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%

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

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
You are missing the point........ :-)


Why would someone use a large heavy piece of equipment weighing up to
several hundred pounds with several large heat generating glass things in
them, several large metal cubes in them, with operating voltages ranging up
to a thousand volts..... When they could use a little light square box,
about the size of two bricks, with a fancy display, that runs off of an
almost harmless 12V DC, and will do the exact same thing?

Because they want to!!!!!!!

Magnetron tubes are too neat looking to throw away, or leave unused.

I think that a set of magnetron tubes that have been removed from the cases,
and set on a set of ceramic standoffs would have definite cool appeal in a
HV power supply.

I wonder what the internal electrode to electrode breakdown voltage would
be? That would be the PRV operating limit if you took a magnetron tube and
put it in a one gallon paint bucket filled with mineral oil. It wouldn't
have a problem with arcing over on the outside in that setup. Wouldn't need
cooling fins on the tube any more, and you could put the filament
transformer in the bucket with the magnetron. all you would have coming out
of the bucket is the AC line running the transformer, and the two HV
feedthroughs for the HV connections to the magnetron.