How to measure length of a coaxial cable?

Question

If I need to determine distance to an open in a cable how can I do that?

Answer 1

It's called a Time-Domain Reflectometer, not to be confused with a Frequency-Domain Reflectometer that serves a similar function.  It's an expensive device to pinpoint faults within an otherwise inaccessible cable to minimize search and repair.  These days, with cheap digital circuitry, it's possible to build your own device to be used in conjunction with a good oscilloscope.

If it's a one-time operation or repair, such a device isn't really worth it.  Something that's more practical for companies that make a living out of repairing such problems on a daily basis with many clients.

If there is an open in the cable, no matter what length it is, you're going to end up cutting it, anyway.

Answer 2

it says it on the cable cutting tool. Its different for every type of coaxial cable. So it all depends on the type you have to cut

http://www.satcure.co.uk/tech/fconn.htm

Answer 3

Without a TDR as Percival said, you cannot do it.

In the USAF we used those to troubleshoot coax cables buried in miles of wiring inside the aircraft.  Very cool test instrument.