[Elecraft] KPA500 AC power

[Jim Brown]

On 12/12/2018 4:44 PM, Jack Brindle via Elecraft wrote:
> Noting that the current is double for 110V, the heat losses in the power line will actually be quadrupled.
>
> If you have #12 wire in your walls (the current NEC code), and use the supplied power cord, things should be just fine.

That can depend on how long the run is from the power panel to the 
outlet. For CQP and 7QP expeditions, we run KPA500s on 120V, and have 
had issues with under-voltage faults caused by too much IR drop combined 
with regulation issues with the generator.

At home, I run my KPA500 on 240V, because I had 240 brought to the shack 
before I moved in. Since the power supply is unregulated, an advantage 
of running on 240V is slightly less voltage drop when the radio is keyed.

BTW, IR drop and the associated power lost in wiring feeding electronic 
loads is significantly greater than predicted by Ohm's law for a sine 
wave because the current drawn by power supplies is not a sine wave -- 
current is drawn at the peaks of each half of the AC cycle to recharge 
the input filter capacitor.

73, Jim K9YC