[Elecraft] Re: K2 Rev B problems and solutions

[Wayne Burdick]

Hi Gus,


augie.hansen@comcast.net wrote:

> This note is primarily directed to K2 builders who bought an early K2, but
> didn't build it....
>
> NO SIDETONE. ...tap DISPLAY to force the rig to get it's sidetone from the
> correct source (U8, pin 4 instead of U6, pin 25)...
> 
> Recommended action: This information is currently not in the manual...

The first step on page 11 of the K2 Rev A to Rev B Instructions says:

     Test your sidetone using the ST L menu entry. If the sidetone is 
     missing, EDIT the ST L parameter, then tap DISPLAY to change the 
     sidetone source. The default is U8-4, compatible with the Control board 
     modifications required for the KPA100 and KIO2. If you have never 
     installed a KIO2 or KPA100, the source should be set to U6-25.

Perhaps you had a very early version of these instructions in which this step
was missing. Or, if the step is there but you didn't see it, please let me know
if there's some way we can improve the document to assure that others will. 


> ...while tuning any signal, there was a chirp or warbling with every
> frequency step as the main tuning dial was turned....
> 
> Finally, I found that RFC15/C91 "mod" to the RF board...
> was the culprit. I removed the two parts and put in a jumper to bridge the
> trace that had been cut between U4, pin 16 and the nearby circuit trace. Voila! The receiver
> warble was gone and the transmitted CW signal was perfect.

This is the first such occurence of such a problem due to RFC15/C91 that I've
heard of. We'll keep an eye on this.

Also, please verify that R19, which you may have added in conjunction with PLL
reference oscillator modifications, is 2.7 k, not 220 ohms. We mistakenly
shipped 220 ohms with some of the very first Rev A to Rev B mod kits.


Thanks for keeping us informed of your modification efforts. I hope the K2 works
well for you.

73,
Wayne
N6KR