On 11/04/2018 8:10 AM, Allodoxaphobia wrote:

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....
**Correct. It was.

I thought someone would have come up with an answer before now. It's not

an overly difficult calculation.

--

Trevor Wilson

www.rageaudio.com.au