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ID = 29023
United States of America (USA)
Brand: Connecticut Telephone & Electric Company (Sodion); Meriden (CT)
Tube type:  Gas Triode   Detector 
  <1925 very rare. ***
Identical to D-21_Sodion
First year 1924 ? -- Collector info (Sammler) See tyne page 339
Predecessor Tubes Sodion_S14  
Successor Tubes B6_Donle  

Base UV-Base (4 Pins+Bayonet, USA 1914 WE)
Filament Vf 5 Volts / If 0.25 Ampere / Direct / Battery =
Description Designer was Dr. H.P. Donle, then still chief engineer at Connecticut Telephone and Electric Company, Meriden, Connecticut, USA. In 1925 Dr.Donle left Connecticut and Electric Company to establish his own company, the Donle Bristol Corporation of Meriden, Connecticut, where later sodion types were developed and manufactured. See Tyne, beginning page 336. The D21 is the last tube Donle designed for Connecticut. His next, the B6 was designed at Donle-Bristol Corportation. The IF=0.25 Amp. is including heating spiral. The filament is made of tanralium. Transconductance 260 micromhos, internal resistance 51,000 Ohm, amplification factor=22. The D21 can be used as an oscillator. Is a good detector but poor amplifier. On the market in 1924. 
Text in other languages (may differ)
Dimensions (WHD)
incl. pins / tip
31 x 97 x 35 mm / 1.22 x 3.82 x 1.38 inch
Weight 62 g / 2.19 oz
Tube prices 4 Tube prices (visible for members only)
Information source Radios von gestern, 2. Auflage   page 213
Saga of the Vacuum Tube, Tyne   page 339
Geri Meier

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