Ham Radio Glossary — A to Z

A – F

APRS — Automatic Packet Reporting System. Real-time GPS tracking and messaging over 144.390 MHz.
ARES — Amateur Radio Emergency Service. ARRL-coordinated volunteer emergency communications program.
ARRL — American Radio Relay League. The US national amateur radio organization (arrl.org).
CQ — General call seeking any station to respond. From telegraphy; still used on all modes.
CTCSS — Continuous Tone-Coded Squelch System. Sub-audible tone that opens repeater access.
CW — Continuous Wave. The FCC term for Morse code transmission.
DCS — Digital Coded Squelch. Alternative to CTCSS using a digital sub-audible code.
DMR — Digital Mobile Radio. Digital voice mode used on linked repeater networks and hotspots.
DX — Long-distance communication. "To DX" means to make long-distance contacts.
Elmer — An experienced ham who mentors a new operator. A term of deep respect in the hobby.
FM — Frequency Modulation. Standard mode for VHF/UHF voice and repeater operation.
FRN — FCC Registration Number. Unique identifier required for all FCC license applications.
FSK/AFSK — Frequency Shift Keying / Audio FSK. Digital modulation methods for data transmission.

G – P

General — Middle FCC amateur license class, granting most HF band access.
HF — High Frequency (3–30 MHz). The shortwave spectrum enabling worldwide contacts.
HT — Handie-Talkie. A handheld transceiver.
ITU — International Telecommunication Union. The UN body coordinating global radio spectrum.
MPE — Maximum Permissible Exposure. FCC limit on RF radiation exposure.
Net — An organized on-air meeting at a scheduled time and frequency.
Offset — Difference between a repeater's input and output frequencies.
PL Tone — Private Line. Motorola's trademark name for CTCSS tone.
PTT — Push-To-Talk. The button that activates transmit on a radio.
QRP — Low-power operation (5W or less). Also a distinct operating community.
QSL — Acknowledgment; also a confirmation card exchanged after a contact.
QSO — A two-way radio contact.
QTH — Location ("What is your QTH?" = "Where are you?").

R – Z

RACES — Radio Amateur Civil Emergency Service. FEMA-administered emergency communications program.
RF — Radio Frequency. Electromagnetic energy used for radio transmission.
RST — Readability, Strength, Tone. The signal report system used in amateur radio contacts.
Shack — Any amateur radio operating location. Originally meant the wooden structure housing a ship's radio.
Simplex — Direct radio-to-radio on one frequency, without a repeater.
SSB — Single Sideband. Efficient voice mode used on HF bands for long-distance contacts.
SWR — Standing Wave Ratio. Measure of antenna impedance match to the feed line.
Technician — Entry-level FCC amateur radio license class.
Transceiver — A combined transmitter and receiver in one unit.
UHF — Ultra High Frequency (300 MHz–3 GHz). Includes the 70cm amateur band.
ULS — Universal Licensing System. The FCC database for all radio licenses.
VEC — Volunteer Examiner Coordinator. Organization that coordinates ham radio exam sessions.
VHF — Very High Frequency (30–300 MHz). Includes the 2-meter amateur band.
YL — Young Lady. Any female amateur operator (used regardless of age).
73 — Best regards. The universal ham radio farewell.
88 — Love and kisses. Informal, used between friends.

• What does "73" actually mean and where did it come from?
  "73" means "best regards" and originated in 19th-century telegraphy as part of a standard numeric code system. Telegraphers used numbers to represent common phrases — 73 meant "best regards" in the original Phillips Code. When amateur radio adopted Morse code from telegraphy, the numeric shortcuts came with it. "73" survived the transition from CW to voice and remains the universal ham radio farewell more than a century later.