N9WOS wrote:

Woops ..... calculation errors.......
Let me correct a few figures.

For a 4KV 500mA 2000Wsupply.
A full wave supply with a 4.5KV-0-4.5KV transformer driving two de-maged
magnetrons driving a filter choke.
It would drop about 500V in the magnetrons.
Power loss would be 40Wfiliment plus 250W plate loss, for a total loss of
290W each.
Total losses would be 580W at full load. 80W at no load.
77.5% efficient at full load.

That should be
Total losses would be 330W at full load. 80W at no load.
85.8% efficient at full load.

The largest supplies you could probably make is a 10KV 500mA 5,000W
supply with two tubes and an efficiency of 90%.

10KV 500mA 5,000W supply with two tubes and an efficiency of 93.8%.

Or a 20KV 500mA 10,000W full wave bridge supply, with four tubes, with
and efficiency of around 90%

20KV 500mA 10,000W full wave bridge supply, with four tubes, with and
efficiency of around 93.8%

These are interesting experiments, though if I wanted a high voltage diode
from a microwave oven, I would be tempted to take the small one made from
silicon instead.

What is the advantage over using several secondary windings, each with its
own rectifier made from 1N4007 (or better) diodes, and then connecting the
DC outputs from the rectifiers in series?

(or the standard old technique of using several 1kV diodes in series, with a
capacitor and resistor in parallel with each diode, to keep the voltage
sharing even)

Chris