Jim,
That is normal. The Transmit RF Gain varies from band to band, and that
will cause the current draw to vary. I am surprised that 12M is so low,
it is normally on a par with 10 meters.
Part of the RF Gain variation is in the base K2 and some more of it is
in the KPA100.
Remember that those are steady state current draws. The dynamic current
such as with SSB operation may peak at greater than what you measured.
Yes, use the LP-100 for calibrating the KPA100 wattmeter. Since the
LP-100 has NIST traceable calibration, I would believe it over the
readings on a calibrated BIRD.
73,
Don W3FPR
On 11/9/2018 5:56 PM, Jim KO5V wrote:
Don and Bob,
The K2 and amp are both powered from the amp's supply.
I used a known good DVM to measure the voltage across R7, and it agrees with
old Beckman. I now think my old kit-built Ten Tec power meter may be badly out
of calibration. I have a dead LP-100 that is on its way back to Larry for
upgrade and calibration, so I'll just wait until it is back to finish
calibrating the KPA's power setting.
Here are what I measured and calculated at the approximate center of each band,
in cw, when the K2's LCD read 100W:
10M: .067V, 13.4A
12M: .049V, 9.8A
15M: .064V, 12.8A
17M: .065V, 13A
20M: .048V, 9.6A
30M: .056V, 11.2A
40M: .052V, 10.4A
60M: .056V, 11.2A
80M: .054V, 10.8A
The current seems to vary significantly between bands, but maybe that's normal?
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