Tektronix 1503C, User Manual, Page: 98 / 128

Appendis B: Operator Performance Checks
B–6
1503C MTDR User Manual
There are three screens of data presented in this diagnostic. The Pass/Fail level is
3% for any single gain setting tested.
2. Exit from Offset/Gain Diagnostic, but do not leave the Service Diagnostic
Menu yet.
If the instrument fails this check, it should not be used for loss or impedance
measurements.
1. In the Service Diagnostic Menu, select the Impedance Diagnostic and follow
the directions on the screen. Passable tolerances are:
50 47.0 to 50.0
75 71.0 to 75.0
93 88 to 93
125 118 to 125
2. Exit from the Impedance Diagnostic, but do not leave the Service Diagnostic
Menu yet.
If the instrument fails this check, the waveforms might not look normal. If the
efficiency is more than 100%, the waveforms will appear noisy. If the efficiency is
below the lower limit, the waveform will take longer (more pixels) to move from
the bottom to the top of the reflected pulse. This smoothing effect might completely
hide some faults that would normally only be one or two pixels wide on the display.
1. In the Service Diagnostic Menu, select Sampling Efficiency and follow the
directions on the screen.
2. When done with the test, press the MENU button repeatedly until the instrument
returns to normal operation.
If the aberrations are too large, they can be confused with minor faults in the cable
near the instrument.
1. Turn the
n o
POSITION control counterclockwise until the display distance
window reads less than 20.00 ft (6.10 m).
2. Set the DIST/DIV control to 1 ft/div (0.25 m/div).
5. Impedance Check
6. Sampling Efficiency
Check
7. Aberrations Check