[RFI] 80m RFI with QSB

K9MA k9ma at sdellington.us
Fri Dec 12 00:45:21 EST 2025


This seems very strange: At 0520Z Dec. 12, I'm hearing harmonics of 39 
kHz from 3507 up. They're drifting around a lot, like SMPS harmonics, 
and are 2-3 kHz wide. But they have QSB, so they're almost certainly not 
local. The seem to be coming from the NE or SW from EN53. They are 
completely absent in the daytime. They peak at about S7 on the shunt fed 
tower at 350 Hz bandwidth. In AM mode, there appear to be harmonics of 
120 Hz, so the source is likely in NA. (Besides, they are way too strong 
to be coming from EU.) The QSB seems to be somewhat periodic, with 
cycles of 7-16 seconds, so I suppose it could be something local that 
just mimics quasi-periodic QSB. When I watch several harmonics at once, 
they peak and fade together, with no sign of selective fading.

Is anyone else hearing anything like this?

73,
Scott K9MA

-- 
Scott  K9MA

k9ma at sdellington.us


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