In a message dated 1/15/01 1:24:32 PM Pacific Standard Time, brewer@flash.net
writes:
> I have the following that I want to put on my "new-to-me" 64 foot Rohn 45g
> tiltover: 2 element Cushcraft 40 meter beam, TH3-Mk 4 tri band beam, 5
> element 6 meter beam, and 13 element 2 meter beam. All of this on a 15
foot
> mast and turned with a TX2 rotor. Does this sound unreasonable?
According to my current Rohn catalog, it'll take 17.2 square feet of load
and a total weight of 135 pounds at 30 PSF wind pressure (86.6 MPH). It looks
like you're below the max. How come this info isn't in your Rohn catalog?
(They're available from Champion Radio Products - <A
HREF="www.championradio.com">www.championradio.com</A> )
What is your local windspeed? (TIA-222 windspeeds available at <A
HREF="www.championradio.com">www.championradio.com</A> under Tech Notes.)
A problem is that Rohn doesn't say where the the load is relative to the
top of the tower. Is it 1-foot or what? By adding ten-feet of mast sticking
out from the top of the tower with antennas up it, you're increasing the
length of the lever arm and the resultant forces. I'm not an engineer but I
suspect the forces would be significant.
> Is there
> any modifications which would allow more capacity with respect to the
> tilting mechanism?
Nope. These are relatively dangerous contrivances and DO EVERYTHING with
care - from planning to installation to use. I've rarely seen one that wasn't
damaged at one time or other. I really don't like them so don't even TRY
anything different than what the books says.
> Will the 15 foot mast allow for sufficient separation without interaction?
For separation, sure. But see comments above.
> Given what I want this tower to do, would I be better suited with a quad?
Six of one, half-dozen of another. What would the decision be based on?
> Finally, is it necessary to use galvanized J bolts? Anyone have a
> source for them-I'm figuring 1 inch diameter by 18 inches.
J-bolts for what? Anchor bolts? Could be but you'd have to run the calcs
to find out. What do you need anchor bolts for? There are 3 or 4 different
methods and hardware for installing the base section. They're in the Rohn
catalog or visit their website <A HREF="http://www.rohnnet.com/";>Rohn</A>.
> As you can tell from the questions, this is my first tower project.
Great! The results will be worth it - hi. It's a lot of work particularly
if you haven't done anything like this before. There's no such thing as a
dumb question around here and you can take a look at the responses and see
which ones have good answers for you as well as a couple of different ways to
look at it or do it.
TowerTalk is here to keep amateur tower and antenna builders out of
trouble and I think we do a pretty good job of it. Good luck and welcome to
TowerTalk.
Cheers, Steve K7LXC
Tower Tech
Champion Radio Products
TT Admin
--
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|