[Top] [All Lists]

Erecting Long Masts

To: <>
Subject: Erecting Long Masts
From: (rattmann)
Date: Wed, 18 Dec 1996 23:07:54 -0800
Terry, KK6T writes:
>I am curious as to the need to have so much mast buried in the tower.
>Wouldn't the rotator be just as isolated from side forces with say half as
>much embedded mast as long as the intermediate support was still there?  I
>understand about erring on the side of caution but isn't this huge overkill

K6NA writes:
Hi Terry... Isolating the rotator from sideload is important but only a part
of the reason.  The main reason I like the rotator down 7 or 8 feet from the
tower top is a practical one-- you need room to work!  I do most things with
a come-along, and it's a good idea to have 3 or 4 feet of fairly clear area
within which to work.  Otherwise it gets too crowded for the come-along,
your hands, your feet, your tools, bucket, maybe a partner.... A "long
throw" for the come-along means it is pulling mostly parallel to the axis of
the mast, rather than fighting it sideways at an angle. So if the
intermediate plate is too close to both the rotator plate and the tower top
you find it's very difficult to work efficiently and safely.  Remember,
these remarks apply mainly to substantial installations with long masts and
very top-heavy loads. As N4SI points out, it is very important to keep
things carefully centered, too, when dealing with an intermediate plate.
This keeps the rotator happy.  If there is 3 or 4 feet of mast below the
intermediate plate, there is some mast flexibility available which can help
minimize binding at the rotator.

73! Glenn K6NA

FAQ on WWW:     
Administrative requests:
Sponsored by Akorn Access, Inc & KM9P

<Prev in Thread] Current Thread [Next in Thread>