[R-390] R390-A problem

[Gord Hayward]

>
>
>Sounds like cathode to filament short (hum is the smoking gun but the gain shift is telltale too). These are often intermittent. Switching to or through standby interrupts B+.
>
I had that happen in the limiter (limiter switched off gave no problem).
Swapping tubes is the best diagnostic as my tube tester didn't catch the 
fault.
Cheers de Gord, VE3EOS.

-- 

Gordon L. Hayward, Ph.D., P.Eng.,
Associate Professor, Biological Engineering,
School of Engineering, University of Guelph,
Guelph, Ontario, N1G 2W1.