[RFI] Not your typical invisible fence RFI

[Jim McDonald]

I haven't used our Invisible Fence system for several years, but it did generate RFI.  I easily stopped it with a Corcom AC line filter.

73,  Jim N7US

-----Original Message-----
From: RFI <rfi-bounces+jim=n7us.net at contesting.com> On Behalf Of Don Kirk
Sent: Sunday, January 23, 2022 09:23
To: RFI <rfi at contesting.com>
Subject: [RFI] Not your typical invisible fence RFI

I just uploaded a video onto YouTube that documents wideband RFI on 20 meters that I tracked down to my neighbors invisible fence transmitter, and it's not the typical approximate 7 or 10 KHz interval RFI encountered with inground invisible fences.  The RFI which is at least 150 KHz wide at my house moves around based on outdoor temperature and on warmer winter days it drops down to slightly below the 20 meter band.

I was hoping the problem was with the wall-wart power supply feeding the transmitter but it was not.  The transmitter has battery backup and the RFI is still present with the wall wart unplugged, and we also tried a linear lab grade power supply in place of the 19.0 Vdc 1 amp wall wart with no noticeable difference in the level of RFI at my house.

Unfortunately the transmitter is not part of a DIY system so the manufacturer (Radio Systems Corporation) requires that we deal with the local "Invisible Fence" Dealer which is our next step.

An interesting note is that when I first tracked the RFI down to my neighbors home I wound up near the main circuit breaker box.  We then tried sniffing the circuit breakers with a very small loop to see what circuit in the house the RFI was originating (assuming the RFI was being conducted on house wiring) and this technique typically works great.  We did not detect the RFI on 20 meters on any of the circuit breakers which was interesting because the RFI was strong near the main circuit breaker box.  It turned out that the invisible fence transmitter is just a few feet away from the main circuit breaker box which explained why the signal was strong near the main circuit breaker box.

For those interesting here is a link to the video documenting the RFI:
https://youtu.be/rHABjR0GZWg

P.S. I have great neighbors that are wonderful to work with on RFI issues.

73,
Don (wd8dsb)