On Sun, 20 Sep 1998 06:05:58 GMT "Rick Bullon" <kc5ajx@hotmail.com>
writes:
>
> I need some help doing some calculations for a tower. It has been
>over
>30 years since I took trig in school and I can't remember my formulas.
> The tower is going to be 70 ft Rohn 25 guyed as per the Rohn book,
>70
>mph wind area guy wires at 32' and 65' guyed at 56' from tower base
>it
>will right now have a TH 6 tribander on it.
>My questions are
> 1. With 2 of the guy points on the property line how far is it from
>the
>property line to the tower? ( I need this measurement so I can figure
>the postion of the 3rd guy point to see if the proposed site is big
>enough)
I'm on vacation, and I don't have the Rohn book with me, but
there is a drawing in there somewhere that shows how much real
estate you need for the various guying layouts. In your case
the distance from the property line is 28' (56cos60), or
1/2 of the guying baseline.
> 2. Will elevating the guy points make the guys wires longer or
>shorter?
>and if so by how much? ( XYL requires elevaterd guy points)
Shorter. For every foot of guy elevation, you can move the guy
point in by 0.8 foot to keep the same 80% guying angle. You can
then place your tower closer to the property line.
For example, if the guys are elevated 8 feet, the baseline is
shortened by 6.4 feet, to 49.6', and the tower base can move to
24.8' from the property line.
> I seem to remember reading on here that "I" beams were stronger than
>
>round pipe for elevated guy points right or wrong?
> Do I need to use an equlizer plate for this setup or is that over
>kill?
As I remember the discussion, the recommended method was to use an
I-beam, grind off one of the flanges near the guy attachment points,
and drill a separate hole for each guy. (Have all that done at a
machine shop.) You could probably also get both guys through one
larger hole, using two thimbles, or you could use an equalizer plate.
Dave Hachadorian, K6LL
San Diego, CA
K6LL@juno.com
_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|