Before I begin - A WORD OF CAUTION!

I have been involved in amateur radio for a long time and have experience with high voltage projects. This project involved LETHAL VOLTAGES. Typical consumer grade voltmeters and test probes are not appropriate for direct measurement of the plate voltage required by this amplifier.

If you are contemplating a high voltage project, and do not have experience with high voltage, seek the advice and support of someone that can help you get started. You will not get a second chance if you make a mistake around 3000 volts and the energy stored in the power supply filter capacitors.

Note: This project description is being offered simply to share my experiences and is not a recommendation to build or proceed as I did.



  1. This was the initial cut at a load line. It turns out that everyone runs 650 to 700 volts on the screen grid instead of 500 volts (for class AB1 operation). Unfortunately I do not have the tubs curves for this higher screen voltage. I can transform this curve using the 3/2 power rule ( more later) though.