Please click your language flag. Bitte Sprachflagge klicken.


Information - Help 
ID = 28432
Great Britain (UK)
Brand: Osram-Valves GB (not MO-Valves)
Developer: Osram-Valves GB (not MO-Valves) 
Tube type:  Triode, vacuum   Audio Frequency 
  <1925 very rare. ***
Identical to C_Osram
Similar Tubes
Normally replaceable-slightly different:
First year Sep.1918 Saga of the Vacuum Tube, Tyne Seite 222

Base IS-1 (Interservice, UK 1918)
Was used by Military and/or Government
Filament Vf 3 Volts / If 0.75 Ampere / Direct

Is also named "Air Force C-Valve".

Since the Museum search system allows only criteria of two or more digits we name all single digit valves/tubes with an appended underline. Therefore you can search C_ to get all single digit "C"-tubes.

This is a "hard" tube made by Osram GEC for the Royal Air Force, first made in September 1918. Also later made by Ediswan. The Ediswan version had the "four pillar" glass stem. This tube was sometimes branded Royal Ediswan.
The British Military inter-service tube base IS-1 was developed early in 1918 by Captain Stanley R Mullard as part of his work at HMS Hero, a reaearch facility of the British Navy in Portsmouth, England. The base consisted of a moulded ebonite "cup", 31 mm diameter with a centre contact for one end of the tube filament. The other end was connected externally by a copper strip about 3 mm 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 plate was identified by a red dot.The design of the base was to reduce internal capacitance between the electrodes. The base was 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
Tube prices 2 Tube prices (visible for members only)
Information source British Radio Valves - The Vintage Years: 1904-1925   Pages 27&28, 31,78,86
Saga of the Vacuum Tube, Tyne   P. 222
The Saga of Marconi Osram Valve
- - Data from my own collection

is1_base~~4.png C_Osram: Fin Stewart
Fin Stewart

C_Osram: Banneitz, TB der drahtl. Teleph. 1927
Anonymous 15 Collector

Collection of



You reach this tube or valve page from a search after clicking the "tubes" tab or by clicking a tube on a radio model page. You will find thousands of tubes or valves with interesting links. You even can look up radio models with a certain tube line up. [rmxtube-en]

Data Compliance More Information