Hi Jeff,
I know you said the neighbor is not interested in doing a circuit breaker
test but I assume you mean turning off one circuit breaker at a time until
the RFI goes away. I now try and avoid turning off a circuit breaker at a
time if at all possible. My first step which is often very successful is
to sniff the circuit breakers one at a time with a 1 inch diameter loop
connected to a receiver with a good signal strength indicator (normally my
laptop based SDR receiver but sometimes just my shortwave receiver) and
sometimes I have an external preamp in line. Sometimes it’s very obvious
which breaker is feeding the device causing RFI but other times I only see
a 6dB difference between the guilty circuit and other breakers in the panel
but with careful observation I’m normally very successful using this method.
Here is a link to a video showing how I sniff the circuit breakers in case
you’ve not seen my method before and in this particular case it was very
obvious. A few weeks ago I had another case which was not as obvious but I
still successfully identified the correct circuit by just sniffing the
breakers.
https://youtu.be/vDB8rAwVt5Y
Just FYI,
Don wd8dsb
On Sun, Nov 23, 2025 at 2:20 PM Jeff (W4DD) <w4dd09@gmail.com> wrote:
>
>
>
>
> I am working on a RFI case that we believe is coming from a nearby home.
> The owner is a little cooperative, but is not interested in doing a ckt
> breaker test. The noise exhibits some interesting characteristics that may
> help us in suggesting he unplug a device. Perhaps someone has seen this
> before.
>
>
>
>
>
> 1. On the pan adapter, looks like power line noise. Random dots
> across
> the screen.
> 2. No repeating clusters of noise vs frequency that might suggest a
> SMPS.
> 3. No correlation to sunlight or darkness. No correlation to time of
> day.
> 4. Has distinct levels of interference; we have noted -85dBm, -78dBm,
> -72dBm (S-9), -66dBm. Interesting the levels are about 6dB apart. -78 and
> -72 are most common.
> 5. The neighbor has a solar system installed roughly 2 years ago, but
> as mentioned, no correlation to sunlight/darkness or time of day.
> 6. Affects mostly 80M but can be heard on other bands
>
>
>
> Has anyone seen 4 levels of noise from a device before?
>
>
>
> Thanks for any ideas.
>
>
>
>
>
> Jeff, W4DD
>
>
>
>
>
>
>
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>
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