To measure a cable's impedance yourself would be fairly complex. Look for
an types of numbers on it to see if you can identify it from catalogue
listings.
The impedance is determined by the type of dielectric material that the
centre conductor is passing through and the shielding is around, and the
distance between the centre conductor and shield. The gauge of the centre
conductor, and outside diameter is also a determining factor.
By doing precise physical measurement, knowing the types of materials
involved, and the type of alloys used in the composition of the conductors,
a mathematical model of the characteristics of the cable can be determined.
This is very complex, and would not be accurate in all practicality for you
to determine.
The best way would be to use a cable network analyser, or to use a sweep
signal generator and oscilloscope, with a RCL matching network to determine
the impedance curve over a range of frequencies. From this the actual
impedance can be determined.
Accurately measuring the characteristics of any type of cable or wire can
turn out to be a complex and expensive ordeal.
If your piece of cable is from a cable TV distributor, or from a video
distribution system, it is most likely a 75 ohm cable. If it is from an
older Ethernet system, it is probably a 150 ohm cable. If it is from the
antenna system used on communications radio, it is most likely a 50 ohm
cable.
--
Greetings,
Jerry Greenberg GLG Technologies GLG
=========================================
WebPage
http://www.zoom-one.com
Electronics
http://www.zoom-one.com/electron.htm
=========================================
How do I determine the impedance of a length of coax that I have?
I don't imagine an ohmmeter will do it?
P