Robots make radios (1940s style)

    John Adolphe Szabadi was born in London of Hungarian parents in 1906, changing his name to Sargrove in 1938. He was employed by British Tungsram Electric Lamps Ltd (soon to become British Tungsram Radio Works Ltd) in 1930 and soon became chief engineer in their technical department.

    In 1936-7, he made an experimental radio to try out his idea of an integrated ‘sprayed circuit’ chassis. Did this idea anticipate the printed circuit board? Not really. With the printed circuit board (the invention of Paul Eisler in 1943) the circuits are formed by an etching process on which the separate components are later attached. In the Sargrove method the circuits, resistors, inductances and other components were formed by spraying on to a pre-moulded bakelite panel.

    Much of Sargrove’s work at British Tungsram was concerned with developing new types of electronic valves (or tubes). One in particular was a ‘universal’ valve, type UA55. It had a slightly reduced performance compared with valves designed for specific uses, but had a wide range of applications. A pamphlet in the Museum’s collections describes the construction and use of the valve, dating from about 1948.

    The British Tungsram brochure described how the UA55 valve was used with the simple radio receiver designed by John Sargrove for manufacture by Electronic Circuit Making Equipment (ECME) in 1947-8.