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)
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