[TenTec] RE: 450 Ohm feedline

[Ron McConnell]

Rob Atkinson, K5UJ, k5uj at hotmail.com, says,
"The purpose of twisting the line is 
not to reduce noise pickup and radiation, 
it is to help keep the line balanced."

  ?

The purpose of twisting flat transmission line 
is to obtain a great degree of electrical balance
between the individual conductors of the line
and its surroundings.  The purpose of electrical
balance is to reduce noise pickup and radiation.

A. G. Bell came up with the idea of twisting
telephone transmission lines over 100 years ago
to do just that.  The only telephone wiring 
that is not twisted are short individual drop wires 
from a pole to a residence and much of the cheap
interior residential telephone wiring these days.
If you have more than one line with this stuff
you can often hear one line on the other.
Outdoor telephone wire pairs have several feet per twist.
CAT-5 wire pairs have several twists per inch
- all to reduce noise pickup and radiation.

There may also be mechanical advantages to twisting
450 ohm ladder line.  I haven't thought that through.

Cheers, 73,

Ron McConnell

w2iol at arrl.net

WGS-84: N 40º 46' 57.9" W 74º 41' 21.9"
        FN20ps77GV75

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