[Elecraft] K3S Receiver Spurious

[Victor Rosenthal 4X6GP]

Is the noise blanker on? It might sound like this if there is repetitive 
noise being blanked by the NB.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/

On 04/12/2023 5:11, Michael Tope wrote:
> Hi All,
> 
> I noticed when operating the ARRL 160 contest this weekend that my K3S 
> has developed a nasty case of what appears to be some sort of LO 
> spurious. When tuning across strong signals, I can now hear a low-level 
> buzz (like phase noise reciprocal mixing) as I tune off them followed by 
> a distinct tone peak 400 Hz off the fundamental frequency (as if there 
> is a discrete spurious at that offset from the carrier frequency). I had 
> noticed that a few days or weeks ago on one signal and dismissed it as 
> being someone with a dirty transmit signal. After tuning across a number 
> of strong signals on 160 and seeing the same phenomenon, it is clear 
> that the problem is coming from my rig.
> 
> I don't know if the problem is showing up on my transmit signal as I 
> haven't received any reports that I have a dirty transmit signal. I just 
> listened to my carrier on a WebSDR and it sounds clean and I don't see 
> any sidebands on the waterfall, so I think it may be confined to receive 
> only.
> 
> So far I have been troubleshooting this remotely over the internet, so I 
> haven't had a chance to twist knobs or look at the hidden menus 
> carefully. Any ideas as to what might be causing this? Is there some 
> problem common to the K3S that manifests itself like this?
> 
> Thanks & 73,
> 
> Mike W4EF...................
> 
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