Tektronix 1502C - page 28

Operating Instructions

1–10 1502C MTDR User Manual

ii. Noise Diagnostic measures the internal RMS noise levels of the

instrument.

iii. Offset/Gain Diagnostic reports out-of-tolerance steps in the program-

mable gain stage. This can help a service technician to quickly isolate

the cause of waveform distortion problems.

iv. RAM/ROM Diagnostics Menu performs tests on the RAM (Random

Access Memory) and the ROM (Read Only Memory).

v. Timebase Is: Normal - Auto Correction / Diagnostic - No

Correction. When in Normal - Auto Correction, the instrument

compensates for variations in temperature and voltage. This condition

might not be desirable while calibrating the instrument. While in

Diagnostic - No Correction, the circuits will not correct for these

variations.

b. Front Panel Diagnostics aids in testing the front panel.

c. LCD Diagnostics Menu has these choices:

i. LCD Alignment Diagnostic generates a dot pattern of every other

pixel on the LCD. These pixels can be alternated to test the LCD.

ii. Response Time Diagnostic generates alternate squares of dark and

light, reversing their order. This tests the response time of the LCD and

can give an indication of the effectiveness of the LCD heater in a cold

environment.

iii. LCD Drive Test Diagnostic generates a moving vertical bar pattern

across the LCD.

iv. Contrast Adjust allows you to adjust the contrast of the LCD. It

generates an alternating four-pixel pattern. The nominal contrast is set

internally. When in Contrast Adjust mode, VERT SCALE is used as the

contrast adjustment control. This value ranges from 0 to 255 units and

is used by the processor to evaluate and correct circuit variations caused

by temperature changes in the environment. When the diagnostic menu

is exited, the LCD contrast returns to that set by internal adjust.

d. Chart Diagnostics Menu offers various tests for the optional chart

recorder.

i. LCD Chart allows adjusting the number of dots per segment and the

number of prints (strikes) per segment.

ii. Head Alignment Chart generates a pattern to allow mechanical

alignment of the optional chart recorder.

Contents

Main Page WARRANTY Contacting Tektronix Table of Contents Page List of Figures Page Page Page General Information Installation and Repacking Unpacking and Initial Inspection Repacking for Shipment Power Source and Power Requirements Page Page General Safety Summary Safety Terms and Symbols Page Page Page Operating Instructions Overview Powering the 1502C Handling Care of the Battery Pack Battery Charging Low Battery Low Temperature Operation Preparing to Use the 1502C 1502C Tektronix Operating Instructions 161502C MTDR User Manual Display Figure 14: Display and Indicators Front-Panel Controls Menu Selections Main Menu Page Page Page Test Preparations The Importance of Vp (Velocity of Propagation) Finding an Unknown Vp Operating Instructions 1502C MTDR User Manual 113 Figure 17: Vp Set at .66, Cursor at Reflected Pulse (Set Correctly) Figure 15: Vp Set at .30, Cursor Beyond Reflected Pulse (Set Too Low) Figure 16: Vp Set at .99, Cursor Less Than Reflected Pulse (Set Too High) Cable Test Procedure Distance to the Fault Page Page Reflection Coefficient Measurements Return Loss Measurements Ohms-at-Cursor Using VIEW INPUT How to Store the Waveform Using VIEW STORE Using VIEW DIFF Page Page Using Horizontal Set Reference Page Using Vertical Set Reference Vertical Compensation for Higher Impedance Cable Page Page Additional Features (Menu Selected) Max Hold Pulse On/Off Single Sweep Page Operator Tutorial What is the Tektronix 1502C? How Does It Do It? You, the Operator Menus and Help Getting Started Page Page The Waveform Up Close Page A Longer Cable Ohms-at-Cursor Page Page Noise Page Set Ref (Delta Mode) HORZ SET REF Page VERT SET REF Page VIEW INPUT STORE and VIEW STORE Page VIEW DIFF Menu-Accessed Functions Max Hold Page Pulse On / Off Single Sweep Page TDR Questions and Answers Page Page Options and Accessories Option 04: YT-1 Chart Recorder Option 05: Metric Default Option 07: YT-1S Chart Recorder Power Cord Options Test Data Record Option Option DE Optional Accessories Accessories Standard Accessories Options and Accessories 1502C MTDR User Manual 33 Page Appendix A: Specifications Electrical Characteristics A21502C MTDR User Manual Table A1: Electrical Characteristics (Cont.) 1502C MTDR User Manual A3 Environmental Characteristics Table A2: Environmental Characteristics A41502C MTDR User Manual Certifications and Compliances (continued next page) 1502C MTDR User Manual A5 Physical Characteristics Table A3: Physical Characteristics Page Appendix B: Operator Performance Checks Equipment Required Getting Ready Power On Metric Instruments Set Up 1. Horizontal Scale (Timebase) Check Page Page 2. Vertical Position (Offset) Check 3. Noise Check 4. Offset/Gain Check 5. Sampling Efficiency Check 6. Aberrations Check 7. Risetime Check Page 8. Jitter Check Conclusions Appendix C: Operator Troubleshooting Appendix C: Operator Troubleshooting C21502C MTDR User Manual Operator Troubleshooting (with cases on) Error Messages Message: Occurrences: Meanings: Message: Remedies: Page Page Page Appendix D: Application Note Pulse Echo Testing of Electrical Transmission Lines Using the Tektronix Time-Domain Reflectometry Slide Rule Terms and Symbols Relationships VSWR vs. Percent Reflected Voltage Return Loss (dB) vs. Percent Reflected Voltage Appendix D: Application Note D41502C MTDR User Manual Percent Reflected Voltage vs. Characteristic Line Impedance Figure D3: Slide Rule 50 ohm Source +1r = W+.03r = 53.1W Appendix D: Application Note 1502C MTDR User Manual D5 Percent Reflected Voltage vs. Load Resistance Characteristic Line Impedance or Load Resistance vs. Reflection Amplitude (as seen on your TDR) Centimeters vs. Inches or Meters vs. Feet Dielectric Constant vs. Velocity Factor Time vs. Short Distances, in Centimeters or Inches Time vs. Long Distances, in Meters or Feet Page Glossary Page Page Page Page Page 1502C MTDR User Manual Index1 Index A B C D I L M N O Q R S T U