A broadband contest antenna for 80m
Origins & Refinement of the Contest Knob – I

Strange 20m RFI

This morning I noticed a very strange new RFI source on 20m. The signal repeats every 25 KHz across the band (above and below as well) and drift slowly lower in frequency over time.

From my location it peaks towards the North – I listened to one QSO where it was clear the folks on the frequency could hear the signal as well so it's not a local source of RFI.

I've uploaded a WAV file of the signal - click to listen.

You can hear a distinct chirp at the start of each transmission as though this was an oscillator being keyed by turning the power on and off. There are three distinct frequencies that repeat – you can see them in the following waterfall I captured from the Flex 5000.

This is one of the strangest RFI sources I've seen in quite a while… it's a ways away from Woodside I suspect so I'll probably never know what it was…


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