By Mike Cecil
Head of Military Heraldry and Technology
Australian War Memorial

Call it a ‘handie-talkie’ or a ‘walkie-talkie’, by any name, the United States (US)-designed and manufactured SCR-536 lightweight, hand-held receiver-transmitter was a revolution in tactical radio communications. While the British Commonwealth - including Australia - were concentrating on the development of larger, more cumbersome wireless sets with a greater range of functions, the American Galvin Manufacturing Company, based in Chicago, Illinois, were developing a compact receiver-transmitter for simple voice communication over short distances. By the middle of 1941, the set was being mass produced for US forces and supplied to allied nations.

The SCR-536 consisted of the BC611 transmitter-receiver (BC being ‘Basic Component’) housed in a slender, waterproof, aluminium case. With gradual improvement, the BC611 developed through six models during the Second World War, designated from ‘A’ to ‘F’. The top of the set had a tall screw cap that protected the antenna. On one side was a pressel switch with a rubber cover, while fixed to the main face were the ear and mouth pieces, angled so the operator could hold the set like a telephone. The base of the set was a shutter, hinged on one edge and held in position by a thumb screw. It provided access to the plug-in frequency crystal and the battery compartments. There were two dry-cell batteries: a short 1.5 Volt and a much longer 103.5 Volt. These would last about 15 hours with the set receiving, but transmitting only intermittently.

Operation of the ‘handie-talkie’ was simple. Unlike other combat radios of the period, with their separate mouth and ear pieces, external cables and array of variable dials and meters, the SCR-536 was operated like a telephone, with only one additional switch. It was designed to be held in the left hand, thus leaving the right hand free to write messages and so on. Extending the telescopic antenna to its full 102cm turned the set on. To receive, the operator simply held the set to his ear. To transmit, he pushed the pressel switch on the side and talked into the mouth piece. Transmitting and receiving were done on the same frequency, set previously by inserting the frequency crystal into the socket in the base. Volume could not be varied by the operator, having been pre-set at the factory.

The range of such a simple and low-powered set was only about 1.5kms, and was very dependant on terrain and atmospheric conditions. However, for intercommunication within a combat unit and to units in the near vicinity, it was considerably lighter and easier to use than more conventional sets. It weighed just 2.5kgs while the nearest Australian-produced short range, man-packed combat wireless, the WS108 Mk2, weighed nearly 15kgs and needed a trained signaller to operate it. No wonder the ‘handie-talkie’ was such a popular set when introduced into Australian service in late 1942. Officially issued on a scale of 30 per battalion, larger numbers were often provided (or ‘acquired’) for specific operations.

Obtained under lend-lease arrangements, the SCR-536 filled the need for a simple, robust means of communication that could be operated by almost anybody with virtually no training. It was the forerunner of the modern, compact tactical communications equipment in use today.