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[TowerTalk] Rohn 25G

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Subject: [TowerTalk] Rohn 25G
From: (K7LXC)
Date: Mon, 20 Apr 1998 23:20:30 EDT
In a message dated 98-04-20 20:48:10 EDT, writes:

> I have a Rohn 25G that I am going to 140 feet with it. I am going with
>  1/4 inch guy wire and the Rohn guy brackets and will have the TA25
>  torque bracket at the top guy level.
>  The Antennas at the top of the tower will be a DB-224 and a pair of
>  cushcraft a-14722 vhf beams and a pair of a-449 11 uhf beams amd a ham
>  II rotor.
>  at 138 feet will be a uhf omni antenna
>  at 137 feet will be a DB uhf Corner refelcter antenna
>  at 135 Feet will be a 3 element vhf yagi on the n side of the tower .
>  at 130 feet will be a  Ar2 Ringo vhf antenna .
>  at 125 feet will be a 25-1300 mhz discone antenna
>  at 100 feet will be a antron 99 10m omni antenna.
>  Will the 25G work for my needs???

      Pretty ambitious guy, eh? 
     First of all, Pontotoc County is only a 70 MPH windspeed zone, the lowest
they give, so no big deal wind-wise. 

     140 feet of 25G is rated at 13.9 sq.ft @ 70 MPH. Add them all up,
compensate for feedlines between Rohn spec and actual and see what you wind up
with. I suspect that while all of the aforementioned antennas are realtively
small and have pretty minor torque characteristics, they will add up to an
overload condition. The DB224 is 3.1 sq.ft. by itself. Now you're down to 10.8
sq.ft. and you've got 8 antennas to go.  

     With this aggressive and populated tower, I suspect that you'll want to
add even more stuff over time so my recommendation is to erect 45G and you'll
never have to worry about it (it's rated at 20.7 sq.ft.).

      Rohn does not spec 1/4 inch EHS guys on any 25G configuration. If you do
use it, I would suggest tensioning it to 3/16 tension (400#) and not the 1/4
inch spec of 670#. Leg strength is the limiting factor and you don't want to
put too much preload on the system or legs. It adds lots of additional
deadweight as well. Maybe you shouldn't use it at all. 

     You really don't need the TA25G either - you don't have anything that'll
produce significant torque so they're kind of superfluous. 

     Other than that, go nuts!

Cheers,  Steve  K7LXC

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