Hoffman 6G15 Power Problem

[AScott]

I built a Hoffman 6G15 and although my PT and rectifier are working fine, my power voltage is high. 350V with no tubes and around 310V with the tubes in. When I isolate and check the PT and the at the bridge rectifier output I get 250V. What did I do to pull up the power? Where should I look?

[sluckey]

I built a Hoffman 6G15 and although my PT and rectifier are working fine, my power voltage is high. 350V with no tubes and around 310V with the tubes in. When I isolate and check the PT and the at the bridge rectifier output I get 250V. What did I do to pull up the power? Where should I look?

I think your voltages are fine. My B+ is 332Vdc with tubes in. I suspect that when you measured 250v at the bridge you did not have any filter caps connected. B+ will be much lower without the filter caps connected.

[PRR]

> 310V with the tubes in.

http://www.prowessamplifiers.com/schematics/fender/reverb_6g15_schem.pdf

Shows 300V at the first DC cap, all-up.

310V is just modern wall voltage AND using a FWB instead of 1962's half-wave rectifier.

> at the bridge rectifier output I get 250V.

The rectifier and filter capacitor is a "peak catcher". 250V RMS roundy sine-wave without a cap is 225V of average DC but with a cap 350V peak. If all were perfect and exact, that's what you expect with and without the first filter cap.

Of curiosity: are you using Leo's 6K6? or the modern alternative 6V6? They bias a little different, which will affect the DC reading in this small power supply.

{edit} Sluckey posted while I was feeding fire...

[AScott]

I'm using the 6V6. What concerns me is that i am losing tubes much more frequently than I am used to. I was thinking that with that high of a plate voltage, it is causing my tube failures.

[shooter]

I've had 2 6V6 die way before life expectancy this year, I re-biased and installed some 60's 6K6's.  Amp is in the wild currently.
fwiw, both 6V6 were EH bought couple years back.

[PRR]

...i am losing tubes much more frequently than I am used to. I was thinking that with that high of a plate voltage, it is causing my tube failures.

So 310V with the tubes in, say 25V at cathode, the tube 'feels' 285V plate to cathode?

1941 tube manual says 285V on screen 315V on plate. Limits were raised in the TV era by reducing the safety margin for designer screw-up.
https://frank.pocnet.net/sheets/127/6/6V6.pdf
If a 6V6 can't stand 285V, it is junk.