--- In ham_amplifiers@..., PA3DUV <pa3duv@...> wrote:
Will,
How does a series regulator for 300 amps look like?
The efficiency from such a regulator seems to questionable, the > >
voltage difference x current is obviously dissipated and turned > >
into heat. ([22 loaded - 16] x 300 = 1800 watt)
The largest one I made and sold was a 200 amp. I designed a 300 and
400 amp but never built one as I never had an order for one over 200
amps. Anyhow, the ones I built used 10 pass transistors connected in
parallel (I forget the part number but they had a TO-3 case), which
had a maximum dissapation rating of 300 watts each, and a 30 amp
current rating running in the safe area at the specified voltage.
These were driven from a variable regulator circuit. They were
mounted on a large heatsink I had made from sheet aluminum bent into
C channels where one was slightly narrower than the other so they
stacked together making the fins. They were stacked up to make a base
about 3/8" thick. I'd have to look at the prints for the other
dmensions like width and length sense it's been a while building one.
Your correct, there's heat generated by the pass transistors as it
works the same as any series pass power supply. As was mentioned by
another, FET's can be used here also. The pass elements I used were
NPN transistors. Each had a 0.1 ohm balancing resistor in series with
each emitter lead.
The charging circuit was switched by using starter solenoids rated at
400 amps each. The RF keyer turned the regulator on then keyed the
amp afterwards so the amp would have power before the RF got to it.
This was done by a simple relay timing. For a ham rig, you can do
this without a RF keyer of course using the keying from the rig like
on running an external amp. The problem of the switching here though
creates a slight delay after the mic is keyed before you can
broadcast of about 1/2 to 1 second due to the speed of the starter
solenoids and relays. The regulator has to come on and supply the
amps source voltage before the amps RF relay closes. So the regulator
keys the amps RF relay.
The regulator box and batteries were mounted in the trunk or in the
back of a Bronco, Suburban, or van. The remote that mounted under the
dash had an on/off switch, volt meter, and voltage adjustment pot on
it.
Best,
Will
