Marconi-Osram Radio Valve Type R, by Marconi Company, London, c. 1923
Inventory Number: 85569
Date: c. 1923
Maker Details: Signed by Marconi-Osram Valve Co. Ltd.
Inscription: "MARCONI OSRAM VALVE / MADE AT THE LAMP WORKS / GOVERNED BY VARIOUS PATENTS" stamped on one side of exterior surface of bulb. See Documents for other inscriptions.
Size: 110 mm in overall length (including base pins)
Materials: Glass, nickel, plastic?, brass?, assorted metals.
Other Given Number(s): Christie's 119, Science Museum Loan 1947-303.
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. 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. Previously catalogued with Marconi Receiver Type 226B (Inv. Num. 40124), Marconi Note Magnifier Type 227B (Inv. Num. 76594), Marconi Long Wave Panel Type 229B (Inv. Num. 41345) and other associated Radio Valves (Inv. Num. 88794).