Recommended Bias Setting

First I’d like to thank the Fryette team for pulling through and sending replacement tubes!

I’d like to avoid having to go to the tech again and spending money when the new tubes arrive, and since the PS-100 has a bias pot I’d rather do the rebiasing myself.

Currently the bias was brought all the way down to around 17mA at a plate voltage of 697V so the tubes wouldn’t red plate anymore.

The circuit board under the pot says the bias should be set at 35mA, would that be correct for the PS-100?

neglecting screen current, 35 mA by 700 V is 24.5 W, which is around 70% of the 6550’s max rated plate dissipation (35 W). this is a reasonable value.

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Yes, 35mA is correct.

Dave