Automatic Radio
subminiature tube radios



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Subminiature tube coat pocket radios
Tom Thumb models 528 & TT-600 & Firestone model TT-528

circa 1953/54

Tom Thumb 528

Tom Thumb 528 insides

Tom Thumb TT-600

Firestone TT-528

The subminiature tube (developed by Raytheon) was used during W.W.II to help prevent the German "Buzz Bombs" from reaching their target in England. The technology of the day prohibited construction of the electronics needed to build a receiver that could be placed in the nose of a ground launched shell that could then be aimed toward the incoming German Missiles. Raytheon developed the "Proximity Fuze" using the "subminiature tubes", the "fuze" was in reality a sensitive metal detector that could be placed in the nose of an exploding shell that was launched towards the incoming "Buzz Bomb". When the shell came within proximity of incoming aircraft or "Buzz Bomb" it would explode. That explosion either destroyed the aircraft or "Buzz Bomb" or knocked it off course. I understand the "Proximity Fuze" was also used successfully in the pacific to knock down Japanese aircraft.

As a result of the WWII development of the Proximity fuze, a few companies made radios using even smaller versions of these tiny tubes. They were: Belmont, Private Ear, Crosley, Hoffman, Emerson, Motorola, Sears "Silvertone" and Westinghouse. Some of these sets were "hybrids" using a combination of tubes and transistors and some sets incorporated a miniature tube and 3 subminiatures. 1955 saw the last use of these neat little tubes in consumer radio products as the transistor technology was taking over the small radio design

The images above represent Automatic Radio Corporation's models of subminiature tube radios: the "Tom Thumb" 528 & the Firestone version TT-528 have a full compliment of subminiature tubes The "Tom Thumb" TT-600 although labeled as a transistor radio is actually a hybrid with three subminiature tubes and two transistors.

Battery requirements: All require a 45 volt "B" battery. The all tube models; a 1.5 volt "A" battery, while the Hybrid requires a special 4 volt cell (which are *no longer available). These sets measure 6X4X1.5" and weigh (without batteries) 1, 1/4 lb.

be sure and visit the subminiature tube page

© C.E. Clutter


Member of:
Northwest Vintage Radio Society

Member of:
Antique Wireless Association


RadiolaGuy collection, not for sale