"John" wrote in message ...
Does coax have a shelf life?

I was rummaging around my father's garage the other day and came across a
roll of URM43 that I know to be over 20 years old. It looks OK and the
copper is shiny. However, can I be confident that it will not have lost any
of its electrical or physical properties?

1) Build, beg, borrow or buy a decent wattmeter and dummy load of the
characteristic Z of the cable.

2) Connect the output of your rig to the dummy load through the cable
to be tested. Put the wattmeter between the rig and cable to be
tested. Measure power on the highest band.

3) Move the wattmeter so that it is between the cable to be tested and
the dummy load. Measure power on the highest band (don't change
anything else!)

Difference is loss at the highest band when matched. A little math
will give you the answer in dBs.

73 de Jim, N2EY