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ID = 29000
Great Britain (UK)
Brand: Osram-Valves GB (not MO-Valves)
Developer: Osram-Valves GB (not MO-Valves) 
Tube type:  Gas Triode   Detector 
  <1925 very rare. ***
Identical to D_Osram = D_Ediswan

Base IS-1 (Interservice, UK 1918)
Was used by Military and/or Government
Filament Vf 5 Volts / If 0.46 Ampere / Direct
Description Soft valve - Receiving and Detector. First made by Osram GEC January 1919 and Ediswan.
The 1920 exhibition at the Physical Society in London by MOV gives the filament rating as 3V at 0.46A and the anode voltage as 28. The British Military interservice base IS-1 was developed by Captain Stanley R Mullard as part of his work at HMS Heron, a research facility of the British Navy in Portsmouth, England. The base consisted of a molded ebonite "cup" 31 mm diameter, with a center contact for one end of the filament. The other end was connected externally by a copper strip about 3mm wide. The anode and grid connections were made with two brass plates 7 mm square and on either side of the base, near the rim. The anode was identified by a red dot. The design of the base was to reduce internal capacitance betwen the electrodes. The base was also used on at least 12 other tube types. 
Dimensions (WHD)
incl. pins / tip
31 x 85 x mm / 1.22 x 3.35 x inch
Weight 29 g / 1.02 oz
Information source Saga of the Vacuum Tube, Tyne   page 216, 222
British Radio Valves - The Vintage Years: 1904-1925   pages 27&28, 78 ,86
The Saga of Marconi Osram Valve
- - Manufacturers Literature

is1_base~~6.png D_Osram: Fin Stewart
Fin Stewart


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