[TowerTalk] Re: Long mast, intermediate bearing

[Pete Smith]

At 08:58 AM 4/3/98 -0500, Henry G Chapoton wrote:
>     Larry:
>     
>     I don't think you want to hook your tram line to the mast unless it's 
>     a real small beam on a short tower.  There is a LOT of tension on that 
>     line. Hook it to a tower leg at the top of the tower.  If the tower is 
>     guyed, remove one guy (loosen the other 2 a bit) and let the tram line 
>     (I used 3/16 EHS for a tram line) be a temp guy.  When you get the ant 
>     up there, hang it from the tower, relocate the tram, move the pully up 
>     on the mast and then pull the ant UP.  If you do tram on the mast, 
>     consider a couple back guys on it.
>     

I think this is a case of "your mileage may vary."  I ground-crewed last
year for the installation of a Mosley 40-meter yagi - incredibly heavy
critter above a TH-7 on top of 120 feet of Rohn 45.  The mast was a 10-foot
Rohn.  The station owner rigged a tram using 3/16 EHS from the top of the
mast to a point on the ground well outside the guy circle (actually the
base of his second tower) and directly opposite one guy set.  He made up a
rope cradle, such that when the tram pulley hit the mast the boom was right
where it wanted to be, and used a "tiller" with a second pulley to keep the
antenna oriented in the plane of the tram.

It worked really well, and there was no sign of excessive strain on the
mast.  With Rohn 25 and a piece of water pipe, it'd be another story, and
even with what he had I think in retrospect a back guy from the top of the
mast would have been a good precaution.  But the advantage of not having to
horse that heavy beam around while on top of the tower was substantial.  


73,  Pete Smith N4ZR
In wild, wonderful, fairly rare WEST Virginia

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