On 8/12/2013 9:32 AM, James Rodenkirch wrote:
Does it matter which twisted pair of wires I use?
The Zo of all pairs is the same, to manufacturing tolerances, but each
pair has a different twist ratio (called the "lay"). This is done to
minimize crosstalk between pairs. A higher twist ratio (more turns per
inch) improves interference rejection of the line, so the one with the
greatest number of turns per inch would be the one to use. I don't
remember which one that is, but it's sort of obvious when you open up
the cable.
BTW -- Belden CAT5/6/7 cables have pairs with each pair molded together,
so they tend to be better transmission lines (more uniform over their
length). Not a big deal for loss on 160M, but uniformity does minimize
interference rejection.
73, Jim K9YC
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Topband Reflector
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