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Allodoxaphobia[_2_] Allodoxaphobia[_2_] is offline
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Default Coax cable calculation

On Tue, 10 Apr 2018 08:11:37 -0700, Jeff Liebermann wrote:
On Tue, 10 Apr 2018 16:42:43 +1000, Trevor Wilson
wrote:

Here's a question that stumped me back in the old slide rule days:

A coaxial cable, having an inner diameter of 0.0254mm (0.001") and using
an insulator with a dielectric constant of 2.56, is yo have a
characteristic impedance of 2,000 Ohms. What must be the outer conductor
diameter?


https://www.rfcables.org/coax-calculator.html
- Select inches.
- Plug in any number for outside dia (D) trial an error.
- Plug in 0.001 for inner diameter (d).
- Plug in 2.56 for permittivity (er) (same as dielectric constant
in this example).
- Punch "calculate"

I used 1,000,000 inches for outside diameter and still obtained only
776 ohms. 1,000,000,000 inches yielded 1035 ohms. I don't think it's
going to make it to 2,000 ohms unless the coax cable is absurdly huge.


Almost sounds like an OLD ("slide rule") homework problem....

Jonesy