[Elecraft] K2/100, KAT100 strange tuning problem

[Don Wilhelm]

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?
>