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ID = 70751
United States of America (USA)
Brand: Apco Manufacturing Company; Providence, RI
Developer: Apco Manufacturing Company; Providence, RI 
Tube type:  Double Triode   RF/IF-Stage 
  Ca. 1925 up to 1945 very rare. ***
Identical to Twin_Apco
Similar Tubes
Other base:

Base UX-Base (4 Pins (2 thick, USA 1924, UX)
Was used by Radio/TV-reception etc.
Filament Vf 5 Volts / If 0.25 Ampere / Direct / Battery =

The Apco twin triode was two tubes of the 201A style in one and was made from 1925 to 1926. It contained two complete sets of elements which were connected in parallel except for one end of each filament. When the first filament failed, the second could be brought into service by slightly unscrewing one of the filament pins in the base so that a switch arm could be moved from one contact to another. This bought the second filament into the circuit. The tube shown in the illustration in Tynes' book "Saga of the Vacuum Tube, page 347 shows that the tube probably had an outside frosted (acid etched) bulb.

Dimensions (WHD)
incl. pins / tip
x 108 x 45 mm / x 4.25 x 1.77 inch
Weight 51 g / 1.80 oz
Information source Saga of the Vacuum Tube, Tyne   Pages 347 and 351
-- Collector info (Sammler)   
Twin_Apco: found by Lucas Gross
Robert Gillespie


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