----- Original Message -----
From: "Phil - KB9CRY" <kb9cry@comcast.net>
To: "Jim W7RY" <w7ry@centurytel.net>
Sent: Saturday, October 25, 2003 8:05 PM
Subject: Re: [TowerTalk] Top of 45G Tower- Stress
> Not to be killjoy Jim but it seems that you're overloading the tower.
> What is the combined sq ft. area of the two antennas? Is it more than
> what Rohn states for that size tower? Also, the stated max area is for
> a concentrated area one foot above the top of the tower; your top
> antenna will derate that max loading figure a lot. Personally I tend to
> over-engineer my towers; I don't like to have to repair them a lot! I'd
> decrease the spacing to around 8 ft. and place the rotator lower into
> the tower to counterbalance the top cantilever load. If you haven't
> purchased the rotator, I'd suggest you look into the Alfa Spid rotator
> with better specs and cheaper cost. Phil KB9CRY
>
> Jim W7RY wrote:
>
> >I'm in the process of installing my 70' Rohn 45 tower. I'm looking at
where the rotator is placed in reference to the top of the tower. I'm using
a 21 ½ foot mast (1/4 wall chrome molly etc). I'm using a Rohn 45AG4 top
section with a heavy duty thrust bearing on the top of the tower. I will be
using a Orion OR-2800 rotator.
> >
> >The lowest that I can get the rotator plate in the tower is 3 feet below
the top of the tower.
> >
> >
> >
> >I will be putting a 2 element 40 on the top of the mast and a TH7 just
above the thrust bearing. I want to keep as much spacing between the 2
antennas as possible. I estimate about 14 feet between the 2 antennas with
the boom support of the 2EL 40 at the very top of the mast.
> >
> >
> >
> >How much stress will this put on the top of the tower? How about on the
rotator? Too much? What about changing the rotator? The sort end of that
mast could get a little unruly!
> >
> >Opinions please...
> >
> >
> >
> >Thanks and 73!
> >
> >Jim W7RY
> >
> >
> >_______________________________________________
> >
> >See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> >
> >_______________________________________________
> >TowerTalk mailing list
> >TowerTalk@contesting.com
> >http://lists.contesting.com/mailman/listinfo/towertalk
> >
> >
> >
>
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
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