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[TowerTalk] Re: Remove enamel from CU wire

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Subject: [TowerTalk] Re: Remove enamel from CU wire
From: (Tom Rauch)
Date: Tue, 9 Oct 2001 16:56:10 -0400
I agree that the enamel could just be left on with no ill effects, but:

> 1.  The only reason bare wire is specified for AM BC stations is that
> it is cheaper than enamel wire. 

The main reason is bare wire is easier to work with, when soldering 
hundreds of connections. The cost of the wire is insignificant when 
compared to the labor and other expenses in the system.

2.  The reason to bury of a radial
> system is so that you can mow the law to keep the XYL happy.  An ideal
> system would be on short posts insulated from the earth.  (Ground rods
> at the tower take care of lightning ground.) 

When a sufficient number of radials are used, it makes absolutely 
no difference whether the system has or does not have direct soil 
contact for RF. It is only when a sparse, poorly efficient system 
with a few radials is used that insulating radials by spacing them 
above earth helps.

Insulation on a wire makes no difference at all for a wire in contact 
with earth for RF performance, any increase in efficiency comes 
from physical separation from earth and that is important only when 
the radial system is small. At about 15-20 radials, it makes no 
difference at all if the radials are slightly buried or elevated several 
feet so far as system efficiency is concerned. With more radials, 
all elevating the radials does is hurt the overall system by reducing 
effective height.

It is the physical distance the wire is from earth compared to the 
wavelength that matters. A spacing of .005 inches from a layer of 
insulation is meaningless on any frequency, except near direct-
73, Tom W8JI 

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