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ID = 28728
Great Britain (UK)
Brand: Osram-Valves GB (not MO-Valves)
Tube type:  Triode, vacuum   Universal 
Identical to R4B_MO = R4B_BTH = R4B_Marconi
First Source (s)
1918 : British Radio Valves - The Vintage Years: 1904-1925 p.26
Predecessor Tubes R4A  

Base Europe 4-Pin B4 (Eu A, E, 4A) 1914
Was used by Military and/or Government
Filament Vf 3.8 Volts / If 0.65 Ampere / Direct / Battery =

This tube was made with either a European B4 base or an Edison E12 base (the measurements above are for a tube with E12 base). In the latter case, the plate and grid connections were from wire leads on the top of the bulb. First made by Osram GEC June 1917. Two tubes are known to exist where the E12 base is in place but was not used.

Dimensions (WHD)
incl. pins / tip
x 86 x 50 mm / x 3.39 x 1.97 inch
Weight 33 g / 1.16 oz
Information source Saga of the Vacuum Tube, Tyne   page 380
- - Manufacturers Literature   Gec cat. about 1924
- - Manufacturers Literature

b4_1~~70.png R4B_MO: Fin Stewart
Fin Stewart

Just Qvigstad
R4B_MO: own collection
Peter den Boer

Collection of



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