Tube of the Month : The 1625


This months tube, handpicked by Thomas Mayer, is a transmitting beam power amplifier, the 1625. The 1625 was designed for use as AF amplifier or modulator as well as for RF amplification. 


Except for the heater it is identical to the 807.

"The 1625 has a 7 pin base and a small top cap for the plate connection. It is an indirectly heated tube with a 12.6V heater which consumes 0.45A. It is electrically and mechanically identical to the 807 with the only exception that the latter is heated with 6.3V / 0.9A. 


While it was intended to be used in Class AB2 configuration where it can deliver up to 120W, I have seen 807s used in singe ended amps and in triode connection as well. I never built anything with these tubes, so cannot share any practical experience but I am sure these are some excellent amplification devices. 


Since I have some of them in my tube stash I thought I write up a tube of the month post about them."