The 212D was a 200 watt triode designed as an audio tube and RF tube at low frequencies. Maximum ratings to 1.5 MHz and a mu of 16. The first example is a Western Electric and was used in the 1928 transmitter at KFBK in Sacramento. The second tube was made by Sylvania.

Length = 12.5" Diameter = 3.25"
Max voltage = 1750
Max current = 180 ma
Fil voltage = 14
Fil current = 6 amps         GOTO INDEX