Elecraft

K2 Transmitter Power Issue, K2 s/n 4276

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kc4wvl

K2 Transmitter Power Issue, K2 s/n 4276

K2 s/n 4276
Firmware Revision(s): 2.04P 1.09

Finally had time to open up the rig and check the soldering and check the
placement of the components on the back of the control board.

Still no change. When transmitting, again the power output fluctuates
rapidly and the current draw fluctuates as well.

Help!

73 de KC4WVL
William Smith

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "kc4wvl" <[hidden email]>
Cc: <[hidden email]>
Sent: Tuesday, December 11, 2007 17:01
Subject: Re: [Elecraft] K2 Transmitter Power Issue

> William,
>
> Check the soldering carefully, particularly on the Control Board. Also
> check and re-check the placement of the components mounted on the back
> of the Control Board (they are part of the power control circuits).
>
> Check soldering, then re-check the soldering, and when that is finished,
> check the soldering.
>
> Good luck in finding it.
> 73,
> Don W3FPR
>
> kc4wvl wrote:
> > K2 s/n 4276
> > Firmware Revision(s): 2.04P 1.09
> >
> > I am having a problem with output power stability. Example: Power set to

5 watts. When transmitting (into a dummy load), power out is all over the
place, from as low as .2 watts to as high as 12 watts. This fluctuation is
very rapid. Measured current (at the P/S) fluctuates with the power output
fluctuation.

> >
> > Can anyone give me an indication of any possible cause and solution?
> >
> > Thanks.
> >
> > 73's de KC4WVL
> > William Smith
> >
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> >
> >
> >

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Don Wilhelm-4

Re: K2 Transmitter Power Issue, K2 s/n 4276

William,

Is the DC voltage also fluctuating? If so, your power supply or the
connecting cable may be the cause. Also make certain you have a good
coax between the K2 and the dummy load. If you have the KAT2 or KPA100
installed, check the shield of the input coax to be certain it is not
broken at either the board end or the cable end connector. Are the
crimp pins properly inserted into the housing? The small locking tabs
should be latched into place in the housing and if properly assembled,
you can move the crimp pin slightly in the housing.

If it is not the power supply nor the coax assemblies, then the easy
part of diagnosing your problem is over and it is time to do some real
troubleshooting to determine the source of the fluctuation.
Strip down to the base K2 (remove the KPA100 or KAT2 if these are
installed) and connect the K2 to a dummy load.
Then with an RF Probe in hand and the K2 power level set to 5 watts,
check the RF voltages at each of the points listed starting with the
middle of the 1st column of page 14 in Appendix E of the manual. Find
the first point in this list where the RF voltage fluctuates and let us
know which point that is.

73,
Don W3FPR

kc4wvl wrote:

> K2 s/n 4276
> Firmware Revision(s): 2.04P 1.09
>
> Finally had time to open up the rig and check the soldering and check the
> placement of the components on the back of the control board.
>
> Still no change. When transmitting, again the power output fluctuates
> rapidly and the current draw fluctuates as well.
>
> Help!
>
> 73 de KC4WVL
> William Smith
>
>
> ----- Original Message -----
> From: "Don Wilhelm" <[hidden email]>
> To: "kc4wvl" <[hidden email]>
> Cc: <[hidden email]>
> Sent: Tuesday, December 11, 2007 17:01
> Subject: Re: [Elecraft] K2 Transmitter Power Issue
>
>
>
>> William,
>>
>> Check the soldering carefully, particularly on the Control Board. Also
>> check and re-check the placement of the components mounted on the back
>> of the Control Board (they are part of the power control circuits).
>>
>> Check soldering, then re-check the soldering, and when that is finished,
>> check the soldering.
>>
>> Good luck in finding it.
>> 73,
>> Don W3FPR
>>
>> kc4wvl wrote:
>>
>>> K2 s/n 4276
>>> Firmware Revision(s): 2.04P 1.09
>>>
>>> I am having a problem with output power stability. Example: Power set to
>>>
> 5 watts. When transmitting (into a dummy load), power out is all over the
> place, from as low as .2 watts to as high as 12 watts. This fluctuation is
> very rapid. Measured current (at the P/S) fluctuates with the power output
> fluctuation.
>
>>> Can anyone give me an indication of any possible cause and solution?
>>>
>>> Thanks.
>>>
>>> 73's de KC4WVL
>>> William Smith
>>>
>