Date: Sun, 18 Nov 2012 11:08:27 -0800
From: Bill Turner <dezrat1242@yahoo.com>
To: Amps <amps@contesting.com>
Subject: Re: [Amps] Microwave Oven Power Transformer
Guys.... it pains me to see you screw around with a transformer which was
designed to cook food.
Save your pennies, get a real Peter Dahl transformer and be done with it. Build
it into a universal power supply you can use with any of your amps and it will
last you the rest of your life and your children's and grandchildren's too.
That will be two cents, please. :-)
73, Bill W6WRT
## MOT’s are a pita. They all have sky high primary magnetizing current. And
that is caused
by not enough primary turns ! The primary to sec turns ratio remains the
same..as a real xfmr.
You really need between 2 or 4 of em ( all identical) to do the job right.
You also have to knock
the shunt out of them with a drift punch. One side of the sec on most of them
is bonded to the frame,
IE: grnded. Even with 2/4 of em, you still have sky high magnetizing current.
## using a series drop resistor in one leg on RX... + a relay to shunt out
the same resistor on TX will work, but
its still a pita.
## Time to get off the ....“get cheap program” and just do it right the 1st
time. Buy a new dahl 46-68-86-120 lb
xfmr with LOTS of primary AND sec taps. Get the primary tapped for
220/230/240. Get the sec tapped at several voltages.
Like at least 4-6 sec taps. Then you now have a xfmr that will run any amp
you can think of. Its resale value will be
a LOT higher....with all the taps. Your wife and kids will get all their $$$
back out of a good xfmr...which means one that
can be used.
## The heart of any amp project is the HV supply. And the heart of the HV
supply is the plate xfmr. Screw that up, or try and
go cheap, and lose it right there. The big xfmr’s are the way to go. They
don’t break a sweat, don’t heat up, and best of all, their
V regulation is a helluva lot better. On a buddy’s hb 2 x GS35B 6M amp, he
had 2 x xfmrs to play with. One of em resulted in a
700 vdc v drop. The bigger one resulted in a 50 vdc V drop...and loads more
po. You don’t put a light duty eng in a dump truck.
later........ Jim VE7RF
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