Chris,
The insulators would by 30ft up the tower, so although I think this would
work nice at ground level, doing something like this up there would require
additional hardware.
I think as of now, the WB0W insulators makes a lot of sense....
73's
NJ0F
-----Original Message-----
From: Chris
Sent: Tuesday, December 15, 2015 2:07 PM
To: Jim Lux
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] WTB Rohn 25G tower insulator
Did we ever come to a conclusion as to whether or not a flat sheet (like 1"
thick or more) of HDPE plastic would work? Sandwich the sheet between the
concrete and a flat bottomed pier pin type base. Obviously taking care to
insulate the pier pin bolt.
Chris
KF7P
On Dec 15, 2015, at 1:03 PM, Jim Lux wrote:
On 12/15/15 10:06 AM, Andre VanWyk via TowerTalk wrote:
I am getting parts together for a 160m vertical, using Rohn 25G sections.
I am looking for a Rohn insulating tower section. If someone has one,
please drop me an email. I managed to locate one a while back, but sold
it to friend whom I felt needed it more that I did at the time.
For my 80m Four Square, I had insulators made out of G-10 fiberglass rod,
but I feel these are not suited for such a tall structure.
Why wouldn't you think it's strong enough. G-10/FR-4/Garolite is pretty
strong stuff.
The rod probably has more compressive strength than the tubing used in the
tower sections. Likewise in shear: there's a lot more cross sectional area
resisting the shear force).
Bending might be the area where it's different, but bending loads on a
guyed tower base are pretty low (and zero, with a pier pin type base.
Rohn 25G is 1.25" diameter 16ga tubing. wall thickness is 0.065"
So the cross sectional area is 1.25*pi*0.065 about 0.25 square inch
The solid rod will have cross section on the order of a square inch.
Figure steel yield is around 36 ksi, G10 is around 10 ksi, so the
compressive strength of both is pretty similar.
(In reality, the failure mode for the vertical tubes is probably buckling,
not compression)
Rohn does not manufacture this item anymore either.
73’s
NJ0F
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