Gary,
I used to do all my antenna work with a crane. I used what they called a 45
ton crane. Cost me about $350 for a three hour minimum. My tower was about
90 feet with a mast about 15 feet. At various times I had various antennas
on top including a KLM 15 (36 ft boom) and KLM 10 at the top. None of these
approach the weight you are talking about, though. They did have trusses.
I haven't seen a picture of your antenna, and I am having difficulty
picturing your description "the truss will make the connection on the mast
itself". If you are talking about a regular boom to mast truss using some
kind of cable or phillystrand (sp?), I would pre-construct the truss, tape
it to the boom near the boom to mast clamp so you can reach it easily when
you install the antenna. (I think this is what Paul, W8AEF, was suggesting).
My crane company always had a metal box, large enough for two guys to
comfortably stand in. They would attach it to the crane cable and take me
and one of my buddies up to the antenna like an elevator. I didn't have to
climb the mast to install the truss. (I don't like climbing towers!) We
installed the antennas the same way. We lashed the antenna to the box and
rode up with it. Once there, it was a fairly simple matter to put the
antenna on the mast. I am not sure that this procedure would work with
antenna that heavy. Two guys might not be able to lift and place it.
If the crane operator is worth their salt, all you have to do is attach the
antenna at the midpoint, and the crane operator can lift the antenna and put
the boom to mast clamp exactly where you want it. You can climb up to your
spot and attach the boom to mast clamp. If necessary you can then climb up
high enough to attach the truss. Once I had to stand on the boom of the
antenna but I didn't like that very much. On two occasions I have seen guys
"shinny" up the mast to work on one of these..."it gives me chills!"
Sounds like your gonna have some fun...gud dxing!
Bill, W5VX
>-----Original Message-----
>From: towertalk-bounces@contesting.com [mailto:towertalk-
>bounces@contesting.com] On Behalf Of Gary Stone
>Sent: Saturday, May 07, 2005 10:54 PM
>To: towertalk@contesting.com
>Subject: [TowerTalk] mounting large antenna question
>
>Hi,
>
>I am about to assemble and hopefully mount at 80 feet a fairly large
>antenna. It is the Optibeam 17-4 and weighs 212 lbs. It has heavy
>duty 3 inch x 3 inch square boom and it is a little less than 40 feet
>long. The boom has provision for truss but unless I am reading
>something wrong the truss will make a connection on the mast itself -
>not a separate truss support. This is perhaps common with beams that
>need a boom truss support. (there is separate truss support for each
>of the three larger elements - 40 meters).
>
>I had planned to raise the beam (probably with a crane) and the mast
>would already be in the tower. The crane I can easily get into my land
>area could not accomodate hauling up the mast and the antennas
>assembled (78 foot tower - RG45 and 22 foot mast - with plans for 8
>foot into the tower) because of the restriction of height (87 feet) of
>the crane.
>
>So, do you put lots of ropes around the beam at different points to
>safely craddle the antenna to mast already on the tower? Then you have
>to connect the truss support once it is lifted to the mast. Does this
>plan sound ok? Ideas appreciated.
>
>73 de N5PHT, Gary
>
> <><><> Gary Stone - N5PHT <><><>
> <> 347 CR 1250 <>
> <> Savoy, Texas 75479 <>
> <> UNITED STATES OF AMERICA <>
> <> (903)965-7724 <>
>_______________________________________________
>
>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
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>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.
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