Hi JC,
I've got several ways to do it for you. First way, put it in the tower and
then hoist it up the middle. That's the easiest.
If it's too late for that (it was for me), you still have a few options.
Second way is to use a big gin pole. My gin pole is a WB0W pole and I've got
a 24 foot aluminum pole for it so I can do exactly what you've got to do but
notwithstanding there's still a third way. This is where it gets fun.
Carefully find the center of gravity of the mast. Call that point "A".
Define another point about a foot higher than that on the mast and call that
point "B". Now carefully determine where the point farthest from the end you
can grab it with your gin pole and get the bottom to clear the top of the
tower. Call that point "C". Call the bottom point "D". If you were to pick
it up there, figure out how much extra weight (mass "M")you'd have to put at
the bottom end (D) to make it balance at the point where you have to put the
gin pole attachment rope. Attach your tag line as close to the bottom point
(D) as you can remembering that it will have to remain tied to the mast
while you're getting the mast into the top thrust bearing. Attach your gin
pole to (C). Run the gin pole rope up the mast to point B and make a
temporary lashing of the gin pole rope to that point. That point (B) becomes
your temporary lift point.
Make sure you've got some pieces of rope at the top of the tower to help
guide the mast down into the thrust bearing. They are used to keep the mast
from kicking up when it's being guided into the bearing.
Find something you can use as a weight as calculated above (M) and have it
standing by. Hoist the mast up to the highest point where the guy on the
tower can reach the temporary lashing at point B. Lifting the weight M up a
few feet off the ground attach it to the tag line. You've now moved the
balance point of the mast below the gin pole attachment point C. Now remove
the lashing at point B carefully. Host the mast above the top of the tower.
Guide the mast into the thrust bearing while lowering. Once the mast is in
the thrust bearing, you can guide it into the second thrust bearing
carefully while gently removing the tag line. I've used U bolts for the
attachment points.
Go over this procedure carefully so you UNDERSTAND it before starting. If
anything is unclear, don't start until it is. Make sure you know what you're
going to do at every step before you start. Make sure all the people in the
project know what to expect and what to do. Ask questions if you don't.
We've done this at K0TV successfully with a 2 1/2" 21 foot section of
galvanized pipe that weighs 160 pounds using a standard Rohn 12 foot gin
pole. I've decided to go to aluminum masts for new installations because the
chrome moly masts don't hold antennas as well. Because they're so hard you
can't get as good a grip on them with the antenna U-Bolts. Matt (KC1XX)
tells me that he's had a lot of antennas slip and rotate on chrome moly. I'm
using a 24 foot 3" aluminum mast for my 4 element 40 and 7 element 6 meter
antennas, both on top of 90 feet of R-45 and using two TB-4s.
Good luck and 73,
Jerry
----- Original Message -----
From: "JC Smith" <jc-smith@comcast.net>
To: <towertalk@contesting.com>
Sent: Tuesday, June 07, 2005 3:02 PM
Subject: [TowerTalk] installing monster masts in towers
> OK, so lets say I've got my new, super HD, 70', freestanding, Trylon or AN
> Wireless tower up in place. Now I've got to get that 24' Chrom-Moly mast
> up there and through the thrust bearing somehow. How the heck do you do
> that (no cranes allowed, it looks like I'm going to have to stick build
the
> tower)? The antennas I can tram up on temporary guy wires, but even if I
> could do that with the mast I've still got to stand it up to get it
through
> the center of the tower. Big gin pole? Seems like you'd need a gin pole
to
> raise a gin pole big enough to handle one of those monster masts.
> Helocopter? Maybe... gee, might as well have them pick up the tower as
> well, but how much does that cost? Anyone have experience with that and
can
> give me a ballpark number? It's gotta be big bucks, and doing it over a
> residential neighborhood? Maybe not even possible. So, how the heck do
you
> do that? Build the tower around the mast and pull it straight up the
> middle? Any other suggestions?
> Thanks & 73 - JC, k0hps@amsat.org
>
>
>
> _______________________________________________
>
> 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.
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