[Elecraft] K2: KPA100 fan issue + current question

[Don Wilhelm]

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?
>
>