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Old 25-Jul-2014, 6:21 AM   #6
GroundUrMast
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Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
I agree with tripelo, coax such as RG-6 has proven itself superior to twin-lead in applications such as down-lead and distribution. Twin-lead must be installed with care to ensure it is not too close to metal that will alter it's characteristic impedance (the exact effect of which is hard to predict, but will always be negative in terms of overall signal quality). Also, a uniform twist of about 1 to 1.5 turn per foot needs to be maintained in order to reduce the tendency for twin-lead to act as it's own antenna (which will almost always result in the signal from the real antenna being interfered with).

And as tripelo already mentioned, to install twin lead correctly, you'll need stand-off insulators to ensure that the wire stays where it supposed to be.

I would only use it as a part of a phasing harness that ties two or four identical antennas together in a ganged/stacked array.

I'd use coax for the down-lead and distribution portions of my system given that it performs well in the UHF band and has much better self shielding properties, allowing it to be run in contact with metal mast, conduit, pipe and duct work if needed.
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