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Marconi-Osram Radio Valve Type R, by Marconi Company, London, c. 1923

Inventory Number: 59257

Date: c. 1923

Maker Details: Signed by Marconi-Osram Valve Co. Ltd.

Inscription: "R. 5V / BBC [LOGO] / _13578" printed on exterior surface of bulb. "MARCONI OSRAM VALVE / MADE AT THE OSRAM LAMP WORKS / COVERED BY VARIOUS PATENTS" printed on exterior surface of bulb.

Size: 110 mm in overall length (including base pins)

Materials: Glass, nickel, plastic?, brass?, assorted metals.

Other Given Number(s): Christie's 215.


Marconi-Osram Radio Valve Type R, made by Marconi-Osram Valve Co. for the domestic radio market and dating from the early era of broadcasting in the 1920s. This valve is unusual for an R type in that the electrode assembly is held vertically, with neat and minimal supports. The glass envelope is partially silvered inside, and the valve itself is gettered. The filament is single thread and is spring loaded. The grid is a bright wire helix fixed to single vertical rod support. The anode is a bright cylinder fixed to the pinch by a single stout support. With nickel-plated plastic? base and brass? base pins. The BBC Logo stamp ("TYPE APPROVED BY POST MASTER GENERAL") was used from November 1922 until September 1924 and is a good indication of date of origin.

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