[Elecraft] K2 Problem

[Don Wilhelm]

Kurt,

You could be correct that rectification in the TR switch in the KPA100 is at
fault, BUT that should not take place under normal conditions.

Check the bias voltage to the TR switch (junction of R11 and R12) if it is
lower than 90 volts, that is your problem - trace it back to the origin.  A
non-functioning Q6 or Q7 could also cause similar problems.

The diodes themselves are likely OK unless they have suffered abuse
resulting from some other problem.

73,
Don W3FPR

> -----Original Message-----
>
> I have discovered a problem with my K2 #3511 which has all the
> latest updates, and has been an excelent radio for the last
> couple of years.  While using the K2 in the contest this weekend,
> and operating from 40  meters and up using my center fed dipole
> that is 250 long fed with 450 ohm ladder line and 4-1 balun on
> all bands, when I run the power control up on the K2 so that the
> radio switches to high power I get intermod at the point of
> transintion form low to high.  I do have the KAT100 tuner in line
> and it tunes well on all bands. I realize that the KAP100 is
> using diode switching in the ant changeover circuit. Is it
> possible that rectifaction is happening with local broadcast
> stations, and why should this start up at this time? is it
> possible that the switching diodes have failed? The intermod is
> enough to take out all but the strongest stations. I can
> eliminate the intermod with an external T- match home brew tuner.
>  Any ideas?
> K0ARO
> Kurt
>