Operator Tutorial
2–81502C MTDR User Manual
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ac 362.800 ft
Cursor
Cable Scrolling
in this direction
Figure 2–9: Scrolling Down the Cable
NOTE. When testing a long cable, it is helpful to set DIST/DIV to a higher setting
when scrolling to either end of the cable. For example, if testing a 1,500-ft cable,
it would be very tiring to scroll the entire length from end to end at 1 ft/div.
Ohms-at-Cursor
Using the long cable as an example, we can find the impedance at the cursor.
1. Set the 1502C front-panel controls:
CABLE available longer cable
NOISE FILTER 1 avg
VERT SCALE 500 mr
DIST/DIV 50 ft (25 m)
Vp .66 (or whatever your cable is)
2. Press MENU.
3. Scroll to Setup Menu and press MENU again.
4. Scroll to Ohms at Cursor is: Off and press Menu. This line will then change
to Ohms at Cursor is: On.
5. Press MENU repeatedly until the instrument returns to normal operation
mode.
6. Turn the
n
o
POSITION control to set the cursor near the end of the cable as
illustrated (see Figure 2–10).
In our example, you see the distance reading is 408.000 feet and the
ohms-at-cursor is 59.5 W. The ohms-at-cursor tells you that the loss in the
cable results in an impedance measurement of 59.5 W. You may then assume