[RFI] 80m RFI

[Joseph Bouchard]

Scott,

We had an invisible dog fence with buried perimeter wire. It showed primarily on 80m and spikes were about 10 khz apart.  It was at our house, not the neighbors. 
- turned down the power level, it was set higher than necessary.  
- used snap on chokes on the fence wire, type 31, with about 1/2” ID, wound it about 6 times, then shut and secured with zip ties.
- used an FT240-31 on an extension cord to the squelch the wallwart.
- added additional FT240-31 chokes on coax at feedpoint and entrance
- This brought it down to “barely detectable”. 

A couple months later the fence stopped working.  The “transmitter” which drives the fence wire was dead and the dogs got loose.  I suspect the chokes on the fence wire overloaded and burnt it out. We got a different brand of fence with new dog collars. Choked that on the AC side but not the fence wire, and this one is quiet.

Hope that helps.  Start with the chokes on feedline to antenna.

Joe K1VW

> On Dec 17, 2025, at 12:22 AM, K9MA <k9ma at sdellington.us> wrote:
> 
> A new source has just shown up:
> 
> https://sdellington.us/hr/RFI/25.12.17%200454Z.jpg
> 
> The harmonics are about 8 kHz apart, which is awfully low for a SMPS, though that's what it looks like. I'm only hearing it on 80. It's not coming from my house, but I have many nearby neighbors. It's definitely local. So far, I haven't been able to detect it with a portable receiver, but I need to do some more tracking. Any ideas on what this might be?
> 
> 73,
> Scott K9MA
> 
> --
> Scott  K9MA
> 
> k9ma at sdellington.us
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