I always get a kick out of it when someone mentions SimSmith. The Sim Smith
Bridge in Indiana was built in 1883.
(OK, I'm in a weird mood today.)
:-)
Zack W9SZ
On Thu, Feb 25, 2021 at 4:59 PM David Eckhardt <davearea51a@...>
wrote:
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?
--
*Dave - W?LEV*
*Just Let Darwin Work*
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