[Elecraft] Mysterious K3 Symptoms - RFI?

[Bayard Coolidge, N1HO]

 Although I don't have an amp, and ran my K3 barefoot, and run my K4D barefoot as well, I do have a 100 foot CAT5E cable running into the shack from the other end of the house, through the attic (there being no basement here in south Florida!). Initially, I was seeing a fair amount of noise from it, and was able to quench it by winding a couple of turns around a small clamp-on choke.
That doesn't seem to affect the network performance, so I can reliably run it at 400MBit/second, and it seems to clean up whatever other noise it's picking up from nearby homes (most are on small lots of about 1/5 acre) and the condominium complex next door. I still have some strange noise from other sources coming in from the antenna, and the HVAC's air handler is very noisy, particularly on 30m through 15m, but I know it's not the twisted-pair Ethernet line. My CAT5E cable plugs into a small AC-powered router, and feeds my Mac, the K4D, as well as a laptop occasionally.
HTH, and 73,
Brandy, N1HO (EL96xh)

    On Wednesday, March 13, 2024 at 10:22:02 AM EDT, Pete Smith N4ZR <pete.n4zr at gmail.com> wrote:  
 

One culprit I can think of is a 100-foot Ethernet cable between my 
station and my FIOS router.  I have bought a shielded replacement but 
have not yet installed it.  After reading some of the recent commentary 
about so-called "shielded" cables, I'm wondering if this is worth doing.

Any suggestions, either K-3-specific or more general, would be much 
appreciated.