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

Inventory Number: 48922

48922-2t 48922-1t

Date: c. 1923

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

Inscription: "MARCONI OSRAM VALVE / MADE AT THE OSRAM LAMP WORKS / COVERED BY VARIOUS PATENTS" printed on exterior surface of bulb. See Documents for other inscriptions.

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

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

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


Marconi Radio Valve (or Tube) Type DER (Dull Emitter R), with glass balloon envelope, steel-plated plastic? base and four brass? base pins. The construction was of a cylindrical anode with a helical grid passing through it, threaded by a filament.

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