Re: HF noise.
I use 2 loops at 90 Degrees and can switch between them which covers the directivity nulls quite well and is great for all band low noise RX.
BUT when I split the RX/TX on my IC7300, easily done via available mod kits using plugs just inside the cover, I found the TX side ALC and SWR indication of the IC7300 is sensitive to RF coming in on the separate receive socket giving incorrect SWR readings and TX instability.
I measured the RF coming in from the active antenna and it was in the volts range with about 25 Watt TX on the doublet TX antenna so put back to standard and having a re think on antenna separation and switching out the active antenna.
Not sure how that is handled in the transceiver normally but is a big problem with a separate loop.
Pete
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