On Mon, 30 Dec 2019 13:33:24 -0800 (PST), "
wrote:

Same suggestions, although a bad Russian tube is no surprise whatsoever. Jeff is linking you to a reasonable site, however.

Peter Wieck
Melrose Park, PA
I already have a really nice isolated auto transformer with a meter.
The amp does draw a little more than 50 watts. I measured it when I
made up the buck xmfr power supply for it. If the 5u4 tube starts to
conduct much different than 80 volts what does that mean?
Eric