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[RFI] RFI Source

To: "rfi@contesting.com" <rfi@contesting.com>
Subject: [RFI] RFI Source
From: K9MA <k9ma@sdellington.us>
Date: Wed, 8 Feb 2023 10:23:51 -0600
List-post: <mailto:rfi@contesting.com>
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@sdellington.us
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