The way I determine the correct turns ratio for my Beverage matching
transformers is simple--measure the SWR. Adjusting the turns ratio for
minimum SWR always produces the correct match without knowing in advance
what the Beverage impedance is. Fix the number of turns on one side of the
transformer. Usually it's best to fix the primary on the receiver feedline
side because you then tweak the secondary winding which has more turns and
allows for finer adjustment increments. Measure the SWR on the primary
side of the transformer and trim the number of turns on the secondary for
minimum SWR. An antenna analyzer like the MFJ is ideal for this operation,
although you could also feed RF from your rig if you're careful to keep the
power low enough so as not to fry anything. If you do this on 160, you'll
probably find that the match is also very good on the higher bands as well,
provided your transformer is broadband.
73, John W1FV
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