Thread: Old microwave
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Old April 16th 07, 04:12 AM posted to rec.radio.amateur.homebrew
Jimmie D Jimmie D is offline
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First recorded activity by RadioBanter: Feb 2007
Posts: 287
Default Old microwave


"Bill Bowden" wrote in message
ups.com...
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


I tried one for a 4cx250 amp, sucked bilge water big time. I dont think the
primary had 100 turns on it.

Jimmie