Thread: Old microwave
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Old March 19th 07, 05:03 AM posted to rec.radio.amateur.homebrew
Bill Bowden Bill Bowden is offline
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First recorded activity by RadioBanter: Feb 2007
Posts: 13
Default Old microwave

On Mar 14, 10:04 am, "N9WOS" wrote:
The HV transformer. Output 1 to 2KV at several hundred to a thousand
KVA


Wow. Message received. It'll be fun to disassemble a microwave...when
I was a pre-teen, I used to do it to old 1st generation TV's the best
part used to be imploding the picture tube.


Thanks!


John
AB8O


Ow ow ow ow....... forgot to mention something........

Microwave oven transformers (MOTs) are current limiting. They have magnetic
shunts between the primary and secondary. You can short the secondary out,
and it won't blow any breakers. The transformer may hum loudly, but it but
nothing will blow.

That is why people say that they have poor voltage regulation when used in a
HV power supply.

You can remove the current limiting by just driving out the magnetic shuts
with a punch and hammer. The shunts are just stacks of transformer
laminations stacked up to make a square block, and press fit into the space
between the primary and secondary.

With the magnetic shunts removed, then the output voltage will go up, and
the output voltage regulation will be far better. You will be able to draw a
lot higher peak current from it. But be careful. There is no longer any
current limiting. If you short out the secondary, the breaker, or fuse will
blow.


I never had much luck with Microwave power transformers. They seem to
saturate with light loads and draw several amps of line current. If
the load isn't 600 watts, they go crazy, draw lots of current and
heat up. They also have the laminations welded together which reduces
efficiency (lots of eddy currents). Might be better suited for a boat
anchor.

-Bill