P_WesternElectric

Late in 1918, the US Army Signal Corps approached Western Electric about designing a small tube that would have the lowest possible filament requirement for use in battery operated trench sets. Research by H.J.van der Bijl led to the development of the "P" tube, which was designated VT-3 by the Signal Corps. The tube operated with a 2 volt filament and current of .2 amps. Because of the end of WorldWar One in November 1918, only 1000 tubes were made and delivered. The VT-3 tube was not given a Western Electric type number or offered for sale commercially. Alphabetical letter codes were allotted to each new tube designed and subsequently in most cases coded by the company. According to Tynes' "Saga of the Vacuum Tube" page 280,the letter P for this tube was never coded.