[RFI] RFI Source

[K9MA]

The broadband noise source with the 1.1 kHz AM audio component turned 
out to be an aquarium heater controller at an immediate neighbor's 
house. It was raising the broadband noise floor on 20m by about 10 dB in 
that direction, which is significant, as I have another strong source in 
that direction, probably line noise. A few ferrite cores on the wires to 
the controller knocked it down below the line noise, though I can still 
see and hear the 1.1 kHz tone. If I can get the other noise source 
fixed, I may have to take further action on this one, but for now it's 
not a problem.

The AM audio tone was a very useful tracking aid. I could hear it on the 
station receiver, but the audio spectrum display of the IC-7610 made it 
very obvious, in real time. What was most interesting was that the audio 
tone appeared over a very wide frequency range, so apparently the 
broadband noise generated by the device was being modulated. When I went 
out with a handheld receiver, I could hear that tone as soon as I got 
near the neighbor's house. Back at the station, it was immediately 
obvious that the offending device had been found when my neighbor 
unplugged the heater. This was by far the easiest RFI tracking I've done 
so far, thanks to the very distinctive nature of the RFI.

73,

Scott K9MA

-- 
Scott  K9MA

k9ma at sdellington.us