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B21

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ID = 13796
       
Country:
Great Britain (UK)
Brand: Marconi-Osram - (Valves/Tubes); GB
Developer: Marconi-Osram - (Valves/Tubes); GB 
Tube type:  Double Triode   Power/Output 
  Ca. 1925 up to 1945 rare.
Identical to B21 = CV2864 = VT143_GPO = B230_Hivac = CV1696
Similar Tubes
Normally replaceable-slightly different:
  BB220A
First Source (s)
Aug.1933 : Wireless World (The), London (WW, 79)
Base British-7-Pin, old (M7A) (Codex=Eo)
Was used by Radio/TV-reception etc.
Filament Vf 2 Volts / If 0.2 Ampere / Direct / Battery =
Description

Class B audio output twin triode tube. Filaments connected in series

 
Information source History of the British Radio Valve to 1940   P. 146 & 167
Babani, International Radio Tube Encyclopaedia   p. 52 & 53
Universal Vade-Mecum, Electron Valves and Semiconductor Devices
Taschenbuch zum Röhren-Codex 1948/49
Tube Tester Data Avo CT160
b21_sock.png B21: Tabu Röhren-Codex, 1948
Anonymous 15 Collector

Just Qvigstad 		b21_mov_spec.png
B21: Marconi Advertisement
Anonymous 15 Collector
Usage in Models 2= 1933 ; 1= 1934?? ; 2= 1934? ; 6= 1934 ; 2= 1935 ; 1= 1936
Quantity of Models at Radiomuseum.org with this tube (valve, valves, valvola, valvole, válvula, lampe):14
 
uk_osram_b21_valve.jpg

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