All great points. A tall skinny tower with slip rings, with many large
antennas, in a high wind area, is a temporary setup IMO.
-Steve K8LX
On 06/15/19 20:32 PM, Steve Bookout wrote:
Hello all,
Couple of comments on K4JA's tower failure.
The lower half of the tower was shielded from some of the wind by way of
tall trees at the edge of the field, where the woods started. The upper
half went way above the trees and took the full force of the wind.
Also, his stuff was fully rotating from the base up to the top, with
slip rings at the guy points. Because of this, the guys really had
nothing to do with limiting the twisting of the tower. It just twisted
as it wanted all the way from the ground to the top.
I would not put more on a tower than Rohn's wind load ratings allow
just because a torque guy is used. A 6 way star guy does a great job
of minimizing twisting. There is more leg compression since there are
more guys wires however a Rohn 45 is designed to go 300' high and the
tower in the post is only 110'. I believe that twisting can cause
tower failure, K4JA's tower twisted back and forth in hurricane winds
until it failed. Adding a star guy is probably a good thing if the
antenna has a long boom. I use star guys and a taper pier pin base on
all of my towers.
John KK9A
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|