[Elecraft] K2 Problem

[Don Wilhelm]

Brett,

Rather than looking for similarities, you may want to look for potential
ground loop sources.  Those ground loops are really 'sneaky' and can cause
strange effects.  Locating the real source can be a grand problem in itself
because there are so many possible 'sneak' paths.  I wish you luck and good
troubleshooting.

One 'help' I can offer -- see what happens when transmitting into a dummy
load -- that will eliminate the possibility that RF-in-the-shack could be
the root of your problems.

Sorry, but there are no 'simple' answers.

73,
Don W3FPR

> -----Original Message-----
>
> W3FPR replied to K0ARO, who noticed nasties on transmit when
> K2 switches to KPA100:
>
> >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.
>
> What perfect timing - I put my K2 into service after about a year
> & it does same thing, as well as now making other undesirable
> noises when I plug in SO2R mic switching system that is same
> as when K2 was last used - right down to the cable that plugs
> into the radio itself or the radio the K2 was to replace.
>
> Hopefully some similarities here - cheers!
>
> 73, VR2BrettGraham
>