Re: [RFI] RFI Signature

[K9MA <k9ma@sdellington.us>]

I've seen a couple cases of RFI that looked like random noise. However, 
in AM mode, the audio showed distinct frequencies, in one case around 2 
kHz, another harmonics of 120 Hz. The former was a battery charger, the 
latter a fish tank heater controller.
Yours sounds more like the battery charger, which did have various 
levels depending on the state of charge of the battery.
73,
Scott K9MA

On 11/23/2025 1:10 PM, Jeff (W4DD) wrote:
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> 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.
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> 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
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> Has anyone seen 4 levels of noise from a device before?
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> Thanks for any ideas.
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> Jeff, W4DD
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--
Scott  K9MA

k9ma@sdellington.us
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