Well done, and thanks for the redux on it as well!!!
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 2/8/23 08:23, K9MA wrote:
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
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