The 80 percent guy anchor radius is just a guideline, it can be less if
properly engineered. The bigger problem may be with the rotating rings. I
believe that most rotating tower component manufactures recommend a guy radius
of 100 percent. This puts less stress on the bearings and also allows more
room for the antennas to turn
John KK9A
To: TowerTalk <towertalk@contesting.com>
Subject: [TowerTalk] How to get another 10' in height? Add a mast or add
another section?
From: John W <xnewyorka@hotmail.com>
Reply-to: xnewyorka@hotmail.com
Date: Mon, 9 Jan 2012 20:23:17 -0800
If I have a Rohn 45G tower of a given height, let's say 90', guyed per the Rohn
book, and rotating from the base, hosting several side-mounted yagis for 10m
(3), 15m (2), and 20m (1), and I want to add another antenna up at 100' (a
small 40m 2L) that also rotates with the tower, which one is the safer/better
installation: adding a mast that protrudes 10' above the top of the tower (and
for some distance down into the tower), or adding another 10' section and
sidemounting the new antenna at the top of it?
This is a theoretical question, because I haven't built the tower yet, but I
plan to.
The first reply many might have is probably: Why don't you just build it to
100' per the book, instead of 90'?
The answer to that is that I don't have enough real estate to put guy anchors
80' from the base, I only have 72' available.
Also, I have not even seen hardware that allows adding a FIXED mast at the top
of a Rohn tower - sort of like a thrust bearing that can't turn. How is this
typically done?
Thanks & 73,
John
W2ID
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