|[AMRadio] Ladder-line mounting question|
w5jo at brightok.net
Sun Oct 23 15:42:17 EDT 2005
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.
----- Original Message -----
From: "John Lawson" <jpl15 at panix.com>
To: <amradio at mailman.qth.net>
Cc: <johnson at mailman.qth.net>
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.
> John KB6SCO
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