K2 low power out on 20 meters

[Wiley Kling]

  I am building my 3rd Elecraft K series kit, this time a K2, my second.
All has gone well.  I am on page 80 of the manual, right column, 3rd step,
"adjust C21 and C23 for maximum power output".  Adjusting C21 does
absolutely nothing.  Regardless of a very slow 360 degree rotation, power
out does not change, does not peak.  C23 works normally and peaked as it
should.  I continued with all of the other steps, peaking the power on all
of the other bands.  Here are some facts:

 

1. Into a 50 ohm dummy load with a power meter, K2 power setting of 12
watts,  power out reads as follows: 80M = 12W; 40M = 12W; 30M = 10W; 20M =
2W; 17M = 11W; 15M = 11W; 12M = 11W; 10M = 8W.  All appears fine to me
except 20 meters.
2. I have checked for cold solder joints, etc. especially around C21,
C23, C19, C20, L8.
3. The receiver "hears" very well on 20 meters.
4. Everything else about the radio seems just fine.

 

     I conclude that C21 is defective.  Before I ask for a part replacement
is there anything else I should do or check?  I thank you in advance for
your suggestions and help.

 

Wiley, KG4UPO

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[Don Wilhelm-4]

Wiley,

I trust you are peaking the bandpass filters at the 1.5 to 2 watt level
rather than at 12 watts.  If you are trying at 12 watts, you may not see
the peak because the power is already near the maximum.

Check the values of C19, C20, C28 and C22.  If those are all correct and
well soldered, then the conclusion is that C21 is defective.

If you find anything other than a C21 problem, you will have to re-peak
30 meters before peaking on 20.

73,
Don W3FPR

On 2/25/2013 8:57 AM, Wiley Kling wrote:

>    I am building my 3rd Elecraft K series kit, this time a K2, my second.
> All has gone well.  I am on page 80 of the manual, right column, 3rd step,
> "adjust C21 and C23 for maximum power output".  Adjusting C21 does
> absolutely nothing.  Regardless of a very slow 360 degree rotation, power
> out does not change, does not peak.  C23 works normally and peaked as it
> should.  I continued with all of the other steps, peaking the power on all
> of the other bands.  Here are some facts:
>
>  
>
>

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[Wiley Kling]

     The K2 'low power on 20 meters' problem has been resolved by the replacement of the C21 cap.  Elecraft customer service is beyond compare. Thank you.  Wiley, KG4UPO