Early ground radar transmitter, type TF3, and five valves, made at Bawdsey, late 1936-1938. The TF3 used two NT46 or two NT57 silica radio valves to drive two more NT57 valves in a neutralised push-pull amplifier.

In the late 1930s, Robert Watson-Watt’s team at Bawdsey Research Station in Suffolk developed three different types of experimental radar transmitters, of which this TF3 was the first to be developed and was handbuilt under by great secrecy by Watson-Watt and his team at Bawdsey. Only five TF3 transmitters were produced - four were used in early radar stations in 1937-38 and one was used for experimental work with a new silica tetrode valve, the NT60.

The TF3 was a prototype of the MB2 mobile radar transmitter developed by Metropolitan Vickers Electrical Company in 1939 and put into production in 1940 for Chain Home radar stations during the Second World War.