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In Reply to: RE: The lm317 is a constant voltage source posted by Triode_Kingdom on May 09, 2016 at 12:22:21
Hi, JKt, yes, in its cathode bias w/resistor, the amp was running 70ma at the cathodes. I thought that was too high so i dialed it back a little. The amp is running UL mode but there are no grid stoppers on the suppressor grids. There are 1K resistors on the input grids. As soon as the amp received a signal, it started motorboating.
Follow Ups:
The LM317 shouldn't cause that. It's likely there's another issue in the mix. See JKT's post below. If you have a scope, you can look at the stages ahead of the outputs to see if unwanted signal is leaking back through the B+ lines.
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Buy Chinese. Bury freedom.
Yeah, i did not think it was the lm317 but removing the bypass cap exposed some other situation which has now come to light. I will check the the voltages of the front end tubes and see if something jumps out there. cheers, dak
He'll need to disconnect the GNFB first.
Tre'
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