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Ladder Line Building Pass-Through with Twin-Coax RG-8 2 - August - 2008

Posted by k9zw in Amateur Radio, K9ZW Learned, K9ZW Operations.
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Several older publications mention an interesting way to pass Balanced Line Ladder Line Feed in through a building’s wall and near otherwise interfering objects using a Twin-Coax RG-8 Pair system.

Two lengths about 20 ft each of RG-8

Tape the two lengths solidly together, in the fashion of ladder line, with tape wrappings every 6 inches.

Outside end is cut back so the center conductor is free to solder to one side of the Ladder Line.

The evenly cut off outer-casing, braid shield, and dielectric are sealed against weather & water with Non Conductive caulk, tape or compound.

At the tuner end, again cut back so the center conductor is free to have a connecting lug soldered on.

In this case the outer-casing is cut back so both braids can be soldered together, and a ground strap soldered to the resulting shield.

The sources suggest grounding the shield to the antenna tuner’s ground lug (which you have already hooked station ground, right?).

Will be giving this a try working to fight some fairly rough station RFI issues at a friend’s shack.

Would very much appreciate hearing anyone else’s experiences doing a twin-coax balanced feed-line pass-through.

 

73

Steve
K9ZW

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Comments»

1. Chuck Shinn W7MAP - 11 - August - 2008

I used this method for about 5 feet. I tied the shields to ground on the rear apron of my BT1500A tuner to try to avoid some dsl traffic noise in my own shack. I can’t say it reduced my noise any. My noise is very low. It is just bearly audible on 14029 or thereabouts-this due to a large amount of installed Mix 31 ferrite on my router/modem/power warts etc etc all over my house. I was trying to bust the last little bit but no joy.
You asked elsewhere about vna usage.
I am using
a W5BIG Array Solutions AIM 4170 with great success.
See my blog at w7map/wordpress.

Best, Chas

[ edit - W7MAP's full URL is http://w7map.wordpress.com - Steve K9ZW ]


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