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ID = 7442
United States of America (USA)
Developer: Western Electric Company Inc.; New York (NY) 
Tube type:  Half-Wave Vacuum Rectifier   Power-supply 
Identical to 221A = NN = ML-371

Base Jumbo 4-pin bayonet (1918) Top contact with a cap.
Was used by Transmittertube (Radio)
Filament Vf 5 Volts / If 10 Ampere / Direct

According to Tube Lore II, this tube was made with a 2 volt filament and limited production of 50 tubes.

Dimensions (WHD)
incl. pins / tip
70 x 238 x mm / 2.76 x 9.37 x inch
Information source Tube Lore (II)   p. 235
Taschenbuch zum Röhren-Codex 1948/49   

221a.gif 221A: AH eigene Sammlung
Alexander Hofer

Just Qvigstad

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