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Re: [TowerTalk] base insulators

To: <>, <>
Subject: Re: [TowerTalk] base insulators
From: "Jim W7RY" <>
Reply-to: Jim W7RY <>
Date: Wed, 1 Aug 2012 07:52:02 -0700
List-post: <">>
Use a standard Rohn flat plate with three of these between the concrete and 
the baseplate:

Jim W7RY

-----Original Message----- 
From: David Robbins
Sent: Wednesday, August 01, 2012 6:08 AM
Subject: Re: [TowerTalk] base insulators

be careful with repurposing old insulators, or even in applying new 
insulators in cases that they haven't been designed for.  I bought 4 big 
porcelain insulators  for my elevated radial 80m 4-square array.  the plan 
was for using a roofplate and 10' section of rohn 25, then an insulator, 
then 65' of rohn 25 above that.  The insulator was sandwiched between two 
plates made for the purpose... you can see the construction here:  The insulators and 
plates were sold for this purpose... but obviously not for exactly the 
design that i was using.  one small factor was missed.  While the insulators 
obviously had plenty of compression strength they did not have enough 
resistance to off center or bending forces as i broke 2 of them the first 
winter.  this resulted in adding fiberglass support to reduce the side 
.  The small factor that was missed was tha
t i was not putting a concrete base and tensioned guy cables holding the 
towers rigidly vertical, mine are just sitting on roof plates on the ground 
and are guyed with polyester rope, so there is a bit of movement in them... 
too much for the insulators obviously.  by the way, since those pictures 
were taken i doubled up the angle fiberglass on each leg.  the V bolts are 
from Tessco, the fiberglass from Grainger or McMaster-Carr, i forget which 
right now.  If i were to do it again i would probably go with machined 
fiberglass inserts in each leg, or use the two plates with a much shorter 
piece of fiberglass or lexan between them plus the angle fiberglass 

Aug 1, 2012 08:53:15 AM, wrote:

Years ago I managed to scrounge a few large insulators from the railroad. 
(they used them either on top of electric cars or for hanging the overheads 
along the right of way). Seems that if they were chipped, they could/would 
not use them. They worked very well, and typically were about 1 foot high by 
about 8 inches in diameter with heavy steel end plates.

That was years ago, times probably have changed. Or maybe ask some of the 
electric utility guys what they do with "removals" from HT lines... worth a 

I have long since gone to shunt fed verticals...

Good DX, epecially on T/B
Mike KM1R / HS0ZAI

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