Catalogue
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Marconi Radio Valve Type DEQ, by Marconi Company, England, c. 1923
Inventory Number: 74920
Date: c. 1923
Maker Details: Signed by Marconi-Osram Valves.
Inscription: "D.E.Q. BBC / 041 1_________" stamped on one side of exterior surface of bulb. "MARCONI _____ VALVES / ________ VARIOUS PATENTS" stamped on other side of exterior surface of bulb.
Size: 70 mm in overall length
Materials: Brass, glass, assorted metals.
Other Given Number(s): Christie's 197.
Notes:
Marconi Radio Valve Type DEQ (Dull Emitter Q), in thin glass envelope. With single wire filament running the length of the envelope and tensioned by a spring at end opposite the anode and grid brass supports. The anode and grid connections are on the envelope and pass to a shaped piece of glass rod that supports the electrodes. The grid helix can be clearly seen within envelope. A distinctive feature of DEQ valve is green band of paint around centre of envelope. Type DEQ valves had a very high impedance and primary function was as detector. 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), Mullard ORA/B Valve (Inv. Num. 18833), Marconi FE2 Valve (Inv. Num. 92775).
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