this post was submitted on 15 Sep 2025
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I have an Ethernet cable running PoE+ to a wifi access point outside my shack that is very close to my radios. It exhibits the typical QRM pattern, with birdies at regular intervals making a warbling sound when the rig is on SSB.

I've eliminated this problem before using chokes, but this cable is thicker (meant for outdoor use) and much closer, it runs along the same cable runway as my antenna feedlines.

I'm pretty sure the cable isn't shielded. I just bought the cheapest thing I could find on Amazon. I wouldn't trust it if it did say it was shielded. Anyway, would getting a higher category of cable help the issue? Should I try choking the cable at a different point? I did it at the switch end, not the AP end.

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[–] Zachariah@lemmy.world 2 points 1 day ago

UTP (unshielded twisted pair) Ethernet cable is much more common than STP (shielded twisted pair), but you can find it pretty easily, and it is not much more expensive.

[–] shortwavesurfer@lemmy.zip 2 points 1 day ago (1 children)

What category of cable is it? I've heard high numbers like Cat 7 have good shielding.

[–] early_riser@lemmy.radio 2 points 1 day ago (1 children)

Cat6 per the listing on Amazon, but I don't trust it.

[–] cmnybo@discuss.tchncs.de 1 points 1 day ago

Most cat6 is unshielded. Make sure you're using shielded cat6 and shielded connectors. Check it with a multimeter to make sure there is continuity from end to end too.

[–] aubeynarf@lemmynsfw.com 1 points 1 day ago (1 children)

is the power supply or switch some bargain basement stuff? No-name chinese switched power supplies are garbage. I have an LED power supply that generates interference all the way up through 2 m.

for many POE devices, you could inject voltage from a linear power supply onto the wires. Might be an option if the device isn’t too “smart” about it’s POE protocol.

[–] early_riser@lemmy.radio 1 points 1 day ago

Both the switch and the WAP are Ubiquiti, a reputable brand. The AP does not use passive PoE.