AEG Coolidge Therapy Tube
Ref. C2
This early Coolidge Therapy tube is 32” (80 cm) long, strongly discolored, dating probably to the late second decade of the 20th century, bearing the AEG mark, Type II, No.3007, and has the inscription “Fürstenau Coolidge Röhre, Veifa Werke, Frankfurt A/M”.
It has a concentric spiral filament “hot cathode” in a molybdenum cylinder, with a two-prong external connection, round tungsten target embedded in a lightweight copper anode.
Its technical specifications remain unknown.
Before the U.S.A. entered WW1, AEG had obtained the privilege of manufacturing Coolidge tubes, and they had them made by Veifa. But the patent for using tungsten anodes belonged to Siemens & Halske. So an agreement was concluded in which each partner granted the other the use of both patents, and in which AEG reserved to itself the right to manufacture certain definite quantities of tubes for Siemens & Halske.
By Georg Siemens: ”History of the House of Siemens”, 1957, Karl Alber, Vol II, p.80.