Topband: Fw: 25G insulators

[Donald Chester]

>The arc gaps across the insulated section is a simple and very effective 
>way
>of taking care of the static charge

It is much better to use ONE insulator to support the tower at a pivot point 
than to use 3 separate insulators in an insulated section, with the bottom 
end of the section buried in concrete.  The pivot assembly allows the tower 
to sway slightly under wind conditions and also allows the tower to be 
adjusted for plumb by simply adjusting the guy wire turnbuckles.  The rigid 
base buried in concrete puts much more stress on the tower in heavy winds.  
A pivoting tower is likely to survive much higher winds than one with a 
rigid base.

The best solution would be to find an appropriate size AM broadcast base 
insulator.  I have seen them at the Dayton fleamarket, usually for about 
$50.  New ones are expensive; $500 back in 1980, ??? today.  A good homebrew 
substitute is a large ceramic standoff like the ones used in power 
substations, about 6" in diameter and about 6" tall.  Have a welding shop 
put together a 1/2 to 3/4" base plate with recepticles to fit the bottoms of 
the tower section legs, and make up a pier pin assembly to attach to the 
insulator.  Rohn makes a special tapered base section (25TG) for this 
purpose.  When I put up mine in 1980, the TG cost about twice a normal 25G 
section, but I understand they are far more expensive today.

Don K4KYV

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