Metropoulos Forum

Hello I've got a question about Plate voltage. I convert my SL to JJ Kt88 I set bias but I'm not sure is that correctly. How to measure Plate Voltage correctly? I had to change bias resistor to 82K with 27K NFB resistor, when I back to 47K NFB I had to put 100K bias resistors and my plate voltage changed with min bias. Now I back to 27K NFB and my plate voltage is 510V but I'm not sure that I measure it correct.
Thanks for any advice.

measure pin 3 of the power tubes with the red lead and ground the black lead.

Thanks I did that way but what bias pot should be to correct measure? And with power tubes or not? what influence has NFB on Plate Voltage?

I don't know if nfb would have any influence on the plate voltage, you'll one of the more experience folks to chime in.