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Re: [TowerTalk] base insulators

Subject: Re: [TowerTalk] base insulators
From: David Robbins <>
Date: Wed, 01 Aug 2012 08:08:28 -0500 (CDT)
List-post: <">>
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 forces:
 .  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 reinforcement.

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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