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Figure 2 shows examples of these failures for Cat 6 patch cords. The plot on the left
shows results from a patch cord made with bad cable. The plot on the right shows
results from a cord with a bad plug.
Low-frequency return loss failure
caused by bad cable
Figure 2. Return Loss Failures at Low and High Frequencies (Cat 6 patch cords)
NEXT Failures
NEXT failures are typically caused by the following:
•
Excessive untwisting of pairs at plug. Most NEXT failures occur at plugs, where the
twist in the wire pairs is interrupted.
•
Poor quality plug
•
Poor quality cable
•
Poorly matched plug and jack (Cat 6/Class E applications)
•
Cable compression (pinches, kinks, etc.)
•
Excessive noise source near cabling under test. Use the impulse noise test to check for
noise.
•
Wrong test limit selected
Patch Cord Test Results
High frequency return loss failure
caused by a bad plug
bal25.eps
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