I've got a 75' tower that's been up for 15 years with a Pro 67B (100 lbs on
a 40' boom). It's survived 80mph winds..and I KNOW it's not plumb. Not sure
how out of plumb it is, but one of the guy anchors is about 10' from where
it should be. I don't want to say that one shouldn't exercise extreme
caution when building towers, but any amateur with good sense should be able
to put one up that's gonna survive just about anything to come down the
road.
Bob/WF3H
----- Original Message -----
From: <KI7WX@aol.com>
To: <towertalk@contesting.com>
Sent: Wednesday, March 05, 2003 4:02 AM
Subject: Re: [TowerTalk] how vertical is vertical
>
> Jim,
>
> I didn't copy the linearity part of the prior post as I didn't want to
induce
> any confusion. "snaking" (linearity) and "twisting" (angular rotation)
both
> have their own specs in EIA-222-D.
>
> 6.1.2.2 Linearity - For guyed structures, the maximum deviation from a
> straight line between two points shall not exceed one part in 1000, (1.2
per
> 100 ft.)
>
>
> On a large tower to check all these specs correctly in a reasonable amount
of
> time likely requires a transit (as Paul noted). I only know one ham that
owns
> a transit and knows how to use it. Been a long time since I used one in
> physics 101 and I wasn't real good with it either :-)
>
>
> To me, pragmatism rules. For 100 foot towers with 3 or 4 guy wires per leg
> then I think by taking ones time and carefully checking plumb and guy
tension
> you are going to be just fine. If that wasn't true almost all of us would
> have failed towers because I bet very few (self included) have had their
> towers sighted properly and are perfectly within the EIA-222-D specs.
Heck, I
> bet most folks have never checked guy wire tension - but that's an
entirely
> different thread designed to sell Loos gauges :-)
>
> With all that, I tend to over do things a bit so if I were putting up
several
> towers at once, or perhaps one big one (FWIW I define "big" as over 140
feet
> for hams), I'd probably seek out a professional to sight them and get them
> all perfect. I bet with a bit of poking around you can find someone who
would
> have the right gear and do it at a reasonable cost. I looked into this a
bit
> just to inform myself when I started building in NC. The rental cost on a
> transit was not prohibitive given the cost of towers in general.
>
> $0.02 FWIW YMMV
>
> Mark
> KI7WX
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
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>
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