On Wed, 2006-09-27 at 10:33 -0700, Dick - KC9GSM wrote:
> Dr. Johnson,
>
> Someone mentioned that maybe it would be better to
> locate the power supply at the electrical panel and
> run "High Voltage" lines to the rig. First off, I
> believe that it would not be high voltage that they
> are running but rather 13.8VDC or whatever DC supply
> is needed for the amp, and secondly, if I am not
> mistaken, the loss would be greater over a given
> resistance for the DC at a given wattage because of
> the increased current. Is that not correct?
>
> 73's,
>
> Dick - KC9GSM
>
>
Getting 13.8 volts over a 50' path at enough current to run a solid
state KW PA would be tough. To keep the voltage drop to 0.2 volts at 100
amps would take a wire resistance under 0.002 ohms. For 100' of circuit
that would demand three conductors 1000 MCM cable in parallel for feed
and return. Each 1000 MCM cable is 1.151" diameter plus insulation. They
would be a lot harder to run than 4 10s or 12s for a sturdy 120/240 feed
to ham shack and 240 volt PA.
I think the PA was tube type and so the voltage would have been more
like 1 to 2 KV and the current only an amp.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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