Manuale d’uso / di manutenzione del prodotto 1502C del fabbricante Tektronix
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User Manual 1502C Metallic T ime-Domain Reflectometer 070-7169-05 This document applies for firmware version 5.04 and above. www .tektronix.com.
Copyright © T ektronix, Inc. All rights reserved. T ektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes that in all previously published material. Specifications and price change privileges reserved.
W ARRANTY T ektronix warrants that the products that it manufactures and sells will be free from defects in materials and workmanship for a period of one (1) year from the date of shipment.
Contacting T ektronix Phone 1-800-833-9200 * Address T ektronix, Inc. Department or name (if known) 14200 SW Karl Braun Drive P .O. Box 500 Beaverton, OR 97077 USA Web site www .tektronix.com Sales support 1-800-833-9200, select option 1 * Service support 1-800-833-9200, select option 2 * T echnical support Email: techsupport@tektronix.
1502C MTDR User Manual i T able of Contents General Information vii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Installation and Repacking viii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T able of Contents ii 1502C MTDR User Manual Appendix D: Application Note D – 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pulse Echo T esting of Electrical T ransmission Lines Using the T ektronix Time-Domain Reflectometry Slide Rule D – 1 .
T able of Contents 1502C MTDR User Manual iii List of Figures Figure 1 – 1: Rear Panel V oltage Selector , Fuse, AC Receptacle 1 – 2 . . . . . Figure 1 – 2: Display Showing Low Battery Indication 1 – 3 . . . . . . . . . . . . . Figure 1 – 3: 1502C Fr ont-Panel Controls 1 – 5 .
T able of Contents iv 1502C MTDR User Manual Figure 1 – 32: W aveform Display with No Outgoing Pulses 1 – 30 . . . . . . . . . Figure 1 – 33: A Captur ed Single Sweep 1 – 32 . . . . . . . . . . . . . . . . . . . . . . . . . Figure 2 – 1: Display Showing 3-ft Cable in Start-Up Conditions 2 – 3 .
T able of Contents 1502C MTDR User Manual v Figure 2 – 33: Captur ed Single Sweep of Shorted T est Cable 2 – 25 . . . . . . . . Figure B – 1: Start-up Measur ement Display B – 2 . . . . . . . . . . . . . . . . . . . . . Figure B – 2: Measur ement Display with 3-foot Cable B – 3 .
T able of Contents vi 1502C MTDR User Manual List of T ables T able i: Shipping Carton T est Strength ix . . . . . . . . . . . . . . . . . . . . . . . . T able 1 – 1: Fuse and V oltage Ratings 1 – 2 . . . . . . . . . . . . . . . . . . . . . . . . .
1502C MTDR User Manual vii General Information The T ektronix 1502C Metallic T ime-Domain Reflectometer (MTDR) is a short-range cable tester capable of finding faults in metal cable.
General Information viii 1502C MTDR User Manual Installation and Repacking Before unpacking the 1502C from its shipping container or carton, inspect for signs of external damage. If the carton is damaged, notify the carrier . The shipping carton contains the basic instrument and its standard accessories.
General Information 1502C MTDR User Manual ix T able i: Shipping Carton T est Strength Gross Weight (lb) Carton T est Strength (lb) 0 – 10 200 1 1 – 30 275 31 – 120 375 121 – 140 500 141 – 160 600 2. Install the front cover on the 1502C and surround the instrument with polyethylene sheeting to protect the finish.
General Information x 1502C MTDR User Manual.
1502C MTDR User Manual xi General Safety Summary The safety information in this summary is for operating personnel. Specific warnings and cautions will be found throughout the manual where they apply , but might not appear in this summary . For specific service safety information, see the 1502C Service Manual .
General Safety Summary xii 1502C MTDR User Manual This product is intended to operate from a power source that will not apply more than 250 volts RMS between the supply conductors or between the supply conductor and ground. A protective ground connection, by way of the grounding conductor in the power cord, is essential for safe operation.
General Safety Summary 1502C MTDR User Manual xiii T ektronix Factory Service will accept 1502C batteries for recycling. If you choose to return the battery to us for recycling, the battery cases must.
General Safety Summary xiv 1502C MTDR User Manual.
1502C MTDR User Manual 1–1 Operating Instructions Overview The 1502C front panel is protected by a watertight cover , in which the standard accessories are stored. Secure the front cover by snapping the side latches outward. If the instrument is inadvertently left on, installing the front cover will turn off the POWER switch automatically .
Operating Instructions 1 – 2 1502C MTDR User Manual REMOVE CAP TO REPLACE FUSE REMOVE CAP TO SELECT VOL TAGE V oltage Selector Line Fuse AC Power Cord Receptacle Figure 1 – 1: Rear Panel V oltage Selector , Fuse, AC Receptacle T able 1 – 1: Fuse and V oltage Ratings Fuse Rating V oltage Rating 250 V Nominal Range 0.
Operating Instructions 1502C MTDR User Manual 1 – 3 The battery pack will charge fully in 16 hours when the instrument is connected, via the power cord, to an AC power source with the instrument turned off. The instrument may be turned on and operated while the batteries are charging, but this will increase the charging time.
Operating Instructions 1 – 4 1502C MTDR User Manual Protection circuits in the charger prevent deep dischar ge of the batteries during instrument operation. The circuits automatically shut down the instrument whenever battery voltage falls below approximately 10 V .
Operating Instructions 1502C MTDR User Manual 1 – 5 Preparing to Use the 1502C Check the power requirements, remove the front cover , and you are ready to test cables. The following pages explain the front-panel controls. O F F O F F O F F O N 1 avg 500 m r ac 0.
Operating Instructions 1 – 6 1502C MTDR User Manual Display O F F O F F O F F O N 1 avg 500 m r 0.2 ft ac 0.00 ft Power T ype W aveform Cursor Front-Panel to Cursor Distance Window Selected Noise Fi.
Operating Instructions 1502C MTDR User Manual 1 – 7 Front-Panel Controls 1. CABLE: A female BNC connector for attaching a cable to the 1502C for testing. 2. NOISE FIL TER: If the displayed waveform is noisy , the apparent noise can be reduced by using noise averaging.
Operating Instructions 1 – 8 1502C MTDR User Manual upper right corner of the LCD, showing the distance from the front panel BNC to the current cursor location. 9. MENU: This pushbutton provides access to the menus and selects items chosen from the menus.
Operating Instructions 1502C MTDR User Manual 1 – 9 d. Finding Unknown Vp V alues describes a procedure for finding an unknown Vp. 4. Setup Menu controls the manner in which the instrument obtains and displays its test results. a. Acquisition Control Menu has these choices: i.
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.
Operating Instructions 1502C MTDR User Manual 1 – 11 6. V iew Stored W aveform Settings displays the instrument settings for the stored waveform. 7. Option Port Menu contains three items. T wo items allow configuration of the option port for communicating with devices other than the optional chart recorder and one item test the option port.
Operating Instructions 1 – 12 1502C MTDR User Manual T est Preparations Vp is the speed of a signal down the cable given as a percentage of the speed of light in free space. It is sometimes expressed as a whole number (e.g., 66) or a percentage (e.g.
Operating Instructions 1502C MTDR User Manual 1 – 13 The following three illustrations show settings too low , too high, and correct for a sample three-foot cable. O F F O F F O F F O N ac 3.000 ft Figure 1 – 5: Vp Set at .30, Cursor Beyond Reflected Pulse (Set T oo Low) O F F O F F O F F O N ac 3.
Operating Instructions 1 – 14 1502C MTDR User Manual Cable T est Procedure Be sure to read the previous paragraphs on Vp. 1. Set the 1502C controls: POWER On CABLE Cable to BNC NOISE FIL TER 1 avg VER T SCALE 500 m r DIST/DIV (see below) Vp (per cable) 2.
Operating Instructions 1502C MTDR User Manual 1 – 15 O F F O F F O F F O N ac 20.000 ft Short Figure 1 – 9: Short in the Cable When the entire cable is displayed, you can tell if there is an open or a short.
Operating Instructions 1 – 16 1502C MTDR User Manual O F F O F F O F F O N ac 452.000 ft Open Figure 1 – 1 1: 455-ft Cable 5. Change DIST/DIV to 20 ft/div . The entire cable can now be inspected in detail on the LCD. T urn the n o POSITION control so the cursor travels to the far right side of the LCD.
Operating Instructions 1502C MTDR User Manual 1 – 17 The reflection coefficient is a measure of the impedance change at a point in the cable. It is the ratio of the signal reflected back from a point, divided by the signal going into that point. It is designated by the Greek letter r and is written in this manual as rho.
Operating Instructions 1 – 18 1502C MTDR User Manual similar to the V ertical Compensation for Higher Impedance Cable procedure (see the VERT SET REF section).
Operating Instructions 1502C MTDR User Manual 1 – 19 The 1502C can compute and display what impedance mismatch would cause a reflection as high (or low) as the point at the cursor . This measurement is useful for evaluating the first impedance mismatch (first reflection) or small impedance changes along the cable (e.
Operating Instructions 1 – 20 1502C MTDR User Manual When pushed, the VIEW INPUT button displays the input at the front panel CABLE connector . When VIEW INPUT is turned off and no other buttons are pushed, the display will not have a waveform on it (see Figure 1 – 16).
Operating Instructions 1502C MTDR User Manual 1 – 21 The VIEW STORE button, when pushed on, displays the waveform stored in the memory as a dotted line. If there is no waveform in memory , a message appears on the LCD informing you of this. O F F ac 3.
Operating Instructions 1 – 22 1502C MTDR User Manual O F F O F F O N ac 3.000 ft O N Figure 1 – 19: W aveform Moved to T op Half of Display 2. Push STORE to capture the waveform. Remember , once it is stored, this waveform cannot be moved on the display .
Operating Instructions 1502C MTDR User Manual 1 – 23 O N ac 3.000 ft O N O N O N Stored W aveform VIEW STORE Current W aveform VIEW INPUT Difference VIEW DIFF Figure 1 – 21: Current W aveform Center , Stored Waveform Above, Difference Below Notice the VIEW INPUT waveform is solid, VIEW DIFF is dotted, and VIEW STORE is dot-dash.
Operating Instructions 1 – 24 1502C MTDR User Manual HORZ SET REF ( D mode) allows you to offset the distance reading. For example, a lead-in cable to a switching network is three feet long and you desire to start the measurement after the end of the lead-in cable.
Operating Instructions 1502C MTDR User Manual 1 – 25 O F F O F F O F F O N ac 0.000 ft D Figure 1 – 24: Cursor Moved to End of Three-Foot Lead-in Cable NOTE . Vp changes will affect wher e the r eference is set on the cable. Be sur e to set the Vp first, then set the delta to the desir ed location.
Operating Instructions 1 – 26 1502C MTDR User Manual VER T SET REF works similar to HORZ SET REF except that it sets a reference for gain (pulse height) instead of distance. This feature allows zeroing the dB scale at whatever pulse height is desired.
Operating Instructions 1502C MTDR User Manual 1 – 27 O F F O F F O F F O N ac 19.200 ft Figure 1 – 27: W aveform of Short 75 ohm Cable 2. Adjust the n o POSITION control to position the reflected pulse at center screen. 3. T urn NOISE FIL TER to VER T SET REF .
Operating Instructions 1 – 28 1502C MTDR User Manual O F F O F F O F F O N ac 1.840 ft Figure 1 – 29: Cursor Moved to Desired Position The instrument is now set to measure reflections in millirho relative to the sample cable impedance. T o measure reflections on a 50 W cable, the VER T SET REF must be reset.
Operating Instructions 1502C MTDR User Manual 1 – 29 Additional Features (Menu Selected) The 1502C will capture and store waveforms on an ongoing basis. This is useful when the cable or wire is subjected to intermittent or periodic conditions. The 1502C will monitor the line and display any fluctuations on the LCD.
Operating Instructions 1 – 30 1502C MTDR User Manual O N ac 0.000 ft O N Captured changes Figure 1 – 31: W aveform Showing Intermittent Changes 8. T o exit monitor mode, push ST ORE again.
Operating Instructions 1502C MTDR User Manual 1 – 31 6. Repeatedly press MENU until the instrument returns to normal operation. CAUTION. This function is used mostly for tr oubleshooting by qualified techni- cians. It is not r ecommended that you use the 1502C as a stand-alone monitor- ing device.
Operating Instructions 1 – 32 1502C MTDR User Manual O F F O F F O F F ac 0.000 ft O F F Figure 1 – 33: A Captured Single Sweep 8. T o exit Single Sweep is: On , access the Acquisition Contr ol Menu again, turn the Single Sweep back off, then repeatedly push MENU until the instrument returns to normal operation.
1502C MTDR User Manual 2 – 1 Operator T utorial This chapter will show , step by step, the features and uses of the 1502C. What is the T ektronix 1502C? The T ektronix 1502C Metallic T ime-Domain Reflectometer is a short range metallic cable tester capable of finding faults in metal cable.
Operator T utorial 2 – 2 1502C MTDR User Manual Getting Started Let ’ s start by inspecting a cable. For the next few examples, we will use the 3-foot precision test cable provided with the 1502C (T ektronix part number 012 – 1350 – 00). 1. Pull on the POWER switch.
Operator T utorial 1502C MTDR User Manual 2 – 3 O N ac 0.000 ft O F F Figure 2 – 1: Display Showing 3-ft Cable in Start-Up Conditions 3. The rising pulse on the left is the test pulse (incident pulse) leaving the instrument. The rising reflected pulse on the right displays the echo coming back.
Operator T utorial 2 – 4 1502C MTDR User Manual O F F O F F O F F O N ac 3.000 ft Open Figure 2 – 3: W aveform with VERT SCALE Increased Showing an Open 5. The n o POSITION control moves the waveform up and down the display . Adjust this for best viewing.
Operator T utorial 1502C MTDR User Manual 2 – 5 The W aveform Up Close It helps to know what makes up a pulse. Here is the waveform anatomy using the 3-foot test cable as an example: 1. T urn the n o POSITION control counterclockwise until the distance window reads – 2.
Operator T utorial 2 – 6 1502C MTDR User Manual O F F O F F O F F O N ac – 0.520 ft Figure 2 – 6: 3-foot Cable with Cursor at Incident Pulse 5. Adjust the VER T SCALE control to approximately 25 m r . Adjust the n o POSITION control to keep the middle portion of the pulse on the display .
Operator T utorial 1502C MTDR User Manual 2 – 7 A Longer Cable Longer cables might not fit in the display . Let ’ s demonstrate that with a longer cable. Obtain a known length of 50 W cable. For this example, we are using a coaxial cable approximately 452 feet long.
Operator T utorial 2 – 8 1502C MTDR User Manual O F F O F F O F F O N 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 scr olling to either end of the cable.
Operator T utorial 1502C MTDR User Manual 2 – 9 50 W impedance plus 9.5 W series resistance. Y ou can check this by putting a known reference on the end of the cable and measuring its impedance with ohms-at-cursor . The difference between the actual reading and the expected reference reading is the series resistance.
Operator T utorial 2 – 10 1502C MTDR User Manual O F F O F F O F F O N ac >=1 K W 578.000 ft Figure 2 – 12: Ohms-at-Cursor Beyond Reflected Pulse 9. T urn the n o POSITION control to move the cursor to the far left side of the display ( – 2.000 ft).
Operator T utorial 1502C MTDR User Manual 2 – 11 Noise On a longer cable, “ grass ” might appear on the displayed waveform. This is primarily caused by the cable acting as an antenna, picking up nearby electrical noise. 1. Set the 1502C front-panel controls: CABLE 3-ft cable NOISE FIL TER 1 avg VER T SCALE 500 m r DIST/DIV 1 ft (0.
Operator T utorial 2 – 12 1502C MTDR User Manual O N ac 40.000 ft O F F O F F O F F Figure 2 – 15: Noise Reduced 5. Increase the NOISE FIL TER setting to 128. NOTE . The higher the setting, the mor e time the instrument takes to average the waveform.
Operator T utorial 1502C MTDR User Manual 2 – 13 Set Ref (Delta Mode) Horizontal Set Reference establishes the starting point at which the distance window begins reading the distance to the cursor . If, for example, you have a 3-foot cable leading to a patch panel, you could eliminate this jumper from your distance readings.
Operator T utorial 2 – 14 1502C MTDR User Manual O F F O F F O F F O N ac 3.000 ft return FILTER to desire setting . . . Figure 2 – 18: Cursor at 3.000 ft 5. T urn the NOISE FIL TER control to 1 avg. Note that the distance window now reads 0.00 ft D .
Operator T utorial 1502C MTDR User Manual 2 – 15 This control is nearly the same as HORZ SET REF except it sets the vertical zero reference. It would be helpful to read the section of VER T SET REF in the Operating Instructions chapter to give you some technical background.
Operator T utorial 2 – 16 1502C MTDR User Manual O F F O F F O F F O N ac 0.000 ft return FILTER to desired setting ... Figure 2 – 21: VERT SCALE adjusted to Make Pulse T wo Divisions High 6. Return NOISE FIL TER to the desired setting. The vertical scale now reads 500 m r /div .
Operator T utorial 1502C MTDR User Manual 2 – 17 VIEW INPUT This push button allows you to view what is coming in the CABLE connector , or to eliminate it from the display . 1. Set the 1502C front-panel controls to: CABLE Attach 3-ft cable NOISE FIL TER 1 avg VER T SCALE 500 m r DIST/DIV 1 ft/div (0.
Operator T utorial 2 – 18 1502C MTDR User Manual This function can be used to make the display less busy when viewing stored waveforms. ST ORE and VIEW ST ORE These functions allow you to store a waveform and view the stored waveform.
Operator T utorial 1502C MTDR User Manual 2 – 19 O F F O N ac 0.000 ft O N O F F Figure 2 – 25: W aveform with Cable Shorted 7. Press VIEW STORE to view the stored waveform. What you see on the display is the waveform you stored previously with the open cable and the current waveform with the shorted cable.
Operator T utorial 2 – 20 1502C MTDR User Manual VIEW DIFF Press VIEW DIFF . This adds a waveform in the lower portion of the display that is the mathematical difference between the stored waveform and the current waveform. O N ac 0.000 ft O N O N O FF O N Difference VIEW DIFF Figure 2 – 27: Stored, Current, and Difference W aveforms NOTE .
Operator T utorial 1502C MTDR User Manual 2 – 21 Menu-Accessed Functions NOTE . If you get lost or confused while in a menu, r epeatedly pr ess the MENU button until the instrument r eturns to normal operation mode.
Operator T utorial 2 – 22 1502C MTDR User Manual 13. Press MENU again to enter normal operations mode. Note that the VIEW STORE and VIEW DIFF indicator blocks have disappeared. This tells you that both of these functions have been disabled. 14. Press STORE.
Operator T utorial 1502C MTDR User Manual 2 – 23 Y ou can probably see how this function is useful for monitoring lines for changes over a period of time, or for intermittent conditions. For example: H A coastal phone line only has problems during high tide.
Operator T utorial 2 – 24 1502C MTDR User Manual O F F O F F O F F O N ac 0.000 ft Figure 2 – 31: Display with Pulse T urned Off CAUTION. This function is used mostly for tr oubleshooting by qualified techni- cians. It is not r ecommended that you use the 1502C as a stand-alone monitor- ing device.
Operator T utorial 1502C MTDR User Manual 2 – 25 10. Press MENU repeatedly until the instrument returns to normal operation. The waveform on the display is the familiar test cable. O F F O F F O N ac 0.000 ft O N Figure 2 – 32: T est Cable 11 . Short the far end of the test cable.
Operator T utorial 2 – 26 1502C MTDR User Manual 15. T o exit Single Sweep, access the Acquisition Control Menu again, toggle the Single Sweep is: line back to Off, then push the MENU button repeatedly until the instrument returns to normal operations.
Operator T utorial 1502C MTDR User Manual 2 – 27 Q8: What is r esistance? A8: Resistance is the opposition to DC current flow , or DC voltage divided by DC current. Q9: What is impedance? A9: Impedance is the total opposition (resistance plus reactance) a circuit offers to the flow of alternating current at a given frequency .
Operator T utorial 2 – 28 1502C MTDR User Manual.
1502C MTDR User Manual 3 – 1 Options and Accessories The following options are available for the 1502C MTDR: Option 04: YT -1 Chart Recorder Option 04 instruments come equipped with a chart printer .
Options and Accessories 3 – 2 1502C MTDR User Manual T est Data Record Option This option provides the test data record obtained during the Performance V erification of the instrument and is limited to the primary characteristics of this instrument type.
Options and Accessories 1502C MTDR User Manual 3 – 3 Connector , BNC female to Dual Banana Plug 103-0090-00 Connector , BNC male to Dual Binding Post 103-0035-00 Connector , BNC male to N female 103.
Options and Accessories 3 – 4 1502C MTDR User Manual.
1502C MTDR User Manual A – 1 Appendix A: Specifications The tables in this chapter list the characteristics and features that apply to this instrument after it has had a warm-up period of at least five minutes. The Performance Requirement column describes the limits of the Characteristic.
Appendix A: Specifications A – 2 1502C MTDR User Manual T able A – 1: Electrical Characteristics (Cont.) Characteristic Supplemental Information Performance Requirement Distance Measurement Accuracy 1.6 inches or ± 1% of distance measured, whichever is greater For cables with Vp = 0.
Appendix A: Specifications 1502C MTDR User Manual A – 3 Environmental Characteristics T able A – 2: Environmental Characteristics Characteristic Performance Requirement Supplemental Information T .
Appendix A: Specifications A – 4 1502C MTDR User Manual Certifications and Compliances Category Standard or description EC Declaration of Conformity – EMC Meets intent of Directive 89/336/EEC for Electromagnetic Compatibility .
Appendix A: Specifications 1502C MTDR User Manual A – 5 Category Standard or description Pollution Degree A measure of the contaminates that could occur in the environment around and within a product. T ypically the internal environment inside a product is considered to be the same as the external.
Appendix A: Specifications A – 6 1502C MTDR User Manual.
1502C MTDR User Manual B – 1 Appendix B: Operator Performance Checks This appendix contains performance checks for many of the functions of the 1502C. They are recommended for incoming inspections to verify that the instrument is functioning properly .
Appendix B: Operator Performance Checks B – 2 1502C MTDR User Manual off, these checks must be repeated again when the instrument is powered on again. Set the 1502C front-panel controls: NOISE FIL TER 1 avg VER T SCALE no adjustment DIST/DIV 1 ft/div (0.
Appendix B: Operator Performance Checks 1502C MTDR User Manual B – 3 O N ac 0.000 ft O F F O F F O F F Figure B – 2: Measurement Display with 3-foot Cable 3. Using the n o POSITION control, measure the distance to the rising edge of the waveform at the open end of the cable.
Appendix B: Operator Performance Checks B – 4 1502C MTDR User Manual O N ac 1.360 ft O F F O F F O F F Figure B – 4: Cursor at End of 3-foot Cable, Vp Set to .30 6. Remove the 3-foot cable and connect the 50 W terminator . 7. Change the DIST/DIV to 200 ft/div (50 m/div) 8.
Appendix B: Operator Performance Checks 1502C MTDR User Manual B – 5 O F F O F F O F F O N ac – 2.000 ft Figure B – 6: Flat-Line Display at – 2.000 ft This last step has set up the instrument for the next check. If the instrument fails this test, it can be used, but should be serviced when possible.
Appendix B: Operator Performance Checks B – 6 1502C MTDR User Manual O F F O F F O F F O N ac – 2.000 ft W aveform Figure B – 8: W aveform at the Bottom of the Display If the instrument fails th.
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.
Appendix B: Operator Performance Checks B – 8 1502C MTDR User Manual If the aberrations are out of specification, the ohms-at-cursor function might be less accurate than specified. 1. Connect the 50 W precision terminator to the front-panel CABLE connector .
Appendix B: Operator Performance Checks 1502C MTDR User Manual B – 9 All the aberrations, except the one under the cursor (see Figure B – 12), must be within one division of the center graticule line from out to 10 feet (3.5 m) past the rising edge of the pulse.
Appendix B: Operator Performance Checks B – 10 1502C MTDR User Manual 3. T urn the VER T SCALE control clockwise until the leading edge of the incident pulse is five major divisions high (about 205 m r ). 4. Position the waveform so that it is centered about the middle graticule line.
Appendix B: Operator Performance Checks 1502C MTDR User Manual B – 11 Jitter is the uncertainty in the timebase. Its main effect is that the waveform appears to move back and forth a very small amount. If the jitter is too great, it will affect the repeatability of very precise distance measurements.
Appendix B: Operator Performance Checks B – 12 1502C MTDR User Manual If the instrument failed Jitter or Risetime checks, it is probably still adequate for all but extremely precise distance measurements. If it failed the Horizontal Scale check, you should not use the instrument until the cause of the failure has been identified and corrected.
1502C MTDR User Manual C – 1 Appendix C: Operator T roubleshooting For assistance in troubleshooting, use the following flow chart to determine if you have a simple problem you can fix or if the instrument needs to be sent to a T ektronix Service Center .
Appendix C: Operator T roubleshooting C – 2 1502C MTDR User Manual Preset front panel and turn the power on. Is there a greed display? YES NO Is the power source a battery? Did “ Initializing ” message appear on LCD? YES NO YES NO Check line voltage switch for correct setting and change if necessary .
Appendix C: Operator T roubleshooting 1502C MTDR User Manual C – 3 Error Messages Any time the instrument displays an error message, the troubleshooting procedures should be used to judge the extent and severity of the problem. Some errors will still permit some kinds of measurements.
Appendix C: Operator T roubleshooting C – 4 1502C MTDR User Manual At power on during initialization only . The instrument expects the pulse height to be slightly less than two major divisions high and adds gain to make the pulse exactly two divisions high.
Appendix C: Operator T roubleshooting 1502C MTDR User Manual C – 5 At power on during initialization only . The instrument changed the gain while adjusting the pulse to be two divisions high and the change in the gain circuitry did not make the expected change in the signal size.
Appendix C: Operator T roubleshooting C – 6 1502C MTDR User Manual errors, which means that no measurements should be made with this instrument before it is repaired. The instrument searches for a point on the leading edge of the pulse that is on the cable inside the instrument (about 10% up the pulse).
1502C MTDR User Manual D – 1 Appendix D: Application Note Pulse Echo T esting of Electrical T ransmission Lines Using the T ektronix Time-Domain Reflectometry Slide Rule Most people who make quantitative reflectometry tests or measurements should find the T ektronix TDR Slide Rule helpful.
Appendix D: Application Note D – 2 1502C MTDR User Manual Relationships Z O = (138 / p κ )* (log 10 D / d) for coaxial cable %= r * 100 VSWR = (1 + r ) + (1 – r ) for the case where VSWR is the same for all frequencies c = 30 cm / nanosecond = 0.
Appendix D: Application Note 1502C MTDR User Manual D – 3 NOTE . The r elationship between % holds only when the loss is a single imped- ance discontinuity with negligible capacitive or inductive components (e.g., a 75 W termination at the end of a 50 W cable).
Appendix D: Application Note D – 4 1502C MTDR User Manual Percent Reflected V oltage vs. Characteristic Line Impedance (50 or 75 ohm Source) T o find the characteristic impedance of a line, or section of a line, knowing the reflection coefficient or the %, you should first know the impedance of the pulse generator .
Appendix D: Application Note 1502C MTDR User Manual D – 5 If the reflection is downward from the 50 W or 75 W reference level, set the reference level to the top of the chosen scale. If the reflection is toward a higher impedance than the reference level, set the reference level to the bottom of the chosen scale.
Appendix D: Application Note D – 6 1502C MTDR User Manual Percent Reflected V oltage vs. Load Resistance T o find the terminating load resistance (R L ) of a line, knowing the percent reflected voltage or reflection coefficient, use the preceding instructions.
Appendix D: Application Note 1502C MTDR User Manual D – 7 Y ou should note that the peak level of any reflection that does not have a discernable plateau might be an erroneous indication of the impedance disconti- nuity that caused it. There might be several reasons for the error .
Appendix D: Application Note D – 8 1502C MTDR User Manual Dielectric Constant vs. V elocity Factor Dielectric Constant and V elocity Factor appear on two identical scales next to a sliding scale labeled ROUND TRIP TIME. T o find one, knowing the other , read across the sliding scale.
Appendix D: Application Note 1502C MTDR User Manual D – 9 Time vs. Long Distances, in Meters or Feet (any dielectric) Distances to or between discontinuities farther apart than about three meters (10 feet) can be found on the METERS and FEET scale. Use the sliding ROUND TRIP TIME scale just below it and follow the same procedure as above.
Appendix D: Application Note D – 10 1502C MTDR User Manual.
1502C MTDR User Manual Glossary – 1 Glossary Aberrations Imperfections or variations from a desired signal. In TDRs, a pulse of electrical energy is sent out over the cable. As the pulse-generating circuitry is turned on and off, the pulse is often distorted slightly and no longer is a perfect step or sine-shaped waveform.
Glossary Glossary – 2 1502C MTDR User Manual Characteristic Impedance Cables are designed to match the source and load for the electrical energy that they carry .
Glossary 1502C MTDR User Manual Glossary – 3 Impedance Mismatch A point in a cable or system where the incident electrical energy is redistrib- uted into absorbed, reflected, and/or transmitted electrical energy . The transmitted electrical energy after the mismatch is less than the incident electrical energy .
Glossary Glossary – 4 1502C MTDR User Manual means that each division is 0.5 rho (500 millirho). A pulse set to be four divisions high would make each division 0.25 rho (250 millirho). Noise Any unwanted electrical energy that interferes with a signal or measurement.
Glossary 1502C MTDR User Manual Glossary – 5 Return Loss The amount of energy reflected or returned from a cable indicates how much the impedance in the system is mismatched. The ratio of the energy sent out by the TDR, divided by the energy reflected back, expressed in the logarith- mic dB scale, is called return loss.
Glossary Glossary – 6 1502C MTDR User Manual denote changes resulting from environmental influences, such as tempera- ture, humidity , vibration, and shock. TDR An acronym for T ime-Domain Reflectometer . These instruments are also called cable radar .
1502C MTDR User Manual Index – 1 Index A AC (see Power), xii Accessories, 3 – 2 Optional, 3 – 2 Standard, 3 – 2 accessories, standard, 3 – 2 Address, T ektronix, x Altitude Spec, A – 3 B B.
Index Index – 2 1502C MTDR User Manual I Indicators, 1 – 6 Inspection, viii L List of Figures, iii List of T ables, vi Loss, 1 – 18 M Maintenance, C – 1, D – 1 Manual Changes, vii Max Hold (.
Index 1502C MTDR User Manual Index – 3 Source, viii V oltage Rating, 1 – 2 V oltage Selector, 1 – 2 V oltages, 1 – 1 Product Description, vii Product support, contact information, x Pulse, 1 .
Index Index – 4 1502C MTDR User Manual.
Un punto importante, dopo l’acquisto del dispositivo (o anche prima di acquisto) è quello di leggere il manuale. Dobbiamo farlo per diversi motivi semplici:
Se non hai ancora comprato il Tektronix 1502C è un buon momento per familiarizzare con i dati di base del prodotto. Prime consultare le pagine iniziali del manuale d’uso, che si trova al di sopra. Dovresti trovare lì i dati tecnici più importanti del Tektronix 1502C - in questo modo è possibile verificare se l’apparecchio soddisfa le tue esigenze. Esplorando le pagine segenti del manuali d’uso Tektronix 1502C imparerai tutte le caratteristiche del prodotto e le informazioni sul suo funzionamento. Le informazioni sul Tektronix 1502C ti aiuteranno sicuramente a prendere una decisione relativa all’acquisto.
In una situazione in cui hai già il Tektronix 1502C, ma non hai ancora letto il manuale d’uso, dovresti farlo per le ragioni sopra descritte. Saprai quindi se hai correttamente usato le funzioni disponibili, e se hai commesso errori che possono ridurre la durata di vita del Tektronix 1502C.
Tuttavia, uno dei ruoli più importanti per l’utente svolti dal manuale d’uso è quello di aiutare a risolvere i problemi con il Tektronix 1502C. Quasi sempre, ci troverai Troubleshooting, cioè i guasti più frequenti e malfunzionamenti del dispositivo Tektronix 1502C insieme con le istruzioni su come risolverli. Anche se non si riesci a risolvere il problema, il manuale d’uso ti mostrerà il percorso di ulteriori procedimenti – il contatto con il centro servizio clienti o il servizio più vicino.
