Rob -
Your definitions are most likely correct and more precise, but I have seen
the 450 ohm version referred to as Ladder Line. For example, the 450-ohm
"Ladder Line" used with the DX Engineering Reversible Beverage antenna (see
their web site).
Not taking sides on this one - just wanted to point out that other
interpretations of the term "ladder line" seem to be out there.
73, Bob - W3YY
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Rob Atkinson, K5UJ
Sent: Thursday, April 19, 2007 10:54 PM
To: towertalk@contesting.com
Subject: [TowerTalk] ladder line
First, let's make sure we're talking about the same thing:
Ladder Line = Parallel wire line spaced every 12 to 18 inches with ceramic
or plastic spreaders. Usually wires are 3 inches apart. Z = 600 to 800
Ohms.
Window line = Parallel wire line encased in plastic to make a flat plastic
strap that has rectangular holes cut in it between the wires. Wires are
usually 1 or 1 1/4 inch apart. Z usually 450 ohms.
Open wire feedline = Parallel wire line with no spacers, wires usually taut
and suspended and held by pole supports and tower standoffs holding
insulators the wires pass through. Z depends on space between wires and
wire gauge.
I solved the lighning problem (I hope, and I hope I never get tested) by
putting banana plugs on the ends of my ladder line wires and banana jacks in
my basement window where the line enters. When I'm not operating I pull the
outside line out of the jacks and away. This works for me because I don't
do any activity that requires operating during thunderstorms. there's a
photo of this on my qrz.com page.
rob / k5uj
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