Western Electric 215A Small Filamentary Triode
1919. Work began on this tube during WW I by Hendrik Johannes van der Bijl. Its design, for the Army, had the lowest possible filament power for use in battery-operated trench sets. Also identified as Signal Corps VT-5, Navy CW-1344 and later CW-38015. Because of its size, it was called a “peanut” tube and known to WE as type “N”.
The filament was wound from a single-strand barium- and strontium-coated “Konel” core, mounted vertically. The grid was a spiral nickel wire, and the anode a nickel cylinder. This construction was sensitive to mechanical shock and was improved by adding a glass reinforcing bead at the top of the tube structure, made of 1/16" cane glass, and a 0.010" nickel wire embedded in the stem press parallel to the tubular plate. It had a magnesium getter.
Although designed for portable military equipment, it appeared too late for WW I. The 215A functioned as an audio and intermediate-frequency amplifier, detector, or oscillator. It was used in the Wireless Specialty Apparatus BC-144 receiver (1928) and the WE 23A amplifier.
The 215A was also used for civilian purposes and appeared in WE 500-kHz monitor for broadcasting stations (3A TRF model and 4-type super heterodyne receivers) and audiometers. Also used in TRF broadcast receivers specially built by WE for the New York police (1925). Every precinct house had a radio fixed-tuned to the city's station WNYC. Using railroad-type rotary selectors controlled by a 3000-Hz tone, a dispatcher could selectively alert every location.
Western Electric finally refused to provide the Navy with the tubes in 1983 after 64 years of production.
Fiche technique • Data sheet • Datenblatt:
Hauteur • Height • Höhe : 63 mm • 2" 1/2
Diamètre • Diameter • Durchmesser : 16 mm • 5/8"
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