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ID = 7722
Great Britain (UK)
Tube type:  Space Charge Tetrode   Text 
Identical to DE7
Similar Tubes
Heater different:
First Source (s)
1924 : British Radio Valves - The Vintage Years: 1904-1925 p.65
Predecessor Tubes FE3_MO  

Base Europe 4-Pin B4 (Eu A, E, 4A) 1914 (Codex=So) Sidecontact.
Filament Vf 1.8 Volts / If 0.4 Ampere / Direct / Battery =
Description Va 6-20 V. Inner grid 6-15 V. For H.T.less circuits, Unidyne receivers. In the commercial life of this tube, four variations were made. 
Information source Taschenbuch zum Röhren-Codex 1948/49   1925 Brown Brothers Catalog 217
Saga of the Vacuum Tube, Tyne   Pages 382 & 383

b4_space_charge~~2.png DE7: Fin Stewart
Fin Stewart

Just Qvigstad
DE7: Banneitz, TB der drahtl. Teleph. 1927
Anonymous 15 Collector

Collection of



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