[TheForge] somewhat off topic: antenna tower

[theforge@mailman.qth.net]

hello;

i have searched the amatuer radio pages and have found alot about
antenna but nearly nothing about building a tower. the little information
i did find was assuming a large antenna with high wind loading.

basically what i want to do is build a 100 ft tall monopole tower.
the only antenna on this tower is a 24 db gain parabolic dish microwave
antenna. the wind loading is slight since it is a wired grid design.
(
if you are interested the antenna may be seen at:
http://www.hyperlinktech.com/web/hg2424g.html
)

one person suggested i get an aluminum flag pole. hey right they cost about
the same as a self supporting tower not including the foundation work.

rohn self-supporting towers cost $10K+. that is way out of my price range.

i thought of using schedule 80 pipe and start out with 8 in pipe.
use an 8 inch to 6 inch reducer. go with 6 inch for 40 ft and then reduce
down to 4 inch for 20 ft then end in 2 inch. 

         |  |    <---- 20 ft of 2 inch
         |  | 
         |  |
         |  |
        /    \ <---- 4 inch to 2 inch reducer
        |    |   <---- 20 ft of 4 inch
        |    |
        |    |
        |    |
       /      \ <---- 6 inch to 4 inch reducer
       |      |  <---- 20 ft of 6 inch
       |      |
       |      |
       |      |
      /        \ <---- 8 inch to 6 inch reducer
      |        | <---- 20 ft of 8 inch
      |        |
      |        |
      |        |

i am unable to find my copy of the machnist handbook to look up the weight
of each section, so i have no good feel for what it would weigh nor what kind
of foundation should it have. it does seem to be over kill for such a small
antenna. the only experience i have to go by is when i worked on putting in
cellular towers. some of those had 50 ft deep 4 feet diameter concrete piers.
with 20 ft long 4 inch bolts embedded in the concrete.

aluminum schedule 80 pipe cost more than steel schedule 80 pipe.
there are benefits to using aluminum such as weighs less, will not rust.

the reason for building a new tower is the current tower is a rohn 25gt.
it is next to the house. ( i know bad place to put it. ) at 40 ft it does not
need guy wires at 100 ft it need three guy wires per leg. the family has voiced
rather loudly that they do not want guy wired. i do not like guy wires either
for safety reasons. people get 'clotheslined' by them.

-- 
Terry L. Ridder
Blue Danube Artistic Forge (Blaue Donau Kunstschmiede)
"We do not bend metal, we sculpt it."

digging deep, i feel my conscience burn
i need to know who and what i am
this hunger jolts me from complacency
rocks me, makes me meet myself
----kendall payne---closer to myself---