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History of Science Museum

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

Inventory Number 18833


Acknowledgement: © History of Science Museum, University of Oxford, inv.18833

Item type
Object
Makers
Mullard
Provenance
Presented by the Marconi Corporation.
Primary inscriptions
"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.
Object type
Radio valve
Dimensions
Diameter: 25mm Height: 75mm
Inventory No
18833
Accession Number
2004-9/193

Description

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).