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Mohr CT100 Operator's Manual

Automated metallic time-domain reflectometers
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Operator's Manual
CT100 and CT100HF
Automated Metallic Time-Domain Reflectometers
Part No.: CT100-M-OM-004
CAGE Code: 4JEE1
Revised: August 12, 2013

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Summary of Contents for Mohr CT100

  • Page 1 Operator's Manual CT100 and CT100HF Automated Metallic Time-Domain Reflectometers Part No.: CT100-M-OM-004 CAGE Code: 4JEE1 Revised: August 12, 2013...
  • Page 2 MOHR. MOHR products are covered by U.S. and foreign patents, issued and pending. Information in this publication supersedes all previously published material. MOHR reserves the right to change product specifications or pricing at any time without notice.

  • Page 3: Warranty

    (1) year from the date of shipment. If any such product proves defective during this warranty period, MOHR, at its option, either will repair the defective product without charge for parts and labor, or will provide a replacement in exchange for the defective product.

  • Page 4: Contacting Mohr Test And Measurement

    Contacting MOHR Test and Measurement Contacting MOHR Test and Measurement Phone Phone Sales 1-509-946-0941 Technical Support 1-509-946-2240 Toll-free 1-888-852-0408 Mail Mail MOHR Test and Measurement 1440 Agnes Street Richland, WA 99352 E-mail E-mail info@mohrandassociates.com www.mohr-engineering.com...

  • Page 5: Table Of Contents

    Table of Contents Table of Contents Copyright Notice..........................ii Warranty.............................iii Contacting MOHR Test and Measurement..................iv Phone............................iv Mail..............................iv E-mail............................iv Web...............................iv General Information..........................1 Product description........................1 Battery pack and AC power requirements..................2 Options and accessories........................2 Unpacking and initial inspection....................2 Repacking for shipment.........................2 Safety Summary..........................5 Terms in the manual........................5...
  • Page 6 Preparing to use the CT100......................12 Front panel controls and connectors...................12 Rear panel connectors and switches...................15 Setting up the CT100........................16 Setting date and time.......................16 Navigating dialog boxes......................16 Display features...........................17 License codes..........................17 Menu selections and function buttons..................18 M-FUNC button........................18 SCAN button and menu......................18 SELECT button........................20...
  • Page 7 Options ............................55 Accessories ..........................55 Standard accessories (CT100)....................55 Standard high-frequency accessories (CT100HF)..............55 Optional accessories (CT100 / CT100HF)................56 Service accessories (CT100 / CT100HF)................56 Appendix A: Specifications......................57 Electrical specifications........................57 Mechanical specifications......................59 Weight............................59 Dimensions..........................59 Environmental specifications.......................59 Temperature..........................59 Certifications and Compliances....................60 EC............................60 FCC Compliance........................60 Appendix B: Subassembly Drawings and Parts List...............61 Subassembly drawings........................61...
  • Page 8 Pulse Frequency Check.......................77 Appendix D: Calibration Procedures....................79 General information........................79 Calibration interval........................79 Required equipment........................79 Getting ready..........................79 Pulse measurement checks (optional)..................80 Turn off temperature adjustment....................80 Set manual calibration values......................81 Capacitive load calibration......................81 Driver start calibration........................82 Resistive load calibration......................82 Vertical calibration........................82 Manually verify calibration values....................82 Manually verify capacitive calibration..................82 Manually verify resistive load calibration.................84 Enable temperature adjustment....................87...
  • Page 9 Figure 26: Example of an incomplete capacitive calibration............83 Figure 27: Example of a correctly set capacitive calibration............84 Figure 28: Typical trace from a CT100 with a shorting terminator applied to the test port.....85 Figure 29: Hybrid Comp adjustment with open BNC and cursor at the reflected rise....85 Figure 30: Hybrid Comp adjustment with open terminator, detail...........86...
  • Page 10 List of Tables List of Tables Electrical specifications........................57 Mechanical specifications: weight....................59 Mechanical specifications: dimensions....................59 Environmental specifications......................59 Subassemblies and parts list......................68 Cable types: Dielectric materials....................103 Cable types: RG standards......................103 Cable types: MIL-C-17 standards....................104 Cable types: Commercial designations..................105 Cable types: Twisted pair.......................105...

  • Page 11: General Information

    The CT100 is able to perform continuous sequential sampling at up to 250 kHz, continuously acquiring up to 500 full 500-point TDR traces per second. In concert with the CT100's high-speed internal 32-bit processor, this allows for rapid automated cable scans, sophisticated real-time digital filtering techniques (averaging, subtraction, derivatives, and more), and accurate characterization of transient cable defects.

  • Page 12: Battery Pack And Ac Power Requirements

    The shipping carton should have at least 200 lb. (90.7 kg) test strength. 2) Make sure the CT100 is turned off by setting the rear panel power switch to the OFF position. 3) Install the front panel cover.
  • Page 13 5) Place the CT100 in its soft case. 6) Cushion the CT100 on all sides with equal amounts of urethane foam or other firm packing material so that the instrument is centrally situated in the shipping container and there is no free space for the CT100 to move about during shipment.

  • Page 14: Safety Summary

    Safety Summary Safety Summary The safety information presented in this brief summary is only intended for operators of the CT100 and CT100HF. Safety information relating to specific circumstances is present throughout this manual and is not necessarily present in this summary. Please read this manual in its entirety before using the CT100 and take note of safety information not included in this summary.

  • Page 15: Symbols In The Manual

    AC power source AC power source The CT100 is intended to operate only from a 120 VAC or 240 VAC RMS power source using the CE- and UL-approved 24 VDC external power supply / adapter provided with the instrument. Mohr CT100 / CT100HF Operator's Manual...

  • Page 16: Grounding The Ct100

    Grounding the CT100 Grounding the CT100 When the CT100 is connected to the external AC adapter, the CT100 chassis, front panel USB, screen, and controls are grounded through the grounding conductor of the power cord. To avoid electrical shock, it is essential that the protective ground connection is present when operating the unit under AC power.

  • Page 17: Explosive Atmospheres

    Do not remove covers panels To avoid personal injury and risk of electric shock, do not open the CT100 case and do not operate unless the case is fully intact. Connecting cables to the front panel BNC Connecting cables to the front panel BNC...

  • Page 18: Operating Instructions

    Care should be taken to protect it from excessive mechanical shock, vibration, static electrical charges, and water hazards. The CT100 front panel is protected from impact by a snap-on front cover, in which an optional small-format version of the Operator's Manual can be stored. The carrying handle rotates 360°...

  • Page 19: Caring For The Battery

    However, as long as the internal pack remains fully charged, the CT100 will immediately switch to charging the external battery each time it is disconnected and a external pack is reconnected. In this fashion, a single CT100 can be used to charge several external battery packs in sequence.

  • Page 20: Batteries And Long-Term Storage

    Operating Instructions source. If green, then that source is powering the CT100. If red, then that source is being charged. Batteries and long-term storage The CT100 has NiMH internal batteries. These batteries will drain if the CT100 is left in storage over long periods.

  • Page 21: Preparing To Use The Ct100

    Preparing to use the CT100 Preparing to use the CT100 Before using the CT100, make sure you have read and understand the Safety Summary section and power requirements described in the previous sections. Then remove the front cover and turn on the power.
  • Page 22 Operating Instructions 6) MENU button. Push to display the top-level menu screen. Allows you to call up and navigate the CT100's internal menus. This button also activates on-screen help when held down while pressing other buttons. 7) VERTICAL POSITION knob. Controls the vertical position of the currently selected trace.
  • Page 23 M-FUNC button (18). 20) V1 function button. Function depends on menu. 21) V2 function button. Function depends on menu. 22) V3 function button. Function depends on menu. 23) V4 function button. Function depends on menu. Mohr CT100 / CT100HF Operator's Manual...

  • Page 24: Rear Panel Connectors And Switches

    25) 24 VDC power adapter plug. The provided 24 VDC AC adapter plugs into this port. Only MOHR-approved positive center tip, 24V adapters may be used. 26) Client USB connection. Allows the CT100 to be connected to a host computer for data transfer and PC control.

  • Page 25: Setting Up The Ct100

    Setting up the CT100 Setting date and time The date, time, and time zone must be accurately set for saved data in the CT100 to be correctly time-stamped. Change the date and time by pressing the blue (MENU) button. This calls up the Main menu.

  • Page 26: Display Features

    Display features Display features The CT100 screen holds a lot of useful information. Figure 3 shows some of the typical features you will encounter during testing. Many other features are available, however, and most of them are configurable by the user. These features are described in detail in the following sections.

  • Page 27: Menu Selections And Function Buttons

    If your CT100 has a license with pending expiration and you are unsure how to upgrade to a permanent license, please contact MOHR Test and Measurement LLC.
  • Page 28 S11 parameter. Phase Creates a new trace that shows the phase angle of the currently selected trace. This operation only applies to Fast Fourier Transform traces and S-Param traces. Mohr CT100 / CT100HF Operator's Manual...

  • Page 29: Select Button

    If the AUTOFIT button is held down for one second then released, the CT100 will vertically center the currently selected trace at the active cursor. More information can be found in the section describing the Vertical Correction menu below.

  • Page 30: Menu Button And Top-Level Menu Selections

    Use this setting for accurate measurements of short cables of less than 200 feet in length. Medium Use this setting for measurements of medium cables of less than 1000 feet in length. Long Use this setting for measurements of long cables of less than 4000 feet in length. Mohr CT100 / CT100HF Operator's Manual...

  • Page 31: Display Settings

    (internal) analog board as a calibration reference. It also serves to display to the user when the device may be running at potentially high temperatures on critically sensitive electronic components. Mohr CT100 / CT100HF Operator's Manual...

  • Page 32: Power Menu

    This toggles whether external battery information is displayed on the screen. Connections Use this menu to change the way the CT100 connects to external sources. This menu is important for setting up the CT Viewer™ software. Items within this menu need only be used if a CT100 is connected to a network via Ethernet.

  • Page 33: Network Settings

    CT Viewer™ server. Push test This item moves a single saved trace from the CT100 to a CT Viewer™ database. Push all tests This item moves all saved traces from the CT100 to a CT Viewer™ database.
  • Page 34 Use this menu to change units, Vp control, and reflection coefficient calculation method. Extra long mode Extra long mode allows the CT100 to take traces out to more than 10000 meters (33000 feet). Extra long is not as usable as other cable length modes, and some features don’t work properly.
  • Page 35 Advanced operators can use the M-FUNCTION knob to manually set vertical measurements to a known value. The adjusted value is never saved; restarting the CT100 will cancel the adjustment. When this correction is in use, automatic temperature adjustment will not correct vertical readings.
  • Page 36 The Envelope Plot system can create captures of transients, min-max envelope traces, and trace density plots. It has three options. Envelope Plot On/Off This menu option enables or disables the feature. When turned on, the CT100 begins capturing trace data and displaying the envelope plot on the screen. Reset The reset option clears the captured trace data, clears the plot on the screen, and begins drawing a new plot.

  • Page 37: Diagnostics Menu

    This option defragments the database, freeing up unused space, then turns off the CT100. For daily use this option is not necessary. Use clean shutdown only when the CT100 is plugged into a power supply. Do not shutdown the CT100 while a clean shutdown is in progress.

  • Page 38: Calibration Menu

    Jitter measures signal noise, timebase jitter, and sampling efficiency of the trace. These values are used as part of the calibration checkout for the CT100, and results of interest are explained in the manual section on calibration. A 36 in., 50 Ω test cable must be attached to the CT100 during the measurement.

  • Page 39: Software Version

    Temperature adjustment When temperature adjustment is on, the CT100 will correct measurements for temperature variations and the CT100 will from time to time pause to adjust to a new temperature. Temperature adjustment should be turned off when calibrating, except when setting horizontal calibration, in which case temperature adjustment should be turned on.
  • Page 40 Set time zone Change the time zone. Requires a reboot for changes to take effect. Daylight savings on/off Set whether the CT100 will automatically adjust for daylight savings time on the appropriate dates. Requires a reboot for changes to take effect. Time/Date Set the current date and time.

  • Page 41: Test Preparations

    With the CT100, Vp can be set in ranges between 0.25 and 1.0. See Appendix F for cable types and their estimated Vp.

  • Page 42: Find An Unknown Vp

    2) Attach the test cable to the CT100. 3) Press the AUTOFIT button. The CT100 will now show the beginning and the end of the test cable (Figure 4). Figure 4: Screenshot showing AUTOFIT result. The cable end, in this case an open termination, has been found at 3.002 feet and...

  • Page 43: Temperature Correction

    The final Vp value is the true Vp value of the cable. Temperature correction The CT100 may take control of the trace from time to time in order to adjust to changes in internal temperatures. A notice will appear on the screen during the adjustment, which may take several seconds.

  • Page 44: Figure 6: Autofit Cable

    Operating Instructions 3) Press the AUTOFIT button. The CT100 trace is now scaled to show the entire cable from beginning to end. See Figure 6. Figure 6: AUTOFIT cable. The cable termination is an open. Mohr CT100 / CT100HF Operator's Manual...

  • Page 45: Figure 7: After Adjusting The Vertical Scale

    The distance measurement to the active cursor is the distance to the fault. See Figure 8. Figure 8: A zoomed-in view of the cable fault in the previous figure, in this case a standard 50 Ω cable with a bad cut in the shielding. Mohr CT100 / CT100HF Operator's Manual...

  • Page 46: Common Types Of Cable Faults

    Figure 9: An open cable fault. The step pulse is completely reflected by the open termination of the cable. Short faults appear as a pulse downward (Figure 10): Figure 10: A short cable fault. Mohr CT100 / CT100HF Operator's Manual...

  • Page 47: Figure 11: An Open Cable Fault At 1000 Ft

    Operating Instructions Faults that are a long distance from the CT100 will show shallow reflections that are very long because the length of cable attenuates the high frequencies necessary for precise fault localization and characterization (Figure 11). Position the active cursor at the beginning of the reflection where it first deviates from the straight line trace of the cable.

  • Page 48: Reflection Coefficient Measurements

    The second and third methods rely on the relative reflection coefficient, which is a measure of the signal reflected between two points in the cable. For the CT100 this is between the passive cursor and the active cursor. The CT100 has two ways to calculate the relative reflection coefficient: 1) In Classic mode, the measurement is related to the input signal at the fault.

  • Page 49: Ohms-At-Cursor

    Note that Vp must be set accurately for the section of cable between the cursors for the CT100 to measure relative distance accurately. The pulse velocity of any part of the cable that is not between the cursors will not affect the measurement.

  • Page 50: Scan A Trace

    3.8 cm and return loss estimated at 15.5 dB. Scan a trace The CT100 can scan and save a trace into memory. Saved traces can appear on the screen in addition to the live trace. New traces can be selected by repeatedly pressing the SELECT button, and traces can be adjusted vertically independent of other traces.
  • Page 51 Figure 13: Screenshots showing selection of (A) a live trace, (B) a scanned trace that has been translated vertically using the VERTICAL POSITION knob, and (C) a trace representing the difference between the two. Mohr CT100 / CT100HF Operator's Manual...

  • Page 52: Store A Trace

    3) Select the Save option from the menu. 4) The CT100 requires a name for storage and will prompt you for one with a dialog box. 5) A dialog menu appears. Choose the menu option to show the on-screen keyboard.

  • Page 53: Load A Trace (Cable Records)

    Operating Instructions Load a trace (cable records) Cable records describe configurations used to test individual cables with the CT100. A cable record stores the Vp, tester configuration, and the scanned trace from a test of an individual cable. Use of cable records helps ensure that multiple tests of the same cable use the same tester configuration and Vp value.

  • Page 54: Storage Space

    See the CT Viewer™ manual for details. Deleting traces Once scans are backed up to a computer, they can be deleted from the CT100 either through the CT Viewer™ software or directly as follows. 1) Press the LIBRARY button to open the Library menu.

  • Page 55: View The Difference Between Traces

    5) Select Difference from the Math menu. A new trace is created that displays the difference between the base trace and the selected trace. See Figure 16. Figure 16: Difference trace. The bold trace is created by subtracting the bottom (live) trace from the top trace. Mohr CT100 / CT100HF Operator's Manual...

  • Page 56: View A First Derivative Of A Trace

    4) Select the Math menu option to open the Math menu. 5) Select the FFT menu option. The CT100 will now take a high resolution scan of the live trace between the cursors, then convert the scan into an FFT plot. This may take some time.

  • Page 57: View S-Param Trace

    Remote control only functions over Ethernet connections. It does not work when the CT100 is connected by USB only. The CT100 must first connect to the CT Viewer™ software over Ethernet. Please see the Connecting the CT100 to the CT Viewer™ software over Ethernet section of the CT Viewer™”...

  • Page 58: Cable Type

    CT100. Please consult the CT Viewer™ manual for details about starting remote control and manipulating a remote trace. Cable type The CT100 has a library of common cable types. Vp for these cable types can be loaded from the library. Load a cable type's Vp 1) Press the LIBRARY button.
  • Page 59 Vp readout on the screen when Vp 6 Sig Figs is shown on the menu. 5) When the CT100 is in Fine Vp mode, a new function, Fine Vp, is added to the M- FUNCTION knob. When the M-FUNCTION knob is set to Fine Vp, turning the knob will change the Vp value by the millionths.
  • Page 60 This position can be changed after the setup. 4) Select the Set Vert. Ref option. 5) A set of terminators, both open and short, are included with the CT100 for calibration purposes. Attach these terminators to the CT100 when prompted to do so. (For the CT100, CT100-AC-IBMM is used to open the shorting BNC.) For the short condition,...

  • Page 61: Configurations

    The CT100 allows the user to save configurations with a name. A saved configuration stores the values of all CT100 settings. A configuration can be called up by its name, restoring all settings to the values saved in that configuration. By default, the configuration load screen is displayed at start up for easy loading of configurations.

  • Page 62: Ct Viewer

    CT Viewer ™ The CT Viewer™ host computer software allows users of the MOHR CT100 and CT100HF Metallic Time-Domain Reflectometer (TDR) to transfer, view, and manipulate the cable scans that have been saved on their instruments. This software package allows the user to select scans from a stored database that can contain thousands of scans and compare, subtract, or find the first derivative of any of the traces.

  • Page 63: Options And Accessories

    Options and Accessories Options and Accessories Options Options Model CT100 — standard pulser-sampler (100 ps system risetime, 20-80%) Model CT100HF — high-frequency pulser-sampler (60 ps system risetime, 20-80%) Accessories Accessories Standard accessories (CT100) Precision BNC 36 in. 50 Ω Test Cable CT100-AC-W536 50 Ω...

  • Page 64: Optional Accessories (Ct100 / Ct100Hf)

    Impedance Matching Adapter, 125 Ohm (SMA) CT100-AC-I50125-SMA Service accessories (CT100 / CT100HF) Technical Service Manual, Printed CT100-M-TSM-xxx* Technical Service Manual, Digital w/ CT Viewer™ Installation CT100-S-CTVTSM-xxx* * xxx applies to revision number. Accessory part number is incremented per revision. Mohr CT100 / CT100HF Operator's Manual...

  • Page 65: Appendix A: Specifications

    <1 Ω to >1.5 kΩ Impedance resolution 3 significant digits Impedance accuracy ±10%, relative measurement ±2% < 1% or 1 Ω typ. Horizontal scale 0.01 m/div (0.03 ft/div) to ≥ 61 m/div (200 ft/div) (variable with pulse width) Mohr CT100 / CT100HF Operator's Manual...
  • Page 66 Overcharge protection Charging discontinues once full charge is attained. Discharge protection Instrument turns off prior to battery Software shutdown when battery damage is low. Charge capacity 2.7 Amp-hours (nominal-new) Mohr CT100 / CT100HF Operator's Manual...

  • Page 67: Mechanical Specifications

    Width w/o handle 26.2 cm (10.30 in.) Depth w/ cover 17.5 cm (6.90 in.) Depth, handle extended 27.9 cm (11.00 in.) Environmental specifications Environmental specifications Temperature Operating temperature 0°C to +50°C Non-operating temperature -20°C to +60°C Mohr CT100 / CT100HF Operator's Manual...

  • Page 68: Certifications And Compliances

    Certifications and Compliances The CT100 and CT100HF comply with all applicable EU directives. FCC Compliance CT100 and CT100HF emissions comply with FCC Code of Federal Regulations 47, Part 15, Subpart B, Class A Limits. Mohr CT100 / CT100HF Operator's Manual...

  • Page 69: Appendix B: Subassembly Drawings And Parts List

    The following drawings of the CT100 and associated mechanical and electrical subassemblies are included on the next six (6) pages: 1) CT100 full assembly, demonstrating the entire CT100 with all included subassemblies — see Figure 18. 2) CT207 power and charger subassembly — see Figure 19.

  • Page 70: Figure 18: Ct100 Complete Mechanical And Electrical Assembly

    Appendix B: Subassembly Drawings and Parts List Figure 18: CT100 complete mechanical and electrical assembly. Mohr CT100 / CT100HF Operator's Manual...

  • Page 71: Figure 19: Ct207 (Power) Subassembly

    Appendix B: Subassembly Drawings and Parts List Figure 19: CT207 (power) subassembly. Mohr CT100 / CT100HF Operator's Manual...

  • Page 72: Figure 20: Ct208 (Analog) Subassembly

    Appendix B: Subassembly Drawings and Parts List Figure 20: CT208 (analog) subassembly. Mohr CT100 / CT100HF Operator's Manual...

  • Page 73: Figure 21: Ct209 (Back Panel) Subassembly

    Appendix B: Subassembly Drawings and Parts List Figure 21: CT209 (back panel) subassembly. Mohr CT100 / CT100HF Operator's Manual...

  • Page 74: Figure 22: Ct290 (Front Panel) Subassembly

    Appendix B: Subassembly Drawings and Parts List Figure 22: CT290 (front panel) subassembly. Mohr CT100 / CT100HF Operator's Manual...

  • Page 75: Figure 23: Ct290Hf (Front Panel) Subassembly

    Appendix B: Subassembly Drawings and Parts List Figure 23: CT290HF (front panel) subassembly. Mohr CT100 / CT100HF Operator's Manual...

  • Page 76: Parts List

    Washer, internal tooth # 6 CT336 Standoff, round, thru-hole, AL, #2 X 3/16L CT338 Belleville disc spring CT339 Washer, internal tooth #8 Ferrite EMI filter SMA bulkhead connector W2W7C1 Digicomp-video PCB FFC 40 pin flat-flex 0.5mm space Mohr CT100 / CT100HF Operator's Manual...
  • Page 77 Standoff, round, thru-hole, #6X1/4L CT343 Screw, pan head, cross top, 6-32X9/16L CT327 #6 Nylon Flat Washer 0.032 THK A4/A5 Power Charger assembly CT307 Screw, pan head, cross top, 6-32x3/4L CT333 Washer, internal tooth #6 Mohr CT100 / CT100HF Operator's Manual...

  • Page 78: Appendix C: Operator Performance Check

    The CT100 and CT100HF Operator Performance Check is a series of procedures used to verify the calibration of a CT100 or CT100HF unit. The following series of checks should be performed after a unit has been newly calibrated to verify compliance to published specifications, but may also be performed to determine if it requires recalibration.

  • Page 79: Reflected Rise Time Check (10-90%)

    Reflected Rise Time Check (10-90%) Reflected Rise Time Check (10-90%) To measure reflected rise time of an individual CT100 it is important that nanoseconds and millirho are visible on the unit screen. The two units may be enabled within the Display submenu.

  • Page 80: Reflected Rise Time Check (20-80%)

    3) Select Jitter. After a moment, a results window appears with a list of measurements. The value for Jitter used in the specification for a CT100 is Jitter P2P, the second value in the second to last line of the results.

  • Page 81: Pulse Amplitude Check

    36-inch calibration cable to the CT100 front panel cable connector. A waveform should appear on the device display. Switch the CT100 into the short pulse setting from the Main menu. Measure the pulse amplitude coming off the front panel cable connector. The pulse amplitude into 50 Ωs should be between 290mv and 300mv.

  • Page 82: Sequential Sampling Rate Check

    Vertical Accuracy Check 1) Attach a 50 Ω precision terminator to the CT100. 2) Position a cursor on the trace so that it is well after the connection between the CT100 and the terminator. 3) The absolute value of the vertical measurement in mρ divided by 2000mρ full scale is the percent error for vertical measurement.

  • Page 83: Cursor Readout Resolution Check

    Resolution Check Position a cursor at a point of the trace where the vertical impedance measurement is greater than 1 ohm and less than 1000 Ohms. The CT100 should display 3 digits for this measurement. Mohr CT100 / CT100HF Operator's Manual...

  • Page 84: Vertical Accuracy Check

    Connect one end of the 36-inch calibration cable to a capable pulse measurement device and the other end of the 36-inch calibration cable to the CT100 front panel cable connector. A waveform Mohr CT100 / CT100HF Operator's Manual...
  • Page 85 Appendix C: Operator Performance Check should appear on the device display. Switch the CT100 into the short pulse setting from the Main menu. Measure the pulse frequency coming off the front panel cable connector. Repeat pulse frequency measurements for short, medium, and long pulse settings. The pulse frequency should be 250 kHz for short, 50 kHz for medium, and 12.5 kHz for long.

  • Page 86: Appendix D: Calibration Procedures

    General information General information The purpose of this procedure is to calibrate the CT100 to published specifications. Following this procedure will ensure that a CT100 or CT100HF unit will provide accurate measurements within published specifications. This procedure should only be performed if a CT100 is found to need recalibration, or is operating outside of published specifications after following the CT100 and CT100HF Operator Performance Check.

  • Page 87: Pulse Measurement Checks (Optional)

    Refer to the label attached to the 36-inch cable for a precise Vp. 4) Set the CT100 to use meters as the length unit. From the main screen press the blue MENU button. Select the Measurement submenu (Button 2). The menu item above Button 4 displays the current units.

  • Page 88: Set Manual Calibration Values

    To set the Step Pulse Reference: 1) Press Step Pulse Ref (Button 20) to display the Driver Comp Value on the CT100 screen. 2) Twist the M-FUNCTION knob until the displayed Driver Comp Value reads 10000. This will ensure the driver activation signal is timed correctly.

  • Page 89: Driver Start Calibration

    Vertical calibration Vertical calibration should be performed immediately after resistive load calibration has completed. An open attachment is required if the connector on the CT100 is a BNC. 1) If the CT100 has a BNC connector, attach the open. 2) Start vertical calibration by selecting Vertical Calibration (Button 23) from the Calibration submenu.

  • Page 90: Figure 26: Example Of An Incomplete Capacitive Calibration

    50ns point. The separation between traces is indicative of a CT100 that needs Sampler Comp adjustment. At this point, the CT100 should display the live trace diagonally across the screen. If calibration needs additional manual adjustment the live trace will appear to show a break at the 50ns point.

  • Page 91: Manually Verify Resistive Load Calibration

    Comp” appear at the top of the screen with a 5 digit number as shown in Figure 28. This trace is typical of a CT100 with the self-grounding BNC test port and/or with a shorting terminator applied. The CT100HF does not have the shorting BNC and will show an open condition at the end of the trace if a shorting terminator is not applied.

  • Page 92: Figure 28: Typical Trace From A Ct100 With A Shorting Terminator Applied To The Test Port

    The value of Hybrid Comp can be adjusted by turning the M-FUNCTION knob on the front panel. For CT100 units with the self- grounding BNC test port, a male–male BNC adapter is used to provide an open condition.

  • Page 93: Figure 31: Hybrid Comp Adjustment With The Shorting Terminator

    The horizontal scale should be 0.004 ft/div and the vertical scale should be set to 2 mρ/div to obtain maximum accuracy. Mohr CT100 / CT100HF Operator's Manual...

  • Page 94: Enable Temperature Adjustment

    To horizontally calibrate the CT100: 1) Connect the shorting cap to the front panel cable connector. 2) Set smoothing to 64 frames. 3) Position one cursor immediately before the falling edge of the live internal cable trace. Mohr CT100 / CT100HF Operator's Manual...

  • Page 95: Figure 33: Identification Of Cable Start Position

    Horizontal calibration must be set for each pulse setting. Change to the next pulse setting and repeat steps 1 through 9. Repeat again for the final pulse setting. After horizontal calibration, measure a known length of cable to verify accurate start point positioning. Mohr CT100 / CT100HF Operator's Manual...

  • Page 96: Clear Temperature Lookup Table

    After calibration is completed, it is necessary to clear the temperature lookup table used to expedite temperature calibration while the CT100 is in use. Clearing this table will force the temperature lookup table to be rebuilt using the newly calibrated values.
  • Page 97 General information General information Use this troubleshooting guide when there is a problem with a CT100 or to assist with problem identification. This will help you to determine if the instrument should be repaired or is acceptable to continue using.

  • Page 98: Appendix E: Operator Troubleshooting

    Appendix E: Operator Troubleshooting Mohr CT100 / CT100HF Operator's Manual...
  • Page 99 Main Board Test outlet with Power Board and Does the light on the working device or Fan Diagnostics power supply come on? outlet tester. Analog Operations File Finished Diagnostics Mohr CT100 / CT100HF Operator's Manual...
  • Page 100 CT100 Does the fan Replace DC in the back of the PowerSupply CT100 turn on? Does the fan Send in for in the back of the servicing CT100 turn on? Screen and Computers Diagnostics Mohr CT100 / CT100HF Operator's Manual...
  • Page 101 Does the screen start showing boot CT100 Requires messages after a moment, then load the Servicing operation screen? Do the boot messages pause on the “Time” message or show interrupt fail ? Front Panel Diagnostics Mohr CT100 / CT100HF Operator's Manual...

  • Page 102: Front Panel

    Icons indicate specific knob icons turn button or knob failures grey? RTC Diagnostics Did The Power button Press the red front panel CT100 Requires failure (monitored power button Diagnostics Screen Servicing by power panel) Disappear? Mohr CT100 / CT100HF Operator's Manual...
  • Page 103 Change the date and time CT100 Requires Servicing Choose the “OK” menu option Turn power off , Does the Reset Correct Main Board then restart the CT100 Display the Date and Time Diagnostics CT100 new time? Mohr CT100 / CT100HF Operator's Manual...
  • Page 104 Download a trace Were there any trace transfer via Ethernet (See failures? fail? CTViewer manual ) Choose the Download a test Were there any Peripheral Menu via USB (see failures? Option CTViewer manual ) Mohr CT100 / CT100HF Operator's Manual...
  • Page 105 Press the Main Menu button until the Main Menu appears Choose the “Diagnostics” menu item Choose the “Analog Diag” menu item Did “power” pass? CT100 Requires “communications” Servicing pass? Did all tests pass? Operations Diagnostics Mohr CT100 / CT100HF Operator's Manual...
  • Page 106 Is the distance Position a cursor Does it measure measurement correct to on the trace of the the correct ohms to specification? cable specification ? The CT100 File diagnostics requires servicing Mohr CT100 / CT100HF Operator's Manual...
  • Page 107 Plug a thumb drive Did the Choose the hide into a USB port on Cable Record window menu option the front disappear? Choose the Cable Diagnostics Send CT100 for Records menu Successfully servicing option Completed Mohr CT100 / CT100HF Operator's Manual...

  • Page 108: Appendix F: Vp Of Common Cables

    The most accurate way to test a cable is to determine the Vp of the cable using the CT100 and a known length of the cable you wish to test.

  • Page 109: Mil-C-17 Standards

    MIL-C-17 standards Designation (Ω) M17/2-RG6 (RG-6/U) 0.66 M17/163-00001 (RG-8/U) 0.66 M17/6-RG11 (RG-11/U) 0.66 M17/155-00001 (RG-58/U) 0.66 M17/29-59 (RG-59/U) 0.66 M17/173-00001 (RG-174/U) 0.84 M17/169-00001 (RG-178/U) 0.69 M17/094-RG179 (RG-179/U) 0.67 M17/172-00001 (RG-316/U) 0.66 M17/127-RG393 (RG-393/U) 0.66 Mohr CT100 / CT100HF Operator's Manual...

  • Page 110: Commercial Designations

    Commercial designations Designation H155 0.79 H500 0.82 LMR-200 0.83 HDF-200 0.83 CFD-200 0.83 LMR-400 0.85 HDF-400 0.85 CFD-400 0.85 LMR-600 0.87 LMR-900 0.87 LMR-1200 0.88 LMR-1700 0.89 Twisted pair Designation (Ω) CAT5 0.71 CAT6 0.71 Mohr CT100 / CT100HF Operator's Manual...

  • Page 111: Appendix G: Maintenance And Service Instructions

    Cleaning and lubrication Clean the CT100 with a damp cloth. Clean the LCD screen with Windex. Do not use any powerful solvents when cleaning the CT100. The CT100 does not require lubrication. Cleaning and lubrication interval Cleaning and lubrication interval Clean once per week, or as necessary.

  • Page 112: Inspection

    5) Use the instructions in Appendix C of this manual to perform a calibrations check. Inspection interval Inspection interval The CT100 should be inspected every 6 months. Calibration and calibration interval Calibration and calibration interval See Appendix D for the appropriate calibration interval and detailed instructions on how to calibrate a CT100.

  • Page 113: Glossary

    Higher frequencies are typically the most susceptible to attenuation. Cable attenuation can distort some TDR measurements. Attenuation is often expressed in decibels (dB) at one or more frequencies. See also dB and Return Loss. Mohr CT100 / CT100HF Operator's Manual...
  • Page 114 V is the voltage reflected back by the load. The dB vertical scale on the CT100 refers to the amount of voltage gain the instrument applies to the signal before displaying it. For example, when the instrument is amplifying the voltage by a factor of 100, this indicator would read vertical scale=20⋅log...
  • Page 115 The excitation pulse produced by a TDR and injected into the cable under test. The trace produced by the TDR is the temporally-resolved reflections produced by the cable in response to the incident pulse. The incident pulse in the CT100 is a step rise signal with a finite risetime. See Risetime.
  • Page 116 ρ ranges from -1 (short circuit) to +1 (open circuit). A reflection coefficient of zero indicates there is no impedance mismatch and no reflection of electrical energy. Reflectometer An instrument that measures reflections to determine the state of a system. The CT100 measures the reflections of electrical energy. Resistance A conductor's opposition to electrical current.
  • Page 117 Sampling Efficiency The CT100 makes measurements through a process known as sequential sampling. In sequential sampling, a succession of incident pulses followed by discrete samples progressively builds up a given TDR trace. Sampling efficiency describes the ability of the sampling circuitry to adjust to rapid changes in impedance within a TDR trace.
  • Page 118 TDR traces produced by step-rise TDRs like the CT100 describe the impedance of a cable along its length and can accurately detect a wide range of cable faults that can impair high-frequency analog/RF and digital communications systems.

  • Page 119: Index

    Cable fault............Explosive atmosphere........8 Common types........37 Fine Vp control..........50 Distance to fault........34 First derivative..........47 Open faults..........37 Floating............7 Short faults..........37 Floating ground..........7 Cable resistance correction ......51 Functional block diagram......91 Cable scans..........41 Fuses.............6 Calibration Procedures........79 Grounding............Mohr CT100 / CT100HF Operator's Manual...
  • Page 120 Options and Accessories......55 Thermal overload.........91 Panels............8 Time-Domain Reflectometry......1 Performance Check........71 Trace..............Power and charger subassembly....61 Difference..........46 Power requirements......... First derivative.........47 AC power...........2 Loading............44 External AC power adapter.......2 Selection..........41 External battery.........2 Storing.............43 Internal battery...........2 Trace scans..........41 Mohr CT100 / CT100HF Operator's Manual...
  • Page 121 Index Troubleshooting...........91 Finding an unknown........33 Troubleshooting flowchart......91 Vertical reference.........50 Units.............49 Vibration............9 Unpacking............2 Voltage standing wave ratio......40 Velocity of propagation........Water hazards..........9 AUTOFIT button........33 Water spray............9 Changing the value of......32 Watertight............9 Definition..........32 Mohr CT100 / CT100HF Operator's Manual...

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