Feedline mathematics

Schițe, elemente, formule, etc. - în ajutorul celor ce fac antene
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For an 80m doublet antenna cut to 135ft, fed with 450 ohm ladder line, to a 4:1 current balun, then about 2m of RG213 to the tuner.
The author at KV5R.com provides a nice tidy formula, 123/MHz x VF, and recommends using odd multiples for feedline length.
https://kv5r.com/ham-radio/ladder-line/ ... ne-page-3/
So in my setup: 123/3.650 x 0.92 = 31.00ft and according to the formula I may use any odd multiple of this number, so 93ft should be perfect.
The author at TrueLadderLine.com provides a very useful table.
https://www.trueladderline.com/read-first/
He agrees with KV5R but he provides a range of usable lengths. In my case for an 80m doublet, use of 90-102ft of feedline is recommended.
(original post by David Gerrard)
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