I have missed that. What are the problems?
Even the power supplies I have made which power 1500+ liners have held up
fine. I do notice they seem to run a bit warmer than their expensive
counterparts.
I am convinced without arguement that their efficiency is lower than a more
conventional xfmr--one reason--microwaves are usually only in operation for
short periods of time.
However, all I can see which might be happening is my electric bill is a few
cents higher...

Regards,
John

--
I would like to point out, I do appreciate the "Been there--done that!"
posts. Indeed, now your observations, comments and discourse should be
filled with wisdom--I am listening!!!
"Michael A. Terrell" wrote in message
...
John Smith wrote:

I have gleaned 1.5KW commercial microwaves for their transformers (they
had
timers which maxed out at 1 hour!), removed the secondary and replaced it
with heavy copper wire to make 13.8 V high amp supplies for mobile
linears
converted to shack use.
The ones I have come across--where I bothered to measure the voltage of
the
secondary, were 3000+ V, as I remember 3300-3500 V.
Two matched transformers should be able to serve as a center tapped
transformer without much re-engineering.
In amplifier use, a transformers 50% duty cycle specs should be
sufficient--I wouldn't be surprised if they could serve well in amps (and
it
never hurts to make sure the xfmr benefits from a fans output.)
The only red flag which pops up in my mind is if there would be
sufficient
isolation of the primary from the secondary at low freq. rf., if not,
something there could probably even be worked out (and, my worry may be
false to begin with.)
In extreme cases, a heat sink could be fitted to the exposed section of
the
top and sides of the core (heat conductive epoxy would work.)
And, hey, if I guy gets long winded and smokes a xfmr, a trip to the dump
for a replacement is cheap!
Take care, those transformers can pack a lethal wallop!

Regards,
John


The welded cores can cause problems. This has been discussed on the
various sci.electronics.* groups a number of times

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

On Mon, 4 Apr 2005 22:03:21 -0700, "John Smith"
wrote:

I have missed that. What are the problems?
Even the power supplies I have made which power 1500+ liners have held up
fine. I do notice they seem to run a bit warmer than their expensive
counterparts.
I am convinced without arguement that their efficiency is lower than a more
conventional xfmr--one reason--microwaves are usually only in operation for
short periods of time.
However, all I can see which might be happening is my electric bill is a few
cents higher...

Regards,
John
I couldn't get the laminations apart because of the welds. I would go
down to the garage and chisel away at them every couple of day, but I
finally gave up. My intended use was a hi current 13.8 V supply

Te KX4OM

Yes, I see.
I never attempted to get the laminations apart. Using a hacksaw blade, I
cut the secondary turns and drove them out of the core with a punch.
Next, I used teflon tape around the core for insulation, and wound the heavy
thermaleze insulated wire though the windows in the core to complete my low
voltage winding.

Regards,
John
--
I would like to point out, I do appreciate the "Been there--done that!"
posts. Indeed, now your observations, comments and discourse should be
filled with wisdom--I am listening!!!
"Ted Bruce" wrote in message
...
On Mon, 4 Apr 2005 22:03:21 -0700, "John Smith"
wrote:

I have missed that. What are the problems?
Even the power supplies I have made which power 1500+ liners have held up
fine. I do notice they seem to run a bit warmer than their expensive
counterparts.
I am convinced without arguement that their efficiency is lower than a
more
conventional xfmr--one reason--microwaves are usually only in operation
for
short periods of time.
However, all I can see which might be happening is my electric bill is a
few
cents higher...

Regards,
John
I couldn't get the laminations apart because of the welds. I would go
down to the garage and chisel away at them every couple of day, but I
finally gave up. My intended use was a hi current 13.8 V supply

Te KX4OM