AFC - Automatic frequency control. Used in FM receivers to prevent drifting off the received station's frequency.

AFSK - Audio frequency shift keying (as opposed to frequency shift keying, FSK)

AGC - Automatic Gain Control. A feedback voltage in the receiver circuit to prevent fading of a received signal.

ALC - Automatic level control. A feedback voltage in the transmitter's output amplifier used to prevent amplifier overload. Also used as feedback from a linear amplifier back to the exciter to prevent overdriving.

AM - Amplitude Modulation. 

AMTOR - AMateur Teletype Over Radio. An advanced form of RTTY usually operated on the HF bands.

analog - A signal that varies in a continuous manner as a wave as opposed to a discrete signal such as digital.

antenna tuner: Impedance-matching device that matches the impedance of the antenna system input to the transmitter, receiver, or transceiver output impedance. 

antenna: a device that intercepts or radiates radio frequency energy.

APRS - Automatic Packet Position Reporting System.

ARES - Amateur Radio Emergency Service.

ARRL - American Radio Relay League , the national amateur radio organization in the USA

ASCII - American Standard Code for Information Interchange. A seven bit code established by ANSI to achieve compatibility between digital devices.

balun - balanced to unbalanced. A device used to couple a balanced antenna to an unbalanced feed line (e.g., dipole to coax) .

band - a range of frequencies allotted for a particular use (e.g., 20 Meter Band) 

bandpass - range of frequencies permitted to pass through a filter or receiver circuit.

band-pass filter: a circuit that passes a range of frequencies and attenuates signals above and below this range.

barefoot - transmitting with a transceiver alone without a linear amplifier.

base - a radio station located at a fixed location as opposed to a mobile. Used to identify the control location in a network of radio stations.

baud - A unit of signaling speed equal to the number of discrete signal events per second. Baud is the same as BPS only if each signal event represents exactly one bit.

Baudot - A five level code for the transmission of data in digital form.

BBS  - Bulletin Board System. An automated computer system which can be controlled from a remote location. Usually capable of sending and receiving messages and files.

beacon - a station that transmits one-way signals for the purpose of navigation, homing, and determining propagation conditions.

beam - an antenna that gives a directional beam pattern. Also called a Yagi.

BNC - Coax connector commonly used with VHF/UHF equipment -- Bayonet Niell-Concelman (standard connector type used on COAX cable, named for its inventors).

BPS - Bits per second. A rate of data transfer.

BPSK - Binary Phase Shift Keying. Digital DSB suppressed carrier modulation.

bug - a semi-automatic mechanical code key.

bureau - International Amateur organizations set up to process QSL cards between countries. Provides an inexpensive way to send and receive QSL cards.

burro - Slang for bureau.

call book - a publication or CD ROM that lists licensed amateur radio operators.

calling frequency - A standard frequency where stations attempt to contact each other. Example -- 146.52 is the North American FM simplex calling frequency.

carrier - a pure continuous radio emission at a fixed frequency, without modulation and without interruption. Several types of modulation can be applied to the carrier, See AM and FM. 

CC&R's - Covenants, Conditions, and Restrictions - an extensive set of rules drawn up by homeowner's associations and their lawyers which, among other things, typically restrict or completely prohibit a homeowner from having most forms of antennas on their property.

coax ( coaxial cable) - A type of wire that consists of a center wire surrounded by insulation and then a grounded shield of braided wire. The shield minimizes electrical and radio frequency interference. 50-ohm and 72 ohm characteristic impedances are typical.

code - usually refers to Morse code, but used for others such as baudot.

CQ - calling any amateur radio station, may be sent in CW, phone or some digital modes

CTCSS - (Repeater Term) abbreviation for continuous tone-controlled squelch system, a series of subaudible tones that some repeaters use to restrict access.

CW - Continuous Wave, see carrier. In truth a continuous wave is an unmodulated, uninterrupted RF wave. However in common usage refers to Morse code emissions or messages which is an interrupted wave. 

cycles (cps) - term used for measuring frequency prior to the term Hertz replaced it - hence kc, Mc, etc.

demodulation - the process of retrieving data from a modulated signal. (See modulation, modem.)

digipeater - A simplex packet repeater which stores an incoming packet, and, if so instructed, re-transmits it. The digipeater does not retain a copy of the packet once sent or wait for an acknowledgement from the next node.

digital - A discrete or discontinuous signal whose various states are identified with specified values. (See analog, RS-232, 7'TL.)

dipole -  the basic antenna consisting of a length of wire or tubing, open and fed at the center. The entire antenna is ½ wavelength long at the desired operating frequency. This antenna often used as a standard for calculating gain, dBd.

dummy load - a device which substitutes for an antenna during tests on a transmitter. It converts radio energy to heat instead of radiating energy. Offers a match to the transmitter output impedance.

DXCC - Award offered by ARRL for contacting and confirming 100 or more different countries first introduced in 1937.    DXCC is copyright ARRL and its use here is printed with permission of the ARRL.

DXpedition - Radio expedition to remote and rare locations 

filter - A circuit or device that will allow certain frequencies to pass while rejecting others.

FM - Frequency Modulation. frequency - the rate of oscillation (vibration). Audio and radio wave frequencies are measured in Hertz. (cycles per second).

FSK Acronym for Frequency Shift Keying. A method of frequency modulation in which the frequency varies. (See AFSK, PSK).

ham - an amateur radio operator.

hamfest - ham festival, a social and commercial event at which hams meet to buy, sell, and swap equipment.

Hertz - the standard unit used to measure frequency (one Hertz equals one complete cycle per second).

HF - High Frequency - 3 MHz to 30 MHz.

high-pass filter - a filter designed to pass high frequency signals, while blocking lower frequency signals.

IC - Integrated Circuit.

ID -- Identification, as announcing station callsign at intervals.

intermod - Short for "intermodulation." This generally means false or spurious signals produced by two or more signals mixing in a receiver or repeater station.

ionosphere - The electrically charged region of the Earth’s atmosphere located approximately 40 to 400 miles above the Earth’s surface that refracts radio signals.

IOTA - Islands On The Air.

IRC - International Reply Coupon. A coupon that can be purchased at post offices which can be exchanged in foreign countries for return postage for a surface mail letter to the country that issued the coupon.  

IRLP Internet Radio Linking Project  developed by David Cameron, VE7LTD. Uses a network protocol called VoIP (Voice over IP) audio streaming. There are now over 1000 repeaters around the world connected by the internet through the Amateur radio internet radio linking project, 24 hours per day, 7 days a week.

key - to press a key or button physically or electronically by computer.

keyer - Electronic device for sending Morse Code semi-automatically. Dits are sent by pressing one paddle of the key, dahs sent by pressing the other one paddle.

kilocycles - thousand cycles per second. Replaced by kiloHertz (kHz).

kiloHertz - one thousand Hertz (see "Hertz").

LCD - Liquid Crystal Display. A display device commonly used in portable computers. Contains a crystalline liquid whose optical properties change in the presence of an electric field to appear either light or dark. Must have an external light source to be visible.

low-pass filter - a filter that allows signals below the cutoff frequency to pass through and attenuates signals above the cutoff frequency. 

LSB - Lower Side Band, the common single-sideband operating mode on the 40, 80, and 160 meter amateur bands. 

megacycles - million cycles per second. This terminology has been replaced by MegaHertz (MHz)

MegaHertz - million hertz (see Hertz)

mobile - an amateur radio station installed in a vehicle - a mobile station can be used while in motion. (see also, portable). 

modulation  - The process of adding a signal to a carrier to transmit information. Can be used in reference to voice communications, but refers to digital data in the context of packet radio. (See demodulation, modem.)

MSK - Minimum Shift Keying. A modulation method similar to FSK in which the shift in Hertz is equal to half the signaling rate in BPS. (see AFSK, FSK, PSK).

node  - A general term used to indicate the different stations in a packet network. Nodes may be terminal nodes, network nodes, station nodes, and others. (see TNC, digipeater).

offset - (a repeater term) In order to listen and transmit at the same time, repeaters use two different frequencies. On the 2 metre ham band these frequencies are 600 kilocycles/second (or 600 kHz) apart. As a general rule, if the output frequency (transmit) of the repeater is below 147 MHz then the input frequency (listening) is 600 kHz lower. This is referred to as a negative offset. If the output is above 147 MHz then the input is 600 kilohertz above. This is referred to as a positive offset.

packet controller - Term used for a hardware TNC with an on-board modem.

packet radio - a system of digital communication whereby information is transmitted in short bursts. The bursts ("packets") also contain callsign, addressing and error detection information.

packet  - A group of bits including data and control elements which is transmitted as a whole. 

portable - A portable station is one that is designed to be easily moved from place to place but can only be used while stopped. Portable operation is away from the home base station. (see also, mobile). 

PSK - Phase Shift Keying. A method of transmitting digital information in which the phase of the carrier is varied in accordance with the digital signal.

PTT - Push To Talk, the switch in a transmitter circuit that activates the microphone and transmission circuitry.

QRP - Low power operation, usually 5 watts output or 10 watts input power. 

QSL - to acknowledge receipt. Commonly used to indicate "I understand", "I coped your transmission (or report) all OK". Also used as a term for sending cards by mail to confirm a two way contact with a station, such as QSL via the bureau. (see bureau or burro).

QSL Manager - A person, usually an Amateur Radio operator, who manages the receiving and sending of QSL cards for a managed station). A QSL Manager is needed because the managed station either has difficulty handling the volume of incoming QSL cards, or the station is geographically located such that it is difficult or impossible for that station to accept and/or send QSL cards. It is very common for "rare" DX stations and DXpeditions to have a QSL Manager. 

QSO - two way conversation.

RAC - Radio Amateurs of Canada, a national amateur radio organization in Canada.

RF - Radio Frequency, emissions in the radio portion of the electromagnetic spectrum.

RFI - Radio Frequency Interference.

RTTY - radio teletype - A form of digital communications.

SASE - Self-addressed, stamped envelope.

SSB - Single Side Band.

SSTV - Slow Scan Television.

SWR - Standing Wave Ratio, a measure of how much radio energy sent into an antenna system is being reflected back to the transmitter.

third-party communications - messages passed from one amateur to another on behalf of a third person.

ticket - slang for an amateur radio license.

TNC - Terminal Node Controller, a device which interfaces a computer to a transceiver and performs a function similar to a modem.

traffic - a message or messages sent by radio.

transceiver - a radio that both transmits and receives.

TVI - Television interference.

USB - Upper Side Band  the common single-sideband operating mode on the 20, 17, 15, 12, and 10 meter HF amateur bands, and all the VHF and UHF bands. 

VE - Volunteer Examiner, a person authorized to administer examinations for amateur radio licenses.

VOX - Voice Operated Transmit.

WARC - World Administrative Radio Conference. Also used to reference the WARC bands 10, 12 and 17 meters.

WPM - Words per minute; as in Morse code or typing speed.

XCVR - Transceiver.

yagi - in 1926 Hidetsugu Yagi and Shintaro Uda invented the "beam" antenna array. A directional antenna consisting of a dipole and two additional elements, a slightly longer reflector and a slightly shorter director. Electromagnetic coupling between the elements focuses maximum power (or reception) in the direction of the director.

YL - Young Lady, any female amateur radio operator or the significant other of a amateur.