Arfa Daily wrote:
"Jim Yanik" wrote in message
...
"Arfa Daily" wrote in
:
"Charles" wrote in message
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"geoff smith" wrote in message
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Can anyone suggest an interesting use for microwave oven
transformers .
Regards Geoff.
Ham radio enthusiasts use them in power supplies for high-power
vacuum tube transmitters.
Although they're not actually terribly good for this use, as their
design makes them self-limiting by way of core saturation, as I
understand it.
Arfa
Uh,the microwave magnetron is a vacuum TUBE just like any RF transmitting
tube,just for a different frequency.
I see no reason for having the xfmr core saturate for a MW oven.
--
Jim Yanik
jyanik
at
kua.net
Agreed, but the point I was making Jim, is that a microwave oven is a high
power CW oscillator. Most required ham radio use is for high power tube
linears which are most likely to be used for SSB transmissions, where the
current demand will swing from maybe as little as zero, to some maximum,
depending on the class and exact configuration of the amp. There is
something about the construction of the microwave oven transformer core -
and it seems to be the consensus that this is the presence of magnetic
shunts rather than any core saturation - that makes them inherently self
current limiting, thus keeping the magnetron operating in spec.
I would accept though that there should be no problem using one of these for
an RF amp intended for FM or any other constant carrier amplitude mode,
where the current demand on the power supply, will be largely constant.
Arfa
Don't get too excited about the magnetic shunts.
Grab a hammer and knock 'em out.
But since the transformer is designed to have high leakage inductance,
the core is made of lousy material and NO effort is made to have tight
coupling.
I made a battery tab spot welder outa one. Cut off the secondary and
put two turns of 2/0. Typical weld was 6 cycles of 60 Hz. Transformer
got hot pretty fast. Weld repeatability was poor.
mike
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