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Marconi-Osram Radio Valve Type R, by Marconi Company, London, c. 1925

Inventory Number: 82041

Date: c. 1925

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

Inscription: "MARCONI OSRAM VALVE / MADE AT THE OSRAM LAMP WORKS / COVERED BY VARIOUS PATENTS / MADE IN ENGLAND" printed on one side of exterior surface of bulb. "D.E.V.X / 375" printed on other side of 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 198.


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 particular model was made in 1925 or thereafter as indicated by the lack of a BBC stamp. 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. Previously catalogued with three other Type R Radio Valves (Inv. Num.s 94475, 22908, 80773).

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