Operation Manual

Diagnosing Copper Cabling Faults
Common Causes of Copper Cabling Failures
6-5
6
Table 6-1. Diagnosing Twisted Pair Test Failures (cont.)
Return loss gives FAIL, FAIL*, or PASS* result
• Patch cord or cable impedance not 100 Ω
• Patch cord handling causing changes in impedance
• Excessive amount of cable jammed into outlet box
• Tight service loops in telecommunications closet
• Excessive untwisting of pairs at connector
• Poor quality connectors
• Cable impedance not uniform (poor quality cable)
• Mismatches in cable construction (such as cable from
different manufacturers)
• Water in cable jacket
• Cable compression (tight cable ties, pinches, kinks, etc.)
• Poorly matched plug and jack (6A/Class E
A
applications)
• Wrong test standard selected
• Defective link interface adapter
Tip:
The HDTDR test in Single Test mode features a
scanning function that runs the HDTDR test
continuously. This function can be helpful for locating
return loss faults caused by tight loops and cable
compression. See page
6-10.
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