TT:
For your consideration and comments. When one climbs a mast, the
climber's weight adds to the weight of the mast, antennas, feedlines, etc.
These weights are all supported by the rotator mounting plate inside the
tower top. I suggest that mast climbers ought to ensure that the top
bearing is properly utilized to provide additional support. By this I do
NOT mean relying on the set screw(s) on the top bearing, but rather relying
on a clamp of some sort to fit around the mast and to sit right on top of
the bearing collar. Ideally, I would suggest that a third mounting plate,
intermediate between the bearing and rotator plates, be used, along with a
second clamp set on the mast, to provide yet even more support to the
combined mast/man/antenna system.
My Trylon's shelf support angles are rated, per Trylon, to support 300
pounds each. My CM mast weighs 110 pounds by itself; add the antenna and
coax weights (about 90 pounds, I rekon), and I'm up to 200 pounds on the
rotator shelf alone.
In my installation I used two face-to-face muffler clamps and carriage
bolts to go around the mast right on top of the top bearing. (I had to cut
a piece of the ears off each clamp to they wouldn't touch when installed.)
So the weight of the mast assembly is positively supported by two Trylon
shelves. If I were to climb my mast (not likely in this lifetime), I'd
install a second clamp set to rest on the second shelf, between the top and
rotator shelves, to provide additional support, or 900 pounds total (300# X
3 shelves.) Adding my 200 pounds to the 200 pounds of mast system weight
doesn't eat into much of the safety factor this way. (And no - 600 pounds
of support from two plates is NOT enough IMHO. Especially since the second
clamp set costs $4, even in Wa$hington, D.C.)
73 de
Gene Smar AD3F
P.S. The muffler clamp idea is from K7NV.
-----Original Message-----
From: n6kj <kelly@thejohnsons.ws>
To: towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Tuesday, November 26, 2002 3:38 PM
Subject: [Towertalk] Climbing Masts
>I've seen several towers with climbable masts on top. The masts had foot
>pegs of some kind on them. How is this done? Where do you get the pegs or
>masts with pegs already installed?
>
>Kelly Johnson
>N6KJ
>_______________________________________________
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