On May 26, 2005, at 12:33 PM, Vic Rosenthal wrote:
I don't know the actual power requirements, Jim, but I would expect
overall efficiency of around 50%, taking into account the power
supply and amplifier efficiency. However, if you are installing
ANY high power amplifier, it's generally thought that a 20-amp 240V
circuit is appropriate.
15-amp service is probably sufficient.
This is probably more than you will need for a KPA800, which
would probably work fine with 15 or perhaps even 10 amp service at
240V, but (depending on the length of the line to your service
entrance) it probably means no. 12 wire, which is not a big deal.
An electrician can tell you what you need to do to meet code in
terms of wire size, type of conduit, type of receptacles, etc.
NEC requires 12-2 for a 20 amp circuit, 14-2 for a 15 amp circuit.
What I did was install 20 amp breakers and use no. 10 wire to
ensure the minimum voltage drop under load. I brought out 4
wires: two hots, one neutral, and one ground.
Why would you need a neutral? On a 240v circuit, there's only three
connections - both hot sides and ground.
The neutral is ONLY connected to the ground at the service
entrance, noplace else. Most amplifiers only need the two hot
leads and ground (there are exceptions). I use the hot-to-neutral
connections to provide two 120v circuits for other shack equipment.
I would not do this. I would run a single 240 volt circuit for the
amp. If you need other circuits, you can run a separate 120 volt runs
for them. You really shouldn't have offset neutral runs away from the
panel like that. I'm pretty sure that's not to code. (Consider what
would happen if the neutral line from the panel to your 120v circuits
should open in that case)
In my current basement shack (which I wired myself), I have two
separate 120v (14-2) circuits feeding a total of 10 outlets (with
GFI), a separate 240v (14-2) circuit for the (future) amp, and a
forth circuit that feeds the lighting (which is shared with another
room). (Its generally good practice to run lighting and outlet
circuits separately)
I would not run a 1KW amp on a 120v line if I could avoid it, due
to the greater voltage drop that would be incurred. I understand
that the KPA800 is capable of 1000w or more output on CW (it's
limited to 800w on SSB due to increased IMD at higher power levels).
Agreed. A 15-amp 240v circuit should do it, or you can go to 20-amps.
(It is sometimes easier to find a 20-amp dual-gang breaker than a 15-
amp. Size the breaker according to the wiring used)
Bill Coleman, AA4LR, PP-ASEL Mail: [EMAIL PROTECTED]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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