K2/100 output power issues

[DL9HDA-2]

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[DL9HDA-2]

Hi, I tried to drive an external linear PA with my K2/100 (no tuners installed) and I have some issues with the output-Power:

I used a DIAMOND SX20C and a 50 ohms dummy-load for my measurements. I also used a Elecraft W2/2K. I think, the 2K-coupler is not the best choice but the tendency is the same.

1. I mesasured at 10.0, 50 and 100W output power at the KPA100 PL-antenna connector:

 3.500    9.5    90    110
 7.000    9.5    95    109
10.100    9.0    78     90
14.000    9.2    75     85
18.068   10.5    70     70
21.000    8.9    60     65
24.890    8.9    60     68
28.000    6.8    59     70


2. I measured at 10.0W output power with switched off KPA100 at the K2 BNC-antenna connector:

 3.500    11.0
 7.000    10.1
10.100    10.1
14.000    10.8
18.068     2.8
21.000     2.8
24.890     5.0
28.000     8.5


So I think there is a Problem with the 17-12m bands at the K2. But I think, there is also somethink wrong with the KPA100. The Output Power at 50W is to high.

Any hints?

Vy 73, Holger - DL9HDA
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[Don Wilhelm-4]

  Holger,

There is the possibility that the wattmeter in the KPA100 is not
properly balanced and calibrated, and deserves to be re-checked.  
Calibrate the wattmeter at 80 watts rather than at 100 watts for best
results.

You can expect some variation in the response of the wattmeter diodes
with frequency, but not as much as you have observed.  Try
re-calibrating first (you must achieve a deep null before attempting
calibration), and then replace the diodes if the band to band variation
is still quite high.  Use a non-metallic tool to adjust C1 for the null.

The measurements you made at the BNC connector are not valid since you
did not completely remove the KPA100.  When the KPA100 is attached, that
BNC connector is still connected to the input of the KPA100 and should
not be used for output in that configuration (that is why a boot is
supplied with the KPA100).

You may want to remove the KPA100 and test the base K2 for maximum power
output on all bands.  If you do not have at least 10 watts of output
from the base K2, you will not drive the KPA100 to a full 100 watts output.

73,
Don W3FPR

On 11/9/2010 7:19 AM, Holger Dörschel wrote:

> Hi, I tried to drive an external linear PA with my K2/100 (no tuners installed) and I have some issues with the output-Power:
>
> I used a DIAMOND SX20C and a 50 ohms dummy-load for my measurements. I also used a Elecraft W2/2K. I think, the 2K-coupler is not the best choice but the tendency is the same.
>
> 1. I mesasured at 10.0, 50 and 100W output power at the KPA100 PL-antenna connector:
>
>   3.500    9.5    90    110
>   7.000    9.5    95    109
> 10.100    9.0    78     90
> 14.000    9.2    75     85
> 18.068   10.5    70     70
> 21.000    8.9    60     65
> 24.890    8.9    60     68
> 28.000    6.8    59     70
>
>
> 2. I measured at 10.0W output power with switched off KPA100 at the K2 BNC-antenna connector:
>
>   3.500    11.0
>   7.000    10.1
> 10.100    10.1
> 14.000    10.8
> 18.068     2.8
> 21.000     2.8
> 24.890     5.0
> 28.000     8.5
>
>
> So I think there is a Problem with the 17-12m bands at the K2. But I think, there is also somethink wrong with the KPA100. The Output Power at 50W is to high.
>
> Any hints?
>
> Vy 73, Holger - DL9HDA
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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