West. Elect. Type A
DC Amplifier Triode
1913

The Type A was the first WE tube to be given a type letter, but a type number was never assigned. The A was based on the DeForest audion but was redesigned with a coated platinum strip filament and pumped to a higher vacuum. Glass arbors were added for mechanical stability and an inverted V filament was used. This tube, #80, was employed in a Philadelphia repeater amplifier used as a part of transmission tests on the #9 New York-Baltimore circuit in late 1913. These tests were the first known use of a high vacuum tube amplifier in commercial service. The tests were set up by B.W. Kendall of WE and his memos indicate that the tubes performed well enough to justify further development. The vacuum obtained was inconsistent as some tubes were unusable due to blue haze.

Data from WE records shows that this particular tube, as well as a few others, had a strontium resinate coated filament. Barium resinate, barium nitrate and other coatings were more commonly used on the A's. For the tubes using a strontium resinate coating the filament ran at 1.5 to 1.6 amps and voltages of 3.1 to 4.1 volts. This tube was used with 40 volts on the plate, and was sent to Philadelphia with Kendall on 11/13/13. The lab sticker shows an amplification of 27 miles, which equates to a voltage gain of 18.9, very good for a tube of this vintage and much better than a DeForest audion. For comparison the initial production of the GE VT-11 of 1918 only had a gain of 8 miles, which improved to over 20 miles only after about 40,000 tubes had been made.