[TowerTalk] Force 12 C31XR Modeling

[Jim Brown]

On 2/21/2023 9:47 AM, David Needham wrote:
> I came
> up with that the impedance of the transmission line must be about 120 ohms
> to get the approximate curves with the stock dimensions.

A pair of #12 THHN taped together is in the range of 105 ohms (two 
colors to keep track of polarity). Twisting the pair would likely raise 
Zo slightly. I see zero reason for a third conductor. With a line that 
short, I would not expect Zo to be critical.

We've often used a C3SS when operating portable for CQP and 7QP county 
activations, and found that it is very picky about chokes. It does like 
the right number of turns of #12 THHN around a 2.4-in o. d. #31 
Fair-Rite toroid.

73, Jim K9YC