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@contesting.com> on behalf of K9MA
<k9ma@sdellington.us>
Sent: Wednesday, July 31, 2024 5:08 PM
To: rfi@contesting.com <rfi@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@sdellington.us
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