[Johnson] RE: [AMRadio] Ladder-line mounting question

Craig C. Heaton wd8kdg at worldnet.att.net
Sun Oct 23 14:37:31 EDT 2005


Hi John,

	Why not just try your idea, see how the feed line/antenna performs? If you
make the contacts desired, its a good antenna system and for a while the job
is done.

	I doubt the bicycle hooks will adsorb/radiate much RF or change the
impedance where a tuner can't handle the situation if all else has been
designed within limits. Not having a picture of the installation, I can't
see where drilling a hole through a 2X4, etc. and hanging the open wire with
plastic wire ties would be any better.

	The proof is in eating the pudding.

73s
wd8kdg
Craig


-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net]On Behalf Of John Lawson
Sent: Sunday, October 23, 2005 9:30 AM
To: amradio at mailman.qth.net
Cc: johnson at mailman.qth.net
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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