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.