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


thanks

Easy way to gte a rough idea is to measure the power of your TX at the
TX output, then connect the coax and measure the power at the end of it.
The loss/diff should be a published figure that is frequency dependent.
If the loss exceeds the published number you have to suspect the
cable/connectors.

Cheers Bob

ml wrote:

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

"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!

Something else possibly interesting

I use to work for a company that amongst other things installed mobile
phone base systems. One of the mandatory tests was to sweep the coax
from the TX end after it had been terminated to the antenna. Return loss
(SWR) was the major criteria for the test pass but it also showed the
location of the impedance discontinuity. (ie in metres from the
feedpoint) In most cases this was a cable indentation where it wasnt
unwound from the drum carefully, or where the coiled stuff had been laid
down flat instead of being kept vertical. (ie was distorted by its own
weight) We did have a few cases however where the inside of the inner
core had slight amounts of corrosion causing the problem. This was
commonly LDF4-50 or LDF5-50 (foam coax a little less and a little more
than 1" dia and had an inner core "pipe" with an inside air space.

Cheers Bob


Sal M. Onella wrote:

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!

In article NrIpg.833$lv.144@fed1read12,
"Sal M. Onella" wrote:

"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!

just wanted to thank everyone for the responce,
i wish i had a network analyzer(wasnt that for pc's?) or an coax/ant
analyzer
however easy wasn't ment to mean common tools that a ham might have

i want to buy some used coax to taking adv of price but i need to test
it,


tnx