Fluke DSX-600 CableAnalyzer Troubleshooting Handbook page 14

Now let's run the HDTDR diagnostics, the results of which are shown in figure 8. First
let's find and view the worst pair which was pair 7,8. Now let's pinch and zoom on the
vertical axis to see the 1% horizontal grid lines in greater detail. Events should not
exceed 0.8% so we have drawn red lines on the diagram to make it easier to see which
and how many events pass the 0.8% lines. No more than four events maximum should
pass over the red lines. In the case we have many along the whole length of the cable
going in the positive and negative direction. This would suggest we have a cable issue
as we have many reflective events all along the cable. This would mean we would have to
replace the cable.
In figure 9, we see another Return Loss failure, but this time from the main unit or
near end. If we examine the graph we find that all four pairs fail and the failures are
especially bad at the lower frequencies. The worst Return Loss for all four pairs is at 5.4
dB with a really bad margin of -12.4 dB at 42MHz. This often suggests water in the cable.
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Figure 8
HTDR showing Return loss issues
along the whole cable
Figure 9
Return Loss failures on all pairs at
the low frequencies.