[AMRadio] Panasonic microwave oven parts for radio

John Coleman jc at pctechref.com
Wed Oct 10 13:11:42 EDT 2007

About switching power supplies:
	I have found that computer power supplies are pretty cool as well.
I buy two identical supplies and remove the transformer out of one of them.
Then I manufacture some sort of mount such as another pc board for the
second XFMR.  I connect the low voltage winding all in parallel with the
transformer in the supply and get about 160V PTP form the HV side of the
second XFMR with great isolation.  The 160V PTP can be put in to single
diode, bridge, doubler, tripler or quadrupler rectifier circuit to get up to
600VDC output at .5 amp or more depending on the supplies capability.  It
may require some small amount or dummy load on the 5 and / or 12 volt
original outputs.  The rectifier diodes that you use will need to be fast
recovery type in order to handle the high speed switching. 

I have found them to be great for audio preamp supplies as well.  Getting
rid of the 60HZ power XFMR gets rid of a lot of 60HZ loop current in the
chassis and cabling but does require some extra filtering and bypassing to
get rid of the high frequency ripple and harmonic radiation.

John, WA5BXO

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Rick Brashear
Sent: Wednesday, October 10, 2007 10:54 AM
To: jtml at vla.com; 'Discussion of AM Radio in the Amateur Service'
Subject: RE: [AMRadio] Panasonic microwave oven parts for radio

Thanks John.  Great info.

The light Panasonic ovens that say something like Inverter on the logo are
switchers. No heavy transformer anymore. They provide negative polarity hot
and operate in a current limit mode, not voltage regulation. There is a
website on them, if you search for it, that talks about dissection of one,
and the test results. They are pretty neat power supplies, providing like
1/2 amp of DC at >2kV. But very dangerous to play around with, unless you
isolate, isolate, isolate. 

If you do decide to pass on the power supply, I would love to have one to
play around with sometime. Might eventually be reconfigured to make a nice
tube power supply. 


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