I'd be careful about non-symmetric guy placement - it changes the horizontal
forces so they are out-of-balance. Last field day a tower at N1FD bent over
because one of the guys was much longer (further away) than the other two.
We had a major flap over that. I'm going to make sure my guys are
symmetric!
K1HI
Rex Lint
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Tom Wagner
Sent: Monday, April 17, 2006 6:15 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Guying on a small lot
This is a job for a PE, but I expect any PE would stamp 44' guys in an
instant.
All short guys do is increase the downward force on the tower (and of course
in the guy and anchor). Obviously a guy 1' from the tower would be pretty
useless, but 4' shorter than 48' is a pretty small variation. Rohn 25 can
be used to 200', so you aren't anywhere close to the limit of the tower.
If I were you, I would make the two short guy bases a bit larger (20%) and
use 1/4" for the guys. In fact, I would always use 1/4" EHS for guys on
any normal ham tower. Cheap safety margin.
DO NOT GUY except at the corners. The tower is not made for that.
If you want to calculate the force in the guys at 48' and at 44'
(to a first order approximation) you can do it with trig. I
just woke up, so I won't attempt it, but it is very simple. Note
that Rohn recommends 1/4" guys to be tensioned to 660 lbs.
73,
Tom Wagner - N1MM
Check out the N1MM Free Contest Logger at:
http://www.n1mm.com
http://groups.yahoo.com/group/N1MMLogger/
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of Jon M. Knodel
Sent: Monday, April 17, 2006 4:39 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Guying on a small lot
I don't know if this question has been brought up on the reflector or not,
but here it is:
I have a small lot (73' x 122') and want to install a 60' Rohn 25G. Because
of how the house is set and other structures, I am having problems placing
the tower where I can get the specified 80% guy length (48'). I am pretty
close to getting it but come up just short on two of the legs. On the third
one I can get 48' without any trouble. On the other two, I am about 4'
short (73% instead of 80%).
I definitely plan on constructing and loading the tower to Rohn guidelines
and would like to know if this would be a problem. Would it be possible to
add 2 additional guys to each leg off center of the normal guy placement at
equal angles in order to supplement it at it's slightly shorter length?
Does anyone know of any books, reports or other information where I can find
the necessary equations to perform the calculations? Thanks for the help.
73 es gud DX,
Jon, N7XW
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