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Author Topic: How do you manage extra twin lead  (Read 999 times)
K7NHB
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Posts: 230




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« on: April 21, 2013, 01:18:27 PM »

A lot of twin lead setups I've seen or read about are for home situations - permanent installations. But if camping, the QRP rig might be positioned anywhere from 15 feet to 45 feet from the antenna. I'm hoping to use a "generic" delta loop with twin lead to a 4:1 balun to a tuner - or maybe it will be cut for 20M and I'll take what else I can get.

But how do you manage the extra twin lead. I've been told not to lay it on the ground if I can help it and I've been told not to coil it. I suppose I could cut various lengths, like 15 ft and 25 ft, and connect them with some kind of plug or clip when longer lengths are needed.

What is the best way to deal with any extra length?

Thank you and 73,
Paul
K7NHB
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WB2EOD
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Posts: 219




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« Reply #1 on: April 21, 2013, 02:07:13 PM »

Before you trim twin lead, remember that when using balanced feed line, the length may be critical. 
I don't recall the exact numbers, but for given band(s) certain lengths must be avoided. 
If you trim your twin lead and the new length lies in one of these "forbidden zones", you may find yourself unable to tune the antenna

73
WB2EOD
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K2DC
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Posts: 1385


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« Reply #2 on: April 22, 2013, 07:03:13 AM »

Paul,

   You're already aware of the two cardinal rules for managing balanced feed line that's in use - don't tightly coil it, and don't lay it against anything.  Beyond that, the number of ways to manage the length are only limited by your imagination.  For one thing twisting the feedline makes it more stable in the wind, and the tighter you twist it the shorter it gets.  You might also be able to coil it very loosely, in some manner that doesn't allow the turns to come close to each other.

73,

Don, K2DC
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WB6BYU
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Posts: 13576




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« Reply #3 on: April 22, 2013, 08:19:13 AM »

I would just hook it over a tree branch or tie it off at an angle with a piece
of string to take up the slack and keep it from hanging on the ground.

But that is one reason that I switched to RG-174 coax for my backpack
portable operation - I don't worry about it laying on the ground, and I don't
need to carry a tuner with me.
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N4CR
Member

Posts: 1702




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« Reply #4 on: April 22, 2013, 02:28:05 PM »

Run a messenger string between the two end points. Run the messenger through the balanced line and let it hang like a roller coaster or sine wave. Should be easy to collapse it to 1/3 it's normal length like this.
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73 de N4CR, Phil

Never believe an atom. They make up everything.
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