Dictionary of Ham Radio Terms

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A

AC : Alternating Current

AF : Abbreviation for Audio Frequency. AF is in the range 20Hz to 20 000Hz

AFC : Automatic Frequency Control - used to prevent drift in FM receivers

AGC : Automatic Gain Control - a feedback system to reduce fading by automatically adjusting gain

Ampere :(A) The unit used for measurement of current. Usually abbreviated to Amps

Amplitude : the height of a wave from the average or median position.

AMSAT : The name for amateur radio satellite organizations world-wide, but in particular the Radio Amateur Satellite Corporation

AMTOR : A specialised form of RTTY protocol. An acronym for AMateur Teleprinting Over Radio.

ARRL : The American Amateur Radio League - the national ham radio association for the USA

APRS : Automatic Position Reporting System.

ATV : Amateur Television - "moving picture" ham TV transmissions.

B

Balun : A passive electronic device that converts between balanced and unbalanced electrical signals using some form of electromagnetic coupling.

Balanced Line : parallel conductots at equal and opposite potentials. Neither conductor is at ground poetential. Band : The portions of the Electromagnetic Spectrum that are allocated to ham radio operators

BFO : Beat Frequency Oscillator. An oscillator that is mixed with an incoming signal to produse an Audio Frequency (AF tone for CW reception.

Boat Anchor : A slang term used to describe obsolete ham radio gear - often applied to old transceivers

BPSK : (Binary Phase Shift Keying). A digital modulation method for transmitting data.

C

Callsign A unique identifier for each radio amteur throughout the world

Capacitor : A passive electronic component composed of two conducting plates separated by a dielectric (insulating material).

CNDX : Abbreviation for Conditions

Coaxial Cable : Cable that has a central conductor and an outer shield as the second conductor. Known as coaxial because the cable is cylindrical and the conductors share the same central axis.

CW Abbreviations Used by CW operators to reduce the length of transmissions by shortening words or phrases to a 2 or three letter code

Conductor : A material through which electricity flows easily.

CQ : Request for contact - specifically "calling any operator"

CTCSS : Continuous Tone-Coded Squelch Syatem - a sub audible tone that is frequently used on repeaters. The signal "opens" the repeater for use.

Current : The flow of electicity through a conductor - usually associated with electron movement, but current is actually the transfer of charge between atoms.

CW : Continuous wave - used in morse code transmissions.

D

dB : Decibel - the rato of two power measurements.

dBd : dB relative to a dipole

dBi : dB relative to a theoretical isotropic (point) source.

De or DE : "this is" or "from" - for example an operator may use VL2TK de VK4ZW .......

Dipole : An antenna with two sides, usually of equal length.

Dish : A highly directional antenna, parabolic in shape. Often used at microwave frequencies.

DTMF Dual Tone Multi Frequency - the allocation of a unique tone to each button on an appliance (made up of two frequencies - high and low) that allows a computer to recognize the tone.

Dummy Load : An artificial antenna that does not radiate. used when alligning transceivers.

Duplex : Transmit and receive are on two different frequencies - often use in repeaters with a shift (difference) of 600Hz.

DXCC : DX Century Club

DX : Distance or distant station

E

Electromagnetic Waves : The waves emmitted by an antenna, having two dimensions, electric and magnetic.

EHF : Extremely High Frequency - from 30GHz to 300GHz

EME : Earthe Moon Earth - bouncing a signal off the moon to a remote station that would not normally be accessible.

EMF : Electromotive Force - Voltage

EMI : Electromagnetic Interference.

F

Feedline : The wire or cable that joins a transmitter or receiver to an antenna

Filter : An electric circuit (often called a network) that allows certain frequencies to pass but rejects (attenuates) other unwanted frequencies.

Frequency: The number of complete waves that pass a reference point per second. Expressed in Hertz (Hz)

Fuse : A device that self destructs when too much current passes through it - used for circuit protection.

G

Gain : How much more effective an antenna is as a radiator than a half wave dipole

Ground : A direct connection from electrical equipment to the Earth - often achieved by driving a conducting spike into the ground, and connecting equipment to it.

GMT : Greenwich Mean Time - the time at Greenwich UK. Also known as zulu and UTC

H

Harmonic : Multiples and sub multiples of the frequency of a reference equation

Henry :(H) The unit for inductance

Hertz : Hz - The unit of measure for frequency.

HF : High Frequency. Frequencies in the range 3MHz to 30MHz

I

Inductance : A measure of how well a coil stores energy in the form of a magnetic field.

Insulator : A substance through which electricity does not pass easily - known as a dielectric in capacitors

IRLP Internet Radio Linking Project. A method of linking cross-world linking of repeaters so that very basic equipment can be used to communicate with hams in other countries.

J

JOTA : Jamboree On The Air - an annual event in which scouts worldwide can communicate with each other and radio amateurs using ham radio equipment.

K

Kilohertz : one thousand Hertz (Hz) or one thousand cycles per second.

L

LPDA : Log Periodic Dipole Array. A multiband Antenna

M

Microphone : A device that converts voice into electrical signals.

Morse Code The code used by CW operators instead of voice communications

N

O

Ohm : (<math> \Omega</math>) The unit for resistance

OM : Abbreviation meaning Old Man

OSCAR : Orbiting Satellite Carrying Amateur Radio

OCF : Off Centre Fed Dipole. A dipole that has sides of unequal length. These are multiband wire antennas

P

Period : the time it taks in seconds for a complete wave to pass a reference point.

Phonetic Alphabet Specific, easily identfiable, non-confusable words are used instead of the letters of the alphabet.

Propagation : How well a signal is transferred from the sending station to the receiving station.

PSK : Phase Shift Keying - a digital mode.

Q

Q Code Three letter codes used instead of sentences or phrases.

QRM : Man made noise. Can be used to indicate noise interfering with an amateur station or an amateur station interfering with other spectrum users.

QRN : Electromagnetic noise from natural sources interfering with amateur transmissions.

QRP : Low power operations - usually understood to mean power at or below 5 watts.

QRPp : Very low power operation - at or below 1 Watt.

QSL : Confirmation of receipt of transmission