On Aug 24, 9:12*pm, raypsi wrote:
I almost forgot this thing draws more filament current at a lower
voltage
25 amps at 7.3 volts DC.

Filaments like lamps are not ohmic, but I don't think they should ever
draw more current at lower voltage. That would mean "negative dynamic
resistance".

Seems more likely there's some measurement difficulties. Getting good
contact on the filament pins through thermal cycles is often an issue.

Tim N3QE