Connecting a balanced antenna like a ZS6BKW to a coax feedline can cause serious problems be means of a high noise levell, for the cabinet of the transceiver is connected to the antenna. This means that all nearby QRM is transported to the trx by the coax schield. A galvanic isolator helps reducing this noise. 11 turns of side by side 1.2 mm magnet wire on a FT140-61 or 4C65 toroid formes the coupler. The coupler is placed at the low-Z feedpoint in the balanced feedline of the antenna. SWR is 1:1.3 at 3 MHz and 1:2 at 30 MHz. A additional line choke is a good option.
I used the 4C65 toroid for it was in stock but a FT140-43 with aprox. 8-10 turns might even be a better choise.
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