[Elecraft] K2 Frequency Shift On 80 Metres

[Don Wilhelm]

  Ray,

Before you do anything desperate, try the same thing into a dummy load.  
If it does not happen with the dummy load, you can conclude that it is 
RF getting into the K2 somehow.

Off-center fed antennas are notorious for creating RF in the shack 
unless you take drastic steps to suppress it.  The proper place to do 
that is within the antenna system - maybe adding a balun at a point 
outside the house where the feedline changes from balanced to unbalanced.

73,
Don W3FPR

On 5/2/2011 5:21 PM, Ray Spreadbury wrote:
> Hi Elecrafters
>
> I have recently bought a second-hand K2 with the KSB2 SSB module, the KPA100
> 100 watt amplifier&  the KAT100-1 antenna tuner. Everything appears fine
> running either QRP or 90+ watts on all bands except 80 metres. I am using an
> off centre fed dipole (133') and the KAT100-1 antenna tuner to match.
>
> Running in excess of 10 watts or so on 80 metres however when I switch the
> microphone, the tuning apparently shifts to another frequency on the band.
> The shift may be a few Hz or even a few 100Hz. The receiver is then on that
> new frequency. Reducing power back to a QRP level, the transmitter&
> receiver behave normally.
>
> I guess there's something wrong with the 80 metre sections of the KPA100
> and/or the KAT100-1.
>
> Any clues of what I should check please?
>
> 73
>
> Ray, G3XLG
>
>
>
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