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K2/100 pwr out control problem

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RobertG

K2/100 pwr out control problem

I'm running a K2/100 Ser# 5957, operational for about three years. Just
now, control of pwr out has become intermittant. I can control pwr out
in the basic K2 thru the range 0 -13w. Anything over that and the K2
meter sticks at about 13w, but the amp output jumps immediately and
somewhat randomly to between 50-100w with no "smooth" control.
Decreasing the K2 pwr out below 10w or so, and the overall pwr out drops
accordingly, the K2 meter reads "correctly," and the total unit pwr out
(external meter) agrees with the K2 meter. I've tried cycling on/off,
different bands, different modes. All the same. Any suggestions most
welcome.

...robert

--
Robert G. Strickland, PhD, ABPH - KE2WY
[hidden email]
Syracuse, New York, USA
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Ken Alexander-2

Re: K2/100 pwr out control problem

Hi Robert,

What happens if you try that into a dummy load instead of your antenna? How's your SWR?

73 - Ken

--- On Fri, 4/22/11, Robert G. Strickland <[hidden email]> wrote:

> From: Robert G. Strickland <[hidden email]>
> Subject: [Elecraft] K2/100 pwr out control problem
> To: "Elecraft" <[hidden email]>
> Date: Friday, April 22, 2011, 10:46 AM
> I'm running a K2/100 Ser# 5957,
> operational for about three years. Just
> now, control of pwr out has become intermittant. I can
> control pwr out
> in the basic K2 thru the range 0 -13w. Anything over that
> and the K2
> meter sticks at about 13w, but the amp output jumps
> immediately and
> somewhat randomly to between 50-100w with no "smooth"
> control.
> Decreasing the K2 pwr out below 10w or so, and the overall
> pwr out drops
> accordingly, the K2 meter reads "correctly," and the total
> unit pwr out
> (external meter) agrees with the K2 meter. I've tried
> cycling on/off,
> different bands, different modes. All the same. Any
> suggestions most
> welcome.
>
> ...robert
>
> --
> Robert G. Strickland, PhD, ABPH - KE2WY
> [hidden email]
> Syracuse, New York, USA
> ______________________________________________________________
> 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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Don Wilhelm-4

Re: K2/100 pwr out control problem

In reply to this post by RobertG

Robert,

Make the following setup and check into a dummy load with an external
wattmeter between the K2 and the dummy load. Please follow the testing
method given, there is a reason for that test methodology.
1) Remove the APP power cord from the KPA100 and power the K2 only from
the coaxial power jack on the lower rear panel. Set the K2 to 40 meters.
2) Set the power requested knob to 5 watts and press TUNE - what is the
power on the external meter?
3) Set the power to 2 watts and again press TUNE - what is the power on
the external meter?

If the actual power was 10 watts or more in both cases above, change
diodes D16 and D17 in the KPA100.
If the actual power tracked the requested power, then you have a
different problem - power the KPA100 from the APP power cable and try
again into a dummy load (not an antenna). Set the power requested to 50
watts and do a TUNE - the actual power should be near 20 watts. If it
goes to a large value, then we need to investigate your KPA100 - remove
it from the base K2 and take the shield off, and let us know the status
of your results.

73,
Don W3FPR

On 4/22/2011 10:46 AM, Robert G. Strickland wrote:

> I'm running a K2/100 Ser# 5957, operational for about three years. Just
> now, control of pwr out has become intermittant. I can control pwr out
> in the basic K2 thru the range 0 -13w. Anything over that and the K2
> meter sticks at about 13w, but the amp output jumps immediately and
> somewhat randomly to between 50-100w with no "smooth" control.
> Decreasing the K2 pwr out below 10w or so, and the overall pwr out drops
> accordingly, the K2 meter reads "correctly," and the total unit pwr out
> (external meter) agrees with the K2 meter. I've tried cycling on/off,
> different bands, different modes. All the same. Any suggestions most
> welcome.
>
> ...robert
>