[TenTec] OT: coax versus parallel wire

[Stuart Rohre]

Remember that the amount of insulation to wire ratio increases the loss 
of a transmission line.  Thus, coax being dense insulation has higher 
loss than ladder line, with sparse plastic.   The loss tangent of the 
rubber or plastic dielectric material is the penalty you have to be 
concerned about.

Zip cord is closer to 102 ohms Impedance, for many types.   It is 
believed here that the ARRL loss factors for zip cords were for colored 
PVC or even colored Rubber types.  Colorant may increase losses, 
depending on its metal derivation, or carbon derivation.  Zip cord 
spacings and wire diameters vary widely for various types.  Clear 
speaker cable might make a good zip cord antenna material, rather than 
the rubber zip cords.

Ten Tec content:   Black cased Ten Tec radios need to be protected from 
direct sun exposure at Field Day, or they could overheat.  Same for any 
dark radio case.  Once we had a tuner, (Tokyo High Power) that detuned 
itself by mid afternoon at Field Day.  Placing a hand on the dark case 
told me it had sat in the sun.  Retuning was successful.  Apparently, 
the coil turns spacing changed as the tuner heated up.

Stuart
K5KVH