Highfields Amateur Radio Club
Glossary of Radio Terms.

copyright date

B  -  Bravo  -  dah-di-di-dit

B- (B negative or B minus).

Used in valve (tube) equipment schematics to show the connection of the negative terminal for the plate circuit.

B+ (B positive or B plus).

Used in valve (tube) equipment schematics to show the connection of the positive terminal for the plate circuit.

B Battery.

In early radio, batteries were the prime source of power. The A battery provided the filament voltage, the B battery furnished the B+ or the Voltage to the plates of the valves, and the C battery provided the grid-bias voltage to the valves.


A form of ionospheric propagation via the E and F layers allowing stations to hear other stations within the skip zones.

Balanced Line.

Antenna feed line with two conductors having equal but opposite voltages, with neither conductor at ground potential.

Balanced Modulator.

A mixer circuit used in a single-sideband suppressed-carrier transmitter to combine a voice signal and the RF carrier-oscillator signal. The balanced modulator isolates the input signals from each other and the output, so that only the sum and the difference of the two input signals reach the output. The original carrier-oscillator signal or the pure audio signal do not reach the output. A modulated RF signal contains some information to be transmitted.

Ballast Resistor.

A special resistor used primarily in valve (tube) equipment to compensate with variations in the mains line voltage, usually connected in series with the with the power supply. The ohmic value of the resistor increases with the amount of current flowing through it, thereby tending to maintain a constant current despite variations in line voltage.

Ballast Tube.

A Ballast Resistor (above) mounted in an evacuated glass tube. This construction method improved the regulation by reducing radiation of heat from the resistor.


Contraction for balanced to unbalanced, not to be confused with the Choke Balun. A Balun is a device to couple a balanced load to an unbalanced source, or vice versa, in Amateur Radio use they are most often used as a Transmission Line Transformer, often, but not always, changing the impendence.
See also: Unun.


A section of the Radio spectrum. Various bands are allocated to various users. Bands are often described by using an approximate wavelength for example the 144-146 MHz Amateur band is approximately 2 meters in wavelength so it is called the 2 meter band.
See also: EHF. HF. MF. SHF. UHF. VHF.


A condition that results in greater than normal communication range on the VHF and UHF bands.

Band Pass Filter.

A circuit that allows signals to go through it only if they are within a certain range of frequencies. It attenuates signals above and below this range.


A voluntary system of frequency allocations in each amateur radio band.

Band Spread.

A receiver quality used to describe how far apart stations on different nearby frequencies will seem to be. We usually express band spread as the number of kilohertz that the frequency changes per tuning-knob rotation. Band spread and frequency resolution are related. The amount of band spread determines how easily signals can be tuned.


1. The width of a frequency band outside of which the mean power is attenuated at least 26 dB below the mean power of the total emission, including allowances for transmitter drift or Doppler shift.

2. The useful tuning range of an antenna. A narrow bandwidth antenna may mean that the antenna will not tune for optimum SWR across the whole frequency band.

3. The range of frequencies that a radio transmission occupies.


Bangladesh Amateur Radio League, the national amateur radio organization in Bangladesh.


A collection of cells that converts chemical energy into electrical energy.
Schematic symbol: schematic symbol
May be disploasble (use until exhausted then disopse of) or rechargable (once exhausted can be recharged and used again).
See also: Lead Acid, Lithium-Ion, Nickel Cadmium, Nickel Metal Hydride, Valve Regulated Lead Acid,
the Rechargable Battery Information page,
and the Battery Equivalents. pages.

Baud / Baud Rate.

A measure of the symbol rate; that is, the number of distinct symbol changes (signalling events) made to the transmission medium per second in a digitally modulated signal. It is distinct from the bit rate, because one symbol may carry more than one bit of information.
See also: Digital Modes page.

Baudot / Baudot Code.

Named after its inventor Émile Baudot, is a five-bit digital code mainly used in teleprinter applications.


See: Busy Channel Lock Out.

Beacon Station.

An amateur station transmitting communications for the purposes of observation of propagation and reception or other related experimental activities.

Beam Antenna.

A directional antenna. A beam antenna must be rotated to provide coverage in different directions.


The angle between the half-power (3 dB) points of the main lobe of a beam antenna when referenced to the peak effective radiated power of the main lobe.

Beat-Frequency Oscillator (BFO).

A receiver circuit that provides a signal to the detector. The BFO signal mixes with the incoming signal to produce an audio tone for CW reception. A BFO is needed to copy CW and SSB signals.

Beverage Antenna.

A horizontal, long wire antenna designed for reception and transmission of low-frequency, vertically polarized ground waves. Also known as Wave Antenna. Invented by Dr. Harold Henry Beverage.


Belarussian Federation of Radioamateurs and Radiosportsmen, the national amateur radio organization in Belarus.

Bidirectional Array.

An antenna array that radiates in opposite directions along the line of maximum radiation.

Bipolar Transistor / Bipolar Junction Transistor.

A Bipolar Junction Transistor, or BJT, is a solid-state device in which the current flow between two terminals (the collector and the emitter) is controlled by the amount of current that flows through a third terminal (the base). Contrast to the other main transistor type, the FET, in which the ouput current is controlled by input voltage (rather than by input current).
See also: FET,


A false or spurious signal in a receiver inadvertently produced by the receiver's own circuitry.

Bit Rate (Bitrate / Bits Per Second / BPS).

The number of bits that are conveyed or processed per unit of time. Bit rate is often used as synonym to the terms connection speed, transfer rate, channel capacity, maximum throughput and digital bandwidth capacity of a communication system. The bit rate is quantified using the 'bit per second' (bit/s or bps) unit, often in conjunction with a SI prefix such as kilo (kbit/s or kbps), Mega (Mbit/s or Mbps), Giga (Gbit/s or Gbps) or Tera (Tbit/s or Tbps). Not to be confused with baud.
See also: Digital Modes page.

Bits Per Second.

See: Bit Rate.

Bleeder Resistor.

A large value resistor connected to the filter capacitor in a power supply to discharge the filter capacitor when the supply is switched off.

Block Diagram.

A drawing using boxes to represent sections ofa complicated device or process. The block diagram shows the connections between sections.


A Coax connector commonly used with VHF & UHF equipment -- Bayonet Niell-Concelman (named after its inventors). This type of connector is also commonly found on test equipment.
See also: Fitting a BNC plug.

BNC plug    BNC socket
    Male (plug)   Female (socket)

Boat Anchor.

Term used for antique radio equipment. So named because of weight and size.


See: Band Pass Filter.


See: Bit Rate.


Early experimenters used a wooden board or bread board to lay out circuits. Now used to describe an experimental layout on any media.


The word used between overs to interrupt an on-going conversation (should always be accompanied by your callsign).


A switch that is configured to break (open) the first set of contacts before engaging (closing) the new contacts. This prevents the momentary connection of the old and new signal paths. Applies to mechanical systems (e.g. that use relays or manual switches) and to solid-state analogue multiplexers and switches.


Transmissions intended to be received by the general public, either direct or relayed.

Broadside Array.

An array in which the direction of maximum radiation is perpendicular to the plane containing the elements.

Brown and Sharpe Wire Gauge.

See: American Wire Gauge.


A semi-automatic mechanical CW key.


International Amateur organizations set up to process QSL cards between countries. Provides an inexpensive way to send and receive QSL cards (sometimes called burro).

Busy Channel Lock Out (BCLO / Busy Lockout).

A setting on some radios that prevents transmission on a frequency that is already in use. If there are stations using the frequency with a different CTCSS code then you wouldn't hear them. If their signal is strong enough to be detected by the radio then the frequency cannot be used while BCLO is active.

Busy Lockout.

See: Busy Channel Lock Out.