Hi, Luis,
Others have commented that the transformer on the FT140-43 core results
in anywhere from 3:1 SWR to 5:1 SWR. W7LR solved the problem with his by
adding a capacitor in series with the 50-ohm winding to cancel the
inductive reactance on 160 meters. Of course, that makes it a
single-band transformer.
Your results with the FT114-77 core are much closer, and I would
recommend that core for you. The 77 type material has greater
permeability than type 43, and you might try using 17 turns on the
antenna side and 4 turns on the coax side when using the FT114-77 toroid.
This might give even better SWR results.
Let me know if you try it and what the results are.
Hope to CU on 160m this winter.
73, de Earl, K6SE
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