[Milsurplus] Testing 1625s

[Ian Wilson]

Volume 6 Number 3 of GE Ham News:
http://n4trb.com/AmateurRadio/GE_HamNews/ge_ham_news.htm

..has a handy power oscillator circuit that I've found to be a good way to
get a go/no go check
on all sorts of power tubes. You will want a variable supply for this. Start
at 100V or so on the
plate and look for oscillation on a scope loosely coupled to the tank. You
can ramp up the
plate voltage and look for ionization (gas), etc.

A simple Hartley will work with triodes and tetrodes with a dropper resistor
from B+ to the screen in
the latter case. Component values are highly non-critical: you want enough
feedback to get the
thing oscillating. My benchtop lashup (pictures suppressed for the
squeamish) takes off somewhere
around 15MHz.

73, ian K3IMW