[AMRadio] Ladder-line mounting question


Jim Wilhite 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.

73  Jim
W5JO

----- 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.
>
>
>
>  Cheers
>
> John  KB6SCO





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