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[TowerTalk] AB-577 Experience

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Subject: [TowerTalk] AB-577 Experience
From: (N8UM)
Date: Wed, 23 Jun 1999 08:03:20 -0400
Hi Barry,

I use two AB-577 in the field for VHF contests.  Both support multiple
arrays of VHF/UHF arrays on Hazer style rotator/bearing fixtures that are
banded to the top section at 55 feet.

However, AB-577 was designed for temporary installation only.  It is not
corrosion proofed.  If you have never seen one in real time, I suggest you
invest the $10 and study the manual.  The mast was designed for hand
rotation.  The mid and upper guys rings are not locked in place so any
rotational torque is transmitted the full length of the mast down to the 8
foot level where the mast is locked in place by a auto style brake fixture
and guys.  I would try to get a professional opinion on whether the
rotational torque applied on the 5 locking rings (at each tubing joint) and
a base that is not fixed in 2000 pounds of concrete would survive torque
applied by 8 sq feet of antenna in a 70 mph wind.  Maybe k8LX or W3LPL is
listening.  I think both have experience with the masts and could offer

The Mil manual specs the mast at 75mph wind survival with 0.5 inch ice load
on the guys.  This is with 2 huge 1960 vintage microwave horns fixed on a
cross arm at the top.  The mast can also be safely erected to 70 feet with
an add on kit.

Also remember that this stuff is still thin wall aluminum tubing, so any
dent or pellet gun ding to compromise the diameter integrity, and you could
be toast...

Good luck,

John N8UM

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