General description: Separate transmitter and receiver, designed to be worn in place of ammunition pouches.

Receiver: Five valve superhet; RF and two IF stages, the second of which is reflexed to provide an AF amplifier as well; fixed frequency BFO. Continuously variable tuning, which is netted on to the transmitter frequency in use.

Transmitter: Four valves, of which two operate in parallel as PA. Four switched, crystal controlled channels: crystals (HC6 pattern) can be changed by the operator.

Aerial system: 8 ft rod, half and quarter wave end fed wire, half wave dipole.

Power supply Dry batteries providing 1.5V LT, 90V HT and 7.5V bias.

Origin Developed in Australia and manufactured by the Amalgamated Wireless (Australasia). Purchased in limited numbers by the British army (750 units in 1954 and a further 230 units in 1963).

Remarks: While electrically straightforward, considerable thought and ingenuity is evident in its design and construction. Functionally, this is the most sophisticated of the three sets - and, equally, the most complicated to operate: the wide variety of aerials and associated matching arrangements, probably intended to make the most of its rather low power, accounts for much of this.

The construction is reasonably robust and physically the set is not at all cumbersome. But it was perhaps a mistake, in retrospect, to have a separate transmitter and receiver, which could be inconvenient to carry in any but the standard arrangement. The handbook actually suggests that the operator should experiment with the set slung on a strap across the shoulder, for example. But judging by one of the EMER modifications, the interconnecting cable often seems to have been used - wholly unofficially! - for carrying purposes.

Frequency range 2.5 - 7.5Mc/s

Receiver sensitivity 3mV for 12dB S/N

Receiver selectivity 6 kc/s at 6dB down

Receiver IF 465 kc/s

RF output 0.9 - 2.5W

Weight (complete station) 36 lbs

General description The entire equipment is contained in a single die cast case, whose dimensions are very slightly larger than the boxed versions of the SR 128. It is, however, much more solid, and weighs more than twice as much.

Receiver Six valve superhet; RF and two IF stages; variable BFO. AM and CW facilities. Six switched, crystal controlled channels on a selection of frequencies designed to allow communication throughout the day and night: crystals cannot be changed in the field. Separate crystals are used for the receiver and transmitter, the crystals for the receiver being signal frequency minus IF.

Transmitter Five valves, of which two operate in parallel as PA. Six switched, crystal controlled channels. AM and CW facilities.

Aerial system 8ft rod; quarter wave end fed wire with counterpoise; half wave dipole. The wire aerials are cut into preset lengths, with jumpers, to match the channel in use. The handbook suggests that it may not always be necessary, in practice, to change the aerial length on changing frequency.

Power supply 4V lead acid accumulators feeding a transistorised inverter; alternatively a dry battery supplying 4.5V LT, 60 and 150V HT and 19.5V bias could be used with a special adaptor (it is unclear whether this version was used by British forces).

Origin Appears to have been a private venture by the British Communications Corporation (later part of the Racal group), probably aimed at the overseas market: Burmese and Malayan versions were produced, and the set is known to have been used by the Nigerian and Indonesian armies. Purchased in limited numbers by the British army in about 1961; also by the Royal Marines, judging by the names Albion and Bulwark which someone has written inside my set.

Remarks I would have thought that the accumulators could have been a bit of a problem, but my set shows remarkably little damage from spilled electrolyte. From personal experience, the inverter can be extremely temperamental. Crystals are an obsolete 10XJ design, but not particularly difficult to change in the workshop

Frequency range 2 - 8 Mc/s

Receiver sensitivity 15-40mV for 15dB S/N

Receiver selectivity 4 kc/s at 6dB down

Receiver IF 470 kc/s

RF output (CW only) 1W

Weight (complete station) 17¾lb

General description The receiver and transmitter are constructed as separate units, normally carried as a single item. The earlier models are built into a wooden case - the later ones are carried in a canvas haversack.

Receiver Five valve superhet, continuously tuneable, with variable BFO: AM and CW.

Transmitter Two valves, crystal controlled: CW only. Individual crystals (10X or FT-243 pattern) are selected by the operator and netted to the receiver.

Power supply Dry batteries providing 1.5V LT and 135V HT.

Aerial system A 100ft end fed wire is provided as standard, but the transmitter 'can be matched to almost any antenna system likely to be used'.

Origin Unclear, but of very similar construction to sets from the Foreign Office Radio Service and possibly developed specially for the SAS. In service from mid 1950s.

Remarks Lightweight and not at all rugged, although the carrying arrangements give some protection. Not hermetically sealed, unlike the A510 and HF 156. Generally very pleasant to operate, despite a slightly insensitive receiver with a tendency to drift.

© G0TJD