[TowerTalk] WTB Rohn 25G tower insulator

Jim Lux jimlux at earthlink.net
Tue Dec 15 15:03:42 EST 2015

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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