the ionosphere. When there are few sunspots, long-distance high-frequency (HF) radio propagation is poor on the higher-frequency bands. When there are many sunspots, long-distance HF radio propagation improves.
sunspot cycle - The number of sunspots increases and decreases in a predictable cycle that lasts about 11 years. The broader sunspot cycle is 22 years because the polarity of the sunspots reverse every 11 years.
sunspot number (SSN) - A quantity that measures the number of sunspots and groups of sunspots present on the surface of the sun.
super-high frequency (SHF) - The frequency range of 3 to 30 gigahertz (GHz).
superheterodyne - A classic receiver architecture in which an incoming signal is beat, or heterodyned, with a signal generated in the local oscillator (LO) to translate the incoming signal to an intermediate frequency for processing. The receive frequency is changed by moving the LO to shift a different incoming frequency to the same intermediate frequency (IF). This allows the same circuit elements to process signals of different frequencies providing consistency of operation and performance. (See heterodyne)
surface-mount technology (SMT) - A method of mounting minuscule components on circuit boards without leads.
surface wave - (See ground wave)
swinging - (1) (Archaic) A synonym for fading. (2) (Archaic) The behavior of a signal having an unstable frequency.
swishing - (CW Term) A synonym for changing the frequency of a transmitter while it is keyed.
switch - A device used to connect or disconnect electrical contacts.
switching power supply - A power supply that uses switching transistors (ON-OFF) to increase the efficiency of the power conversion, rather than the simple transformer/rectifier design of traditional power supplies.
synchronous detection - An ingenious method of processing an amplitude modulation (AM) signal to improve audio quality and reduce interference from adjacent stations. It is similar to exalted carrier reception, but the replacement carrier tuning and tracking is done automatically by the receiver.


To the top!   T

T-match - A double-Gamma match that provides a balanced connection to an antenna. The circuit gets its name because it looks like the letter T. (See Gamma match)
T pad - One of the possible configurations used in attenuators. (See attenuator)
tactical call signs - Names used to identify a location or function during local emergency communication.
tactical communications - A first-response communication under emergency conditions that involves a few people in a small area.
talk-in (TI) - A term for when a volunteer at a hamfest mans a radio and sets up on a repeater to provide general information and directions.
talk around - (See simplex)
Tango - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter T. Used in radio communication, particularly when spelling out a call sign.
tap - An electrical connection made to some point between the end terminals of a transformer coil or other component. Also tapping.
Technical Coordinator (TC) - An appointee of the American Radio Relay League (ARRL) who coordinates all technical activities within an ARRL section.
Technical Specialist (TS) - An appointee of the American Radio Relay League (ARRL) who supports the Technical Coordinator (TC) in two main areas of responsibility: radio-frequency interference and technical information.
Technician Class The current entry-level-1 license that garners all ham radio privileges above 30 megahertz (MHz), including the popular 2-meter (m) band. Many Technician Class licensees enjoy using small, 2-meter hand-held radios to stay in touch with other hams in their area. Technicians may operate frequency modulation (FM) voice, digital packet or computers, television, single-sideband voice, and several other interesting modes. You can even make international radio contacts by way of satellites, using relatively simple station equipment. Technician licensees now also have additional privileges on certain high-frequency (HF) frequencies and may also operate on the 80, 40- and 15-meter bands using Morse code (CW), and on the 10-meter band using Morse code (CW), voice, and digital modes. It does not require familiarity with Morse code.
telecommand - A one-way transmission to initiate, modify, or terminate functions of a device at a distance.
telecommand station - An amateur station that transmits communications to initiate, modify, or terminate functions of a space station.
telegraph - (CW Term) The long-distance transmission of messages without the physical exchange of an object bearing the message. Thus beacons, flag semaphore, radiotelegraphy, reflected-light signals, and smoke signals are methods of telegraphy whereas pigeon post is not.
telegraph key - (See key
telegraphy - (CW Term) The transmission of information in Morse code (CW) and radioteletype (RTTY) format.
telemetry - A one-way radio transmission used for tracking and measurement data.
telephones - (Archaic) An early synonym for headphones in the early 1920s. Also known as receivers.
telephony - The transmission of information in voice format.
teleprinter - A machine that can convert keystrokes, or typing, into electrical impulses. The teleprinter can also convert the proper electrical impulses back into text. Computers have largely replaced teleprinters for amateur radioteletype work.
telescoping antenna - An antenna made of concentric tubular parts that slide into themselves so that the antenna becomes smaller. It may be motorized or unmotorized.
television (TV) - A system for transmitting visual images and sound that are reproduced on screens, chiefly used to broadcast programs for entertainment, information, and education.
television interference (TVI) - Interruption of television reception caused by another signal.
telex-over-radio (TOR) - (Archaic) A radio station in England provided worldwide maritime communication and long-range aeronautical communication beginning in 1928. During the 1950s and 1960s, there was a steady increase in traffic levels, and the TOR system started operations. The long-range services ceased at midnight on 31 August 1999.
Telnet - A remote terminal protocol that is fundamental to the operation of the Internet Protocol (IP).
temperature-compensated crystal oscillator (TCXO) - A heated crystal oscillator used for better frequency stability.
temperature coefficient - The amount a component value changes as a function of change in temperature.
temperature inversion - A condition in the atmosphere in which a region of cool air is trapped beneath warmer air.
temporary state of communication emergency - When a disaster disrupts normal communication in a particular area, the Federal Communications Commission (FCC) can declare this type of emergency. Certain rules may apply for the duration of the emergency.
ten-ten - A club promotion of the use of the 10-meter (m) band. Also known as 10-10 or 10-X.
tera- (T-) - One trillion, or the metric prefix for 1012, or times 1,000,000,000,000.
terminal - An inexpensive piece of equipment that can be used in place of a computer in a packet radio station.
terminal-node controller (TNC) - (1) A device used to convert digital signals from a personal computer (PC) into an analog form that can be transmitted by radio and to convert received analog signals into digital form for display on a personal computer (PC) monitor. It includes a modem and implements the rules of a protocol. (2) A device that groups characters into packets, generates modem tones, and implements the X.25 protocol used for various digital modes of transmission.
termination - A load or antenna connected to a transmission line.
test - Emissions containing no information having the designators with N as the third symbol. Test does not include pulse emissions with no information or modulation unless pulse emissions are also authorized in the frequency band.
test point (TP) - A location within an electronic circuit that is used to either monitor the state of the circuitry or to inject test signals.
that is (i.e.) - An abbreviation for the Latin phrase id est. It means that is and is usually followed by a comma. (See e.g.)
thermionic valve - (See vacuum tube)
third-party communications - Messages passed from one amateur radio operator to another on behalf of a third person.
third-party communications agreement - An official understanding between the United States and another country that allows amateur radio operators in both countries to participate in third-party communication.
third-party participation - The way an unlicensed person can participate in amateur radio communication. A control operator must ensure compliance with Federal Communications Commission (FCC) rules.
third party - An unlicensed person on whose behalf communication is passed by amateur radio.
threaded Niell-Concelman (TNC) - A standard connector type used on coaxial cable, named for its inventors, Paul Neill and Carl Concelman.
throb - An multi-frequency-shift keying (MFSK) digital mode based on tone pairs. (See frequency-shift keying)
throw - The number of alternative current paths for a controlled circuit in a switch.
ticket - A slang word for an Federal Communications Commission (FCC) amateur radio license.
time-out timer (TOT) - (Repeater Term) A device that limits the amount of time any one person can talk through a repeater.
time constant of an inductance - (Archaic) The old term for merit (Q) of an inductor.
time out - (Repeater Term) Excessively long transmission on a repeater causing the repeater's timer circuit to stop further transmissions. (See alligator)
timer - (Repeater Term) A time limit of a single transmission from a user that is set by a repeater owner. Repeaters often incorporate a timer or transmit time limiter for this purpose.
tolerance - The amount the value of a component can be different than nominal value and still be considered good, usually expressed in percent or as a range of values.
tone access - (Repeater Term) A method of activating a repeater station that requires transmission of a brief tone before all transmissions can be relayed.
tone pad - An array of 12 or 16 numbered keys that generate the standard telephone dual-tone multi-frequency dialing signals. The device resembles a standard telephone keypad. (See autopatch)
tone scanning - (See scanning)
tone squelch (TSQL) - A function that mutes the speaker until the correct programmed subaudible tone is received.
top band - The 160-meter (m) amateur radio band which is the highest numbered meter band.
toploading - A shortening of the physical length of a vertical antenna by substituting an inductance at the top in place of additional height.
toroid - A donut-shaped solid, usually constructed of ferrite, used for transformers and inductors.
traffic - A formal message or messages sent by radio on behalf of others, especially formal traffic, meaning messages with a preamble and name of the sender.
traffic net - A scheduled meeting of amateur radio operators at particular time and frequency for the purpose of sending and receiving traffic. (See net)
transceiver (TRX, XCVR) - A device comprising both a transmitter and a receiver that are combined and share common circuitry or a single housing. When no circuitry is common between transmit and receive functions, the device is a transmitter-receiver.
transcon - (Archaic) An abbreviation for a transcontinental message that was used in the early 1920s.
transformer - An electrical component that transfers electrical energy from one circuit to another by means of a magnetic field shared by two or more inductors.
transient - A short pulse of energy on a power line, usually lasting for a few microseconds (μs).
transistor - A solid-state replacement for a vacuum tube that is made of three layers of semiconductor material. A bipolar junction transistor (BJT) has terminals labeled base, collector, and emitter. A small current at the base terminal (that is, flowing between the base and the emitter) can control or switch a much larger current between the collector and emitter terminals. For a field-effect transistor (FET), the terminals are labeled gate, source, and drain, and a voltage at the gate can control a current between source and drain. (See bipolar junction transistor, field-effect transistor, negative-positive-negative, and positive-negative-positive)
transistor-transistor logic (TTL) - A family of logic gates found in many current lines of digital integrated circuits (ICs).
translator - A device that receives multiple signals within a certain frequency range and simultaneously retransmits them in another frequency range. (See transverter)
transmatch - (See antenna tuner)
transmission-line loss - The fraction of power dissipated as heat as it travels through a feed line. Also known as feed-line loss.
Transmission Control Protocol (TCP) - One layer of the Internet protocol suite that deals with opening and maintaining connections between Internet hosts. (See Internet Protocol
transmission control protocol/Internet protocol (TCP/IP) - The Internet protocol that is designed to be independent of the underlying hardware.
transmission line - The wires or cable used to connect a transmitter, receiver, or transceiver to an antenna. Also known as feed line.
transmit (TX) - To broadcast or send out a radio signal.
transmit-receive switch (TR switch) - A mechanical switch relay or electronic circuit used to switch and antenna between a receiver and transmitter. (Also known as T-R switch and T/R switch.
transmitter (XMTR) - A radio that produces radio-frequency signals with sufficient power to be useful for communication.
transponder - A device usually used on satellites that emits a radio signal when it receives a radio signal on a certain frequency or that retransmits all signals in a range of frequencies.
transverter (XVTR) - A device that takes one signal in a specified frequency range and simultaneously retransmits it in another frequency range. This differs from a translator, which can handle more than one signal. (See translator)
trap - The parallel resonant windings used to electrically isolate sections of an antenna to provide resonant operation on more than one frequency range.
trap-dipole antenna - A dipole antenna with several coils, or traps, that allow the antenna to be used on several bands. Also known as trap vertical antenna.
trimmer capacitor - A small adjustable capacitor, generally screwdriver adjustable, to set a calibration point as part of a system alignment.
trimmer potentiometer - Small adjustable resistor, generally screwdriver adjustable, to set a calibration point as part of a system alignment.
trip - To activate when a threshold is exceeded or an event is detected. For example, a circuit breaker trips opening a circuit when excessive current flows.
triplexer - A low-pass filter, a band-pass filter, and high-pass filter with their outputs connected.
tropo - (See tropospheric propagation)
troposphere - The region in Earth's atmosphere just above the Earth's surface and below the ionosphere.
tropospheric bending - A condition that happens when radio waves are bent in the troposphere and return to Earth farther away than the visible horizon.
tropospheric ducting - A type of very-high frequency (VHF) propagation that can occur when warm air overruns cold air—known as temperature inversion. Also known simply as tropo.
tropospheric propagation - Any method of radio wave propagation by means of atmospheric phenomena in the troposphere—abbreviated as tropo.
trunked radio system (TRS) - A complex type of computer-controlled two-way radio system that allows sharing of relatively few radio frequency channels among a large group of users.
trunking - (Repeater Term) A method of switching incoming signals between different repeater stations to prevent interference and ensure access to a repeater.
tube - (See vacuum tube)
tuned circuit - A circuit with a resonant frequency that can be adjusted, usually through the use of adjustable capacitors or inductors.
tuned plate, tuned grid (TPTG) - (Archaic) A style of transmitter circuit, used around 1930.
tuner - (Archaic) Often used as a synonym for receiver in the early 1920s, it referred mostly to a receiver's front end, particularly the grid and plate circuits of a regenerative detector.
tunes - (Archaic) A synonym for frequencies or wavelengths.
tuning - Adjusting the operating frequency of a radio or circuit.
tuning step (TS) - The frequency stop used when moving up or down channels. Also known as incremental tuning steps.
turboscan - (See hyperscan)
twin-lead - (See open-wire line)
twisted pair - An amateur radio nickname for telephone or telephone lines.
two-tone test - A method of testing a side-band transmitter by feeding two audio tones into the microphone input of the transmitter and observing the output on an oscilloscope.


To the top!   U

ultra-high frequency (UHF) - The frequency range of 300 to 3,000 megahertz (MHz).
ultra-high frequency connector (UHF connector) A coaxial cable connector commonly used to connect high-frequency (HF) antennas to radios with a PL-259 male plug and an SO-239 female receptacle and usually used below 300 megahertz (MHz). It was misnamed before World War II for frequencies over 30 megahertz (MHz).
ultra-high frequency mobile (UHF mobile) - The frequency range of 216 to 512 megahertz (MHz).
unattended operation - Operation of a radio station without a human operator at the control point.
unbalance-unbalance (unun) - A contraction for a device that couples an unbalanced antenna of one impedance to an unbalanced feed line of another impedance.
unbalanced antenna - An antenna that can be fed directly by coaxial cable without a balun needed.
unbalanced line - A transmission line, primarily coaxial cable, in which one conductor, the shield, is designed to be at ground potential. Also know as an unbalanced feed line.
Uncle Charlie - The Federal Communications Commission (FCC).
uncontrolled environment - Any area in which a radio frequency (RF) signal may cause radiation exposure to people who may not be aware of the radiated electric and magnetic fields. The Federal Communications Commission (FCC) generally considers members of the general public and an amateur radio operator's neighbors to be in an uncontrolled RF radiation exposure environment to determine the maximum permissible exposure levels. (See controlled environment)
uncoordinated repeater - (Repeater Term) A repeater station operating on frequencies not approved by the appropriate frequency coordinator.
undamped oscillations - (Archaic) A synonym for frequencies or wavelengths used prior to the 1920s. Also known as undamped waves.
unidentified communications - The signals or radio communication in which the transmitting station's call sign is not transmitted. Also known as unidentified signals.
Uniform - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter U. Used in radio communication, particularly when spelling out a call sign.
unintentional radiator - A device that radiates radio frequency (RF) signals not requred for its normal operation.
uninterruptable power supply (UPS) - A power system in which the alternating current (AC) input is used to charge batteries that in turn power an inverter to provide clean alternating current (AC) in case of a commercial AC power failure.
United Nations (UN) - The world's largest, foremost, and most prominent international organization. The stated aims of the UN include promoting and facilitating cooperation in international law, international security, economic development, social progress, human rights, civil rights, civil liberties, political freedoms, democracy, and the achievement of lasting world peace. The UN was founded in 1945 after World War II to replace the League of Nations, to stop wars between countries, and to provide a platform for dialogue. It contains multiple subsidiary organizations to carry out its missions.
unity-gain antenna - An antenna that gives no gain or loss because its effective radiated power is equal to the transmitter power applied to it.
Universal Licensing System (ULS) - The Federal Communications Commission's (FCCs) consolidated database, application filing system, and processing system for all wireless telecommunications services.
universal resource locator (URL) - A specific character string that constitutes a reference to a resource. In most web browsers, the URL of a web page is displayed on top inside an address bar.
universal serial bus (USB) - A standard developed in the mid-1990s that defines the cables, connectors, and communication protocols used in a bus for connection, communication, and power supply between computers and electronic devices.
Universal Time Coordinate (UTC) - An international time and date system derived from the 0-degree meridian at Greenwich that is widely used in international radio communication. Also known as coordinated universal time, Greenwich Mean Time (GMT), and Zulu time.
unmodulated carrier - A steady transmitted radio frequency (RF) signal carrying no information.
uplink - Transmitted signals or the range of frequencies on which a user transmits to a repeater or satellite. It is the opposite of downlink. (See downlink)
upper sideband (USB) - The sideband higher in frequency than the transmitter's carrier. It is the common single-sideband operating mode on the 20-, 17-, 15-, 12-, and 10-meter (m) high-frequency (HF) amateur radio bands, and all the very-high frequency (VHF) and ultra-high frequency (UHF) bands. (See sideband)
utility stations - Stations other than broadcast or amateur radio stations that are not intended to be heard by the public. They include aircraft communication, radiotelephone, marine, embassy, and military communication.
ultraviolet (UV) - Electromagnetic waves with frequencies grdater than visible light. Literally, above violet, which is the high-frequency end of the visible range.
ultraviolet protection (UV protection) - A coating placed on plastics or other materials to prevent degrading by exposure to ultra-violet light from the sun.


To the top!   V

vacuum relay - An electromechanical switching device in which the contacts are enclosed in an evacuated chamber, eliminating most contact oxidation, corrosion, burning, and pitting.
vacuum tube - (Archaic) An electronic component that creates or modifies electrical current in a vacuum or low pressure space between two electrodes. Also known as bulb, electron tube, fire bottle, jug, klystron, magnetron, Radiotron, thermionic valve, tube, or valve. A three-element vacuum tube was called an audion.
vacuum tube era - The time period during which most amateur radio equipment was constructed around vacuum tubes, generally from the mid-1920s to the early 1980s.
vacuum tube voltmeter (VTVM) - (Archaic) A once-popular form of the voltmeter using a vacuum tube in the amplifier circuit. (See multimeter)
vacuum variable capacitor - A capacitor consisting of two electrodes, often concentric cylinders, in an evacuated glass envelope. One element is moved in and out with respect to the other.
valve - (Archaic) A synonym, still used in Europe, for vacuum tube. (See vacuum tube)
vanity call - A call sign selected by a licensed amateur radio operator instead of the one sequentially assigned by the Federal Communications Commission (FCC). A vanity call must be approved by the FCC.
vanity system - One of three methods used to select a call sign for amateur station over-the-air identification purposes. (See call-sign system)
varactor diode - A solid-state two-terminal device used in non-conducting mode. The capacitance between the terminals is changed by applying a different voltage between them resulting in a variable capacitor. (See variable capacitor)
variable-frequency oscillator (VFO) - An oscillator used in receivers and transmitters. The frequency is set by a tuned circuit using capacitors and inductors. The frequency can be changed by adjusting the components in the tuned circuit.
variable capacitor - A capacitor that can have its value changed within a certain range.
variable crystal oscillator (VSO) - An oscillator with an oscillation frequency that is variable and can be electronically changed.
variable resistor - (See potentiometer)
variometer - (Archaic) A transformer with variable coupling controlled by changing the angle of one winding with respect to the other, with one physically inside the other. It is used to get variable coupling between two inductors, or wherever a variable inductor is needed. One can connect the windings in series or parallel or have them independent.
velocity factor - The speed at which radio waves travel in a particular feed line, expressed as a percent of the speed of light.
vertical-interval signaling (VIS) - The digital encoding of the transmission mode in the vertical syncronization portion of an slow-scan television (SSTV) image.
vertical antenna - A common amateur radio antenna, often made of metal tubing, in which the radiating element is vertical. There are usually four or more radial elements parallel to the ground.
vertical metal-oxide semiconductor (VMOS) - A type of metal oxide semiconductor transistor.
vertical polarization - A transmission or antenna in which the electric field is propagated perpendicular to the surface of the Earth. Antennas intended for two-way radio communication with mobile stations, where vertical antennas are common, typically use vertical polarization, while broadcast television frequency modulation (FM) signals are most often horizontally polarized.
vertically polarized wave - A radio wave that has its electric lines of force perpendicular to the surface of the earth.
very-high frequency (VHF) - The frequency range of 30 to 300 megahertz (MHz).
very-high frequency high band (VHF high band) - The frequency range of 148 to 174 megahertz (MHz).
very-high frequency low band (VHF low bands - The frequency range of 30 to 50 megahertz (MHz) and 72 to 76 megahertz (MHz).
very-low frequency (VLF) - The frequency range of 3 to 30 kilohertz (kHz) and wavelengths of 10 to 100 kilometers (km).
very limited coverage area (VLCA) - (Repeater Term) Small portable repeaters deployed by emergency/disaster or public service groups to temporarily provide local communication within a relatively small area.
Victor - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter V. Used in radio communication, particularly when spelling out a call sign.
video-display terminal (VDT) - A device using a video display such as a cathode-ray tube.
visible horizon - The most distant point one can see by line of sight.
voice - Any of the several methods used by amateur radio operators to transmit speech.
voice-activated dialing - (See voice-operated transmit)
voice-operated transmission (VOX) - Systems used to automate routine enquiries to switchboard operators, and are used in many hospitals and large businesses to reduce the caller waiting time. Also known as voice-activated dialing.
voice-operated transmit (VOX) - A function that automatically puts the transmitter in transmit when you talk into the microphone. Although commonly used for base station operation, its use for mobile operation is questionable because of the inherent high background noise level.
voice communication - The communication by voice between amateur radio operators. Amateur radio operators may use several voice modes, including FM and single sideband (SSB).
voice keyer - A device that can transmit pre-recorded voice transmissions, useful for calling any amateur radio station (CQ) or during contest exchanges.
Voice of America (VOA) - The official external broadcast institution of the United States federal government.
voice over Internet Protocol (VoIP) - The communication protocols, technologies, methodologies, and transmission techniques involved in the delivery of voice communication and multimedia sessions over Internet Protocol (IP) networks, such as the Internet.
voice scan control (VSC) - A circuit that provides efficient scanning by skipping unmodulated signals so that the scan behavior can be customized to suit an amateur radio operator's needs.
voice squelch control (VSC) - A circuit that opens the squelch only when a modulated signal is detected and ignores unmodulated, beat noise signals, or heterodynes.
volt (V) - The basic unit of electrical pressure or electromotive force (EMF).
volt amperes (VA) - A measure of apparent power. Note that true power is I2 times R.
volt ohm meter (VOM) - An electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter would include basic features such as the ability to measure voltage, current, and resistance.
voltage (ΔV) - The electromotive force (EMF) or difference in electrical potential that causes electrons to move through an electrical circuit. The Δ is the Greek capital delta.
voltage-controller oscillator (VCO) - A device used to produce video timing.
voltage divider - A device that consists of two or more resistors connected in series across a source voltage. The source voltage must be as high or higher than any voltage developed by the voltage divider. As the source voltage is dropped in successive steps through the series resistors, any desired portion of the source voltage may be tapped to supply individual voltage requirements. The connection to the voltage divider is called a tap and such a circuit or component is said to be tapped. (See tap)
voltage doubler - A kind of power supply rectifier circuit in which a capacitor is charged during one part of the alternating current (AC) cycle and then placed in series with the input on another part to result in an output direct current (DC) voltage approaching twice the peak value of the input waveform.
voltage standing wave ratio (VSWR) (See standing-wave ratio)
voltmeter - A test instrument used to measure voltage.
volts alternating current (VAC) - In the United States, current is controlled to run at 60 cycles per second.
Volunteer Examiner (VE) - A person authorized by a Volunteer Examiner Coordinator (VEC) to administer examinations for amateur radio licenses.
Volunteer Examiner Coordinator (VEC) - An amateur radio organization empowered by the Federal Communications Commission (FCC) to recruit, organize, regulate, and coordinate Volunteer Examiners.


To the top!   W

wabbulation - (Archaic) (See wobbulation)
wall wart - A synonym for a small power-supply unit for low-power equipment with an integral plug for a standard alternating current (AC) wall outlet.
wallpaper - Wall decorations to an amateur radio station of QSL cards, award recognitions, special event certificates, and other items.
want to be (wannabe) - A synonym for a person with an ambition to be someone or something that he or she is not.
waterfall display - A display used with digital modes of transmission that consists of horizontal lines showing signal strength as a change of brightness with frequency represented by position on the line. Older lines move down the display so that the history of the signal's strength and frequency form a waterfall-like picture.
watt (W) - A derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt. The unit, defined as one joule (J) per second, measures the rate of energy conversion or transfer.
wattmeter A test instrument used to measure the power output in watts of a transmitter. A directional wattmeter measures both forward and reflected power in a feed line. Also known as power meter.
waveform - The amplitude of an alternating current (AC) signal over time.
waveguide - A structure that guides electromagnetic waves. A fiber optic weveguide confines energy to travel in two dimensions. (See optical fiber)
wavelength (wave, λ) - The distance a radio wave travels during one radio frequency (RF) cycle. The wavelength relates to frequency in that higher frequencies have shorter wavelengths. The λ is a Greek small lambda.
weak-signal Joe Taylor (WSJT) - A suite of software programs for weak signal and meteor scatter communications. Initially written by Joe Taylor, K1JT, the 1993 winner of the Nobel Prize in physics, it allows radio operators to communicate over long distances with other amateur radio operators. WSJT is now open source and is developed by a small team.
weak-signal propagation reporter (WSPR) - A software program that enables you to participate in a world-wide network of low-power propagation beacons. It was written by Joe Taylor K1JT, the 1993 winner of the Nobel Prize in physics.
weak-signal mode - A single sideband (SSB) or Morse code (CW) mode used in relation to operating on the very-high frequency (VHF) and ultra-high frequency (UHF) bands, where many amateurs only operate frequency modulation (FM) phone.
Weak-signal Operation on Low Frequency (WOLF) - (CW Term) A program written by Stewart Nelson KK7KA, it can operate over a wide range of signal levels. For example, a WOLF beacon transmits a 15-character message repeatedly. If the received signal would be adequate for conventional Morse code (CW), copy will be displayed in 24 seconds.
weather (WX) - An automatic position reporting system (APRS) for transmission of current meteorological readings by way of amateur radio. Many 2-meter (m) hand-held transceivers are also capable of extended tuning to permit reception of forecasts over very-high frequency (VHF) bands assigned to other services, such as marine radio.
weather alert - An alert that occurs when an National Oceanic and Atmospheric Administration (NOAA) or National Weather Service (NWS) weather station transmits alert signals.
weather facsimile (WEFAX) - Reconstructed satellite images and photographs.
whip antenna - An antenna with an element made of a single, flexible rod or tube. (Also known as stinger antenna)
Whiskey - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter W. Used in radio communication, particularly when spelling out a call sign.
white noise - (1) (Repeater Term) A spectrum of broad band noise generated in a receiver's detector and sampled to control the receiver's squelch. This term is often incorrectly used in repeater work to describe the sounds heard when the received transmission is noisy and hard to understand, usually attributed to a weak signal and the repeater receiver limiters are not engaged. (2) White noise generated from a common commercial radio receiver tuned to an unused frequency is extremely vulnerable to being contaminated with spurious signals, such as adjacent radio stations, harmonics from non-adjacent radio stations, electrical equipment in the vicinity of the receiving antenna causing interference, or even atmospheric events such as solar flares and especially lightning. (See static)
wide-range antenna tuner - An antenna system matching device that can compensate for large impedance mismatches typically representing standing-wave ratio (SWR) of at least 10 to 1.
wide-range receiver - (See extended-coverage receiver)
wideband frequency modulation (WFM). A modulation signal that requires a wider signal bandwidth than amplitude modulation. It also makes the signal more robust against noise and interference.
will comply (wilco) - (Archaic) Wilco is radio slang for "Will Comply." The letter R has been used since the early days of Morse code (CW) to indicate that "The message has been received." The voice code equivalent for R is Roger. So, Roger Wilco means "The message has been received and I will comply."
willful interference - Intentional, deliberate obstruction of radio communications.
windom antenna - An off-center-fed wire antenna (OCF). It is named after L.G. Windom W8GZ who described it in the September 1929 QST magazine.
window - A frequency range set aside for foreign amateur radio stations in which to transmit while stations in the United States and Canada do not. American and Canadian stations call foreign stations on frequencies outside the window.
window line - A type of transmission line that is similar to ladder line except the spacing is maintained by a plastic coating with cutouts that look like windows. (See open-wire line)
wing circuit - (Archaic) A synonym for a vacuum tube plate circuit.
winlink - A system of electronic mail (email) transmission and distribution using amateur radio for the connection between individual amateurs and mailbox stations known as radio message servers (RMS). Also known as Winlink 2000 Network.
wireless - Without wires. Wireless radio as opposed to wired telegraph.
Wireless Institute of Australia (WIA) - The national organization for Australian amateur radio operators.
Wireless Telecommunications Services (WCS) - Cellular, personal communication services, specialized mobile radio, enhanced specialized mobile radio, paging, and similar services that currently exist or that may in the future be developed to provide wireless communications services. The term does not include services of any amateur radio facility owned and operated by a federally-licensed amateur radio station operator or used exclusively for receive-only antennas, nor does it include noncellular telephone service.
wobbulation - (Archaic) The modulation of a transmitter's frequency due to instability in its oscillator or amplifier while being keyed or modulated. Also known as wabbulation.
World Administrative Radio Conference (WARC) - (Archaic) The predecessor of the World Administrative Radio Conference (WRC). (See World Administrative Radio Conference)
World Radiocommunication Conference (WRC) - A technical conference of the International Telecommunications Union (ITU) where delegates from member nations of the ITU met to revise or amend the entire international Radio Regulations pertaining to all telecommunication services throughout the world.
words per minute (wpm) - (CW Term) Morse code (CW) speed is measured in words per minute (wpm) or characters per minute (cpm).
work - To communicate with another radio station or stations.
work first, worry later (WFWL) - A DXing term used when the validity of a distant station (DX) is in doubt.
working frequency - A frequency that two or more stations can use to communicate with each other.
World Administrative Radio Conference bands (WARC bands) - (Archaic) An expression to indicate the bands 17-, 12- and 30-meters (m) allocated in 1979 by the World Administrative Radio Conference (WARC), the predecessor of the World Radiocommunication Conference (WRC). (See World Radiocommunication Conference)
World Radio Online Magazine - (Archaic) A monthly amateur radio enthusiast magazine published in the United States from July 1971 to November 2008. It was published in English and drew its subscription base primarily from the United States of America and Canada, although it had subscribers around the world.
Worked All Britain (WAB) - An award from the Worked All Britain (WAB) website to any amateur radio operator who confirms two-way communication with all of Britain's grid system units.
Worked All Continents (WAC) - An award from the International Amateur Radio Union (IARU), to any amateur radio operator who confirms two-way communication with all continents. It is administered by the American Radio Relay League (ARRL).
Worked All Neighbors (WAN) - A station that continually gets complaints about signals showing up on the telephone or televisions at neighbor's houses. Not a desired situation. Polite conversation and changes in operation practices are a common solution. Another is providing simple and often inexpensive filters for the offended neighbor.
Worked All States (WAS) - An award from the American Radio Relay League (ARRL) for to any amateur radio operator who confirms two-way communication with each of 50 United States.
Worked All VE (WAVE) - An award from the Radio Amateurs of Canada (RAC) to any amateur radio operator who confirms two-way communication with an official RAC station using the suffix RAC in at least 10 of the 18 provinces with VE prefixes.
Worked All XE (WAXE) - An award from the Federación Mexicana de Radioexperimentadores, A.C. (FMRE) to any amateur radio operator who confirms two-way communication with operators in all the XE zones in Mexico.
Worked All Zones (WAZ) - An award from CQ magazine to any amateur radio operator who confirms two-way communication with each of 40 zones of the world.
Wouff Hong - An instrument of sadistic torture for the punishment of amateurs who cultivate bad operating habits, who do not follow generally accepted rules of courtesy, and who nourish and culture their meaner instincts on the air. Discovered-by the Old Man, Hiram Percy Maxim W1AW, himself. The instrument looks something like a Saguaro cactus with one arm missing and is framed and hung in the office of the secretary of the American Radio Relay League (ARRL). Unfortunately, the Old Man never prescribed the exact manner in which the Wouff Hong was to be used. (See rettysnitch)
WWV - A radio station run by the United States National Institute of Standards and Technology (NIST) to provide accurate time and frequencies.
WWVH - A radio station run by the United States National Institute of Standards and Technology (NIST) to provide accurate time and frequencies.


To the top!   X

X-ray - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter X. Used in radio communication, particularly when spelling out a call sign.
x-series, latch, resilient (XLR) - A standard for transferring balanced audio among professional audio equipment. An XLR connector is primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins.


To the top!   Y

Yagi antenna - Another name for a beam antenna array, the most popular type of directional antenna or beam antenna. It is a multi-element array in which one element, the driven element, is directly connected to the transmission line and others are coupled through radiation. Electromagnetic coupling between the elements focuses maximum power (or reception) in the direction of the director. Named after Hidetsugu Yagi who, along with Shintaro Uda, invented the array in 1926. Sometimes called the Yagi-Uda antenna, but most often shortened to Yagi.
Yankee - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter Y. Used in radio communication, particularly when spelling out a call sign.


To the top!   Z

Z-signals - (CW Term) Three-letter codes beginning with the letter Z and used only by MARS, in lieu of amateur Q-signals, to speed Morse code (CW) communication. Also known as Z-code. (See Q-signals)
zed - A phonetic for the letter Z and considered by many to be a more precise way of expressing that letter. It prevents one from confusing it with B, C, D, E, G, P, T, and V.
zener diode - A two-terminal semiconductor that has a well defined reverse breakdown voltage. By conducting at that voltage, it can serve as a voltage regulating device.
Zepp antenna - Zeppelin antenna - (Archaic) The end-fed Zepp antenna was simply a weighted wire reeled down and up from early lighter-than-air ships.
zero beat - A circuit that adjusts the frequencies of two signals so that they are exactly equal and in phase.
Zulu - A North Atlantic Treaty Organization (NATO) phonetic alphabet code word representing the letter Z. Used in radio communication, particularly when spelling out a call sign.
Zulu Time (Z) - The military time designation for Greenwich Mean Time. (See Universal Time Coordinate)


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