Listening to the attached files (several emails previous), it sure sounds
like powerline discharges.
SUGGESTION: With an o'scope or using the waterfall of a modern receiver,
verify that the repetition rate is either 16.7 ms (60 Hz) or 8.3 ms (120
Hz). That would clinch the powerline discharge "theory". But it sure
sounds like RFI from the power grid to me!
It could still be a solar installation which ultimately will output at 60
Hz (in the US). Also, be aware that around Christmas time, all kinds of
RFI slithers out of storage in the form of Christmas decorations and
lighting.
Once that is verified, grab your battery portable radio, tune it to the
worst of the RFI and first walk your own home. Then take it on a walk
around your neighborhood.
Dave - WØLEV
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On Tue, Nov 25, 2025 at 6:12 PM Jeff (W4DD) <w4dd09@gmail.com> wrote:
> I set the BW to 20KHz and made another recording.
>
> Also uploaded the full 80M spectrum, 3500 to 4000. Some slight banding is
> visible, -79 lvl @6KHz.
>
> Also uploaded a jpg for the -73 level @ 6KHz.
>
>
>
> Seems to have 4 running levels. The 4 levels I have noticed always seem
> to be -85, -79, -73, -67 +/- 1dB (measured at 6KHz BW).
>
>
>
> As several have noted, strong 60Hz component but not much at 120 or 240Hz.
>
>
>
> Has a slight rhythm to it, not PLN.
>
>
>
> I happened to see it switch levels again, this time staying at the new
> level a little longer, for 15 seconds.
>
>
>
> I will forward the accumulation of facts plus an audio clip to the ham for
> forwarding to the neighbor (in a nice email). If someone thinks of
> something else to check, let me know.
>
>
>
> Thanks for the ideas.
>
>
>
> From: Don Kirk <wd8dsb@gmail.com>
> Sent: Monday, November 24, 2025 9:46 PM
> To: Jeff (W4DD) <w4dd09@gmail.com>
> Cc: rfi@contesting.com
> Subject: Re: [RFI] RFI Signature
>
>
>
> Hi Jeff,
>
>
>
> What was the bandwidth setting for the audio clip? Looking at the audio
> it has heavy 60 Hz content (not 120 Hz). It has an overall repeating
> pattern at a frequency of 60 Hz. When dealing with power line noise I
> typically see spikes at a frequency of 120 Hz (arcing at least once time
> during each half cycle of the sine wave). I know some power line arcing
> can happen during just one half of the sinewave but I've never encountered
> that situation. If the bandwidth of your AM audio recording was less than
> 20 KHz, can you post another audio clip using a bandwidth of at least 20
> KHz (I prefer 25 KHz)?
>
>
>
> Thanks,
>
> Don wd8dsb
>
>
>
> On Mon, Nov 24, 2025 at 8:46 PM Jeff (W4DD) <w4dd09@gmail.com <mailto:
> w4dd09@gmail.com> > wrote:
>
>
>
> I posted some additional pictures of the noise and an audio clip to the
> link
> below.
>
>
>
>
>
>
>
> From: Jeff (W4DD) <w4dd09@gmail.com <mailto:w4dd09@gmail.com> >
> Sent: Monday, November 24, 2025 11:17 AM
> To: 'rfi@contesting.com <mailto:rfi@contesting.com> ' <rfi@contesting.com
> <mailto:rfi@contesting.com> >
> Subject: FW: [RFI] RFI Signature
>
>
>
>
>
>
>
> Thanks to all that replied. Some interesting thoughts to consider. I had
> a
> couple of Laughs also since several experts mentioned things I had been
> thinking. I had pulled out a lawn tool battery charger (K9MA) and
> experimented with that. It did produce a similar spectrum display, but I
> still can't account for why the source would be mostly at power level 2 or
> 3. Seems like the battery would eventually be charge and it would drop to
> level 4, which we seldom see. My battery was fully charged and the noise
> level was very low.
>
>
>
> A demand driven device (K8CN), seems logical. It is not related to wx and
> does not change based on outdoor temperature so likely not HVAC. POE is an
> interesting idea I had not considered.
>
>
>
> A ckt brkr based sniffer (WD8DSB). I actually built one of those (thanks
> Don). Unfortunately, the neighbor is resistant to anyone entering the
> home.
> This is also a remote assist, so I don't get to actually visit the site.
>
>
>
>
>
>
>
> For those that asked, here is a waterfall capture. Noise at the -71/-72
> level (level 2 of 4 levels).
>
> Antenna is a multiband vertical, tuned to 3540KHz.
>
>
>
>
>
>
> https://drive.google.com/drive/folders/1jYH07St1bSd0-Coqhl76HhraKbdYX2e-?usp
> <
> https://drive.google.com/drive/folders/1jYH07St1bSd0-Coqhl76HhraKbdYX2e-?usp=drive_link>
>
> =drive_link
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> _____
>
> From: RFI < <mailto:rfi-bounces+mike.carter <mailto:
> rfi-bounces%2Bmike.carter> =unh.edu@contesting.com <mailto:
> unh.edu@contesting.com> >
> rfi-bounces+mike.carter=unh.edu@contesting.com <mailto:
> unh.edu@contesting.com> > on behalf of Jeff (W4DD) <
> <mailto:w4dd09@gmail.com <mailto:w4dd09@gmail.com> > w4dd09@gmail.com
> <mailto:w4dd09@gmail.com> >
> Sent: Sunday, November 23, 2025 2:10 PM
> To: <mailto:rfi@contesting.com <mailto:rfi@contesting.com> >
> rfi@contesting.com <mailto:rfi@contesting.com> <
> <mailto:rfi@contesting.com <mailto:rfi@contesting.com> >
> rfi@contesting.com <mailto:rfi@contesting.com> >
> Subject: [RFI] RFI Signature
>
>
>
> [You don't often get email from <mailto:w4dd09@gmail.com <mailto:
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> Learn why this is important at
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> content is safe.
>
>
> 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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--
*Dave - WØLEV*
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