Tektronix Telescope 1502C Uživatelský manuál stáhnout pdf (Strana 34)

Operating Instructions

1–16

1502C MTDR User Manual

ac 452.000 ft

Open

Figure 1–11: 455-ft Cable

5. Change DIST/DIV to 20 ft/div. The entire cable can now be inspected in

detail on the LCD. Turn the

POSITION control so the cursor travels to

the far right side of the LCD. Keep turning and the cable will be “dragged”

across the display.

ac 452.000 ft

Short

Figure 1–12: 455-ft Cable

A “rise” or “fall” is a signature of an impedance mismatch (fault). A dramatic

rise in the pulse indicates and open. A dramatic lowering of the pulse indicates a

short. Variations, such as inductive and capacitive effects on the cable, will

appear as bumps and dips in the waveform. Capacitive faults appear as a

lowering of the pulse (e.g., water in the cable). Inductive faults appear as a rising

of the pulse (e.g., fray). Whenever an abnormality is found, set the cursor at the

beginning of the fault and read the distance to the fault on the distance window

of the LCD.

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Tektronix Telescope 1502C Uživatelský manuál Strana 34