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Glossary

Domain

A mathematical term that refers to the set of values for which a function is defined. A time-domain
instrument such as a TDR performs its function by recording measurements as a function of time.

Impedance

The ratio of voltage to electrical current in a cable or circuit.  Impedance is a frequency-dependent
value that is influenced both by resistive and reactive components.  Impedance is expressed in
terms of Ohms but should not be confused with resistance, which is a frequency independent
quantity.  Most cables have impedances that vary little over the range of frequencies with which
they are used.  Impedance is described by

Z

=

R



j

⋅

X

where R is resistance, j is the imaginary

unit, and X is the reactance at a given frequency. Also see Reactance and Resistance.

Impedance Mismatch

A point in a cable or device under test in which the characteristic impedance changes, causing a
partial reflection of the energy in a test signal. See Reflection Coefficient.

Incident Pulse

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.

Inductance

See Reactance.

Insulation

A coating on an electrical conductor that inhibits the flow of electricity. Insulation serves as both a
means of providing electrical safety and ensuring signal integrity.

Jitter

The uncertainty in measurement of time in a TDR, causing a particular voltage sample to be
misregistered slightly with respect to time. The main effect of timebase jitter is to cause apparent
vertical noise in areas of changing impedance. Areas of constant impedance, such as a flat
segment of 50 Ω cable, will show no abnormality.

LCD

Liquid crystal display. The display used by this instrument is an active-matrix thin-film transistor
LCD, abbreviated TFT-LCD.

Millirho

See Reflection Coefficient.

Mohr CT100 / CT100HF Operator's Manual

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Summary of Contents for 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: ...stributed transmitted displayed published or broadcast in any form or medium by any other party without written permission from 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 MOHR Test and Measureme...

Page 3: ...nd its vendors disclaim any implied warranties of merchantability or fitness for a particular purpose MOHR s responsibility to repair or replace defective units is the sole and exclusive remedy provided to the customer for breach of the Warranty MOHR and its vendors will not be liable for any indirect special incidental or consequential damages irrespective of whether MOHR or the vendor has advanc...

Page 4: ...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 USA E mail E mail info mohrandassociates com Web Web www mohr engineering com iv ...

Page 5: ...Terms in the manual 5 Terms on the product 5 DANGER 5 WARNING 5 CAUTION 5 Symbols in the manual 6 Symbols on the product 6 Static charge 6 Fuses 6 AC power source 6 Grounding the CT100 7 Danger arising from loss of ground 7 Explosive atmospheres 8 Do not remove covers or panels 8 Connecting cables to the front panel BNC 8 Battery replacement and disposal 8 Operating Instructions 9 Overview 9 Handl...

Page 6: ...gation 32 Change Vp 32 Find an unknown Vp 33 Temperature correction 34 Cable test procedures 34 Distance to fault 34 Common types of cable faults 37 Reflection coefficient measurements 39 Return loss measurements 39 Ohms at cursor 40 VSWR 40 Relative distance measurements 40 Scan a trace 41 Select a trace 41 Store a trace 43 Load a trace cable records 44 Storage space 45 View the difference betwee...

Page 7: ...1 General information 71 Required equipment 71 Getting ready 71 Reflected Rise Time Check 10 90 72 Reflected Rise Time Check 20 80 73 Jitter Noise and Sampling Efficiency Check 73 Output Impedance Check 73 Pulse Amplitude Check 74 Pulse Width Check 74 Pulse Repetition Rate Check 74 Sequential Sampling Rate Check 75 Vertical Scale Check 75 Vertical Accuracy Check 75 Vertical Position Check 75 Input...

Page 8: ...sistive load calibration 84 Enable temperature adjustment 87 Horizontal calibration 87 Clear temperature lookup table 89 Appendix E Operator Troubleshooting 91 General information 91 Power on test 91 Functional block diagram and troubleshooting flowcharts 91 Appendix F Vp of Common Cables 103 Cable types 103 Dielectric material 103 RG standards 103 MIL C 17 standards 104 Commercial designations 10...

Page 9: ...ivative plot 47 Figure 18 CT100 complete mechanical and electrical assembly 62 Figure 19 CT207 power subassembly 63 Figure 20 CT208 analog subassembly 64 Figure 21 CT209 back panel subassembly 65 Figure 22 CT290 front panel subassembly 66 Figure 23 CT290HF front panel subassembly 67 Figure 24 Trace preparation for rise time measurement 72 Figure 25 Cursor placement for determination of 10 90 rise ...

Page 10: ... 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 x ...

Page 11: ...nts particularly valuable for troubleshooting modern high frequency analog RF and digital communications systems 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...

Page 12: ...ding an Operator s Manual front panel cover external AC adapter and power cord soft transit case and calibration fixture s If the shipping container is intact but there are missing items or if the CT100 is damaged defective or does not meet operational requirements contact a MOHR authorized sales representative Repacking Repacking for shipment for shipment When the CT100 needs to be shipped to a M...

Page 13: ...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 7 Seal the container with packing tape Mohr CT100 CT100HF Operator s Manual 3 ...

Page 14: ...summary Terms in the manual Terms in the manual WARNING Refers to conditions or practices that could result in personal injury or loss of life CAUTION Refers to conditions or practices that could result in damage to this product or other products and in some cases could void the Warranty Terms on the product Terms on the product DANGER Indicates an injury hazard immediately accessible as you read ...

Page 15: ...internal automatic thermal breakers that disconnect the power from the charger and battery to the rest of the system These thermal breakers make an audible click when they actuate One of the circuit breakers automatically resets after time When this breaker cools the CT100 can be restarted There is also a breaker on the CT207 subassembly A4 charger board If tripped this breaker must be reset by ta...

Page 16: ...nnector is floating and is isolated by at least 500 VDC from the remainder of the CT100 This eliminates measurement errors caused by common mode noise and slight ground potential differences in the the cable device under test However care should be taken with respect to electrical safety as the front panel BNC shield is never safely grounded unless connected to a safely grounded cable or device an...

Page 17: ...ct to transient voltage spikes WARNING and CAUTION The instrument should never be used to test any cable or device carrying live electrical signals as this carries a risk of electric shock This could also damage the sampling electronics and will void the Warranty CAUTION Always properly ground the conductor s of any cable or wiring to remove any static charge prior to connecting it either directly...

Page 18: ...Failure to do so could damage the sampling electronics and void the Warranty The CT100 can be stored in temperatures of between 20 C to 60 C with or without a battery installed and can be operated from 0 C to 50 C Powering the CT100 The CT100 can be powered through the included 120 240 VAC RMS to 24 VDC external power adapter This adapter has sufficient capacity to charge the internal battery from...

Page 19: ...external battery pack is connected and fully charged the CT100 will return to trickle charge the internal battery pack 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 sequ...

Page 20: ...le during storage make sure the power switch on the back of the CT100 is set to the OFF position After several months of storage the internal batteries may be completely drained Allow up to 24 hours for the first re charge of the CT100 after coming out of long term storage Low battery When a low battery condition is first encountered the CT100 alerts the user with a red warning An Internal Battery...

Page 21: ...panel diagram below Figure 1 1 POWER button Pressing this button turns the instrument on when the main power switch on the rear panel is in the ON position Pressing the POWER button when the unit is on will turn the unit off If you have any unsaved traces the unit will verify if you really wish to power down If the POWER button is held in for several seconds the unit will turn off regardless 2 H1 ...

Page 22: ...ust be drained from the cable to be tested prior to connection to the BNC connector 11 This is done by shorting the center conductor of the cable to the sheath ground return If this procedure is not followed the sampling electronics can be damaged and you will void the Warranty 12 Host USB port This USB V1 1 connection can be used to interface to a client USB device such as a barcode reader keyboa...

Page 23: ...ition the active cursor over the location of interest and expand the scale to zoom in 18 M FUNC multifunction button The function of the M FUNCTION knob 19 is set by this button The current operation is displayed on the screen 19 M FUNCTION multifunction knob This knob adopts the function selected through the use of the M FUNC button 18 20 V1 function button Function depends on menu 21 V2 function...

Page 24: ...n the preferred battery is detected to be at full charge 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 27 RJ 45 Ethernet port This is a 10 100 Mb Ethernet port that can be used for data trans...

Page 25: ... Select the Time Date menu option A dialog box used to set the date and time appears See the next section for methods of navigating and entering data into a dialog box Press the OK menu option when the correct time and date have been entered Navigating dialog boxes Scroll through the different entry boxes with the M FUNCTION knob With an entry box selected press the Keyboard menu option to call up...

Page 26: ... 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 License codes License codes Each CT100 requires a unique license code to operate Without the correct code menus and buttons still function but there will be no live trace displayed on the screen ...

Page 27: ...knob screen function indicator The M FUNC button has no effect if another function has captured the M FUNCTION knob see descriptions of functions below SCAN button and menu Use this button and the associated Scan and Trace menu to initiate and modify cable scans Save Saves the selected trace to flash memory scanned traces only Hide Removes selected trace from screen but does not delete from flash ...

Page 28: ...race that is the first derivative of the currently selected trace FFT Creates a new trace that is the Fast Fourier Transform of the currently selected trace using the data that lies between the cursors The FFT is transformed using settings from the FFT settings submenu FFT settings Window Selects the data window that is applied after padding the data but before the Fast Fourier Transform Size Sele...

Page 29: ...ld 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 CURSOR Toggles between cursors making the active cursor inactive and the inactive cursor active Pressing and holding the CURSOR button for one second then releasing will move any cursors no...

Page 30: ...ustom mode scans MENU button and top level menu selections If no menu is displayed MENU loads the main top level menu If the top level menu is displayed it closes the menu If a submenu is displayed it displays the parent menu Top level menu selections are listed below Holding down the MENU button while pressing any button or the M FUNCTION knob will display a help dialog for that button s current ...

Page 31: ...ays on or off Change screen profile This item switches between white black and slate grey color schemes Horiz vert ruler This item toggles the horizontal and vertical measurement rulers on and off The rulers make judging trace values simpler but also take up a lot of screen area Noise value This items toggles the display of a noise measurement This is rarely needed except for troubleshooting and c...

Page 32: ...les between voltage or battery voltage percent left Battery charge preference charge internal external This item overrides the automatic preference for the CT100 to charge the internal battery first When selected the CT100 will charge the external battery until full before switching to the internal battery Use external on off This toggles whether external battery information is displayed on the sc...

Page 33: ...ateway optional The gateway server for the tester Nameserver1 and 2 optional DNS server the tester uses to resolve host names Nameserver2 is used if Nameserver1 fails Any changes to the network settings require a reboot to take effect DHCP on off This item enables or disables the use of DHCP on the Ethernet connection When enabled the tester will attempt to acquire network settings from a DHCP ser...

Page 34: ...ation and at the temperature for which it was created Vert ref off on This menu option will toggle on and off a vertical reference as created using the Set Vert Ref option see below Set vert ref This option requires both open and short attachments for the CT100 The CT100 will automatically calculate a vertical reference and prompt for a required open or short When a vertical reference is calculate...

Page 35: ...ength Ohms unit distance correct on off Toggle the application of the Ohms per meter correction as described above If the end point of the correction has not been set then it will be set to the position of the active cursor Set Ohms unit distance position Set the position of the Ohms unit distance position to that of the active cursor Adjust rho offset When activated the adjust rho offset option w...

Page 36: ...e reset option clears the captured trace data clears the plot on the screen and begins drawing a new plot Fill Mode On Off This menu option toggles between fill mode and density plot mode In fill mode the screen is filled in from the lowest value trace up to the highest value trace This is useful for finding rare transients and for finding the minimum and maximum envelope of the trace In density p...

Page 37: ...to a power supply Do not shutdown the CT100 while a clean shutdown is in progress Main board Access this submenu to run a variety of diagnostic memory tests Memory Run automated diagnostics on the main circuit board s memory interface Results are displayed on screen in a message box GPIO Run automated diagnostics on General Purpose IO pins connected to the main circuit board Results are displayed ...

Page 38: ... will corrupt trace data and may damage the unit Cable length selection This item is identical to the Main menu item of the same name Manual calibration menu The Manual calibration menu is for expert users only and allows manual changes of calibration values that are meant to be adjusted automatically Cable length selection This item is identical to the Main menu item of the same name Step pulse r...

Page 39: ...s position as the zero point for distance measurements This is normally the first falling edge when nothing is connected to the front cable connector second rising edge on CT100HF units Info menu This menu provides more information regarding the instrument and its installed software License info This option gives information about the license installed on the CT100 including the license date and e...

Page 40: ...tly selected trace as the base trace used by other actions in the Math menu that operate on more than one trace such as Difference Difference Creates a new trace that is the difference between the base trace see Set base above and the currently selected trace 1st derivative Creates a new trace that is the first derivative of the currently selected trace FFT Creates a new trace that is the Fast Fou...

Page 41: ...cable expressed as a fraction of c the speed of light in a vacuum 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 Change Vp The current setting for Vp appears on the lower center of the screen Press the M FUNC button until the top center information indicator reads Vp If Fine Vp is enabled from the Measurement menu two Vp indicators...

Page 42: ...length in the measurement or set one of the cursors at the end of the adapter before attaching the cable 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 4 Position the active cursor at the end of the test cable Use the HORIZONTAL SCALE knob to zoom in on the end of the cable and get an accurate placement F...

Page 43: ...able length settings At these times the correction takes somewhat longer than during normal operation The readout for temperature on the device screen also shows the last temperature at which the device performed a correction This readout will turn red when the difference between the current temperature and the temperature of last adjustment is too great Cable test procedures Cable test procedures...

Page 44: ...tions 3 Press the AUTOFIT button The CT100 trace is now scaled to show the entire cable from beginning to end See Figure 6 Mohr CT100 CT100HF Operator s Manual 35 Figure 6 AUTOFIT cable The cable termination is an open ...

Page 45: ...on the fault to get a more accurate measurement The distance measurement to the active cursor is the distance to the fault See Figure 8 36 Mohr CT100 CT100HF Operator s Manual 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 Figure 7 After adjusting the vertical scale the cable fault marked by the active cursor i...

Page 46: ...ear as a pulse upward in the trace Figure 9 Short faults appear as a pulse downward Figure 10 Mohr CT100 CT100HF Operator s Manual 37 Figure 9 An open cable fault The step pulse is completely reflected by the open termination of the cable Figure 10 A short cable fault ...

Page 47: ...ponential curves above or below the characteristic impedance of the cable depending on whether they are parallel with the conductor or represent a fault to ground Faults that are not opens and shorts may not appear at the end of the trace after pressing the AUTOFIT button but can appear anywhere along its length Any fault is likely to reduce the pulse strength and change the pulse velocity The acc...

Page 48: ...0 has two ways to calculate the relative reflection coefficient 1 In Classic mode the measurement is related to the input signal at the fault This mode is the standard most accurate way to measure the relative reflection coefficient and is the default mode 2 In Tektronix 1502C mode while the measurement is relative to the passive cursor it is scaled to the input signal at the beginning of the cabl...

Page 49: ...led RVSWR will be calculated from the reflection between the two cursors In other words VSWR is based on the millirho reflection coefficient while RVSWR is based on the RRC relative reflection coefficient calculation VSWR and RVSWR have a menu option to toggle the display of the values on screen in the Display menu Relative distance measurements The CT100 displays the absolute distance from cable ...

Page 50: ...solutions with a single scan Custom scans scan between the cursors as well but use a custom horizontal resolution that can be configured and saved A scanned trace is created with a smoothing factor as set at the time of the scan Cursor or Custom scans that cover a long distance at a high resolution may take a long time During a scan a menu will appear with a Cancel option Select Cancel to immediat...

Page 51: ... trace is active Figure 13 demonstrates this principle with three different traces 42 Mohr CT100 CT100HF Operator s Manual 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 ...

Page 52: ...bers See Figure 14 Also see Navigating dialog boxes on page 15 for more information on using the Keyboard menu Press the Select option to enter the highlighted letter into the name 7 Press the OK option from the menu when finished The trace is now stored and can be recalled later by name under Cable Records An FFT trace can also be stored with the same process However be sure to select the base tr...

Page 53: ...alues A stored trace can be loaded back to the screen 1 Press the LIBRARY button The Library menu appears 2 Select the Cable Records option An interface appears for the selection of a stored trace 3 Use the M FUNCTION knob and the menu keys to select the trace to load 4 Press the selected menu option to load the trace See Figure 15 The stored trace now appears on the screen It can be selected and ...

Page 54: ... 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 2 Select Cable Records A scroll dialog appears showing all saved trace scans 3 Highlight specific traces for deletion using the Toggle Selected option or select them all with the Mark All option 4 Select the Delete option You will have to confirm the deletion ...

Page 55: ...and choose Set Base The selected trace is now a base trace for further Math functions 4 Press the SELECT button again until the second trace is selected 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 46 Mohr CT100 CT100HF Operator s Manual Figure 16 Difference trace The bold trace is created by ...

Page 56: ...t displays the first derivative of the base trace See Figure 17 View a Fast Fourier Transform of a trace 1 Select the live trace with the SELECT button 2 Use the CURSOR button and the HORIZONTAL POSITION knob to set the boundaries for the FFT with a cursor at either end 3 Press the SCAN button to open the Scan menu 4 Select the Math menu option to open the Math menu 5 Select the FFT menu option Th...

Page 57: ...e SELECT button repeatedly 6 Choose the S Param menu item A new trace will be created that shows the selected trace divided by the base trace Calibrated S Param trace The Calibrated S Param feature is a planned software upgrade that may be included with your instrument This feature uses precision open short and 50 ohm load OSL measurements to correct for systemic errors in the pulsing and sampling...

Page 58: ...om Cable Type 2 When Add Custom Cable Type is selected a window appears for entering a cable type name a Vp for pulse velocity and an expected impedance When the window first appears Vp will be set to the current system Vp while impedance defaults to 50 Ohms The other menu option Load Custom Cable Type opens a window with all of the added user types available for selection Use the M FUNCTION knob ...

Page 59: ...Coarse Vp function Relative reflection coefficient The CT100 measures the relative reflection coefficient between cursors When the two cursors of the CT100 are positioned on either side of a change in impedance this measurement is the reflection coefficient for that change By default the value is displayed in Classic mode displaying the true reflection coefficient relative to the signal at the inp...

Page 60: ...the Vert Ref Start menu option By default the impedance value at 0 millirho is taken to be 50 Ohms This value can be changed with the Vert Ref Center Imp menu option The CT100 is now configured for impedance measurements better than 2 across a wide range of impedances The menu option at the top of the right hand side can be used to toggle the vertical reference on and off as needed for a given cab...

Page 61: ... Ohms per unit length correction until the measured impedance reads the correct value 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 ...

Page 62: ...abase that can contain thousands of scans and compare subtract or find the first derivative of any of the traces This software package will also allow the user to create reports and print plots that can be imported into MS Word or other word processing or report creation software to create files of traces suitable for transfer to others and to load trace files created by others For information on ...

Page 63: ...CTVM xxx CT Viewer Installation CD w Digital Operators and CT Viewer Manuals CT100 S CTVOM xxx Soft Carrying Case CT100 AC CS NIST Traceable Calibration with Certificate CT100 AC NISTCC Standard high frequency accessories CT100HF Precision SMA 36 in 50 Ω Test Cable CT100 AC W536S 50 Ω SMA Terminator CT100 AC ER50S BNC Capacitive Terminator CT100 AC C001 Connector SMA male to male CT100 AC ISMM Con...

Page 64: ...apter 50 Ω to 75 Ω CT100 AC I5075 Adapter 50 Ω to 93 Ω CT100 AC I5093 Adapter 50 Ω to 125 Ω CT100 AC I50125 Small Form Factor Keyboard CT100 AC KBD Clear Screen Protector Pack CT100 AC SPC Anti Glare Screen Protector Pack CT100 AC SPAG BNC RF Adapter Kit CT100 AC BNC SMA RF Adapter Kit CT100 AC SMA Impedance Matching Kit 75 93 125 Ohm BNC CT100 IK BNC Impedance Matching Kit 75 93 125 Ohm SMA CT100...

Page 65: ...l sampling rate Adjustable from 8 to 250 kHz Vertical scale 0 5 mρ div Vertical accuracy 3 full scale Vertical position Any trace point is movable to the center of the screen Sampling efficiency CT100 50 to 90 into 50 Ω terminator Sampling efficiency CT100HF 45 to 90 into 50 Ω terminator Noise 5 mρ peak to peak Input susceptibility 1 A Into diode clamps Distance cursor resolution 1 45 of one major...

Page 66: ...nalog board by 500 V DC power supply 24 VDC 2 5A positive tip Use only the MOHR approved power supply The DC power supply is isolated from the analog board by 500 V Battery pack 12 NiMH AA cells fused at 2 5 A Pack may wear out over time External battery pack 12 NiMH AA cells optional This pack is identical to the internal pack and may be charged by the internal battery charger Battery operation t...

Page 67: ...ack 2778 g 6 124 lb Dimensions Height 10 9 cm 4 28 in Width w handle 29 2 cm 11 50 in 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 59 ...

Page 68: ...Certifications and Compliances EC 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 60 Mohr CT100 CT100HF Operator s Manual ...

Page 69: ...blies 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 3 CT208 analog digicomp subassembly see Figure 20 4 CT209 back panel subassembly see Figure 21 5 CT290 front panel subassembly see Figure 22 6 CT290HF front panel subassembly see Figure 23 Mohr CT100 CT100H...

Page 70: ...Appendix B Subassembly Drawings and Parts List 62 Mohr CT100 CT100HF Operator s Manual Figure 18 CT100 complete mechanical and electrical assembly ...

Page 71: ...Appendix B Subassembly Drawings and Parts List Mohr CT100 CT100HF Operator s Manual 63 Figure 19 CT207 power subassembly ...

Page 72: ...Appendix B Subassembly Drawings and Parts List Figure 20 CT208 analog subassembly 64 Mohr CT100 CT100HF Operator s Manual ...

Page 73: ...Appendix B Subassembly Drawings and Parts List Mohr CT100 CT100HF Operator s Manual 65 Figure 21 CT209 back panel subassembly ...

Page 74: ...Appendix B Subassembly Drawings and Parts List 66 Mohr CT100 CT100HF Operator s Manual Figure 22 CT290 front panel subassembly ...

Page 75: ...Appendix B Subassembly Drawings and Parts List Mohr CT100 CT100HF Operator s Manual 67 Figure 23 CT290HF front panel subassembly ...

Page 76: ...x 0 5mm space 29 W3W3C1 1 Front panel to 4 button PCB cable 30 W3W3C2 1 Front panel to 5 button PCB cable 31 W3W3C3 1 Front panel to 6 button PCB cable 32 W5W2W7W3C1 1 Digital power assembly cable High Frequency Front Panel CT 290HF LCD display front control board switches and knobs 1 A3 1 Front panel switch board encoders and controller 2 A5A2 1 Subassembly power switch 3 A7 1 Video assembly boar...

Page 77: ...l port cable assembly 18 W2W3C2 1 USB host cable 19 W2W4C2 1 UMCC Plug plug cable assembly Back Panel CT209 1 A4A2 1 Fan assembly 60 x 60 x 25mm 2 A6 1 Back panel assembly 3 CT100 AC B2700 1 Battery set NiMH with thermistors 2700 mA h 4 CT119 1 Frame aluminum 5 CT120 1 IO bezel aluminum 6 CT121 2 Battery clip aluminum 7 CT134 1 Ferrite support bracket 8 CT207 1 Subassembly Ps battery charger 9 CT3...

Page 78: ...rmance Check it should be serviced Required equipment Required equipment Item MOHR part number 50 Ω precision terminator CT100 AC ER50 for CT100 CT100 AC ER50S for CT100HF Capacitive calibrator CT100 AC C001 Connector SMA male to BNC female CT100 AC ISMBF for CT100HF Shorting cap CT100 AC IBS for CT100 CT100 AC ISS for CT100HF 36 inch calibration cable CT100 AC W536 for CT100 CT100 AC W536S for CT...

Page 79: ...nternal cable the left side of the trace is centered on the screen 5 Adjust the horizontal scale so that the trace is positioned diagonally across the screen and adjust the vertical scale so that the left side of the trace runs along the base of the screen and the right side of the trace runs along the top of the screen The difference between the two sides is considered 100 of the rise time and sh...

Page 80: ...e Diagnostics submenu 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 The value for Noise is the second number on the first line of the result Noise P2P Output Impedance Check Output Impedance Check 1 Disconnect any cables from the ...

Page 81: ...and amplitude 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 should appear on the device display Switch the CT100 into the short pulse setting from the Main menu Measure the pulse width coming off the front panel cable connector The pulse width should be be...

Page 82: ...o 500mρ div by turning the VERTICAL SCALE knob to the left 2 Use the VERTICAL POSITION knob to move the live trace completely above the horizontal midline of the screen 3 Use the VERTICAL POSITION knob to move the live trace completely below the horizontal midline of the screen A CT100 must succeed at both operations to pass the Vertical Position Check Input Susceptibility Check Input Susceptibili...

Page 83: ...TAL POSITION knob The difference between the new distance measurement and the previous is the minimum cursor readout resolution Distance Measurement Accuracy Check Distance Measurement Accuracy Check Accuracy is determined by taking a cable of known length and velocity and comparing the known values against measured values Accuracy is reported as a percentage When determining accuracy ensure that ...

Page 84: ...ose the cable length so that it is set to long maximum cable length Using the M FUNC button and M FUNCTION knob set Vp to 1 00 Turn the HORIZONTAL SCALE knob to the left Horizontal scale should increase beyond 61 meters div or 200 feet div Turn the HORIZONTAL SCALE knob to the right Horizontal scale should decrease below 0 01 meters div or 0 03 feet div Horizontal Range Check Horizontal Range Chec...

Page 85: ...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 78 Mohr CT100 CT100HF Operator s Manual ...

Page 86: ...ternal and external temperatures Ensure that the testing environment will have no temperature variation and that the CT100 internal temperature does not fluctuate Calibration interval Calibration interval The CT100 should be calibrated annually as described in this appendix Required equipment Required equipment Item MOHR part number 50 Ω precision terminator CT100 AC ER50 for CT100 CT100 AC ER50S ...

Page 87: ...measurement checks optional Pulse measurements should be taken with a device that can accurately measure frequency pulse width period and amplitude Connect the CT100 to a capable device using the 36 inch calibration cable Switch the CT100 into the short pulse setting from the Main menu Measure each pulse value and compare it against the values given in the supplied CT100 Calibration Certificate If...

Page 88: ...se DAC button 21 2 Twist the M FUNCTION knob until the displayed Sampler Comp value reads 35000 This will ensure that the timebase DAC sampler voltage is set correctly during calibration To set the Hybrid Reference Value 1 Display the Hybrid Comp value on the CT100 screen by pressing Hybrid Reference button 22 2 Twist the M FUNCTION knob until the displayed Hybrid Comp value reads 45000 This will ...

Page 89: ...libration 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 Vertical calibration will continue and complete Manually verify calibration values Manually verify calibration values After the automated calibrations ha...

Page 90: ... the live trace will appear to show a break at the 50ns point Figure 26 displays the appropriate scale The 50ns rollover is surrounded by a red circle However in Figure 26 the capacitive calibration needs to be adjusted Figure 27 displays a trace that does not need manual capacitive calibration If adjustment is necessary adjust the Sampler Comp value until the live trace shows no breaks as per Fig...

Page 91: ...rsor as shown in Figure 28 on the rising edge of the internal cable segment 4 Center the cursor in the middle of the screen using the position knobs 5 Expand the scale to 0 070 ft div and 40 mρ div 6 Push the Hybrid Comp button to start the manual resistive load calibration The automatic calibration option is discussed elsewhere in this manual At this point the words Hybrid Comp appear at the top ...

Page 92: ... the test port The apparent reflection coefficient of the trace has changed from 31 mρ to 53 6 mρ indicating that an adjustment of Hybrid Comp is required Mohr CT100 CT100HF Operator s Manual 85 Figure 28 Typical trace from a CT100 with a shorting terminator applied to the test port The active cursor is set at the reflected rise The right hand side of the trace shows the effect of the shorting ter...

Page 93: ...ohr CT100 CT100HF Operator s Manual Figure 30 Hybrid Comp adjustment with open terminator and cursor at the reflected rise The horizontal scale is set at 0 004 ft div and the vertical scale is set at 2 mρ div The male male BNC adapter can be used to provide an open condition Figure 31 Hybrid Comp adjustment with the shorting terminator and the cursor at the reflected rise Hybrid Comp has been adju...

Page 94: ...temperature adjustment When temperature adjustment is enabled the menu item will be bracketed by asterisks Horizontal calibration Horizontal calibration Horizontal calibration sets the start position for distance measurements For precise measurements it is extremely important to perform horizontal calibration as accurately as possible To horizontally calibrate the CT100 1 Connect the shorting cap ...

Page 95: ...nt 8 Enter the Calibration submenu 9 Press Horizontal Button 5 to set horizontal calibration 10 Press Button 4 for OK to continue 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 88 Mo...

Page 96: ...kup table to be rebuilt using the newly calibrated values To clear the temperature lookup table 1 From the main screen push the blue MENU button 2 Enter the Calibration submenu Button 4 3 Select OK to continue Button 4 4 Select Manual Calibration Button 21 5 Select Clear Temp Lookup by pressing Button 23 A warning message will be displayed asking to verify the clearing of temperature adjustment 6 ...

Page 97: ...O NOT continue using the CT100 if it exhibits signs of thermal overload such as emitting heat or smoke or if it smells of burning plastic Power on test Power on test Verify that the back switch is in the ON position Press the red front button to turn the instrument on If the instrument does not show anything on the screen within 20 seconds turn the back switch to the OFF position unplug all USB an...

Page 98: ...Appendix E Operator Troubleshooting 92 Mohr CT100 CT100HF Operator s Manual ...

Page 99: ...ight on the power supply come on Test outlet with working device or outlet tester Does the outlet work Change to a working outlet Device power supply is likely defective Replace it with a functional supply no no no yes yes yes Power Board and Fan Diagnostics Start Mohr CT100 Diagnostics DC Power Supply Fan and Power Board Screen and Computer Front Panel Main Board Analog Finished Diagnostics Main ...

Page 100: ...the back of the CT100 Does the fan in the back of the CT100 turn on Replace DC PowerSupply Does the fan in the back of the CT100 turn on Send in for servicing Turn on power switch in the back of the CT100 no no yes yes Power Board and Fan Diagnostics Screen and Computers Diagnostics Power Board and Fan ...

Page 101: ...d power button on the front of theCT100 Does the Splash screen appear after a few seconds Does the screen start showing boot messages after a moment then load the operation screen yes Do the boot messages pause on the Time message or show interrupt fail yes Front Panel Diagnostics no yes no no Screen and Computer CT100 Requires Servicing ...

Page 102: ...rn each knob left and right and press each button except the red power button on the front of the CT100 Do all of the button and knob icons turn grey Press the red power button Did The front panel Diagnostics Screen Disappear RTC Diagnostics Power button failure monitored by power panel yes yes yes yes yes no no no no no Main Menu button failure Diagnostics menu button failure Front Panel Check me...

Page 103: ...e Main Menu appears Choose the Diagnostics menu item Choose the Info menu item Choose the Time Date menu option Change the date and time Choose the OK menu option Turn power off then restart the CT100 Does the CT100 Display the new time Reset Correct Date and Time no yes Main Board Diagnostics Real Time Clock CT100 Requires Servicing ...

Page 104: ...d menu item Choose Mem Test menu option Were there any failures Choose the GPIO test menu option Were there any failures Choose the Peripheral Menu Option Were there any failures Download a test via USB see CTViewer manual no no no no Did the trace transfer fail Download a trace via Ethernet See CTViewer manual no Did the trace transfer fail Analog Board Diagnostics no yes yes Main Board CT100 Req...

Page 105: ...tart Analog Calibration Press the Main Menu button until the Main Menu appears Choose the Diagnostics menu item Choose the Analog Diag menu item Did power pass no Did communications pass Did all tests pass no yes yes Operations Diagnostics yes Analog CT100 Requires Servicing yes ...

Page 106: ...e Is the ohm measurement within specification Position a cursor on the trace of the cable Is the distance measurement correct to specification Switch between short medium and long cable lengths Do all three show a trace Attach a 50 ohm test cable of known length Set Vp to match the pulse velocity of the cable Measure the length of the cable Is the measurement within specification Position a cursor...

Page 107: ...ds menu option Highlight the name of the saved trace Did the trace load correctly Press the Library button Choose the Cable Records menu option Highlight the name of the saved trace Choose the select menu option Choose the USB Save menu option Does the Success Message Appear Plug a USB keyboard into a USB port in the front of the CT100 Choose the Cable Records menu item Press the Escape Key Did th...

Page 108: ...r coiled on a roll and other variables 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 See Operating Instructions Test preparations Find an unknown Vp for more information on determining the Vp of a cable Dielectric material Type Z0 Ω Probable Vp Jelly filled 0 64 Polyethylene 0 66 PTFE TFE 0 70 Pulp 0 72 Fo...

Page 109: ...0 66 RG 316 U 50 0 66 RG 393 50 0 66 MIL C 17 standards Designation Z0 Ω Vp M17 2 RG6 RG 6 U 75 0 66 M17 163 00001 RG 8 U 50 0 66 M17 6 RG11 RG 11 U 75 0 66 M17 155 00001 RG 58 U 50 0 66 M17 29 59 RG 59 U 75 0 66 M17 173 00001 RG 174 U 50 0 84 M17 169 00001 RG 178 U 50 0 69 M17 094 RG179 RG 179 U 75 0 67 M17 172 00001 RG 316 U 50 0 66 M17 127 RG393 RG 393 U 50 0 66 104 Mohr CT100 CT100HF Operator ...

Page 110: ... 0 79 H500 50 0 82 LMR 200 50 0 83 HDF 200 50 0 83 CFD 200 50 0 83 LMR 400 50 0 85 HDF 400 50 0 85 CFD 400 50 0 85 LMR 600 50 0 87 LMR 900 50 0 87 LMR 1200 50 0 88 LMR 1700 50 0 89 Twisted pair Designation Z0 Ω Vp CAT5 100 0 71 CAT6 100 0 71 Mohr CT100 CT100HF Operator s Manual 105 ...

Page 111: ... smooth surface 4 Remove the two cross top screws from the rear of the instrument 5 Swing the handle to the back of the instrument 6 Using a long handled cross top screwdriver remove the two pairs of screws from both ends of the instrument nearest the handle mounts 7 Carefully remove the rear housing CT291 from the front panel CT290 using the handle for gripping The housing may be tight and the ru...

Page 112: ...orm the Memory GPIO and Peripherals check See the section on the Diagnostics menu for more information 4 From the Diagnostics menu perform the Analog check See the section on the Diagnostics menu for more information 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 an...

Page 113: ...digital value for representation on the display and in the instrument s memory Cable Conductors of electricity that are usually shielded and insulated Cables typically contain at least two conductors one to deliver the electrical signal and one to act as the return path The conductor acting as the return path may be referred to as the shield ground or ground wire A cable with such a ground return ...

Page 114: ...rithms When used for voltage ratios as in TDR the formula for decibels is db 20 log10 Vi V l where Vi is the voltage of the incident pulse and Vl 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 ...

Page 115: ... the energy in a test signal See Reflection Coefficient Incident Pulse 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 Inductance See Reactance Insulation ...

Page 116: ...is the reactance at a given frequency If X 0 the impedance is inductive if X 0 then the impedance is purely resistive and if X 0 the impedance is capacitive Reflection Coefficient In TDR a coefficient describing the amplitude of a reflected signal produced by an impedance mismatch in relation to the incident pulse The reflection coefficient Rho ρ is defined by the relation Zt Z0 Zt Z0 where Zt is ...

Page 117: ... The risetime of a pulser sampler system is proportional to the root sum of squares of the pulse and sampler risetimes RMS An acronym for Root Mean Square also abbreviated rms and known as the quadratic mean This is a useful statistical technique when considering time varying electrical quantities for which simple DC definitions are not accurate such as when determining the power dissipated by an ...

Page 118: ...eflected voltage is measured as a function of time If the velocity of propagation Vp is known the length of a cable and the distance to cable faults can be determined 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 system...

Page 119: ...alibration Procedures 79 CAT5 105 CAT6 105 Change units 49 Charging the battery 10 Cleaning 107 Commercial cable 105 Configurations 52 Load 52 Save 52 Connectors 24 VDC power adapter plug 15 BNC connector 13 Client USB 15 Ethernet 15 External 14 4 VDC battery pack 15 Rear panel 15 RJ 45 Ethernet port 15 USB port 13 Controls Front panel 12 Covers 8 Damage Due to static charge 6 During shipping 2 Im...

Page 120: ...r subassembly 61 Power requirements AC power 2 External AC power adapter 2 External battery 2 Internal battery 2 Reflected risetime 57 Reflection coefficient 39 Relative distance 40 Relative reflection coefficient 50 Repacking 2 Return loss 39 RG standards 103 RG 11 U 103 RG 58 U 103 RG 59 U 104 RG 6 U 103 RG 8 U 103 Risetime 1 Safety 5 Terms and symbols CAUTION 5 DANGER 5 Symbols in the manual 6 ...

Page 121: ... Unpacking 2 Velocity of propagation AUTOFIT button 33 Changing the value of 32 Definition 32 Finding an unknown 33 Vertical reference 50 Vibration 9 Voltage standing wave ratio 40 Water hazards 9 Water spray 9 Watertight 9 Mohr CT100 CT100HF Operator s Manual 117 ...

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