"ml" wrote in message
...
hi

If you buy a length of coax w/connectors on it , either a short jumper
say 3ft or a run of say 100ft


what is an easy way to test the coax as well as the quality of
termination connector quality?

accuracy is what i am looking for to ensure realibility at 1gig

"Easy" and "accuracy" may not both come in the same package. Bob Bob is
right but you could also do a swept VSWR. In my experience, it involves a
device called a network analyzer, which sweeps across the band of interest
through a directional coupler at the near end of the cable, into a dummy
load at the far end. It automatically samples the reflected power and
compares it to the forward power to produce the SWR more or less
continuously. (I believe the sweeping is done incrementally, with steps so
small it _appears_ continuous.)

The resulting info is plotted or displayed as a graph with frequency
left-to-right and VSWR up-and-down, with 1:1 being on the bottom. Some
cable is sold as being "100%" sweep tested" to some upper limit.

Last year I had a case of a Navy shipboard satcom uplink transmission line
that failed its sweep test at one spot near the upper end of the frequency
range ... around 8 GHz. We had to replace it. (AN/WSC-6, for those who know
what that is.) We had the contractor "shoot" it three different times with
different test equipment each time -- always the same. The new line was
fine. Until then, I had never seen a defective cable that was quite so
frequency sensitive!