I have had excellent success with the clothesline pulleys. They are clearly
not life-rated or mariner quality, but for ham antenna use I strongly
recommend them. I have had several in trees/sky for 5+ years and have not
observed any UV degradation.
Tim N3QE
On Sat, Sep 20, 2014 at 10:06 AM, Jim Garland <4cx250b@miamioh.edu> wrote:
> 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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