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Old August 25th 04, 08:22 AM
Roy Lewallen
 
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Hal Rosser wrote:

I may be in error, but I THINK if you use 4 equal lengths of 75-ohm coax
with the shields soldered together - and then make them 2 'pairs' of
conductors - you'll end up with a 75-ohm balanced line. (You don't use the
shield as transmission conductors).
If I'm in error, I hope someone will correct me on this.
Thanks
Hal


Twinlead, ladder line, and other symmetrical lines are often called
"balanced" lines -- as you've done here. But it's important to realize
that there's nothing about these lines that causes the currents on the
lines to be equal and opposite (or "balanced"). Imbalanced currents
cause feedline radiation. Symmetrical lines can be unbalanced, and coax
can be balanced. To learn a little more about this, see "Baluns: What
They Do and How They Do It" in the _ARRL Antenna Compendium_, Vol. 1.

Roy Lewallen, W7EL