[TowerTalk] WTB Rohn 25G tower insulator

[Andre VanWyk]

I think I will probably end up using WB0W's insulators. My two main concerns 
with G10 fiberglass:
1) - They DON’T like the sun. Yes, I can probably wrap them, but they will 
be elevated 30ft in the air.
2) - The engineering shop that turned my 80m 4Sq insulators, asked me 
politely not to bring any G10 material to them again for machining for both 
health and abrasive reasons to their equipment.
73
NJ0F

-----Original Message----- 
From: Jim Lux
Sent: Tuesday, December 15, 2015 2:03 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] WTB Rohn 25G tower insulator

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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