HAM Radio Terms

Radio amateur terms dictionary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Other

A
ACC
(ACCessory)
Adaptive filter
Digital filter associated with Digital Signal Processing.
Adjacent-channel interference
When a receiver is tuned to a specific frequency and interference is received on a nearby frequency.
AF
Audio Frequency
AFC
Automatic Frequency Control. Automatically compensate frequency drift
AFSK
Audio Frequency Shift Keying, a form of digital signalling.
AGC
Automatic Gain Control – a radio circuit that automatically adjusts receiver’s gain
ALC
Automatic Level Control – Limits RF drive level to power amplifier during transmit to prevent distortion.
AM
Amplitude Modulation – In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to that of the message signal, such as an audio signal.
Amateur Radio Service
Amateur radiocommunication service is a radiocommunication service for self-education or for mutual connections performed by authorized persons on a non-profit basis. Appropriate authorizations are issued by national authorities on the basis of passing the appropriate examinations.
Amplifier
A device used to increase the output power of a device.
AMSAT
Amateur Satellite. AMSAT is a name for amateur radio satellite organizations worldwide, but in particular the Radio Amateur Satellite Corporation (AMSAT-NA) with headquarters at Kensington, Maryland, near Washington, D.C. AMSAT organizations design, build, arrange launches for, and then operate (command) satellites carrying amateur radio payloads, including the OSCAR series of satellites. Other informally affiliated national organizations exist, such as AMSAT Germany (AMSAT-DL) and AMSAT Japan (JAMSAT).
AMTOR
Amateur Teleprinting Over Radio. A form of RTTY, radio teletype.
Anderson power poles
Used by many emergency radio operators to connect 12 volts DC to their radios.
ANF
Automatic Notch Filter. The notch filters reject/attenuate signals in a specific frequency band called the stop band frequency range and pass the signals above and below this band.
ANL
Automatic Noise Limiter. Eliminates impulse and static noise peaks.
ANT
Antenna
Antenna Gain
An increase in antenna transmission and reception performance in a particular direction at the expense of performance in other directions; performance increase as compared to an isometric antenna or a dipole antenna.
Antenna ground system
Term used for a 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 Ω for most transceivers.
Antenna matching
When the antenna’s impedance at resonance is at optimum performance for your transmitter output circuit.
Antenna tuner
Device used to match an antenna to the output impedance of a transmitter.
AOS
Acquisition of Signal – Satellite signal reception that occurs when the satellite comes up over the horizon.
APC
Automatic Power Control. Current limiting of power amplifier to prevent damage to finals in high SWR conditions.
APRS
Automatic Packet (or Position) Reporting System is an amateur radio based system for real time digital communications of information of immediate value in the local area. Data can include object Global Positioning System (GPS) coordinates, weather station telemetry, text messages, announcements, queries, and other telemetry. APRS data can be displayed on a map, which can show stations, objects, tracks of moving objects, weather stations, search and rescue data, and direction finding data.
ARES
Amateur Radio Emergency Service. ARES is a public-service organization of the ARRL.
ARRL
American Radio Relay League – Organization promoting and supporting amateur radio in the United States.
ASCII
American National Standard Code for Information Interchange. A seven-unit digital code for the transmission of teleprinter data.
ATT
Attenuator. A network designed to reduce the amplitude of a signal.
ATV
Amateur Television: FSTV, SSTV
Auto patch
Used in repeater operation for telephone interconnect.
Average power
Power measured on standard power meter.

B
Backscatter
Radio signals reflected back from ionized patches in the ionosphere.
Backstay
Rigging to support the mast in maritime mobile in stallations, usually insulated for HF antenna pur poses.
Balun
A simple transformer used to change an unbalanced input to a balanced output.
Band
A band – sometimes called a frequency band – is a specific range of frequencies in the radio frequency (RF) spectrum, which is divided among ranges from very low frequencies (vlf) to extremely high frequencies (ehf). Each band has a defined upper and lower frequency limit.
Bandwidth
Bandwidth is the frequency range occupied by a modulated carrier signal. An FM radio receiver’s tuner spans a limited range of frequencies. … One definition of bandwidth, for a system, could be the range of frequencies over which the system produces a specified level of performance.
Bank
Memory bank.
Barefoot
Operating a transmitter without an amplifier such that the output power is produced only by the base transmitter.
BCI
BroadCast Interference.
Beacons
Ham radio signals used for propagation study, found on specific frequencies.
BFO
Beat Frequency Oscillator – a receiver component used to mix the intermediate frequency down to an audio frequency.
Bird
Informal reference to a satellite.
BNC
Bayonet Neill-Concelman is a type of antenna connector.
BPF
BandPass Filter in a receiver allows signals within a selected range of frequencies to be heard or decoded, while preventing signals at unwanted frequencies from getting through. Signals at frequencies outside the band which the receiver is tuned at, can either saturate or damage the receiver.
Bunny hunt
Finding hidden transmitters, sometimes called “T HUNTING” and “Fox Hunting.”
Busy lockout
Inhibits transmit on a frequency in use.

C
Call sign
Sequence of letter and numbers used to identify amateur radio operators and issued by the countries licensing bureau.
CAP
Civil Air Patrol. Volunteer affiliate of the United States Air Force.
Capture effect
Only the strongest signal heard over an FM receiver.
Carrier
An unmodulated transmitted signal.
Carrier frequency offset
Distance between mark and space of the carrier for RTTY or similar communications. (=Carrier Shift)
CBR
Cross Band Repeater. A repeater which receive incoming signal and retransmit it in different bands— e.g. receives 144 MHz bands and re-transmits 430(440) MHz bands.
CCW
Counter ClockWise
CH
Channel. Sequence of memory positions where frequency and related information is stored.
CI-V
Icom computer Control Interface allows multiple radio control simultaneously.
Clipping
The leveling or flattening of the upper and/or lower portion of a waveform due to the driving signal exceeding the output limits of a circuit, particularly an amplifier. (AKA “flat topping”)
Coax
Coaxial cable, commonly used as feedline between transceiver and antenna. It is consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protective outer sheath or jacket.
Contesting
Working as many stations as you can over a specific amount of time.
Conversion
Number of IF circuits in the receiver.
Coronal hole
Sunspot activity that may lead to enhanced VHF and 10 meter propagation.
CPU
Central Processing Unit.
CQ
Radio communications term used to call others. CQ is a code used by wireless operators, particularly those communicating in Morse code, (— · — · — — · —), but also by voice operators, to make a general call (called a CQ call). Transmitting the letters CQ on a particular radio frequency is an invitation for any operators listening on that frequency to respond. It is still widely used in amateur radio.
Crossband repeat
A mode in many dual band radios where a radio transmits on one band, a crossband repeater transmits the received signal on another band, which is heard back by the radio on the other band.
CTCSS
Continuous Tone Coded Squelch System. Adds a continuous sub-audible low frequency tone to the transmitted carrier. Receivers set for the same low frequency tone can decode signal to hear the audio.
CW
Continuous Wave – a transmission mode employing an unmodulated transmission (continuous wave) and Morse Code patterns of transmission / interruption to send a signal. ClockWise.
CW Filter
Used to narrow the IF passband to improve reception selectivity in crowded band conditions.

D
D-LAYER
The lowest layer of the ionosphere, approximately 40km (25 miles) to 90 km (55 miles) high, that fades away at night and is often very weak during short winter days.
D-RATS
Multi-platform integrated tool for communicating digital information, developed for First Responders, using D-STAR radios.
D-STAR
Digital Smart Technologies for Amateur Radio, an open protocol.
Data communications
Transfer of data between two or more locations.
dB
decibel is a unit of measure for comparing power measurements. The decibel (symbol: dB) is a relative unit of measurement corresponding to one tenth of a bel (B). It is used to express the ratio of one value of a power or field quantity to another, on a logarithmic scale, the logarithmic quantity being called the power level or field level, respectively. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately 1.25893) and an amplitude (field quantity) ratio of 10​1⁄20 (1.12202).
dBd
Unit of RF power as compared to an ideal half wave dipole antenna.
dBi
Unit of RF power as compared to an isotropic antenna.
dBm
Decibels measure, 1 mW with a load impedance of 600 Ω (0 dBm=1 mW).
DC
Direct Current.
DC ground
A connection point directly to chassis or battery ground to prevent build-up of hazardous DC voltages.
DCS
Digital Coded Squelch is a method of breaking the squelch of a receiver (especially a repeater station) using a digital code at the start of transmission.
Deviation
In Frequency Modulation, the variance from resting frequency of the modulated carrier signal. Deviation is driven by the amplitude of the audio input signal.
Digipeater
A digital repeater that will temporarily store, then retransmit on the same frequency, a digital packet.
Digital communications
Information sent digitally, which may be decoded as voice, data, and/or video.
Dipole
A common antenna, typically wire, consisting of two segments: One attached to the conductive part of the feedline and one attached to the grounded part of the feedline. Usually ½ wavelength long, each of the two segments is ¼ wavelength.
Distress call
Signals a life-threatening situation. Most commonly referred to as an SOS or MAYDAY call.
Distress frequency
A frequency or channel specific for use in distress calling. Radiotelephone distress frequencies are 2.182 MHz and 156.8 MHz. Survival craft use 243 MHz. Maritime distress frequencies are the same, while general aviation frequencies are 121.5 MHz.
Director
A part of an antenna, e.g. on a Yagi or Quad directional antenna, any of the elements in front of the driven element.
Doppler shift
Common in satellite communications, where signals may very up or down in frequency, as the satellite approaches and departs from view.
Double
On a repeater, two stations transmitting simultaneously.
Downconverter
A device to take higher frequencies, and lower them to appear at a lower frequency, for reception.
Downlink
Frequency that repeater or satellite transmits on to a user. In satellite communication operations a frequency used for the satellite-to-earth channel. (↔Uplink)
Driven Element
The feeded part of antenna.
Drop Out
When a station transmitting to a repeater has insufficient power to consistently break the squelch of the receiver and the repeated communication is noisy and broken.
DSP
Digital Signal Processing is a method of filtering, noise reduction, or otherwise modifying received signals by converting received signals into digital form for manipulations. It is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing. DSPs are fabricated on MOS integrated circuit chips.
DTMF
Dual Tone Multi-Frequency (=touch-tone) used for transmit/receive numeric information such as phone number, PIN, remote radio control commands, etc.
Dual Band
Dual Band antenna is designed for use on two different radio bands. Dual Band Transceiver operates on two different radio bands.
Dualwatch
Receiving two signals simultaneously.
Dummy Load
In place of a radiating antenna, this device presents a matching impedance for a transmitter and converts transmission energy to heat rather than radiating a signal. It is useful for testing transceivers without radiating.
Duplex
A communication mode allowing simultaneous transmitting and receiving (on two different frequencies).
Duplexer
A repeater component allowing a single antenna to transmit and receive simultaneously by implementing sharply tuned filters to separate transmission and reception channels.
Duty cycle
The ratios of transmit to receive time.
DX
A distant station, usually outside of a transmitting station’s country or continent.
DXCC
ARRL award for confirmation of contacts made in a minimum of 100 different countries.
DXpedition
A radio expedition to another country, usually a rare or remote location.

E
E-Layer
A layer of the ionosphere approximately 90km (55 miles) to 145km (90) miles high that typically fades away after sunset. Responsible for “Sporadic E” communications with frequencies above 30 MHz (especially the 6 meter band).
Earth Ground
An electrical connection to the earth, usually to a metal rod driven into the earth.
EBS
Emergency Broadcast System is a system where at first an attention tone is transmitted over all station ad the second tone followed with specific instruction regarding the receivable frequency in the national emergency.
Echolink
A voice over IP internet connection allowing radio stations and/or computers to be connected together for communications.
EEPROM
Electrically Erasable and Programmable Read Only Memory.
Elmer
An experienced and knowledgeable amateur radio operator who guides or mentors newer operators.
Eleven Meter Band
The radio band used for the channels of the civil radio (CB radio).
EME
Earth-Moon-Earth communication, in which signals are reflected off the moon back to earth; “Moon bounce”
EMF
Electromotive Force (E) – voltage; unit of measure is volts.
EMI
Electromagnetic Interference, sometimes caused by battery chargers and inverters.
Emission
Transmission of a signal.
ERP
Effective Radiated Power is the power actually radiated by an antenna.
E-Skip
Also known as “Sporadic E” signal propagation using reflection by the E-Layer of the ionosphere.

F
F-CONNECTOR
Found on 440 MHz and 1.2 GHz antenna circuits.
F-Layer
The highest layers of the ionosphere, from approximately 145km (90 miles) to 400km (250 miles) high, that provide the longest propagation skips with HF frequencies of 30 MHz or lower. During daylight it is two layers, F1 and F2. At night it combines into a single F-Layer.
Fading
Signal reduction due to atmospherics.
FCC
Federal Communications Commission – the US federal government agency that regulates radio spectrum and that sanctions the amateur radio service.
Feed point
Where the coaxial cable or ladder line joins the active antenna.
FET
Field Effect Transistor – Used as an amplifier or a switch in electronic circuits; an input voltage determines output current level.
Field Day
An annual amateur radio event to practice emergency communications (June).
Field Strength Meter
An instrument to indicate the relative strength or presence of an RF field.
Filter
An electronic component or circuit that allows the passage of certain frequencies while blocking others.
Final
(Transmission) – The last transmission of a station during a contact.
Flat Topping
Overmodulating the RF signal such that clipping of the waveform occurs and distorted audio results.
FM
Frequency Modulation is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The term and technology are used in computing, signal processing and telecommunications. FM broadcast.
Foldback
A circuit to limit power output when the transmitter senses elevated SWR or temperatures.
Foxhunt
A competition event in which hidden transmitters are sought with direction-finding equipment.
Frequency
The number of oscillation cycles per second of an electromagnetic wave or an alternating current. The unit of frequency measure is hertz [Hz].
Frequency Coordinator
An individual or a group who recommend frequency pair assignments to repeaters to coordinate repeater use of radio spectrum and to avoid interference between repeaters.
FSK
Frequency Shift Keying.
FSTV
Fast Scan Television: Used on 70 cm and higher frequency bands with NTSC (standard broadcast) signal to transmit television imagery on the amateur bands.
Full duplex
An operation mode, which transmits and receives on different frequencies at the same time, as a telephone communication.
Full Quieting
Commonly used to describe repeater audio having no noise component, but referring to a received signal strength by the repeater that is sufficient to engage the receiver limiters.
Fuse
An intentional weak link to guard against overload.

G
GaAs FET
Sensitive transistor, found in VHF/UHF receiver amplifiers, with a low noise floor.
Gain
With antennas, an increase in the effective radiated power in a specific direction as compared to a reference antenna, such as a half-wave dipole or an isometric antenna. With transistors, the increase in signal output of the transistor as compared to the input controlling signal.
GHz
Gigahertz, meaning one billion cycles per second.
GOTA
Get On The Air – An annual ARRL Field Day event in which non-licensed persons are provided an opportunity totransmit under the control operator supervision of a licensed HAM.
Gray Line
The transition area line on the earth separating daylight and darkness and that promotes an enhanced propagation path for some RF bands.
Green Stamp
A US dollar mailed with a QSL card to pay for postage of a return QSL card.
Ground
The zero voltage reference point of a circuit.
Ground Plane
A horizontal conducting surface or radials extending from the base of an antenna (usually a quarterwave vertical antenna) that produces a virtual image ground element for the antenna, enhancing performance.
Ground Wave Propagation
Radio frequency propagation along the earth’s surface that may extend beyond the visual horizon.
Grounding
Electrical connection to the earth.

H
Half-Wave Dipole
A simple antenna fed at the center point with two one-quarter wave elements extending in opposite directions (one attached to the feedline conductor, one to the feedline ground/shield).
HAM
An amateur radio operator. The word “HAM” as applied to 1908 was the station CALL of the first amateur wireless station operated by some amateurs of the Harvard Radio Club. They were ALBERT S. HYMAN, BOB ALMY and POOGIE MURRAY. At first they called their station “HYMAN- ALMY-MURRAY”.
Hamfest
A ham festival or event at which hams and commercial businesses meet, trade, and display equipment or techniques.
Handheld
(Handheld Transceiver / HT) – a small transceiver that can be carried in the hand.
Hang Time
The brief continued transmission of a repeater following the termination of a transmission to the repeater, and that is often denoted by the transmission of courtesy tones.
Harmonic
Multiple of a fundamental frequency.
Heat sink
The heavy fins on the back of a transmitter to dissipate heat buildup.
Hertz
[Hz] cycles per second, the standard unit of frequency measure. is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second.
HF
High Frequency, defined to be 3 MHz (100m) to 30 MHz (10m). (Normally, 1.9 MHz band also included.)
Hi Hi
A slang term used on the air as the equivalent of laughing. A CW-derived affectation that has been transferred into the phone modes.
Homebrew
Home built, as in home built equipment, antennas, etc.
HPF
High Pass Filter.
Hz
Frequency is measured in the unit hertz (Hz), referring to a number of cycles per second. One thousand hertz is referred to as a kilohertz (KHz), 1 million hertz as a megahertz (MHz), and 1 billion hertz as a gigahertz (GHz). The range of the radio spectrum is considered to be 3 kilohertz up to 300 gigahertz.

I
IC
Integrated Circuit. An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or „chip“) of semiconductor material that is normally silicon.
IF
Intermediate Frequency – the lower frequency value within a superheterodyne receiver that results from VFO frequency mixing with received RF frequencies, and that is further processed by mixing and filtering to lower audiofrequencies for sound production.
IF shift
A function that electronically shifts the IF frequency from a center frequency to reduce interference.
IMD
Inter-Modulation Distortion. Distortion within RF circuits made with upper and lower adjacent channel signals.
Impedance
The opposition to the flow of alternating current, measured in the unit ohms. In operations, impedance is desired to be matched, or equal, from transceiver to feedline to antenna for best system performance. In electrical engineering, electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied.
Inductor
An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around a core.
Inverter
An electrical device that converts direct current, DC, to alternating current, AC. Can be a source of noise on HF bands.
Ionosphere
The ionosphere is the ionized part of Earth’s upper atmosphere, from about 60 km (37 mi) to 1,000 km (620 miles) altitude, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. The ionization of Ionosphere is effective in bending radio frequencies back toward the earth’s surface, providing the long distance, weak signal “skip.”
IRLP
Internet Radio Linking Project – A system of repeaters around the earth that may be linked by Voice Over Internet Protocol (VOIP).
ITU
International Telecommunications Union – a United Nations organization that coordinates the use of electromagnetic spectrum between nations.

J
J-Pole Antenna
A half-wavelength radiating element with a quarter-wave matching stub, popular on VHF and UHF frequencies and a popular homebrew item.
JOTA
Jamboree On The Air – an annual Boy Scout event in which scouts and hams team up to make contacts with other scouting groups all around the world with amateur radio.
JT65
A weak signal digital mode, primarily used on HF and 6 m, for weak signal and EME type contacts (moon bounce, meteor scatter).

K
Kerchunk
A slang term for briefly pressing the PTT to activate a repeater without identifying.
Key
A switch, lever, or button for sending Morse Code; referenced by a “telegraph key.” Alternatively, to push-to-talk,as in to “key the mic” (also, “Key up”).
Kilo
Kilo is a decimal unit prefix in the metric system denoting multiplication by one thousand (103). It is used in the International System of Units, where it has the symbol k, in lower case.
Kilocycles
Thousands of cycles per second (kcyc/s), or thousands of hertz (kilohertz) [kHz].
Knife edge
The refraction of a signal over tall buildings and mountains.

L
Ladder Line
A twin-wire unshielded transmission line or feed line, usually with open space between the wires and thereby resembling a ladder.
LCD
Liquid Crystal Display, primarily used for displaying frequency and radios operations.
LED
Light Emitting Diode, commonly used as a visual indicator on radio electronics.
LF
30–300 kHz range signals.
Li-Ion (Lithium Ion), Li-Pol (Lithium Polymer), LiFePO4 (Lithium Iron Phosphate)
Rechargeable battery which has better capacity than Ni-Cd, Ni-MH, etc., no memory effect after repeated non-full charge/discharge cycles.
Limiter
A processing stage in an FM repeater that limits the amplitude of received FM signals, thereby reducing receiver sensitivity to amplitude variations and noise.
Line of Sight Propagation
Radio frequency path of travel referring to a straight line path from one station to another.
Load
A device in an electric circuit that consumes, converts, or radiates energy. An antenna is sometimes referred to as a load on the transmitter circuit.
Logging software
A computer log of contacts, used for QSL card confirmations on contacts.
LPF
Low Pass Filter.
LSB
Lower Side Band is the single sideband used by convention for bands below 30-meters. (40, 80, 160).

M
Machine
A common reference to a repeater.
Magnetic Mount (mag-mount)
An antenna that quickly installs on a car or metal surface using a magnetic attachment.
Maritime mobile /MM
Amateur radio operation from aboard a marine vessel.
MARS
Military Affiliate Radio System – military affiliated amateur operators and stations that provide free communications for deployed military personnel and others in federal service.
Mega
Mega is a unit prefix in the metric system denoting multiplication by one milion (106). It is used in the International System of Units, where it has the symbol M, in upper case.
Megacycles
Millions or cycles per second (Mcyc/s); megahertz [MHz].
Megahertz
Million hertz, 1MHz = 1.000.000 Hz
Memory bank
A set of memory channels organized into a group.
Memory effect
Rechargeable batteries such as Ni-Cd and Ni-MH types may be temporality getting less capacity as a result of repeated non-full charge/discharge cycles. It is called so since rechargeable batteries lose capacity as if “memorize” wrong full capacity level at less than full charge. Li-Ion batteries are free from this effect.
Meteor Scatter
Radio signal propagation by reflection from short-lived ionization trails of meteors in the atmosphere.
MF
Medium Frequency. 300 kHz–3 MHz range signals.
Mic
Abbreviation for microphone.
Micro
Micro (Greek letter μ or legacy micro symbol µ) is a unit prefix in the metric system denoting a factor of 10−6 (one millionth or 1/1 000 000). Confirmed in 1960, the prefix comes from the Greek μικρό (mikró), meaning „small“.
Microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter; with frequencies between 300 MHz (1 m) and 300 GHz (1 mm).Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF (millimeter wave) bands. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz (wavelengths between 0.3 m and 3 mm).
Milli
Milli (symbol m) is a unit prefix in the metric system denoting a factor of one thousandth (10−3) (1/1000). Proposed in 1793 and adopted in 1795, the prefix comes from the Latin mille, meaning „one thousand“ (the Latin plural is milia). Since 1960, the prefix is part of the International System of Units (SI).
Mixer
An RF receiver component that combines two signals and outputs signals that are the sum and difference frequency of the two input frequencies. Used in superheterodyne receivers to produce the intermediate frequency.
Mobile /M
An amateur radio station installed in a vehicle that can be used while in motion; a verb used on the air to indicate you are transmitting from a mobile station.
Mode
The type of modulation being employed in transmission (FM, SSB, CW, AM, Digital, etc.). Alternative for satellite operations, the frequency ranges used for uplink and downlink for satellite communications.
Modulation
Encoding information into a radio frequency signal. Information may be Morse Code, voice, digital, or other forms, e.g. FM, AM, SSB.
MT63
A weak signal, digital communications mode, being used in MARS net traffic.
MUF
Maximum Usable Frequency – the highest frequency for given conditions that will provide reflection from the ionosphere and promote skip propagation.
Multimode Transceiver
A transceiver with capacity to use more than one type of modulation: FM, SSB, CW, AM, Digital operations.

N
NB
Noise Blanker is a function reducing pulse-type noises.
NBFM
Narrow Band FM. is used for signals where the deviation is small enough that the terms in the Bessel function is small and the main sidebands are those appearing at ± modulation frequency. The sidebands further out are negligible. Narrowband FM is widely used for two way radio communications.
Negative
On-the-air term meaning “No”, “Incorrect” or „Not received“.
Negative Offset
Repeater input frequency (transmit to) is lower than the repeater output (listen to) frequency.
Net
An organized, on-air meeting of multiple stations, usually convened at a scheduled time and usually directed by a net control station who manages the message traffic and transmissions in an orderly fashion.
NiCad/NiCd
Nickel Cadmium, a common (older) type of rechargeable battery.
NiMH
Nickel Metal Hydride, a common type of rechargeable battery.
Node
An Echolink station via personal computer; alternatively a remotely controlled digipeater used to relay packet radio communications.
Notch filter (Band Stop Filter)
Sharp and narrow rejection filter for elimination of interfering signals. A Notch Filter is also known as a Band Stop filter or Band Reject Filter. These filters reject/attenuate signals in a specific frequency band called the stop band frequency range and pass the signals above and below this band.
NR
Noise Reduction. DSP feature reduces unwanted signal noise.
NTSC
National Television System Committee – US standard signal for broadcast TV, also used for amateur Fast Scan TV (FSTV).
NVIS
Near Vertical Incidence Skywave – propagation in which signals are reflected from the ionosphere from a steep vertical take-off angle, resulting in relatively short skywave skip distances, usually not more than a few hundred miles. NVIS is typical on low HF bands (40m, 80m, 160m) where horizontally polarized antennas are raised much less than a half-wavelength above the earth.

O
Odd Split
An unconventional pairing of frequencies, such as one VHF and one UHF frequency. Often used with satellite operations and cross-band repeater functions on some transceivers.
Offset / Offset frequency
Frequency difference between transmits and receives.
Ohm
The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Ohm. Various empirically derived standard units for electrical resistance were developed in connection with early telegraphy practice, and the British Association for the Advancement of Science proposed a unit derived from existing units of mass, length and time, and of a convenient scale for practical work as early as 1861. As of 2020, the definition of the ohm is expressed in terms of the quantum Hall effect.
Old Man
An on-air term of friendship.
Open Repeater
A repeater that may be used by any amateur; no restricted or exclusive use.
Optoisolator
Found in tuning knob circuits, where an LED shines through an interrupter to signal a data pulse.
OSCAR
Orbiting Satellite Carrying Amateur Radio.
Oscillate
To vibrate with a regular period, such as an oscillating radio wave’s electric and magnetic fields.
OSC / Oscillator
A circuit typically employing an inductor and a capacitor for producing an alternating current of a desired frequency. May form the basis of a radio transmitter.
Oscilloscope
An electronic test instrument that receives voltage or current signals and displays a visual representation of variations in signals over time.
Output Frequency
For a repeater, the frequency of retransmission, or the “listen to” frequency
Over
An on-air term used in two-way communications under noisy or difficult conditions to affirmatively alert another station of the end of transmission, and return of communications transmission back to the other station.

P
PA
Power Amplifier.
Packet Radio
Packet radio is a digital radio communications mode used to send packets of data. Packet radio uses packet switching to transmit datagrams. This is very similar to how packets of data are transferred between nodes on the Internet. Packet radio can be used to transmit data long distances. Packet radio is frequently used by amateur radio operators.
PACTOR
Digital radio modulation used mostly on the HF bands for digital messaging.
Paddle
A Morse Code key.
PBT
PassBand Tuning is a function to reduce interference by electronically narrowing the IF bandwidth.
PCB
Printed Circuit Board is a board on which electrical contacts and connections have been imprinted for the electrical connectivity of electronic components to be mounted in a specific arrangement to affect an electronic circuit.
PEP
Peak Envelope Power is the average power of a signal over its largest amplitude peaks.
Phase
With RF waveforms, the relative position of the oscillations of electric and magnetic fields of compared waveforms. Phase is defined as a 360 degree cycle of oscillation.
Phase Modulation (PM)
Encoding information into an RF signal by varying its wave phase characteristics.
Phone
A transmission mode encoding voice information into RF signals.
Phone Patch (Autopatch)
A connection between a two-way radio and a telephone, commonly a utility of repeater stations allowing a radio-to-telephone connection.
Photovoltaic
Solar cell, converting photons to electricity.
Picket Fencing
A rapidly fluctuating sound or signal due to a station in motion during transmission and the associated interferences.
Pile-up
A condition in which multiple stations are attempting to call the same, singular station.
PL
Private Line (inaccurate implication), a term used for CTCSS tone implementation.
PLL
Phase Locked Loop is a circuit to synthesize the different frequencies a radio will operate on.
Pocket beep
Beeping function when specific signal is received.
Portable
A station that may be easily moved from place to place, or a station being operated away from its home location. (A mobile station is one used while in motion; a portable station is a relocated stationary station.)
Positive Offset
A Repeater input frequency (transmit to) is higher than the repeater output (listen to) frequency.
Power supply
Usually converts 110 / 220 Volts AC to 12 Volts DC. Sometimes built in, sometimes external to the equipment.
Priority watch
Reception mode, which by a selected frequency is always periodically, checked when VFO is set to different frequency.
Product Detector
A receiver circuit consisting of an oscillator and mixer used to receive SSB or CW signals.
Propagation
The travel path of RF signals or the means of travel of RF signals.
PSK31
Phase Shift Keying 31 – a digital mode using phase shifts to encode characters at 31.25 baud rate for computer keyboard-to-keyboard chatting. Very effective in high noise conditions such as HF SSB.
PTT
Push-to-Talk is switching on the microphone to transmit, or the radio circuit allowing transmission and microphone activation.
PWR
Power

Q
Q
Response of a circuit over a specific bandwidth. Also, Ham Slang for a contact, or QSO.
Q-Signal
Three-letter codes derived from Morse Code and used as abbreviations for common communication phrases and questions.
Quad
A type of directional antenna employing square element arrangements one-quarter wavelength separated.
QRP
A Q-signal referring to reduced power, or a low-power station operation, typically 5 watts or less.
QSL
A Q-signal meaning “acknowledge receipt” and commonly used to mean “I copy” or “I understand”.
QSL Card
A card exchanged by station operators to confirm a contact and establish a record of it.
QSO
A Q-signal meaning a two-way radio communication or conversation.
Quagi
A directional antenna, commonly homebrewed, that combines elements of both Quad designs and Yagi designs.

R
RACES
Radio Amateur Civil Emergency Service – Volunteer operators that aid civil authorities during emergencies.
Rag Chew
An informal, often extended, on-air conversation. A casual conversation of duration.
RDF
Radio Direction Finding is a device for finding the direction, or bearing, to a radio source. The act of measuring the direction is known as radio direction finding or sometimes simply direction finding (DF). Using two or more measurements from different locations, the location of an unknown transmitter can be determined; alternately, using two or more measurements of known transmitters, the location of a vehicle can be determined. RDF is widely used as a radio navigation system, especially with boats and aircraft.
Reflected power
Non-radiated power dissipated as heat when the transmitter is mismatched to the antenna or load.
Reflector
In a Yagi or Quad directional antenna, the rear passive element. With IRLP, a server that allows multiple IRLP repeater nodes to be linked together simultaneously.
Refract / Refraction
To bend. RF transmissions may be refracted by the ionosphere (not truly reflected, as with a mirror).
Repeater
A station that receives transmissions on one frequency and immediately retransmits the same signal on another frequency, usually at greater power and from a higher vantage point, extending the effective radio range.
Repeater Directory
A publication listing repeaters.
Resonance
An electrical condition promoting very efficient reinforcement of alternating current in a circuit.
RF
Radio Frequency
RF ground
Connection of amateur equipment to earth ground to eliminate hazards from RF exposure and reduce RFI.
RFI
Radio Frequency Interference
Rig
Informal term for a station or radio.
RIT
Receiver Incremental Tuning (AKA Clarifier) – a transceiver control that allows adjustment of the receive frequency without changing the transmission frequency or displayed or memory frequency. Used extensively in SSB operations to tweak receive audio for tone.
Roger
On-air term meaning “I understand” or “100% received.”
Rover
In a radio contest, a station that moves among more than one grid square, counties, or other geographic units.
RST
The R-S-T system is used by amateur radio operators, shortwave listeners, and other radio hobbyists to exchange information about the quality of a radio signal being received. The code is a three digit number, with one digit each for conveying an assessment of the signal’s readability, strength, and tone. The R stands for „Readability“. Readability is a qualitative assessment of how easy or difficult it is to correctly copy the information being sent during the transmission. In a Morse code telegraphy transmission, readability refers to how easy or difficult it is to distinguish each of the characters in the text of the message being sent; in a voice transmission, readability refers to how easy or difficult it is for each spoken word to be understood correctly. Readability is measured on a scale of 1 to 5. 1 Unreadable 2 Barely readable, occasional words distinguishable 3 Readable with considerable difficulty 4 Readable with practically no difficulty 5 Perfectly readable The S stands for „Strength“. Strength is an assessment of how powerful the received signal is at the receiving location. Although an accurate signal strength meter can determine a quantitative value for signal strength, in practice this portion of the RST code is a qualitative assessment, often made based on the S meter of the radio receiver at the location of signal reception. „Strength“ is measured on a scale of 1 to 9. 1 Faint—signals barely perceptible 2 Very weak signals 3 Weak signals 4 Fair signals 5 Fairly good signals 6 Good signals 7 Moderately strong signals 8 Strong signals 9 Extremely strong signals The T stands for „Tone“ and is measured on a scale of 1 to 9. Tone only pertains to Morse code and other digital transmission modes and is therefore omitted during voice operations. With modern technology, imperfections in the quality of transmitters’ digital modulation severe enough to be detected by human ears are rare. 1 Extremely rough hissing note* Sixty cycle a.c or less, very rough and broad** 2 Very rough a.c. note, no trace of musicality* Very rough a.c., very harsh and broad** 3 Rough, low-pitched a.c. note, slightly musical* Rough a.c. tone, rectified but not filtered** 4 Rather rough a.c. note, moderately musical* Rough note, some trace of filtering** 5 Musically modulated note* Filtered rectified a.c. but strongly ripple-modulated** 6 Modulated note, slight trace of whistle* Filtered tone, definite trace of ripple modulation** 7 Near d.c. note, smooth ripple* Near pure tone, trace of ripple modulation** 8 Good d.c. note, just a trace of ripple* Near perfect tone, slight trace of modulation** 9 Purest d.c. note* Perfect tone, no trace of ripple or modulation of any kind** An example RST report for a voice transmission is „59“, usually pronounced „five nine“ or „five by nine“, a report that indicates a perfectly readable and very strong signal. Exceptionally strong signals are designated by the quantitative number of decibels, in excess of „S9“, displayed on the receiver’s S meter. Example: „Your signal is 30 dB over S9,“ or more simply, „Your signal is 30 over 9.“ Because the N character in Morse code requires less time to send than the 9, during amateur radio contests where the competing amateur radio stations are all using Morse code, the nines in the RST are typically abbreviated to N to read 5NN. In general, this practice is referred to as abbreviated or „cut“ numbers. *) 1936 definition; **) modern definition
RTTY
Radioteletype (RTTY) is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations connected by radio rather than a wired link. These machines were superseded by personal computers (PCs) running software to emulate teleprinters. Radioteletype evolved from earlier landline teleprinter operations that began in the mid-1800s.
Rubber Duck
A short rubberized antenna used on a handheld transceiver.
RX
Receive / Receiver.

S
S-Meter
The S-meter is an instrument present on the majority of radio receivers that measures the strength of the signal that is being received, and uses a special unit: the S-point. S-points are often used for RST reports. S-points go from S1 to S9 and each S-point is defined as a 6 dB change in signal strength.
S/N
Signal to Noise ratio.
SAR
Search And Rescue.
Safety
RF exposure limits, set by ANSI (American National Standards Institute), to minimize over exposure to RF signals from a nearby antenna.
Scan
Continually sweeping frequencies looking for signals.
Scan Edge
End and start frequencies for a scanning range. Scratch Pad Memory Temporary frequency memories for quick access.
Selectivity
Selectivity is a measure of the performance of a radio receiver to respond only to the radio signal it is tuned to (such as a radio station) and reject other signals nearby in frequency, such as another broadcast on an adjacent channel.
Semi Duplex
An operation mode in which transmits and receives is accomplished on different frequencies alternatively.
Sensitivity
The sensitivity of a radio receiver determines the weakest signals that can be successfully receiver. Whether it is an audio signal for which the listening quality deteriorates as the signal falls into the noise, or a data signal where the bit error rate rises and throughput falls.
Set mode
An operation mode used for radio. To set less frequently used control features.
Shack
A ham station’s operations area, room, or building.
Silent Key
A deceased amateur radio operator.
Simplex
Communications in which transmission and reception is conducted on one single frequency.
Skip Zone
The skip zone, which may also be called a silent zone or dead zone, is a region where a radio transmission can not be received. The skip zone is the region between the point where the ground wave signals can no longer be heard and the point where the skywave first returns to Earth.
Sky Wave
This curious effect, which often manifests as nighttime interference, is caused by a phenomenon known as „skywave.“ Skywave is essentially radio waves from full power AM stations that travel upward, refracted through the ionosphere (from early evening throughout the night into morning) such that radio signals sometimes …
Skywarn
Trained volunteer storm spotters for the National Weather Service.
SMA
Sub-Miniature a connector. Type of antenna connector, used in VHF/UHF portable.
SP
Speaker
Splatter
Interference from a station on nearby frequencies; transmissions from a station that exceed the necessary bandwidth for normal communications and that cause interference outside of normal bandwidth usage.
Split / Split Operating
Transmitting on one frequency and listening on another, particularly on HF SSB operations, to avoid congestion on the transmit frequency.
Sporadic E
Irregular patches of E-layer ionosphere activation that randomly refract higher frequency signals than are normally refracted. The 6-meter band is commonly used for skip propagation during periods of Sporadic E.
Spurious Emissions
Undesired signals from a transmitter outside of the tuned frequency range.
SQL / Squelch
A control muting the audio output of a receiver when received signal strength is below a set value.
SSB
Single Sideband – A special type of AM mode utilizing only one of the two AM sidebands and deleting the carrier frequency from transmissions.
SSTV
Slow Scan TV – An amateur radio TV transmission using approximately 3 kHz of bandwidth and transmitting single frame images.
Superheterodyne
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency.
SWL
Short Wave Listener
SWR
In radio engineering and telecommunications, standing wave ratio (SWR) is a measure of impedance matching of loads to the characteristic impedance of a transmission line or waveguide. Impedance mismatches result in standing waves along the transmission line, and SWR is defined as the ratio of the partial standing wave’s amplitude at an antinode (maximum) to the amplitude at a node (minimum) along the line.
SWR Meter
The standing wave ratio meter, SWR meter, ISWR meter (current „I“ SWR), or VSWR meter (voltage SWR) measures the standing wave ratio (SWR) in a transmission line. The meter indirectly measures the degree of mismatch between a transmission line and its load (usually an antenna). Technicians use it to evaluate the effectiveness of impedance matching efforts.

T
TCXO
Temperature Compensated Crystal Oscillator. Heated crystal oscillator for better frequency stability.
Third Party Communications
Communications from one operator to a second operator on behalf of a third person; also commonly refers to allowing a non-licensed “third party” communicate on amateur frequencies under supervision of a licensed control operator.
Ticket
A slang term referring to an amateur radio license.
Time-Out
On a repeater, a timer circuit may be employed to avoid excessively long transmissions or “stuck mic” condition. The repeater may time-out, cutting off a long transmission. The time-out duration is determined by the repeater operator.
TNC
Terminal Node Controller – a control box for interfacing a transceiver and a radio, particularly for packet operations.
Tone
See CTCSS; the subaudible tone transmitted as a method of opening squelch of a receiver. Alternatively, see DTMF – a tone used to send activation codes.
TOT
Time Out Timer. Time limiting function for continued repeater or other operations.
Towers
Antenna support structures.
Traffic
A message distributed via radio communications.
Transceiver
A combination of a transmitter and a receiver in one device; a radio that both transmits and receives.
Transverter
A device similar to a downconverter, but used for both receive and transmit.
Tropospheric Ducting
The propagation of VHF signals long distances along a ‘pipe’ created by a temperature inversion in the lowest layer of the atmosphere.
TRX
Transceiver
TS
Tuning Step. Incremental steps.
TSQL
Tone Squelch is a squelch function using subaudible tones, selective call.
TVI
TeleVision Interference
TWT
Traveling Wave Tube, found in microwave amplifier circuits.
TX
Transmit / Transimtter.

U
UHF
Ultra High Frequency; 300 – 3 000 MHz frequency. Includes the 70cm band and higher frequencies.
UHF connector
Sometimes called a PL-259 plug, for coaxial cable, on VHF.
Uplink
Frequency that user transmits to the repeater or satellite. (↔Downlink)
USB
Upper Sideband is in Single Sideband operations, the sideband comprised of frequencies above (higher than) the carrier frequency to which the transceiver is tuned.
UTC
Universal Time Coordinate, AKA Coordinated Universal Time; the 24 hour time reference based upon Greenwich, England’s time and the 0-degree Meridian.

V
VAC
Volts Alternating Current. There is no such thing as VAC power – it is just AC power. When you see 110 VAC on an appliance, it means 110 volts AC power. Voltage is a measure of „circuit pressure.“ It refers to how hard the electricity pushes through a circuit. … AC is also measured in frequency–how fast it changes direction.
VCO
Voltage Controlled Oscillator, found in the PLL section of the modern radio.
VE
Volunteer Examiner, who issues license exams in the amateur service.
VEC
Volunteer Examiner Coordinator – an amateur radio organization coordinated with the FCC to operate and oversee all volunteer examiners.
VFO
A variable frequency oscillator (VFO) in electronics is an oscillator whose frequency can be tuned (i.e., varied) over some range. It is a necessary component in any tunable radio receiver or transmitter that works by the superheterodyne principle, and controls the frequency to which the apparatus is tuned.
Velocity Factor
The speed of electromagnetic signal propagation through a feedline expressed as a percentage of the speed of light.
VHF
Very High Frequency – 30 – 300 MHz frequency. Includes the 6m to 1.25m amateur bands.
VLF
Very Low Frequency – 3 – 30 kHz frequency.
Volt
The basic unit of electromotive force (EMF). It is the SI unit of electromotive force, the difference of potential that would carry one ampere of current against one ohm resistance.
VOX
In telecommunications, a voice operated switch, also known as VOX or voice-operated exchange, is a switch that operates when sound over a certain threshold is detected. It is usually used to turn on a transmitter or recorder when someone speaks and turn it off when they stop speaking. It is used instead of a push-to-talk button on transmitters or to save storage space on recording devices.
VSC
Voice Scan Control / Voice Squelch Control
VSWR
Voltage Standing Wave Ratio; a common measure of SWR using voltages rather than power units.

W
WAC
Worked All Continents, an award from the IARU and administered by ARRL.
WAS
Worked All States, an ARRL award to confirm contact in all 50 US states.
Waveguide
The carrier of microwaves from radio to antenna, and back.
WAZ
Worked All Zones, a CQ magazine award for confirmed contact with each of the 40 world zones.
Weather Alert
NOAA broadcast station transmitting alert signals.
WFM
Wideband FM. Wideband FM is used for FM broadcasting, in which music and speech are transmitted with up to 75 kHz deviation from the center frequency and carry audio with up to a 20 kHz bandwidth and subcarriers up to 92 kHz.
Work
Ham slang meaning to communicate with, as in “I worked seven different countries this morning.”

X
XIT
Transmitter Incremental Tuning, provides slight changes in transmit frequency without effecting receive frequency.
XYL
On-air slang for Ex-Young Lady, referring to one’s wife.

Y
Yagi
A directional or beam antenna of a specific design invented by Hidetsugu Yagi and Shintaro Uda in 1926.
YL
Young Lady

Z
Zed
A phonetic letter for “Z”.
Zener diode
A diode used to regulate the operating voltage.
Zero Beat
An adjustment of two signals to be exactly equal in phase, and thereby producing no beat frequency.
Zepp Antenna
An end-fed wire that was reeled down and up from Zeppelin aircraft.
Zulu
An alternate term for referring to UTC.

Other
73
Best regards
88
Love and kisses
807
A deceptive ham term for ale and also a popular transmitting tube of the early 20th century.