As John Coleman pointed out, the amount of power you will put into the line
is important. Actually wood is not a good insulator. It contains a certain
amount of water and when that is driven out rot will set up in the wood. By
hanging the feed line on metal hooks screwed into wood will present a
problem over the long haul.
Check a farm supply store for ceramic insulators that have a screw in the
middle. The are round in shape and have a notch in the top and bottom to
allow wires to be supported without touching anything. Or get an eye screw
and suspend a insulator of some type to the rafters then run the feed line
through the insulators. Lexan strips, polycarbonate strips or something
like that. Drill a hole in one end, tie it to the eye screw then make a
hook on the other end for the feedline.
73 Jim
W5JO
----- Original Message -----
From: "John Lawson" <[EMAIL PROTECTED]>
To: <amradio@mailman.qth.net>
Cc: <[EMAIL PROTECTED]>
Sent: Sunday, October 23, 2005 11:30 AM
Subject: [AMRadio] Ladder-line mounting question
Just got my fence-perimeter NVIS loop installed yesterday (thanks to the
kind slave-labor assistance of Brad, KB7FQR). I'm using 450-ohm feedline
from the loop back to the tuner in the shack. It comes thru a hole in the
shack wall and I had planned to suspend it along the rafters on those
large 'bicycle hooks' for the 20 or so feet from the entry point over to
where the Gear all lives.
It has been suggested that this is a Not Good Thing - that any metallic
object like that touching the ladder-line will alter the impedance, stress
the insulation, etc.
I can see the insulation concern, but I don't get how a pice of 3/8ths
steel rod covered with plastic at right-angles to the feedline conductors
can make much of an impedance bump.
So I thought to solicit the general wisdom of those of us who might know
the real 411 on this subject, because I'm not the brightest bulb in the
marquee when it comes to HF antennae and feedlines.
Cheers
John KB6SCO
