I want to power my FET amp(200W) from a mobile power supply. Amp
requires
50VDC. It occured to me that car stereo amps use DC to DC converters
that
would produce the voltages and currents that I need. Would like
information
on where I could get parts/information to roll my own. I am
particularily
intersted in the transformer design and where I could get one already
made.
This doesnt seem to be something one can get easily as a replacement
part.



With those power levels you're probably dealing with custom magnetics.
There's a switcher in the '04 handbook with the right power level, I'd
consider basing your magnetics on that, or at least use the stacked
E-core idea.

Barring that you could try to get your hands on someone's surplus car
stereo equipment, and harvest the power supply section from that. You
may also want to shop the surplus suppliers for DC-DC converters. 48V
is a common telco voltage, there ought to be bricks (or combinations of
them) that would step you up from 12V nicely.
=====================================
A solution could be using an off the shelf 12V-DC to 115V or 230V -AC
inverter with an AC to 48V-DC (surplus) power supply unit from the telco
industry . Perhaps not so elegant and a bit bulky ,but readily available.
The AC to 50V-DC power supply unit can also be readily homebrewed with
standard components .With 115 V-AC input , a surplus 2:1 step down
transformer available from the surplus trade would do the trick.
BTW some time ago at a flea market I bought a 230V to 50V-15Amperes
transformer for equiv. US$ 0.50............yes it is a heavy beast , !
Perhaps that's why it was available for 50 cents.

Although at a much lower power level ,this is the usual way providing power
to a laptop computer in a motor vehicle.

Frank GM0CSZ / KN6WH