I want to replace the 450 ohm ladder line for my two DXE 720 ft long
bi-directional beverages with two lengths of WD-1/TT field telephone wire.
The wires will be secured only at the ends, but will be suported along their
length by ceramic insulators mounted on 4x4 posts spaced every 60 ft. The
spacing between the parallel wires will be about six inches. Here are my
quesetions: First, does anybody know what the likely impedance is of this
configuration, or if not, how to measure it? Second, if I keep the DxE
matching trnsformers used with the 450 ohm ladder line, will beverage
performance be degraded noticeably with the new wures if, say, the impedance
of the new line turns out to be 600 ohms or so? In other words, as a
practical matter how important to performance (e.g., F/B ratio and
low-noise) is it to make sure impedances are matched.
Finally, a mechanical question. I want to have a pulley at one end of the
parallel wires to equalize the tension in the wires. I've not been able to
find a good pulley with a five or six inch diameter, except for nylon
pulleys used for clotheslines. Do you think one of these could be used.
There will be no motion of the pulley, since it is only used to equalize
tension. The field telephone wire is rated at 200 lbs maximum tension, and
I'm guessing the actual tension will be about half that.
Thanks!
Jim W8ZR
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