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Mullard Radio Valve Type ORA/B, by Mullard Radio Valve Company, c. 1922

Inventory Number: 18833

18833-1t 18833-2t 15771-18833-33191-35245-74920-92775-1t 15771-18833-33191-35245-74920-92775-2t

Date: c. 1922

Maker Details: Signed by Mullard Radio Valve Co.

Inscription: "MULLARD RADIO VALVE / 36" stamped on one side of exterior surface of bulb. "BBC / PROTECTED BY PATENT / 254" stamped on other side of exterior surface of bulb.

Size: 75 mm in overall length

Materials: Glass, rubber?, assorted metals.

Other Given Number(s): Christie's 197.


Mullard Radio Valve Type ORA/B, in thin glass envelope. ORA stands for Oscillator, Rectifier, and Amplifier. Valve was of bright emitter type and had a mu (amplification factor) of 8.5. In construction, valve has a rubber? skirt and familiar tubular anode. Grid is of curved folded arrangement and has single strand filament, tensioned by support arm. Previously catalogued with five other valves: Marconi Type Q Valve (Inv. Num. 33191), Marconi Type V24 Valve (Inv. Num. 35245), Marconi DEV Valve (Inv. Num. 15771), Marconi DEQ Valve (Inv. Num. 74920), Marconi FE2 Valve (Inv. Num. 92775).

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