[Elecraft] KPA500 on 120 V vs 240 V

[Ron D'Eau Claire]

Steve, I presume you are talking about "all knobs to the right" operation.
In that case, better mains line regulation will hold the HV higher under
load, permitting a little more power. 

However, the KPA500 is rated at 500 watts peak/cw. The KP500 will do that
using either a 120VAC or 240VAC mains supply unless there is an abnormal
amount of "droop" in the mains voltage at 120VAC. That may be a warning of a
possible problem in the circuit - a bad/worn outlet, sub-standard gage wire,
etc., or simply too many other loads on the same circuit. 

73,

Ron AC7AC

-----Original Message-----

I got a new K line from Santa (N1GMR) and built the K3 (loaded) and P3 in 1
day.  Works perfectly.

The KPA500 I had to assemble the next day. ;-)

The amp came from W6 with a 120 V line cord, so, I used that and plugged
into one of the three 20A 120 V circuits I have here in the shack.
Independent breaker.
12 AWG.  The PA made full power easily, ~76 V on the drains.

However, I did notice a bit of ceiling light flicker.  The
color-temp-controlled halogens are on a Lutron dimmer and *any* voltage
delta will show up on these bulbs.

So, I went to Stay On Line and bought their part #4833, a hospital-grade
NEMA 6-15 to IEC60320 cable, 3' long.  Cost was $9.  This plugs into my 240
V outlet.

Now, the same amp at the same drive level puts out a smidgen more peak
power (~30W on the calibrated LP-100; unloaded HV 76.5 V, ~63 V loaded).
And, what is better, no ceiling light flicker, even with my very sensitive
ambient lighting.

If you do the same thing, don't forget to flip the line voltage selector
and change the fuses!!

This story is brought to you by Georg Ohm and Leon Thevenin.  I stand on
the shoulders of giants.

Happy New Year to all.  I will try to be on for SKN.  2011 Elecraft K3
keyed by a 1942 Lionel J-38 operated by a 1961 Jackson Wise Acre, Serial
#1.  Life's good.


Steve KZ1X/4