Glossary
Each entry reads "term: definition". Tap a term in a lesson to land here.
ActIn the licence conditions, The Communications Act 1998. Also: the Act.
Alternating currentCurrent that changes polarity repeatedly in a cyclic manner. Also: AC.
Amateur radioA radiocommunication service for the purpose of self-training, intercommunication and technical investigations. Also: amateur service.
AmpereThe basic unit of electric current, often just called an "amp" and written A. 1000 mA is 1 A. Also: amp, amperes.
AMTORAmateur teleprinting over radio.
Antenna tunerA unit that matches the antenna system's impedance to the transmitter's output impedance, typically 50 ohms, for maximum power transfer and a lower SWR. Also: ATU.
AuthorityIn the licence conditions, the Communications Authority of Kenya, which issues amateur licences. Also: CAK, Communications Authority of Kenya.
Beam antennaAn antenna whose radiation pattern concentrates more of the signal in one direction than others. Also: beam.
Chassis groundThe ground symbol with slanted lines hanging from a horizontal line. It marks the metal chassis of the equipment.
ChirpA slight shift in oscillator frequency each time a CW transmitter is keyed.
Coaxial cableA centre conductor encased in insulation, surrounded by a conducting shield and covered in a weatherproof jacket. Usual impedance is 50 or 75 ohms. Also: coax.
ConductorA material that lets electrons pass easily, such as copper, gold, silver or aluminium. Also: conductors.
Coordinated Universal TimeThe time standard amateurs use. Kenya local time is UTC plus 3 hours. Also: UTC.
CurrentThe flow of electrons in an electric circuit. It is measured in amperes. Also: amps, amperage.
CWContinuous wave: Morse code transmissions, sent by on-off keying of an RF signal. Also: continuous wave, continuous-wave.
DC input powerThe total direct current power input to any device energising the aerial (Annex A, Note 1).
Direct currentCurrent that flows in one direction only, for example from a battery. Also: DC.
Earth groundThe ground symbol made of three parallel horizontal lines that get shorter. It marks a connection to the earth.
Emission designatorA short code of letters and digits, such as J3E, that describes a transmission: how the carrier is modulated, what signal modulates it, and what information is sent. Also: designator.
False or deceptive signalA transmission meant to mislead, for example sending "MAYDAY" when no actual emergency has occurred. It is never permitted.
FeedlineThe cable connecting radio equipment to the antenna. Also: transmission line.
FM phoneA frequency-modulated voice transmission, where the carrier's frequency is varied by the audio.
FrequencyHow often a repeating wave or current completes one full cycle, counted in cycles per second (hertz).
FuseA protective device that limits how much current can pass through equipment, so it protects radio equipment. Also: fuses.
Ground waveRadio signals that travel along the surface of the Earth, up to about 100 miles from the antenna. Also: ground-wave propagation.
HarmonicsSignals at integer multiples of the fundamental transmitting frequency. Also: harmonic.
InsulatorA material that does not let electrons pass easily, such as glass, air, plastic or porcelain. Also: insulators.
IonosphereThe portion of the atmosphere that reflects HF radio signals.
Key clicksClicking noises caused by an excessively square CW keyed waveform, where the RF is switched on and off too abruptly.
LicenseeThe person the Authority has authorised to install and operate an amateur radio station.
Line-of-sight propagationPropagation in which the signal travels in a straight line from the transmitting antenna to the receiving antenna. Also: line of sight.
Malicious interferenceIntentional interference: an amateur transmission intended to disrupt other communications in progress.
Maritime MobileOperating on any vessel at sea.
MobileOperating in Kenya in any vehicle, as a pedestrian, or on any vessel in inland waters.
ModemA modulator-demodulator: it modulates and demodulates signals, typically to send digital data over radio or analogue lines. Also: modulator-demodulator.
NetA scheduled on-air meeting that lets more operators contact each other in a shorter time, run by net control. Also: nets.
Non-pecuniary interestHaving no direct or indirect money interest. All operations under the licence must be non-pecuniary: no business, advertisement or propaganda, and nothing for any social, political, religious or commercial organisation. Also: pecuniary interest.
OhmThe basic unit of resistance, written with the Greek letter omega, . Also: ohms.
Ohm's lawThe rule that ties voltage, current and resistance together: . Also: Ohms law.
On-off keyingSwitching the RF signal on to make a mark (a dot or dash) and off to make a space. Also: OOK.
Peak envelope powerThe average power supplied to the antenna during one radio-frequency cycle at the crest of the modulation envelope. Also: PEP.
PhotoresistorA resistor whose resistance changes with light, drawn as a resistor with arrows pointing in.
PowerThe rate of energy consumption: how fast energy is used.
Practical circuit diagramA diagram using blocks to show signal flow and how the components of a system are connected. Also: block diagram, practical diagram.
RepeaterA station that receives on one frequency and transmits on another, extending the operating range of portable and mobile stations.
ResistanceThe current-limiting property of any material: it opposes the movement of electrons through a circuit.
ResistorAn electrical component that opposes electron movement. Also: resistors.
ResonanceThe state in which an antenna is most efficient at radiating or receiving at a given frequency. Also: resonant.
RST systemA system for reporting signal quality: Readability, Strength and Tone. The best possible report is 599. Also: RST.
RTTYRadio teletype, a way of sending text over radio.
Schematic diagramA diagram that uses symbols to represent components and how they are connected. Also: schematic.
SimplexTransmitting and receiving directly between stations on the same frequency, without a repeater.
Sky waveRadio signals refracted (bent) back to Earth by the ionosphere, reaching a distant point. Also: skip, sky wave propagation.
SplatterThe transmitted signal occupying more bandwidth than necessary, interfering with stations on nearby frequencies.
Spurious emissionsUnwanted RF emissions outside the necessary bandwidth of a transmission. Also: spurious emission.
SSBSingle-sideband suppressed-carrier voice transmission. Also: single sideband.
StationThe radio equipment the Licensee is licensed to install and operate at a Station Location Address, a Temporary Location, while Mobile or while Maritime Mobile.
Station Location AddressThe location of the radio equipment as set out in the Validation Document or Certificate.
Station logThe required record of a radio amateur's radio activities; contacts with other amateur stations must be written in it. Also: log.
Sunspot cycleThe long-term variation in the number of sunspots on the sun. Its average length is 11 years.
SWR meterA meter that measures the standing wave ratio on a transmission line, showing how well the antenna system is matched to the radio. Also: SWR, standing wave ratio.
Temporary LocationA fixed position in Kenya that is not the Station Location Address.
ThermistorA resistor whose resistance changes with temperature, drawn as a resistor marked with a "t".
Third partyAny person for whom a message is passed through amateur channels, other than the control operators of the two stations handling it.
Third-party communicationsA message passed from the control operator of an amateur station to another control operator on behalf of another person.
Time-out timerA repeater feature that limits a single transmission to no more than 3 minutes. Also: time-out.
Unidentified communicationsRadio communications in which the station identification is not transmitted. Also: unidentified signals.
Variable resistorA resistor whose value can be changed, drawn as a resistor symbol with an arrow through it.
VFOVariable frequency oscillator: a tunable oscillator that sets the transmit frequency. Also: variable frequency oscillator.
VoltThe basic unit of voltage, written V. Also: volts.
VoltageThe force that pushes electrons through a circuit, like the pressure in a water pipe. Also called electromotive force (EMF). Also: EMF, electromotive force.
WattThe basic unit of electrical power, written W. Also: watts.
WavelengthThe length of one full cycle of a wave, measured along the wave in metres. It gets shorter as frequency goes up.
XtalShort for crystal: a quartz-crystal-controlled oscillator that fixes the transmit frequency. Also: crystal.
Zero beatTransmission and reception on the same frequency.