Build one is working swimmingly
#2 has not fared as well. Upon initial power up I had a HF oscillation. By initial troubleshooting it appeared to begin between the triods, in the volume and tone pot, but eventually I replaced the entire assembly.
I did discover however that removing the feedback loop, specifically the 68k resistor, leaving it open, the oscillation diminished and the amp sounds fine until….
opening the tone control all the way causes the amp to either shut down output, or oscillate – HF, I would guess over 6k, closer to 8k as it is pretty piercing. The volume works but is limited by the tone setting. The volume at 10% OR so, the tone can be cranked. If the tone control is centered then the volume can be cranked.
So far: Replaced all signal caps and resistors (they all tested ok after being removed). I have not tested the PS caps, but all the voltages are good to the grids.
PT is a Weber 022722 and the Weber WSE15
Checked wiring several times, running out of ideas.
Thanks
Bill