If I recall the specs correctly the highest you can go with Rohn 25 is 40'
with 1.5 sq ft windload in 70 MPH winds. I cannot imagine climbing 40' of
unguyed Rohn 25 or using it for anything other than to support a TV antenna.
Regardless of what anyone tells you, you should follow the Rohn
specifications. If you want a freestanding tower, there are plenty of better
options.
The Polyphaser catalog has a lot of grounding information, you should obtain
one.
John KK9A
To: TowerTalk@contesting.com
Subject: [TowerTalk] New Tower Install
From: Rob Matherly <jimrob@gmail.com>
Date: Mon, 25 Apr 2016 16:42:13 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Hi All -
First time poster to the list, long-time lurker.
I'm getting set to install my first tower after having been in the hobby
for nearly 20 years. I'm going to install 40' of Rohn25 with a Hazer. I'm
going to set it in a 4x4x5 block of concrete that I have the option to make
it taller later on (without the Hazer, of course.)
Please advise if I am correct: I do not need to guy the tower given the
base size and height, correct? I've been told I can go up to 50' unguyed
by some, but others say anything over 40' needs guyed.
Regarding grounding: I've seen different ways of doing it. What is the
best way to ground the tower? Rod at the bottom of the hole? Rod to the
side of the slab?
I'm going to feed it underground with a 3" CPVC line coming up into a
weatherproof box mounted a short distance from the tower. Do I need to tie
the ground bus in the cabinet to the ground in the tower, or do I need to
keep them separate?
Thanks
Rob
w0jrm
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