[Elecraft] K3S Receiver Spurious

[Michael Tope]

Yes, I operate the station remotely, so there is a fair bit of stuff 
attached to the rig including a Windows PC. There probably isn't a good 
intentional bond between the computer chassis and the rig chassis. The 
current setup is "temporary", so I never got around to bonding 
everything to the copper bus bar that I have sitting around waiting to 
be put into service. The plan was to do all that once I finish 
remodeling the inside of the cabin where the station resides. At the 
rate things are going, however, I should probably go ahead and install 
the buss bar. "Temporary" is turning into years. That said, the receive 
spurious seems to be new. I would have noticed it before if it had been 
a longstanding problem.

I did move the Astron RS-35 that powers the K3S off my UPS a few weeks 
ago. There was an issue where UPS output was dropping for no apparent 
reason. It doesn't appear to be the battery which holds the reduced load 
up fine if you pull the plug. I need to troubleshoot that further, but 
for now it seems to be working fine with the reduced load. It is a 
recent configuration change, so it's possible that the spurious is 
somehow related.

73, Mike W4EF................



On 12/3/2023 7:41 PM, David Gilbert wrote:
>
>
> Is your K3S connected to a computer (or some other significant piece 
> of electronics), and if so, are they tightly and closely bonded 
> together chassis wise?
>
> 73,
> Dave   AB7E
>
>
>
> On 12/3/2023 8:11 PM, 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...................
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to w4ef at ca.rr.com