Aircraft Wireless Telephone Type AD2, by Marconi Company, England, c. 1920
Inventory Number: 12938
Date: c. 1920
Maker Details: Signed by Marconi's Wireless Telegraph Co. Ltd.
Inscription: "MARCONI'S WIRELESS TELEGRAPH CO. LTD. / TYPE A.D.2 NO. 175 / AIRCRAFT DEPARTMENT" printed on metal plaque upon front exterior surface of case. See Documents for other inscriptions.
Size: 380 x 170 x 250 mm (case)
Materials: Linen, ebonite, glass, wood, plastic?, assorted metals.
Other Given Number(s): Christie's 144, 862/3 (white tag).
Aircraft Wireless Telephone Type AD2 (Transmitter and Receiver), in varnished linen-covered case with removable front. Case mounted on four short metal legs. With two transmitter valves, transformers, aerial coil with variometer, and receiver with five Type V24/Type Q valves mounted on vertical ebonite panel. With four terminals mounted on vertical ebonite panel upon side exterior surface, marked "+H.T.", "-COM", "+L.T.", "MIC", respectively; these are terminals for power sources, and sound input/output. With plastic? triangular switch upon upper surface, marked "SHORT", "MEDIUM", "LONG", possibly for controlling frequency band. Case slightly damaged. Previously associated and catalogued with Variable Resistance Switch For Aircraft Wireless Telephone Type AD2 (Inv. Num. 99434) and Instruction Manual For Aircraft Wireless Telephone Type AD2 (Inv. Num. 32919).