[RFI] New RFI Source

[K9MA]

The carriers within that main lobe appear to be 120 Hz apart, so likely 
line related. They seem to vary in amplitude, but are very stable in 
frequency.

73,
Scott K9MA


On 7/31/2024 4:28 PM, Michael Carter wrote:
> Hi Scott,
>
> The sidebands are not typical of any SMPS I've
> looked at spectrally.  The fine spectral structure
> inside the main lobe suggest 60 Hz or 120 Hz
> modulation of the nominal 'carrier', but the
> sideband spacing of ~ 1 kHz from the main lobe
> is odd.
>
> What do you see when you zoom into the
> main lobe?  Can you guesstimate the
> spacing of the strongest sidelobes
> within that lump?
>
> 73,
> Mike, K8CN
> ------------------------------------------------------------------------
> *From:* RFI <rfi-bounces+mike.carter=unh.edu at contesting.com> on behalf 
> of K9MA <k9ma at sdellington.us>
> *Sent:* Wednesday, July 31, 2024 5:08 PM
> *To:* rfi at contesting.com <rfi at contesting.com>
> *Subject:* [RFI] New RFI Source
> CAUTION: This email originated from outside of the University System. 
> Do not click links or open attachments unless you recognize the sender 
> and know the content is safe.
>
>
> This RFI source has appeared recently:
>
> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsdellington.us%2Fhr%2FRFI%2F24.07.31.png&data=05%7C02%7Cmike.carter%40unh.edu%7C5b47864c626340c4b55208dcb1a4e911%7Cd6241893512d46dc8d2bbe47e25f5666%7C0%7C0%7C638580569052206306%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=I3QbXdcat4zw3df8oU7lalFjpj9VCt3Qcf%2FvhKK3Hfs%3D&reserved=0 
> <https://sdellington.us/hr/RFI/24.07.31.png>
>
> It appears to be harmonics of about 78 kHz. However, unlike most SMPS
> RFI, it is very stable. It disappears at night, suggesting a solar
> system, but it persists, weakly, an hour or so after sunset. Maybe a
> solar system comm link, with a supercapacitor? However, I'm not aware of
> any new solar systems nearby.  Anyone seen anything like this before?
>
> Needless to say, I'll be out tracking it soon.
>
> 73,
>
> --
> Scott  K9MA
>
> k9ma at sdellington.us
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> <http://lists.contesting.com/mailman/listinfo/rfi>


-- 
Scott  K9MA

k9ma at sdellington.us