30 September 2021:
SFI appeared here suddenly at 1101 UTC, I was already receiving the Desert Whooper for some time.
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I also had a very weak signal just around 4094.1 kHz around 1100 UTC.
Now (1215 UTC) checking the WO7I KiwiSDR in NV, I noticed it is present there, though weak (I could not find it on a bunch of other SW USA KiwiSDRs I tried). This KiwiSDR also has a good signal from SFI.
It's sending a series of dots. Now some sort of ID at 1220 UTC.