This type of base is called pier and pin. It was popularized when AM
broadcast towers frequently used Rohn 25 as radiators. I have seen it used
on 1,500' commercial towers as well. The pier is a huge ceramic insulator
when it needs to be insulated. I just put one in concrete this week in
preparation for moving my 110' 160 Vertical. I don't think they are popular
with hams because they are most safely erected with a crane until the first
guy level is secured and tensioned.
Tom Taormina, K5RC
Virginia City NV
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Cqtestk4xs@aol.com
Sent: Thursday, July 10, 2008 12:57 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] What is..."Pointed Tower vs Flat"
Joe
Most BIG commercial towers are the kind that come to point at the bottom.
This design helps to reduce torque stress on a tower (I think). Most ham
towers are "flat" on the bottom.
The pointed ones use a "pin" of some sort and require guying of some sort
from the first section. The flat ones eventually require guying at some
point.
I prefer the flat type since it is easy to temporarily remove a set of guy
wires to slide an antenna up the side of a tower. One can not do that with
the pointed type since it must be continuously guyed.
W2GD was recently injured by riding down 30 feet of tower that was
"secured"
by a pin. Accidents can and do happen on both types of tower.
Bill K4XS/KH7XS
I
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