**David Eckhardt**2021/02/25 22:58

I was doing some modeling using SimSmith and measured values of the shack

end of my 450-foot long doublet fed with (mostly) 450-ohm window line.

I was not getting what I would expect, so I measured the Zc of a 7.17-foot

length of (claimed) 450-ohm window line. Measured values of total L and C

follow:

8.2 MHz 34.8 pF 3.51 µH Calc Zc: 318 ohms 4.85 pF / Ft

2.6 MHz 32.4 pF 3.07 µH Calc Zc: 308 ohms 4.5 pF / Ft

Measured wire center-to-center spacing is 0.85-inches

Wire is stranded AWG #16 stranded copper weld

Using an εr of 0.91, the physical parameters indicate Zc more like 430 to

440 ohms

using the calculator at: https://hamwaves.com/zc.circular/en/

So, what I have isn't 450 ohms as claimed.

REQUEST: If others have a length of this standard window line, could you

please make measurements and confirm or deny my measurement that indicate a

Zc more like 310 ohms instead of the claimed 450-ohms?

--

*Dave - WØLEV*

*Just Let Darwin Work*