Welcome To The Benton County Radio Operators Monthly Get Together

August 2015

WELCOME TO MEL’S DOG AND PONY SHOW I’M MEL HAGEN AF5GF

LADDER LINE TRANSMISSION WIRE

What is Ladder Line? The simple explanation is: Two parallel conductors separated by a spacer Originally the spacer was wooden dowels Today the spacer is some kind of plastic The most common ladder line today is 300 ohm television lead-in

Why Use Ladder Line? It’s cheap compared to coax Lower signal loss than coax Twin lead, as it is sometimes called, is more prone to interference than coax. Twin lead is NOT shielded. It is a balanced signal line. The current in one conductor is positive and the current in the other conductor is negative. It does not NORMALLY require a balun between it and the antenna or the transmitter. There are some situations, such as The G5RV dipole antenna, where a 6-to-1 balun is useful. It is not flat line as it has “air spaces” between the wires and looks like a ladder.

Ladder line can be found in 600, 450, 300 and 75 ohms impedance. The copper wire itself can be anything from 22 gauge to 12 gauge. The spacing and the wire gauge determines the impedance

If you’re brave enough you can order spacers on the internet and build your own ladder line using zip cord you have separated. All you have to do is follow this math formula: Open wire impedance = 276 log (2S/D) Where S is the center-to-center spacing of the wires D is the diameter of the wire used. [measure the wire only, do not include the insulation]! I suggest using a spread sheet or a slide rule.

Here is the down side Ladder line is very susceptible to metal and very long lengths For this reason you need to use stand-offs along a building Ladder line is NOT a shielded transmission line like coax

IF YOU CHOOSE TO USE LADDER LINE Anytime you use 100 feet or more of ladder line, give it one complete twist For each additional 100 feet of length, give it another complete twist This will cut down on electro magnetic interference across the line. On the good side remember, ladder line has probably the lowest signal loss, the lowest cost and the best overall SWR numbers of any transmission (and/or reception) line.

The BCRO 2-meter Repeater Is located in Centerton, Arkansas The frequency is with a negative offset of MHz and a PL tone of Please join us for our BCRO Net meeting every Thursday at 7:00 PM Please join us for our BCRO Elmer’s Net and BCRO Swap and Shop every Saturday at 11:00 AM Everyone is welcome to join us even if you have no club affiliation Our web site is:

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