vonBronk_triode

This tube was designed by Otto von Bronk while he was working at A.E.G.- Telefunken, where in 1911 he was manager of the Patent Department. The tube is said to be a modification of a Christmas Tree lamp but the actual manufacturer is not known. With the A.E.G connection, it may have been made at their lamp factory. The tube was fitted with a standard E14 screw base of the period. This base had porcelain insulation between the centre contact and the screw shell. The filament was a low voltage tungsten type of the pressed or sintered type as had been invented a few years before. The illustration clearly shows the ends of the filament welded to the lead-in wires. The grid is believed to be copper wire. Anode and grid connections were made by attaching wires to the platinum "looks" on the glass bulb. The tube was designed for use in a high frequency amplifier developed by von Bronk as a pre detector.

Patents were applied for (and granted) in Germany (no 271079, March 3.1914) Great Britain (no 8821, 1913), Austria (no 63593, Feb 25, 1914) and the United States (1087892, July 21, 1914).

Information from notes compiled by the late Kaye Weedon, eminent radio historian from Norway and dated April 25th, 1987