P.I. voltage

[grtamp]

Hi , I have 296V on inverting side and 291V on non inverting side in my #102 Clone!!!
should not be the other way?

Thanks

[grtamp]

anyone?!?

[erwin_ve]

Check https://tubeamparchive.com/viewtopic.ph ... 211#145211, well covered.

[sonicmojo]

Have you tried a couple of different tubes and see how your voltages check out?

[David Root]

It can come out either way depending on the tube. If you try enough different tubes you'll get one that does. It really doesn't matter, so long as the tone is where you want it.

That's what the trimpot is for.

[grtamp]

Hi , I haven't another quartet of power tubes to put in to compare ,but the sound of amp I like it very much!!
the trimpot is already set and I don't think to invert this big voltage difference!

[sonicmojo]

Hi , I haven't another quartet of power tubes to put in to compare ,but the sound of amp I like it very much!!
the trimpot is already set and I don't think to invert this big voltage difference!

We're talking about the PI tube.

[grtamp]

Sorry ,I didn't understand!

I changed the tube but the voltage it's the same.

[sonicmojo]

Well that's kinda odd. I've never had 2 PI tubes measure out just the same. Just to be sure are you measuring the points like in the below picture? Your layout may vary a bit.

[talbany]

The non-inverting side of the PI should have about 6 more volts than the feedback side.The 1st half should have a smaller plate load and a little more voltage..What do you get when you disconnect the GNFB..I also wouldn't rule out a bad trimmer..

Tony

[grtamp]

Sonic , yes , that is the point where I check!

Tony , I already close the chassis in the cab!! (I need for a live concert)

My trim is well setting , sinewave signal at the same amplitude in both side!