[RFI] RFI Source

[Dave (NK7Z)]

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
>