UHF Radio Set A43R

General Description

The A43R is a UHF manpack transceiver used for ground to air communications. It was built in the early 1960's by Redifon, London, for the British armed services.

It features 6 crystal controlled channels, covering the possible range of 240 - 300 MHz. Within Australia, the following frequencies are usually fitted:

Channel 1 251.2 MHz
Channel 2 257.4 MHz
Channel 3 252.5 MHz
Channel 4 258.3 MHz
Channel 5 258.7 MHz
Channel 6 253.9 MHz

Channel spacing is not to be less than 100 kHz.

Aerial impedance is 50 ohms, unbalanced. The set is powered by an internal 12volt lead acid battery or via a special battery charger.

Technical Data

The set is highly transistorized, but does contain some subminiature valves. The internal power unit, via transistor converters, provides the following voltages - +150, +75 and +3.2v. The positive earth 12v supply is also utilized direct.

Power consumption is 2.6 w on receive and on transmit is 32w on AM, 30w on CW beacon and 39w on MCW beacon.

The transmitter has an output power rating of 2 w unmodulated carrier. The MCW tone range is 300-3000 Hz - internally pre-set. The A.F. input is unbalanced, to suit a carbon microphone.

The receiver has a sensitivity of 5 microvolts. The IF frequencies are 19.05 mHz and 930 kHz. The A.F. output is 2 mw into 300 ohms at 1000 Hz for an input signal of 5 microvolts.

One of the interesting features of the set is the provision of a mast mounted discone antenna, in lieu of the short antenna used in manpack operations.

Crystal frequency formulas are: Tx xtal = f/16 Rx xtal = f - 19.05/16

The set is not readily adaptable for amateur use as the operating modes are rarely used on the 2 metre band, the nearest practicable conversion band.

Illustrations of the set

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