Operating Instructions
1503C MTDR User Manual
1–13
O
F
F
O
F
F
O
F
F
O
N
ac
0.00 ft
Figure 1–8: 20-ft Cable at 5 ft/div
If the cable length is unknown, set DIST/DIV to 5000 ft/div and continue to decrease
the setting until the reflected pulse is visible. Depending on the cable length and the
amount of pulse energy absorbed by the cable, it might be necessary to increase the
VERT SCALE to provide more gain to see the reflected pulse.
The best pulse width is dependent on the cable length. A short pulse can be
completely dissipated in a long cable. Increasing the pulse width will allow the
reflected pulse to be more visible when testing long cables. AUTO will select the
pulse width for you, depending on the distance on the right side of the LCD.
CABLE LENGTH
SUGGESTED PULSE
SUGGESTED ft/div
0 to 100 ft
2 ns
10 ft/div
51 to 500 ft
10 ns
50 ft/div
501 to 5000 ft
100 ns
500 ft/div
5001 to 50,000 ft
1000 ns
5000 ft/div
When the entire cable is displayed, you can tell if there is an open or a short.
Essentially, a drop in the pulse is a short and a rise in the pulse is an open. Less
catastrophic faults can be seen as hills and valleys in the waveform. Bends and
kinks, frays, water, and interweaving all have distinctive signatures.
O
F
F
O
F
F
O
F
F
O
N
ac
0.00 ft
Short
Figure 1–9: Short in the Cable
Содержание 1503C
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