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Re: [TowerTalk] [Bulk] WTB Rohn 25G tower insulator

To: Andre VanWyk <kr5dx@yahoo.com>, 'Towertalk' <towertalk@contesting.com>
Subject: Re: [TowerTalk] [Bulk] WTB Rohn 25G tower insulator
From: Grant Saviers <grants2@pacbell.net>
Date: Tue, 15 Dec 2015 12:22:08 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I would agree that a G10 rod the od of the small end R25 id is pretty "iffy". However, you could add 1/2" thick (or thicker) G10 plate maybe 1" wide each side of the R25, with longer GR8 bolts thru the R25 legs. Having an internal G10 rod to keep the legs round seems like a good idea. Since you apparently have a machining source I assume they have carbide drills for getting the holes on size and with minimal tearout. They could mill the plate for the step in od, it would fit better.

The 1996 R25 mechanical spec shows 8.3KIPS allowable tension per leg and 8.4KIPS compression (with 1/3 increase safety factor) so that should help with real engineering of known G10 layups. Another post recommended the layup weave be 45 deg to the load, IMO good advice for a bolted joint that probably can't be slip critical in this geometry (or use a G10 structurally rated for bolts in shear).

Grant KZ1W

On 12/15/2015 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.

Rohn does not manufacture this item anymore either.

73’s
NJ0F
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