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222 MHz : The ham band between 222 and 225 MHz.
2-Meter Band : The ham band between 144 and 148 MHz.
6-Meter Band : The ham band between 50 and 54 MHz , the lowest frequency VHF ham band.
70-cm Band : Also known as "440," the amateur band extending from 420 and 450 MHz.
AM (Amplitude Modulation) : A radio transmission mode; except for some AM activity on 6 meters, you'll generally find only a type of AM, called Single Sideband (SSB), used on VHF.
Amateur Satellites : An international fleet communications satellites carrying amateur radio stations (See OSCAR).
Autopatch : A component which allows telephone calls to be placed through a repeater.
Az/El (Azimuth and Elevation) : When you are aiming an antenna at a satellite or other object in the sky, you need to set the azimuth heading (compass bearing) as well as the angle of elevation above the horizon. An az/el rotator will perform both functions.
BFO (Beat Frequency Oscillator) : A variable pitch tone oscillator, used mostly on older style radios, to permit reception of single sideband and Morse code signals on an AM receiver.
Band Opening : A condition that results in greater than-normal communications range on the VHF and UHF amateur bands.
Band Plan : A voluntary system of frequency allocations for each amateur radio band.
Bandwidth : The width of a signal on the radio spectrum. The greater a signal's bandwidth, the more frequency space it occupies.
CTCSS (Continuous Tone-Coded Squelch System) : Also called sub-audible tones or "PL" tones (trademarked name by Motorola). This is the tone which is transmitted by your radio in addition to your voice signal. When it is equipped with a CTCSS decoder, a repeater will not function unless it hears both the CTCSS tone and the "carrier" signal from your radio.
CW (Continuous Wave) : Commonly use as an abbreviation for Morse Code.
Controller : The "brain" of a repeater. Among its many possible functions are turning the repeater on and off, timing transmissions, sending the repeater's identification signal, and controlling the autopatch and CTCSS encoder/decoder.
Courtesy Tone : An audible signal transmitted by a repeater which lets users know that the repeater has reset at the end of one person's transmission and is available for use by the next person.
Crossband Repeater : A repeater whose input and output frequencies are on two different bands. For example, a signal received on 70 centimeters would be retransmitted on 2 meters, and vice versa. Many dual-band FM rigs include this feature.
DTMF (Dual Tone Multi Frequency) : A tone signaling system used in push-button telephones and many ham rigs. Commonly known bt AT&T's trade name "Touch-Tone".
Duplexer : Highly selectable, tunable filters which allow a repeater's transmitter and receiver to use one common antenna.
FM (Frequency Modulation) : The radio transmission mode used for most VHF amateur communications.
Full Duplex : Simultaneously receiving and transmitting on one radio. Normally, the receiver is muted during transmit to avoid feedback. In full-duplex operation, the receiver stays active, but is generally tuned to a different frequency or, most often a different band.
Frequency Band : A group of frequencies designated by government regulation for a specific purpose. Bands reserved for use by amateurs are called "amateur bands" or "ham bands".
Gateway : A link, or bridge, from one type of communication network to another.
GHz (GigaHertz) : A unit of frequency measurement (1 GHz = 1,000 MHz).
Handheld : An amateur radio transceiver that's small enough to be carried in your hand (often abbreviated "HT"). Typically, amateur handhelds are for VHF/UHF use.
HF (High Frequency) : The region of the radio spectrum between 3 and 30 MHz.
Hz (Hertz) : The basic unit of frequency measurement (cycles per second).
Impendance : A measure of resistance to the flow of RF energy (see below) based on a combination of actual electrical resistance in the wire of a feedline or antenna (resistance) and losses due to inefficiency in the feedline or antenna wire or a mismatch between the two (reactance). Just to confuse matters, resistance, reactance, and impedance are all measured in ohms. most ham transmitters work best into an antenna system with an impedance of 52 ohms. Ideally, you'll use 52 ohm feedline (such as RG-8) to an antenna with an impedance of 52 ohms at it's "feedpoint", the point where you feed in the signal through the feedline.
Input Frequency : The frequency on which a repeater receives and the one on which you transmit to the repeater.
Intermod : Short for "Intermodulation Distortion" (IMD) ; interference that results when strong signals from a nearby transmitter mix with the desired signal in a radio receiver.
kHz (kiloHertz) : A unit of frequency measurement ( 1kHz = 1,000Hz ).
Keplerian Elements (Keps) : A collection of data relating to the position of a satellite in it's orbit at any given time.This information is interpreted by satellite tracking programs to predict time and duration of satellite "passes" and direction in which to point antennas. Named for the 19th century scientist Johannes Kepler.
LCD (Liquid Crystal Display) : A type of display used on many radios and other electronic devices. Characteristics include dark (usually black) numbers and letters on a lighter background.
MHz (MegaHertz) : A unit of frequency measurement ( 1MHz = 1,000 kHz ).
Memory Effect : The tendency of a rechargeable nickel-cadmium ( NiCd ) batteries that are repeatedly recharged without being fully discharged to "remember" the point at which they're normally recharged and indicate a discharged condition. There is debate over the causes of memory effect, but it's always best to fully discharge a NiCd battery before recharging.
NOAA (National Oceanic and Atmospheric Administration) : Parent agency of the National Weather Service. (NOAA Weather Radio is a 24-hour-a-day weather reporting service, using several frequencies in the 162 MHz range).
OSCAR (Orbiting Satellite Carrying Amateur Radio) : Acronym describing amateur satellites generally; with a number attached (e.g., AMSAT-OSCAR-16, or AO-16), the name of a specific ham radio satellite.
Offset : The difference between a repeater's input and output frequencies. The offset for 2-meters is generally 600 kHz.
Output Frequency : The frequency on which a repeater transmits, and the frequency to which you tune your radio.
Packet : Common short form of "packet radio" , also the actual information package sent in in a packet radio transmission..
PL : A trademarked name by Motorola. Has the same meaning as CTCSS.
Packet Radio : The most popular form of amateur radio digital communications, in which computers hooked to radios exchange data in packets.
PACSAT (PACket SATellite) : Amateur satellite used to store and forward digital (packet radio) messages.
Propagation : The means by which radio signals are carried from one location to another.
Rf (Radio Frequency) : The radio waves generated by your transmitter (as well as your computer, your cordless phone , etc. ) are, not surprisingly, within the "radio" portion of the electromagnetic spectrum. Energy produced at these "radio frequencies" is called "RF" or "RF energy".
Repeater : An automatic relay station. generally in a high location, which is used to increase the range of handheld and mobile FM transmitters.
Repeater Control Operator : A licensed amateur designated by a repeater trustee who offers assistance with autopatch and listens for inappropriate use of the repeater. (This is different from the FCC's definition of a control operator, which is anyone in control of an amateur transmitter).
Repeater Directory : A listing of repeaters in a given area. Typically, a repeater directory shows a repeater's location, the output frequency, the offset, and whether or not a CTCSS code is required.
Repeater Pair : Each repeater requires two frequencies : an input and an output frequency.
Rubber Duck : Common term for the flexible rubber-covered antenna generally supplied with handheld radios.
S-Meter : A meter that provides a rough indication of received signal strength. ( Actually, an s-unit is a rather precise mesure, determined by mathematical formula. but it's the rare radio that's calibrated accurately enough for the numbers to be anything more than a rough measure).
Signal Report : A report given in numerical values of signal strength and quality.
Simplex : Generally used among FM operators to refer to making direct contacts without the use of repeaters. Frequencies set aside for simplex contacts (such as 146.52 MHz ) are often referred to as "simplex frequencies".
Single-Sideband (SSB) : A type of AM transmission which occupies less bandwidth than a standard AM signal.
Squelch : A control on a radio that keeps the speaker silenced (squelched) until the signal level exceeds a certain point. Normally, you set the sqyelch to block out noise and allow signals to pass.
Sub-Audible Tone : Another term for CTCSS.
TNC (Terminal Node Controller) : The "box" that goes between the computer and the radio in a packet station.
Tail : Most repeaters continue to transmit for a brief period after someone stops talking. This extra transmission is called a repeaters "tail".
Timer : A component in a repeater system that measures transmission length. The timer is set to a pre-determined length.
UHF (Ultra High Frequency) : The region of the radio spectrum between 300 and 3,000 MHz ( 3 GHz ).
USB (Upper Sideband) : Every AM signal has two side-bands , upper and lower. In single sideband (SSB) , only one is transmitted. USB is used on VHF ( See AM and SSB ).
VFO (Variable Frequency Oscillator) : A general term used to describe the device on a radio that lets you move progressively higher or lower in frequency by turning a dial or pressing a key. Today's digitally-synthesized radios usually use a tunable phase-locked loop (PLL) instead of a true VFO.
VHF (Very High Frequency) : The region of the radio spectrum between 30 and 300 MHz.
VHF Contest : An on-air competition in which activity is encouraged on VHF and UHF bands.
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