Dave,
Why should that calculator be correct?
Second, why not measure the Zo with the nano? in combo with the 1/8 lambda trick or 1/4 lambda + SmithChart trick?
73
Arie PA3A
Op 25-2-2021 om 23:58 schreef David Eckhardt:
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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 ?H Calc Zc: 318 ohms 4.85 pF / Ft
2.6 MHz 32.4 pF 3.07 ?H 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 ¦År of 0.91, the physical parameters indicate Zc more like 430 to
440 ohms
using the calculator at:
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?
Arie Kleingeld PA3A