Tektronix 1502C 4. Offset/Gain Check, 5. Sampling Efficiency Check

Appendix B: Operator Performance Checks
1502C MTDR User Manual B–7
7. Press MENU again.
8. Using the n
o POSITION control, select Noise Diagnostics.
9. Press MENU again and follow the instructions on the display.
10. Exit from Noise Diagnostics, but do not exit from the Service Diagnostic
Menu yet.
If the instrument fails this check, it should not be used for loss or impedance
measurements. Send it to be serviced when possible.
1. In the Service Diagnostic Menu, select the Offset/Gain Diagnostic and
follow the directions on the display.
There are three screens of data presented in this diagnostic. The Pass/Fail level is
3% for any single gain setting tested. A failure message is displayed if the 3%
limit for any combination of gains over the three ranges is exceeded.
2. Exit from Offset/Gain 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.
4. Offset/Gain Check
5. Sampling Efficiency
Check