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Skywave · 9th Oct 2018, 10:07 pm

Astral: my response to your Q. above.

Occasionally, I need a length of co-ax: could be anything between 3 to 4 feet or a much longer run to feed a TV signal from a distribution amp. to another room in a house, for example. Over the years, I have accumulated quite a collection of co-ax cables: some off-cuts; some salvaged from equipment; some from where and when I can't remember! (Yes, all kept in the dry!) But the point is this: sometimes there are no identifying markings of the sheath of a cable. Although 75Ω co-ax is usually thicker than 50Ω co-ax, can't always rely on that. And as I am sure you know, there are usually good reasons for choosing a cable with the appropriate Zo. And my suggested technique, even if does require an instrument or two, is quick, simple and reliable.

Al.

9th Oct 2018, 10:07 pm	#21
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Determining Zo for coax cable Astral: my response to your Q. above. Occasionally, I need a length of co-ax: could be anything between 3 to 4 feet or a much longer run to feed a TV signal from a distribution amp. to another room in a house, for example. Over the years, I have accumulated quite a collection of co-ax cables: some off-cuts; some salvaged from equipment; some from where and when I can't remember! (Yes, all kept in the dry!) But the point is this: sometimes there are no identifying markings of the sheath of a cable. Although 75Ω co-ax is usually thicker than 50Ω co-ax, can't always rely on that. And as I am sure you know, there are usually good reasons for choosing a cable with the appropriate Zo. And my suggested technique, even if does require an instrument or two, is quick, simple and reliable. Al.