Ø - zero with a stroke
3OIP - third-order intercept point.
73 - Ham lingo for "best regards." Used on both phone and CW toward the end of a contact.

A
A - ampere
A-to-D - analog-to-digital.
a.m. - ante meridian.
A/B - "A" display/"B" display switch.
A/D - analog-to-digital.
AARS - Army-Amateur Radio System.
AC - (1) Affiliated Club Coordinator. (2) alternating current.
AC hum - alternating-current hum.
ACC - accessory.
ACDS - automatically controlled digital station.
ACI - adjacent-channel interference.
ACSSB - amplitude-companded single-sideband.
ADC - analog-to-digital.
ADIF - Amateur Data Interchange Format.
ADN - advanced digital network.
AF - audio frequency.
AF signal - audio-frequency signal.
AF-gain - audio-frequency gain.
AFC - automatic frequency control.
AFSK - audio-frequency shift keying.
AGC - automatic gain control.
AGC-F - automatic gain control fast.
AGC-S - automatic gain control slow.
AGL - above ground level.
AGM - absorbed glass mat.
AGS - antenna ground system.
AGWE - agw packet engine.
AIP - advanced intercept point.
AL; AL - inductance index.
AL-MOD - alarm mode.
ALC - automatic level control. ALE - automatic link establishment.
AM - amplitude modulation.
amp - amplifier. Amp - ampere.
AMSAT - Amateur Satellite Organization.
AMTOR - amateur teleprinting over radio.
ANARC - Association of North America radio Clubs.
ANC - active noise control.
ANF - automatic notch filter.
ANI-ID - automatic number identification.
ANR - active noise reduction.
ANSI - American National Standards Institute.
ANT - antenna.
anti-VOX - anti-voice operated.
AP - antenna pattern.
APC - automatic power control.
APCO - Association of Public-Safety Communications Officials-International.
APO - accessory power outlet.
APRS - Automatic Packet Reporting System.
AQS - acquisition of signal.
ARA - Amateur Radio Association.
ARC - Amateur Radio Club.
AREDN - Amateur Radio Emergency Data Network.
ARDF - amateur radio direction finding.
ARDS - Amateur Radio Disaster Services.
AREDN - Amateur Radio Emergency Data Network.
ARES - Amateur Radio Emergency Service.
ARISS - Amateur Radio on the International Space Station.
ARQ - automatic repeat query.
ARRL - American Radio Relay League.
ARS - (1) Amateur Radio Society. (2) Amateur Radio Service. (3) automatic repeater shift.
ARTS - Auto-Range Transponder System.
ASCII - American Standard Code for Information Interchang.
ASK - amplitude-shift keying.
ASL - above sea level.
ASR - automatic send-receive.
ATS - automatic transfer switch.
ATT - attenuator.
ATU - antenna tuning unit. ATV - amateur television.
AVC - automatic volume control.
AWG - American wire gauge.
Az/El - azimuth/elevation.

B
B - bel.
balun - balanced-to-unbalanced.
BBC - British Broadcasting Corporation.
BBS - bulletin board system.
BBTD - (1) broadband butterfly terminated dipole. (2) broad band terminated dipole.
BCB - broadcast band.
BCD - binary-coded decimal.
BCI - broadcast radio interference.
BCL - (1) broadcast listener. (2) busy channel lock-out
Bd - baud.
BER - bit error rate.
BFO - beat frequency oscillator.
BFSK - binary frequency-shift keying.
BHMM - Broadband-Hamnet.
BICMOS - bipolar complementary metal-oxide-semiconductor.
BIPM - International Bureau of Weights and Measures.
BJT - bipolar-junction transistor.
BNC - bayonet Neill-Concelman.
BPF - band-pass filter.
BPL - Brass Pounders League.
bps - bits per second.
BPSK - binary phase shift keying.
BW - bandwidth.

C
c - centi
C - coulomb.
CØG; COG - Electronic Industries Association category.
C4FM - continuous 4-level frequency modulation.
call signal - (See call sign).
CAP - Civil Air Patrol.
CAT - Computer Aided Tranceiver CATV - cable television.
CATVI - cable television interface.
CB - Citizen's Band.
CBA - callbook address.
CBR - cross-band repeater.
CBRS - Citizens Band Radio Service.
CC&R - covenants, conditions, and restrictions.
CCD - charge-coupled device.
CCW - (1) coherent continuous wave. (2) counterclockwise.
CD - compact disc.
CE - chief engineer
CEPT - Conference of Postal and Telecommunications Administrations.
CFA - crossed field antenna.
CFR - Code of Federal Regulations.
CG - Channel Guard.
ch - channel
CI-V - computer interface version five.
CIPM - International Committee for Weights and Measures.
CGPM - General Conference on Weights and Measures.
CLAR - clarifier.
cm - centimeter.
CMC - common mode current.
CME - coronal mass ejection.
CMOS - complementary-symmetry metal-oxide semiconductor.
code - Morse code.
COR - carrier-operated relay.
COTA - Castles on the Air.
cpm - characters per minute.
CPO - code practice oscillator.
CPU - central processing unit.
CPS - cycles per second.
CQ - seek you.
CQ DX - seek you foreign country.
CRC - cyclic redundancy check.
CRT - cathode-ray tube.
CSCE - Certificate of Successful Completion of Examination.
CSQ - carrier squelch.
CTCSS - continuous-tone coded squelch system.
CVE - Contact Volunteer Examiner.
CW - (1) continuous wave, Morse code. (2) clockwise.

D
d - deci
D-to-A - digital-to-analog converter.
D-RATS - multi-platform integrated tool for communicating digital information.
D-STAR - Digital Smart Technologies for Amateur Radio.
D/A - digital-to-analog converter.
DAB - digital audio broadcasting.
DAC - digital-to-analog converter.
dB - decibel.
dBc - decibels to a carrier.
dBd - decibels above a dipole antenna.
dBi - decibels above an isotropic antenna.
dBm - decibels of the measured power.
dBμV - decibels microvolt.
dBo - decibels optical gain.
DC - direct current.
DCHP - dynamic host configuration protocol.
DCS - digital-coded squelch.
DDFS - direct digital synthesizer.
DDS - direct digital synthesizer.
deca - deca
deka - deka
DE - "from" or "this is" DEL-CH - memory channel delete.
DF - direction finding.
DFQ - dead full quieting.
DIY - do-it-yourself.
DMM - digital multimeter.
DMR - digital mobile radio.
DPDT - double-pole, double-throw.
DPSK - differential phase shift keying.
DPST - double-pole, single-throw.
DRM - digital radio mondiale.
DSB - double sideband.
DSB-SC - double sideband with suppressed carrier.
DSP - (1) digital signal processing. (2) digital signal processor.
DSSS - direct-sequence spread-spectrum.
DTCS - digital tone coded squelch.
DTMF - dual-tone multi-frequency.
DVM - digital voltmeter.
DX - distant or foreign station.
DX QSL manager - QSL manager.
DXCC - DX Century Club.
DXer - distant station operator.
DXing - distant station operation.
DXpedition - distant station expedition.
dyn - dyne

E
η - efficiency.
e-FCR - Electronic Code of Federal Regulations.
e-mail - electronic mail.
e.g. - for example.
E-skip - sporadic E.
EAS - Emergency Alert System.
EBCDIC - extended binary coded decimal interchange code.
EBS - Emergency Broadcast System.
EC - Emergency Coordinator.
ECIA - Electronic Components Industry Association.
ECSS - exalted-carrier single sideband.
ECSSB - exalted-carrier single sideband.
EEPROM - electrically erasable and programmable read-only memory.
EFHW - end-fed half-wave.
EHAAT - height above average terrain.
EHF - extremely high frequency.
EIA - Electronic Industries Association.
EIA232 - Electronic Industries Association 232.
EIRP - effective isotropic radiated power.
ELF - extremely low frequency.
ELT - emergency locator transmitter.
email - electronic mail.
EMC - electromagnetic compatibility.
EMCOM - emergency communications.
EME - earth-moon-earth.
EMF - electromotive force.
EMI - electromagnetic interference.
EMI sleeves - electromagnetic interference sleeves.
EOC - Emergency Operation Center.
EMP - electromagnetic pulse.
EMS - Emergency Medial Services.
EMU - electronic-message unit.
ERC - Emergency Response Communications.
ERP - effective radiated power.
eQSL.cc - Electronic QSL Card Centre.
Es - sporadic E.
ES - sporadic E.
ESD - electrostatic discharge.
ESR - equivalent series resistance.
EPROM - electrically programmable read-only memory.
EZ-NEC - Numerical Electromagnetics Code variation.

F
F - farad.
F layer - highest section of the ionosphere.
F region - highest section of the ionosphere.
F10.7 Index - measure of solar radiation at 2800 MHz.
F/B - front-to-back ratio.
F/S - front-to-side ratio.
FA - Friendship Award.br> FAA - Federal Aviation Administration.
fax - facsimile.
FCC - Federal Communications Commission.
FDM - frequency-division multiplexing.
FDMA - frequency-division multiple access.
FEC - forward error correction.
Feld-Hell - Hellschreiber.
FET - field-effect transistor.
FFT - fast Fourier transform.
FHSS - frequency-hopping spread-spectrum.
FIR - finite impulse response.
FM - frequency modulation.
FME - 50 Ω coaxial cable feedline connector.
FMRE - Federación Mexicana de Radioexperimentadores, A.C.
FOC - First Class CW Operators Club.
FPGA - field-programmable gate array.
FRC - Federal Radio Commission.
FRN - Federal Registration Number.
FRS - Family Radio Service.
FSK - frequency-shift keying.
FSK441 - frequency-shift keying, 441 baud.
FSTV - fast-scan television.
FT4 - Franke-Taylor, 4-FSK.
FT8 - Franke-Taylor, 8-FSK.

G
giga - giga
G.I. galvanized iron, Government Issue.
G-TOR - Golay-teleprinting over radi.
GaAs - gallium arsenide.
GCR - General Certification Rule.
geocodes - geographical codes.
GFCI - ground-fault circuit interrupter.
GFI - ground-fault interrupter.
GFO - Government Printing Office.
GHz - gigahertz.
GMRS - General Mobile Radio Service.
GMSK - Gaussian minimum-shift keying.
GMT - Greenwich Mean Time.
GOTA - Get on the Air.
GPS - Global Positioning System.

H
h - hecta
h - hecto
H - henry.
Hz - hertz.
HAAT - height above average terrain.
HASL - height above sea level.
HDTV - high-definition television.
HDX - half-duplex.
Hell - Hellschreiber.
HF - high frequency.
HF bands - high-frequency bands.
HOA - homeowner association.
HPF - high-pass filter.
HSMM - high speed multimedia.
HSMS - high-speed meteor scatte.
HPSDR - high-performance software-defined radio.
HT - high tension; hand-held transceiver.
HWA - hot-wire ammeter.

I
I - intensity.
i.e. - that is.
I/O - input/output.
IARP - International Amateur Radio Permit.
IARU - International Amateur Radio Union.
IC - (1) integrated circuit. (2) Incident Commander.
IC-V - Icom Commputer Control Interface.
ICAO - International Civil Aviation Organization.
ICAO spelling alphabet - International Civil Aviation Organization spelling alphabet.
ICW - interrupted Morse code.
ID - identification.
IDC - insulation-displacement connector.
IF - intermediate frequency.
IF shift - intermediate-frequency shift.
IFK - incremental frequency keying.
IIR - infinite impulse response.
IMD - intermodulation distortion.
IMF - interplanetary magnetic field.
IMI - intermodulation interference.
IMRR - image response rejection ratio.
IMT - Incident Management Team.
indirect FM - indirect frequency modulation.
intermod - intermodulation.
IOTA - Islands On The Air.
IP - Internet Protocol.
IP3 - intercept point.
IP&E - interconnect, passive and electro-mechanical.
IPK - International Prototype Kilogram.
IQ data - in-phase / quadrature
IRC - International Reply Coupon.
IRLP - Internet Radio Linking Project.
IRT - Incident Response Team.
ISS - International Space Station.
ITA2 - International Telegraph Alphabet number 2.
ITU - International Telecommunications Union.
ITU Region - International Telecommunications Union Region.
ITU Zone - International Telecommunications Union Zone.
ITU phonetic alphabet - International Telecommunications Union phonetic alphabet.

J
J - joule.
JFET - junction field-effect transistor.
JOTA - Jamboree On The Air.
JS8 - Jordan Sherrer-designed 8-FSK.
JT65 - Joe Taylor 65.
JT65-HF - Joe Taylor 65-High Frequency.
JT9 - Joe Taylor 9.

K
k - kilo
K-index - geomagnetic index.
kc - kilocycle.
keps - Keplerian data sets.
kg - kilogram.
kHz - kilohertz.
kilo - kilo
KISS - keep it simple, stupid.
km - kilometer.
KW - kilowatt.
kWh meter - kilowatt-hour meter.

L
L band - alternate name for the 23-cm band.
LAN - local area network.
LCD - liquid-crystal display.
LD - ling distance.
LDF - low-density foam.
LED - light-emitting diode.
LEO - low earth orbit.
LF - low frequency.
LFP - lithium ferrophosphate.
LGL - Local Government Liaison.
Li-ion - lithium ion.
Li-Po - lithium-ion-polymer.
LiFePO4 - lithium iron phosphate.
Litz wire - Litzendraht wire.
LiTZ - Long Interval Tone Zero.
LEO - Low Earth Orbit.
LMR - land mobile radio.
LMRS - land mobile radio system.
LNA - low-noise amplifier.
LO - local oscillator.
LORAN - long-range navigation.
LOS - (1) line-of-sight. (2) loss of signal.
LOTW - Logbook of the World.
LowFER - low-frequency experimental radio.
LPDA - log-period dipole array.
LPF - low-pass filter.
lsb - least significant bit.
LSB - lower sideband.
LTZ - Long Tone Zero.
LUF - lowest usable frequency.
LW - long wave.

M
μ - micro
μF - microfarad.
μs - microsecond.
m - (1) meter. (2) milli
M - mega
mA - milliampere.
magnetron - (See vacuum tube)
MARS - Military Auxiliary Radio System.
mc - megacycle.
MC4 connector - multi-contact, 4mm. MCW - modulated continuous wave.
MDF-A - channel mode A display.
MDF-B - channel mode B display.
MDS - minimum discernable signal.
medfer - medium-wave-frequency experimental radio.
mega - mega
MEM-CH - memory channel storage.
MF - medium frequency.
MFSK - multi-frequency-shift keying.
mic gain - microphone gain.
MIC - microphone.
micro - one millionth.
mike - microphone.
milli - milli
MHz - megahertz.
MMIC - monolithic microwave integrated circuit.
MOPA - master oscillator, power amplifier.
MOSFET - metal-oxide semiconductor field-effect transistor.
MOV - metal-oxide varistor.
MPC - multiple-protocol controller.
MPE - maximum permissible exposure.
MPR - mass-produced rig.
MR - memory mode.
MSK - minimum-shift keying.
MSK144 - minimum-shift keying, 144 MHz.
MSK144 Sh - minimum-shift keying, 144 MHz Short.
MUF - maximum useable frequency.
MURS - Multi-Use Radio Service.
mW - milliwatt.
MW - (1) medium wave. (2) megawatt.

N
N - newton.
n - nano
NAQCC - North American Low-power Morse-code Club.
NARA - National Archives and Records Administration.
NASA - National Aeronautics and Space Administration.
NATO - North Atlantic Treaty Organization.
NATO phonetic alphabet - North Atlantic Treaty Organization phonetic alphabet.
NB - (1) narrow band. (2) noise blanker.
NBEMS - Narrow Band Emergency Messaging Software.
NBFM - narrow band frequency modulation.
NBS - National Bureau of Standards.
NCJ - National Contest Journal Magazine.
NCR - Naval Communication Reserve.
NCS - net control station.
NEC - (1) National Electrical Code. (2) Numerical Electromagnetics Code.
nF - nanofarad.
NFM - narrowband FM.
NiCd - nickel-cadmium.
NiMH - nickel-metal hydride.
NIMS - National Incident Management System.
NIST - National Institute of Standards and Technology.
NFM - narrow frequency modulation.
NM - Net Manager.
NMO - new Motorola mount.
NOAA - National Oceanic and Atmospheric Administration.
NPN - negative-positive-negative.
NPOTA - National Parks on the Air.
NR - noise reduction.
NRQZ - National Radio Quiet Zone.
NTS - National Traffic System.
NTSC - National Television System Committee.
NVIS - near-vertical-incidence-skywave.
NWS - National Weather Service.

O
Ω - Ohm.
O-scope - oscilloscope.
O-wave - ordinary wave.
OES - Official Emergency Station.
OET - Office of Engineering & Technology.
OFC - off-center-fed antenna.
OFDM - orthogonal frequency division multiplexing.
OFFSET - frequency shift amount.
ohm - unit of resistance.
OO - Official Observer.
OOC - Official Observer Coordinator.
OOK - on-off keying.
op-amp - operational amplifier.
ORS - Official Relay Station.
OSC - oscillator.
OSCAR - Orbiting Satellite Carrying Amateur Radio.
OT - old timer.
OTC - Old Timer's Club.
OTH - over-the-horizon.
OTS - Official Traffic Station.
OWL - open-wire line.

P
P1db - 1 dB compression.
P25 - Project 25.
π pad - pi pad.
p - pico
P-P - peak-to-peak.
P-static - precipitation static.
p.m. - post meridian; after noon.
PA - power amplifier.
PAL - phase alteration line.
paramp - parametric amplifier.
PBBS - Packet Bulletin Board System.
PBT - passband tuning.
PC - personal computer.
PCB - printed circuit board.
PCM - pulse-code modulation.
PDF - Portable Document Format.
PEV - peak envelope voltage.
PEP - peak envelope power.
pF - picofarad.
PGA - pin grid array.
PIC - (1) programmable interface controller. (2) Public Information Coordinator.
PIN - positive-intrinsic-negative.
PIO - Public Information Officer.
PIV - peak inverse voltage.
PKT - packet radio.
PL - private line.
PL tone - private line tone.
PL-259 - plug-259.
PLD - programmable logic device.
PLL - phase-locked loop.
PM - (1) phase modulation. (2) power meter.
PMR - (1) private mobile radio. (2) professional mobile radio.
PMR446 - Personal Mobile Radio at 446 MHz.
PNP - positive-negative-positive.
PoE - power over ethernet.
PRB - Private Radio Bureau.
preamp - preamplifier.
PROM - programmable read-only memory.
PRS - Personal Radio Service.
PS - power supply.
PSE QSL - please acknowledge.
PSK - phase shift keying.
PSK31 - phase shift keying version 31.
PSU - power supply unit.
PTO - permeability-tuned oscillator.
PTT - push-to-talk.
PTT-ID - push-to-talk identification.
PTT-LT - push-to-talk signal code sending delay.
PV - photovoltaic.
PWM - pulse-width modulation.
PWR - power.
PX - press release.

Q
Q - (1) Response of a circuit over a specific bandwidth. (2) Ham slang for a contact, or QSO. (3) Quality.
Q factor - quality factor.
QC - Quiet Channel.
QCWA - Quarter Century Wireless Association.
QER - quasi-equiripple.
QPSK - quadrature phase shift keying.
QRO - high-power operation.
QRP - low-power operation.
QSL - contact.
QSLL - reply card.
QTH - (1) current location. (2) Slang for home.

R
R-CTCS - receiver continuous-tone coded squelch system.
R/C - radio-control.
RAC - Radio Amateurs of Canada.
RACES - Radio Amateur Civil Emergency Service.
radar - radio detection and ranging.
RAM - random access memory.
RC - resistance-capacitor.
RCC - Rag Chewers Club.
RCCB - residual-current circuit breaker.
RCV - receive.
rcvr - receiver.
RDF - radio direction finding.
RF - radio frequency.
RF burn - radio frequency burn.
RF carrier - radio frequency carrier.
RF choke - radio frequency choke.
RF exposure - radio frequence exposure.
RF feedback - radio frequency feedback.
RF gain - radio frequency gain.
RF ground - radio frequency ground.
RF interference - radio frequency interference.
RF radiation - radio frequency radiation.
RF safety - radio frequency safety.
RF signals - radio frequency signals.
RF overload - radio frequency overload.
RFI - radio frequency interference.
RFID - radio frequency identification.
RG - radio guide.
RI - Radio Inspector.
RIT - receiver incremental tuning.
RJ-11 - registered jack-11.
RJ-45 - registered jack-45.
RMDR - reciprocal mixing dynamic range.
RMS - (1) radio message servers. (2) root mean square. (3) root mean square voltmeter.
ROM - read-only memory.
RP-SMA - reverse polarity SMA.
RP-STE - squelch tail elimination.
RPT-RL - squelch tail repeater delay.
RSGB - Radio Society of Great Britain.
RST - readability, strength, tone.
RTMA - Radio-Television Manufacturers Association.
RTTY - radioteletype.
RWOP - RW open protocol.
RX - receive.
RX-LED - display backlight color receive.

S
S - siemens. S&R - search and rescue.
S-meter - signal-strength meter.
S-unit - strength unit.
S/N - signal-to-noise ratio.
SAR - (1) specific absorption rate. (2) search and rescue.
SAREX - Space Amateur Radio Experiment.
SASE - self-addressed stamped envelope.
SAT - subaudible tone.
SC-REV - scanner resume method.
SCR - silicon-controlled rectifier.
SD - standard-definition television.
SDR - software-defined radio.
SEC - Section Emergency Coordinator.
SET - (1) Simulated Emergency Test. (2) simulated emergency training.
SF - standard frequency.
SFI - Solar Flux Index.
SFT-D - frequency shift direction.
SGL - State Government Liaison.
SHF - super-high frequency.
SI - International System of Units.
SID - sudden ionospheric disturbance.
SINAD - signal-to-noise and distortion.
SINPO - strength, interference, noise, propogation, overall.
SITOR - simplex teletype over radio.
SK - (1) Silent Key. (2) straight key.
SKCC - Straight Key Century Club.
SLA - sealed lead-acid.
SM - Section Manager.
SMA - SubMiniature version A.
SMIRK - Six Meter International Radio Klub.
SMPS - switched-mode power supply.
SMT - surface-mount technology.
SNP - shared non-protected.
SNPF - shared non-protected frequency.
SNR - signal-to-noise ratio.
SO-239 - socket-239.
SOS or SOS - distress call.
SOTA - Summits On The Air.
SP - speaker or loudspeaker
SPAR - Society for the Preservation of Amateur Radio.
SPDT - single-pole, double-throw.
SPE - solar particle event.
speaker mic - speaker microphone.
sporadic E-skip - sporadic E-layer skip.
SPST - single-pole, single-throw.
SQL - squelch level.
SS - spread spectrum.
SSE - spread-spectrum emissions.
SSB - single sideband.
SSB-SC - single-sideband suppressed-carrie.
SSMA - spread spectrum multiple access.
SSN - sunspot number.
SSTV - slow-scan television.
STA - Special Temporary Authority.
STE - squelch tail elimination.
STEP - frequency step.
STM - Section Traffic Manager.
SW - shortwave.
SWL - (1) shortwave listener. (2) shortwave listening.
SWOT - Side Winders On Two.
SWR - standing-wave ratio.
SWR meter - standing-wave ratio meter.

T
Τ - period.
T - tera.
T-CTCS - transmitter continuous-tone coded squelch system.
T-DCS - transmitter digital-coded squelch.
TAPR - Tucson Amateur Packet Radio.
TC - Technical Coordinator.
TCP - Transmission Control Protocol.
TCP/IP - transmission control protocol/Internet protocol.
TCXO - temperature-compensated crystal oscillator.
TDM - time-division multiplexing.
TDMA - time division multiple access.
TDR - dual watch/dual reception.
TDR-AB - dual watch mode transmit selection.
TEP - transequatorial propagation.
TFD - terminated folded dipole.
TFT - thin-film transistor.
THF - tremendously high frequency.
TI - talk-in.
TNC - (1) terminal-node controller (2) threaded Niell-Concelman.
TO-220 - transistor outline 220.
TOA - takeoff angle.
TOI - third-order intercept point.
TOR - telex-over-radio.
TOT - time-out timer.
TP - test point.
TPTG - tuned plate, tuned grid.
TR switch - transmit-receive switch.
TRX - transceiver.
TS - (1) Technical Specialist. (2) tuning step.
TSQL - tone squelch.
TTFD - tilted terminated folded dipole.
TTL - transistor-transistor logic.
TTX - table-top exercise.
TV - television.
TVI - television interference.
TWT - travelling wave tube.
TX - transmit.
TX-LED - display backlight color transmit.
TXP - transmit power switch.

U
UHF - ultra-high frequency.
UHF connector - ultra-high frequency connector.
UHF mobile - ultra-high frequency mobile.
ULS - Universal Licensing System.
UN - United Nations.
unun - unbalance-unbalance.
UPS - uninterruptable power supply.
URL - universal resource locator.
USB - (1) universal serial bus. (2) upper sideband.
UTC - Universal Time Coordinate.
UV - ultraviolet.
UV protection - ultraviolet protection.

V
V - volt
ΔV - voltage.
VA - volt amperes.
VAC - volts alternating current.
VCO - voltage-controller oscillator.
VDT - video-display terminal.
VE - Volunteer Examiner.
VEC - Volunteer Examiner Coordinator.
VFC - Volunteer Frequency Coordinator.
VIS - vertical-interval signaling.
VFO - variable-frequency oscillator.
VHF high band - very-high frequency high band.
VHF low bands - very-high frequency low bands.
VHFK - very-high frequency.
VLCA - very limited coverage area.
VLF - very-low frequency.
VMOS - vertical metal-oxide semiconductor.
VNA - vector network analyzer.
VOA - Voice of America.
VOACAP - Voice of America Coverage Analysis Program.
VoIP - voice over Internet Protocol.
VOM - volt ohm meter.
VOX - (1) voice-operated transmission. (2) voice-operated transmit.
VPO - pinch-off voltage.
VRLA - valve-regulated lead-acid.
VSB - vestigial sideband.
VSC - (1) voice scan control. (2) voice squelch control.
VSO - variable crystal oscillator.
VSWR - voltage standing wave ratio.
VTVM - vacuum tube voltmeter.

W
λ - wavelength.
W - watt.
WAB - Worked All Britain.
WAC - Worked All Continents.
WAN - Worked All Neighbors.
wannabe - want to be.
WARC - World Administrative Radio Conference.
WARC bands - World Administrative Radio Conference bands.
WARD - World Amateur Radio Day.
WAS - Worked All States.
wave - wavelength.
WAVE - Worked All VE.
WAXE - Worked All XE.
WAZ - Worked All Zones.
WCA - World Castle Award.
web SDR - web software-defined radio.
WEFAX - weather facsimile.
WFWL - work first, worry later.
WINSystem - WIN System.
WIRES - Wide-coverage Internet Repeater Enhancement System.
WIRES-X - Wide-coverage Internet Repeater Enhancement System (Extended).
WN - wideband/narrowband switch.
WOLF - Weak-signal Operation on Low Frequency.
wpm - words per minute.
WPX - Worked All Prefixes.
WRC - World Radiocommunication Conference.
WSJT - weak-signal Joe Taylor.
WSJT-X - weak-signal Joe Taylor - experimental.
WSPR - weak-signal propagation reporter.
WT-LED - display backlight color standby.
WTS - Wireless Telecommunications Services.
WX - weather.

X
X Section - Experimenters' Section.
X-wave - extraordinary wave.
XBR - cross-band repeat.
XCVR - transceiver.
XE - Abbreviation for the states of Mexico.
XHF - extremely high frequency.
XIT - transmitter incremental tuning.
XLF - extremely low frequency.
XLR - x-series, latch, resilient.
XMTR - transmitter.
XTAL - crystal.
XVR - transceiver. XVTR - transverter.

Y
YHOTY - Young Ham of the Year.
YOTA - Youngsters on the Air.

Z
Z - Zulu Time.