[Elecraft] K2/100, KAT100 strange tuning problem

[Solosko, Robert B (Bob)]

Thanks Don,

	That could be the problem - my Rev D manual says it .033uf. I'll
check it out and see it that cures the problem.

	Thanks again.

Bob 

-----Original Message-----
From: Don Wilhelm [mailto:w3fpr at earthlink.net] 
Sent: Monday, July 16, 2007 12:32 PM
To: Solosko, Robert B (Bob)
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K2/100, KAT100 strange tuning problem

Bob,

Since you do have early updated version of the KPA100 - there is one
thing yet to check, and that is the value of C31.  If it is not a .22 uf
capacitor, it should be changed to the new value.  Elecraft will supply
one if you ask - the part number is E530295.

The capacitor situation was not discovered until after the updated
KPA100s began shipping.  Under certain conditions the updated KPA100
will oscillate near 600 kHz with the lower value capacitor at C31.

I know this is confusing - the older KPA100s had a 40 meter parasitic,
likely caused by RFC10 while the newer version has this other
oscillation problem if the bypass capacitor is not large enough. 
Similar outward behavior, but entirely different causes.

BTW - the changes from 'D to E' were only to clean up the manual.  There
is only a loose link between the manual level and the hardware revision
level.

73,
Don W3FPR

Solosko, Robert B (Bob) wrote:
> Thanks Don... My KPA100 was ordered in December and is Rev D, so it's 
> the version with the 40m parasitic problem fixed (it doesn't have RFC 
> 10 on the antenna connector that the earlier versions did)- I wonder 
> if the change to Rev D didn't quite fix the problem. Rev. E came out 
> shortly after I built my KPA100, but I don't know what changed from D 
> to E. Are there other things that I should check?
>