Twin lead is twinlead and coax is coax. Two entirely different types of feedline.
The first is a BALANCED line and the second is UN BALANCED line
Twinlead for TV antennas is 300 Ohm parallel conductor line, similar to the larger 450-600 Ohm "ladder line". The spacing and diamater can be plugged into a formula to calculate the impedance.
Coax is COAXIAL conductor line where the center wire is one side of the circuit and the shield or outer conductor is the other side of the circuit. Again the diameter and spacing of the conductors determine the impedance of the line. TV coax is 75 ohms and coax used in radio, Commercial and Amateur is 50 Ohms.
Originally Posted by KD8RYP
Last edited by K8JD; 05-07-2012 at 11:51 PM.
73.....JD, FISTS #3853,cc 455,SKCC # 1395,tribune #12,
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