> Bill:
> > 1. U.S.Towers indicated that the contact between the sections is
> probably
> > not good enough
> > to use the tower as a vertical (or as part of a half-sloper). How do
> > people overcome this?
>
> I do not agree with this. I have shunt feed my US tower 89' crankup as-is
> with no problem for three years....is there connection loss? I doubt it.
> The sections may have grease on them but I'm sure there is fair electrical
> connection, also look at all the steel cables on each section, as well as
> the positive pull down cable running from top to bottom. Not to mention
> the
> coax feed from top to bottom. Seems like lots of electrical redundancy to
> me.
>
[Steve Katz] There's no pulldown cable on a TX-455. But besides
that, the steel cables and the tower sections themselves aren't terribly
good conductors, especially after some years outdoors. The only way I
determined that for myself (although using a Tri-Ex W-51, which is pretty
similar to the TX-455) was when I measured feedpoint Z of my half-sloper
after adding the supplemental, low-Z cable described earlier and compared
that to the feedpoint Z measured prior to adding it. Holy cow -- the
difference was large, about 20 Ohms (lower with the added cable). In a 50
Ohm system, I would think that could represent substantial and measurable
loss, although I would not have known such loss could be eliminated without
trying the supplemental ground cable.
> > 2. They recommend the coax stand-off arms for getting cables to the top.
> I
> > do not see these
> > stand-off arms in most photos of crankups. Does everyone use them?
> What
> > are other ways
> > of getting various cables to the top such that there is not a problem
> when
> > cranking down the
> > tower?
>
> Forget the coax arms. Just stand-off the coax at the top about three
> feet
> and let it "hang" to the bottom....again....no problem for three years.
> The
> bundle of RG-8, and two rotor and switch box control lines support their
> own
> weight with no "carrier cable" which others have used. My tower is
> cranked
> down except when QRV so it goes up and down many times every week....no
> problem the coax bundle just piles up on the ground.
>
[Steve Katz] That's lucky, and I've done this, myself, in a pinch.
But I've also suffered the circumstance where the bundle is on the ground
and then it snows, or sleets, or rains and freezes, and now the bundle is
stuck to the ground, possibly for days or weeks. The bundle on the ground
also tends to pick up loose twigs, branches and just about anything laying
around as it goes back up -- I saw one such bundle pick up a loose 10' steel
mast and hoist it up the side of the tower before I noticed and carefully
lowered it. Etc, etc. Each to his own, but I prefer the stand-off arms,
and also prefer giving the bundle a place to reside that's above the ground
whenever possible. -WB2WIK/6
> gl, de steve VE6WZ http://www.qsl.net/ve6wz/
>
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>
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