[Elecraft] K2- broadband reception on 60 m

[Don Wilhelm]

Hans,

That is very strange for such a condition to be present on only one 
band.  Are you certain it is not also present on 20, 17 and 15 meters?  
If so, that would indicate a problem with the BFO for Upper Sideband.  
The USB BFO is at a higher frequency than the other BFO settings, and it 
may be that the BFO signal is weak at the Product Detector when you 
first turn the K2 on, and it corrects itself after a bit of warmup.

Other than that, I cannot think of any reason for that behavior.

By process of elimination for specific problem areas:
1) You say the signals are loud - that rules out the bandpass and low 
pass filter areas.  The only thing the K60XV does to the bandpass filter 
is to add the capacitors necessary to tune to 60 meters - and that is 
done through relay contacts.  If that relay or the capacitors were a 
problem, the signals would not be loud, but attenuated.
2) It does not happen on any other band - that rules out the BFO and the 
USB filters (even though I suggested it above).  The BFO is not band 
dependent.
3) No other circuits in the K2 should cause the symptoms that you refer to.

I would suggest that the problem could be in your 60 meter antenna 
system.  Loose connections with some oxidation that could be acting like 
diodes which rectify a broad spectrum of RF.  If you transmit, that 
connection can be "healed" temporarily allowing normal reception.  
Loosen all your antenna connections and reseat them. Tighten any PL-259 
connectors tighter than finger tight (use pliers to snug them up a bit 
after tightening).

Sorry, but I don't have any other suggestions.

73,
Don W3FPR


On 1/7/2016 4:43 PM, Hans Bonnesen wrote:
> My K2  (# 7359) has been operating flawlessly SSB on all bands since dec 2013.
>
> Suddenly for unknown reasons reception on 5343 kHz Upper Sideband seems to act very strange.
>
> On 60 meters and on this band only signals are coming in very loudly but seem
>
> to be intermixed and dispersed over several kilohertz without any chance of hitting a proper normal SSB readability.
>
> The receiver acts like a wide open broadband receiver, but strangely enough after app 10 minutes it starts slowly to act normally,
>
> and commence to be tuneable.
>
> Where to look ?
>
>