Home

Tektronix 475A User's Manual

1. S X K Z g O i K 6 p Eo Y T T 3 r 2 Tektronix inc P O Box 500 WARRANTY All TEKTRONIX instruments are warranted against defective materials and workmanship for one year Any questions with respect to the warranty should be taken up with your TEKTRONIX Field Engineer or representative All requests for repairs and replacement parts should be directed to the TEKTRONIX Field Office or representative in your area This will assure you the fastest possible service Please include the instrument Type Number or Part Number and Serial Number with all requests for parts or service Specifications and price change privileges reserved Copyright 1976 by Tektronix Inc Beaverton Oregon Printed in the United States of America All rights reserved Contents of this publication may not be reproduced in any form without permission of Tektronix Inc U S A and foreign Tektronix products covered by U S and foreign patents and or patents pending TEKTRONIX is a registered trademark of Tektronix inc TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS iv BASIC OSCILLOSCOPE DISPLAYS OP NORMAL SWEEP DISPLAY MAGNIFIED SWEEP DISPLAY BEFORE OPERATING 1 DELAYED SWEEP DISPLAY INTRODUCTION 1 MIXED SWEEP DISPLAY SAFETY INFORMATION 1 Dee ene OPERATING VOLTAGE 1 SINGLE SWEEP DISPLAY Line Voltage Selection 2 Regulating Range Selection 2 DM44 DISPLAYS AND MEASUREMENTS OPTIONS 3 5 RESI
2. light shielding Order 016 0592 00 light occiuding Order 016 0566 00 mm O Mesh Filter Im proves contrast and EMI filter 378 0726 01 SCOPE MOBILE Cart Occupies less than 18 aisle space has storage area in base Order 200 Test Lead Set 1 black lead with banana grounding clip 1 red lead with banana plug ai includes retractable hook tip and CI tester pro May be used with other miniature probe tip ac Order 012 0427 00 REV A SEPT 1978 Your instrument may contain the following options E OPTION 1 Deletes the temperature probe from the DM 44 OPTION 4 The instrument is modified to meet certain specifications on radiated interference requirements There is no change in operating instructions OPTIONS OPTION 7 At the time of this writing instruments having the DM44 do not have the Option 7 available Option 7 permits operation on 12 or 24 Vdc with no performance deterioration Circuitry is provided to protect against damage due to connection of 24 V when in the 12 V mode of operation The 24 volt external input permits use with conventional dc power marine and aircraft 475A DM44 Operators 69 s
3. 5 Set the Input Coupling Switch to AC The display will remain on the screen so the ac component of the signal can be measured in the normal manner 28 475A DM44 Operators OPERATOR S ADJUSTMENTS AND CHECKS To verify measurement accuracy perform the follow ing checks and adjustments before making a measure ment See the Calibration section of the Service manual for calibration information Trace Rotation Adjustment Normally not required Obtain a Normal Sweep Display using only steps 1 through 3 Set the CH 1 input Coupling switch to GND to display a free running trace with no vertical deflection Adjust the TRACE ROTATION screw driver adjustment located below the crt graticule to align the trace with the center horizontal graticule line Probe Compensation Miscompensation is one of the greatest sources of operator error Most attenuator probes are equipped with adjustments to ensure optimum measurement accuracy Probe compensation is accomplished as follows Obtain a Normal Sweep Display presentation of the calibrator square wave voltage Set the appropriate VOLTS DIV switch to 1 V position and the Input coupling to DC Check the waveform presentation for overshoot or rolloff and if necessary readjust compensation for flat tops on the waveforms See Fig 11 Refer to probe manual for method of compensating the probe being used PERI TT me ee ee 100 30 OVER COM PENSATED OVERSHOOT AE AEE
4. The most reliable measurements are made when the oscilloscope ground is connected to the ground of the unit under test by the ground strap on the signal probe Also a ground lead can be connected to the ground banana jack on the oscilloscope chassis to establish acommon ground with the unit under test input Coupling Capacitor Precharging In the GND position the input signal is connected to ground through a one megohm resistor to form a precharging network This network allows the Input Coupling capacitor to charge to the average dc voltage level of the signal applied to the probe Thus any large voltage transients accidentally generated will not be applied to the amplifier input The precharge network also provides a measure of protection to the external circuitry bv reducing the current levels that can be drawn from the external circuitry during capacitor charging The following procedure should be used whenever the probe tip is connected to a signal source having a different dc level than that previously applied especiativ if the de level difference is more than 10 times the VOLTS setting 1 Before connecting the probe tip toa signal source set the Input Coupling switch to GND 2 Touch the probe tip to oscilloscope chassis gre und Wait several seconds for the Input Coupling capacitor ti discharge 3 Connect the probe tip to the signal source 4 Wait several seconds for the Input Coupling capacitor to charge
5. divisions setting Determine the arbitrary deflection factor using this formula Arbitrary horizontal TIME DIV Deflection conversion X switch Factor factor setting To measure the time duration of an unknown signal set the TIME DIV switch to a setting that provides sufficient horizontal defiection to make an accurate measurement Do not readjust the VAR TIME DIV control Measure the horizontal defiection in divisions and calculate the time duration using the formula Ti arbitratv horizontal D s deflection X deflection gaa factor divisions or Time horizontal TIME DIV horizontal Duration conversion X switch X deflection factor setting divisions EXAMPLE The reference signal frequency measured is 455 hertz time duration 2 19 milliseconds with a TIME DIV switch setting of 2 ms and the VAR TIME DIV control adjusted to provide a horizontal deflection of eight 475A DM44 Operators 41 divisions Substituting these values in the horizontal conversion factor formula Horizontal l 2 19 ms Conve rsion PRO SE ASSNN pA DAMM dr zm 1 37 8 X 60 2 ms Factor Then with a TIME DIV switch setting of 50 us the time duration of an unknown signal that completes one cycle in seven horizontal divisions can be determined by using the time duration formula This answer can be converted to frequency by taking the reciprocal of the time duration see applications on Determining Frequency PHASE DIFFERENCE MEASUREMENTS
6. Center the compressed display with the vertical and horizontal POSITION con trols release the BEAM FINDER pushbutton 16 475A DM44 Operators 4 Set the CH1 VOLTS DIV switch and vertical POSITION control to locate the display within the display area 5 Adjust the A Trigger LEVEL contro for a stable display 6 Set the A TIME DIV switch and the horizontal POSITION control to locate the display within the display area Then adjust the FOCUS control as needed MAGNIFIED SWEEP DISPLAY 1 Obtain a Normal Sweep Display 2 Adjust the horizontal POSITION control to move the area to be magnified to within the center graticule division 0 5 division on each side of the center vertical graticule line It may be necessary to change the TIME DIV switch setting 3 Push the X10 MAG switch on and adjust the horizontal POSITION control for precise positioning of the magnified display Divide the TIME DIV setting by 10 to determine the magnified sweep rate DELAYED SWEEP DISPLAY NOTE Differential time measurements and measurements using the TIME or 1 TIME functions of the DM44 are invalid when the B Trigger SOURCE switch is not set to STARTS AFTER DELAY 1 Obtain a Normai Sweep Display 2 Set the HORIZ DISPLAY switch to A INTEN and the B Trigger SOURCE switch to STARTS AFTER DELAY 3 Puli out on the B TIME DIV knob and turn cw until the intensified zone is the desired length Adjust the INTENSITV control as need
7. Maximum operating temperature decreases 1 C 1 000 feet above 5 000 feet Humidity Operating and Storage 5 cycies 120 hours referenced to MIL E 16400F 475A DM44 Operators 65 DM44 DIGITAL MULTIMETER RESISTANCE Maximum Safe input Voltage 120 V rms between and COM inputs Resistance Accuracy 200 range within 0 25 1 count plus probe resistance 2 kQ 20 kQ 200 kQ and 2 MQ ranges within 0 25 1 count 20 MQ range within 0 3 21 count Temperature Dependence 20 kN 200 kQ and 2 MO ranges 250 ppm C 200 2 2 kN and 20 MQ ranges 350 ppm C Resolution 0 1 Recycle Time At least 3 measurements second Response Time All ranges within 1 second except 2 MQ and 20 MQ within 5 seconds TIME Accuracy 15 to 35 C within 1 of reading 1 count 15 to 55 C within 1 5 of reading 1 count 66 475A DM44 Operators 1 TIME Accuracy 15 to 35 C within 2 of reading 1 count 15 to 55 C within 3 of reading 1 count TEMPERATURE Range 55 C to 150 C in 1 range Accuracy Original Probe Within 2 C 55 C to 125 C Within 3 C 125 C to 150 C Replacement Probe Accuracy will equal original probe accuracy after DM44 is compensated Maximum Safe Voltage on Measurement 100 V dc peak ac above chassis ground Temperature Storage and Operating ProbeB dy and Cable 55 C to 105 C Probe Sensor Tip 150 C DC
8. VAR control to CAL Continuous from 0 2 us to at least 5 seconds ter the start of A delaying sweep 8 X Y X Axis Sensitivity X10 MAG turned off Same as the vertical system X Axis Bandwidth Dc to at least 4 MHz with a 10 division reference signal Phase Difference Between X and Y Axis Ampiifi Within 3 from dc to 50 kHz Deflection Accuracy Within 4 CALIBRATOR Output Voltage 0 3 V within 1 and within i 20 C to 30 C Output Current 30 mA within 2 from i 30 C Repetition Rate About I kHz 2 AXIS INPUT Sensitivity Noticeable intensity modulation at normal intensity settings by a 5 V p p signal A positive going signal decreases intensity Frequency Range Usable Dc to 50 MHz Maximum Input Voltage 100 V dc plus peak ac or 100 V p p ac at 1 KHz or less OUTPUTS CH 2 Out Output Voltage At least 50 mV div into 1 MQ to at least 25 mV div into 50 ohms Bandwidth Dc to at least 50 MHz into 50 ohms DC Level About 0 volts A and B Gates Output Voltage About 5 5 V of positive going pulse tput Resistance About 500 ohms RYS V to 1 gt AC POWER SOURCE Regulating Ranges 230 V 09 V to 121 va gt _198 V to 242 242 V Line Frequency From 48 Hz to 440 Hz Maximum Power Consumption 100 watts at 115V 60 Hz medium range ENVIRONMENTAL Operating Temperature 1590 to 55 C Operating Altitude To 15 000 feet
9. between the calibrated settings of the A TIME DIV switch It extends the slowest A Sweep rate to at least 1 25 seconds division The A Sweep rate is calibrated when the control is set fully clockwise to the calibrated detent Must be in the detent position to make accurate differential time measurements On instruments equipped with a DM44 the VAR control must be in the detent position to make accurate measurements in the TIME and 1 TIME func tions 38 UNCAL Lamp Indicates the A Sweep rate is uncalibrated VAR contro out of the calibrated detent 39 X10 MAG Lamp Indicates that the X10 magnifier is on 40a DELAY TIME POSITION Provides variable sweep delay to more than 10 times the delay time indicated by the A TIME DIV switch 40b DM44 DELAY TIME POSITION Operates in the same manner as 41a Also when the DMAA is in the TIME or 1 TIME function this control operates in conjunction with the A TIME control The DELAY TIME POSITION contro moves both the reference point and ihe time measurement point The A TIME control moves only the time measurement point With the time measurement point to the left of the reference point the Readout indicates a negative time difference NOTE You can modify your instrument to make the DELAY FIME POSITION control move only the reference point The procedure for making this modification Is located in the Operating Information section of the DM44 Service manual 41 CALIBRATOR A comb
10. shape or time causing an unstable conven tional display It can aiso be used to photograph a nonrepetitive signal 26 READY Lamp indicates A Sweep is armed and upon receipt of an adequate trigger signal will present a single sweep display 27 TRIG Lamp indicates that A Sweep is triggered and will produce a stable display It is useful for setting up the trigger circuits when a trigger signal is available without a display on the crt for example when using external triggers 28 A TRIG HOLDOFF Provides continuous control of time between sweeps Allows triggering on aperiodic signals such as complex digital words In the fully clockwise position B ENDS A A sweep is reset at the end of B sweep to provide the fastest possible sweep repetition i 475A DM44 Operators rate for delayed sweep presentations and low repetition rate signals Use the A trigger controls for the best possible display before using the A TRIG HOLDOFF control 29 COUPLING Determines method used to couple signals to the trigger generator circuit AC Signals are capacitively coupled to the input ofthe trigger generator Dc is rejected and signals below about 60 Hz are attenuated LF REJ Signals are capacitively coupled to the input of the trigger circuit Dc is rejected and signals below about 50 kHz are attenuated It is useful for providing a stable display of the high frequency components of a complex waveform HF REJ Signals are
11. 100 MHz EXT 10 Signal Amplitude requirements are mul tiplied by 10 External Trigger Input Maximum Input Voltage 250 V dc peak ac or 250 V p p ac 1 kHz or less Level Control Range in Ext At least and 2 V 4 V p p EXT 10 is at least and 20 V 40 V p p Trigger View Deflection Factor About 50 mV div in EXT and about 500 mV div in EXT 10 Risetime 5 ns or fess Trigger Centering Point Within 1 0 division of screen center DIFFERENTIAL TIME MEASUREMENT BASIC 475A Accuracy for Measurements Greater than One Major Dial Division Within 1 from 15 C to 35 C Within 1 5 from 15 C to 55 C 475A DM44 Operators 63 Accuracy for Measurements Less than One Major Dial Division Within 40 01 major dial divisions from 15 C to 35 C Within 0 02 major dial divisions from 15 C to 55 DIFFERENTIAL TIME MEASUREMENT DM44 Refer to TIME AND 1 TIME under DM44 DIGITAL MULTIMETER HORIZONTAL Sweep Rate Accuracy Within 2 unmagnified and 3 magnified from 20 C to 30 C for A and B Sweeps Mixed Sweep Accuracy Within 2 plus the measured A Sweep inaccuracy when viewing the A portion only B Sweep portion remains the same as above Trigger Holdoff Variable increases A Sweep holdoff time by at least a factor of 10 Delay Time Jitter 1 part or less in 50 000 0 002 of 10 times the A TIME DIV switch setting 64 475A DM44 Operators Calibrated Delav Time
12. Fig 26 is 16 66 milliseconds Using the formula 1 time duration Substituting the given values 1 Frequency e 16 66 ms 60 hertz TIME DIFFERENCE BETWEEN TWO PULSES FROM DIFFERENT SOURCES BASIC 475A Make sure the VAR TIME DIV control is in the calibrated detent Set the A Trigger SOURCE switch to CH 1 Connect the reference signal to CH 1 and the com parison signal to CH 2 Connect the signals to the input connectors using probes or cables with equal time delay CHANNEL 1 REFERENCE CHANNEL 2 MEASURE TIME FROM A TO B i Pr te HORIZONTAL i DIFFERENCE Set the VERT MODE switch to either CHOP or ALT in general CHOP is more suitable for low frequency signals and the ALT position is more suitable for high frequency signals Center each of the displays vertically see Fig 27A Set the HORIZ DISPLAV switch to A INT and the B Trigger SOURCE to STARTS AFTER DELAY Set the B TIME DIV switch 20 times faster than the A TIME DIV switch when possible VERTICAL REFERENCE S cH 2 SIGNAL ONLY ONE OF THE ABOVE DISPLAYS CAN BE POSITIONED TO CENTER ON INSTRUMENTS WITHOUT DM 40 SERIES 1738 10 Fig 27 Time difference between two pulses from different sources 475A DM44 Operators 51 Use the DELAY TIME POSITION dial to move the intensified zone to the CH 1 pulse Set the HORIZ DISPLAY switch to B DLY D Readjust the DELAY TIME POSITION dial to m
13. See Fig 16B The ADD mode puts the resultant displav within the operating range of the POSITION controls 34 475A DM44 Operators POSITIVE BEVEL hg A CHANNEL 1 SIGNAL WITH 3 DIVISIONS OF POSITIVE DC LEVEL B CHANNEL 2 DISPLAY WITH 3 DIVISIONS OF NEGATIVE OFFSET C RESULTANT DISPLAY 465 DM 0 19 Fig 16 Algebraic addition COMMON MODE REJECTION The ADD mode can be used to display signals that contain undesirable components These undesirable components can be eliminated through common mode rejection The precautions given under algebraic addition should be observed EXAMPLE The signal applied to the CH 1 input contains unwanted line frequency components see Fig 17A To remove the undesired components use the following procedure 1 Connect a line frequency signal to the CH 2 input 2 Set the VERT MODE switch to ALT and the CH 2 INVERT switch to on button in Adjust the CH 2 475A DM44 Operators 35 VOLTS DIV and VAR VOLTS DIV controls so the CH 2 MN EE display is about the same amplitude as the undesired WITH UNWANTED portion of the CH 1 display see Fig 17A LINE FREQUENCY 100 COMPONENT 90 3 Set the VERT MODE switch to ADD Slightly readjust the CH 2 VAR VOLTS DIV control for maximum cancellation of the undesired s gnal component see Fig 17B CH 2 SIGNAL FROM LINE FREQUENCY SOURCE SOURCE AMPLITUDE COMPARISON MEAS
14. capacitively coupled to the input of the trigger circuit Dc is rejected and signals below about 60 Hz and above about 50 kHz are attenuated It is useful for providing a stable display of the low frequency components of a complex waveform DC AH components of a trigger signal are coupled to the input of the trigger circuit It is useful for providing a stable display of low frequency or low repetition rate signals except the combination of the ALT dual trace mode with the trigger SOURCE switch in NORM 30 SLOPE Selects the slope of the trigger signal that starts the sweep Sweep can be triggered from the positive going portion of a trigger signal Sweep can be triggered from the negative going portion of a trigger signal Correct SLOPE setting is important in obtaining a display when only a portion of a cycle is being displayed 31 LEVEL Selects the amplitude point on the trigger signal at which the sweep is triggered It is usually adjusted for the desired display after trigger SOURCE Fig 5 Trigger controls connectors and indicators COUPLING and SLOPE have been selected 10 475A DM44 Operators 32 SOURCE Determines the source of the trigger signal coupled to the input of the trigger circuit NORM Trigger source is displayed signal s It does not indicate time relationship between CH 1 and CH 2 signals However stable triggering of non time related signals usually can be obtained by setti
15. displayed on the crt at the same time The 1 TIME function can provide direct measurement of frequency SAFETY INFORMATION The instrument is designed to operate from a single phase power source with one of the current carrying conductors the Neutral Conductor at ground earth potential Operation from power sources where both current carrying conductors are live with respect to ground such as phase to phase on a three wire system is not recommended since only the Line Conductor has over current fuse protection within the instrument The instrument has a three wire power cord with a three terminal polarized plug for connection to the power source and safety earth The ground earth terminal of the plug is directly connected to the instrument frame For electric shock protection insert this plug only in a mating outlet with a safety earth contact 475A DM44 Operators 1 OPERATING VOLTAGE CAUTION ANA IS MO ol MO MM This instrument may be damaged if operated with the line voltage selector switch or the regulating range selector set for the wrong applied line voltage or if the wrong line fuse is used Line Voltage Selection This instrument operates from either a 115 volt or a 230 vott nominal line voltage source 48 to 440 hertz To convert from one nominal line voltage range to the other move the Line Voltage Selector switch located on side panel to indicate the correct nominal voltage A 115 to 230 volt ada
16. from peak to peak Point A to Point B 475A DM44 Operators 31 POSITION TO CENTERLINE VERTICAL DEFLECTION MEASURE AMPLITUDE FROM A FOB 1738 16 2039 15 Fig 14 Peak to peak voltage of a waveform NOTE if the amplitude measurement is critical or if the trace is thick as a result of hum and or noise on the signal a more accurate measurement can be ob tained by measuring from the top of a peak to the top of avalley This wili subtract the trace thickness from the measurement Multiply the vertical deflection just measured by the VOLTS DIV switch setting Also include the attenuation factor of the probe if the probe does not have a scale factor switching connector Example The peak to peak vertical deflection measured is 4 6 divisions see Fig 14 with a VOLTS DIV switch setting of 5 Using the formula Volts vertical Sadko Hask deflection X p divisions Substituting the given values Volts Peak to Peak 4 6 X 0 5 V 2 3 volts 1 INSTANTANEOUS VOLTAGE MEASUREMENTS DC Obtain a Normal Display Make sure the VAR VOLTS DIV control is in the calibrated detent 32 475A DM44 Operators To determine the polarity of the voltage to be measured set the input coupling switch to GND and vertically position the baseline to the center of the crt Set the input coupling switch to DC If the waveform moves to above the center of the crt the voltage is positive H the waveform m
17. on the measurement surface is 400 V dc peak ac above chassis ground Accuracv Check The sensor tip is fragile and may break if dropped or subjected to excessive stress Force exerted on the sensor tip should not exceed 20 pounds The DM44 is calibrated to its original probe accurate readings within 2 C for examples tha If the reading exceeds 55 C or 150 C remove The DM44 should be recalibrated to any repl fhe probe at once to prevent probe damage probe In the following checks use an accurate thermom to verify water temperature Anything in solution affe the melting temperature and the boiling point is affected 1 Push in the TEMP C FUNCTION button See by changes in altitude and barometric pressure Fig 10 2 Apply the temperature probe to the device to be measured so the flat surface of the probe tip mates against the device to be measured and observe the reading See Table 4 to convert the reading from centigrate to Allow a container preferably insulated of crushed ice _ fahrenheit to melt until there are only a few pieces of ice remaining ma Low Temperature 24 475A DM44 Operators APPLY SILICONE GREASE TO THE SURFACE TO BE MEASURED WHEN POSSIBLE a tt TEMPERATURE SENSOR TIP SEALED PORTION i 465 DM 0 4 2039 11 Fig 10 Temperature 475A DM44 Operators 25 26 CENTIGRADE FAHRENHEIT CENTIGRADE FAHRENHEIT CENTIGRADE FAHRENHEIT CENTIGRA
18. 00 _ 2 MQ 200 measure voltage if the meter is in the resistance 200 kQ J 200 0 20 00 200 kQ 20 KA Q mode of operation OHMS FUNCTION button push 20 00 10 02 00 20 K0 2 KA ed in and the applied voltage is in excess of 120 V 2 000 0 200 2 kQ 200 Q rms m 200 0 000 0 2000 00 f Push in the OHMS FUNCTION button and the 20 MQ RANGE button See Fig 8 A blinking readout on any range when connected to any unknown resistance indicates an overrange condi 2 Connect the and COM leads to the unknown Hon and a need to select a higher range resistance 3 Reduce the range using the following tabie until A blinking re dout when meter leads are disconnected proper readout is obtained is normal 20 475A DM44 Operators 21 465 DM 0 2 2039 9 FUNCTION SELECTION Z o jew O i ai m 2 1181 er O Zz o w lt 2 e o a qg W ef A gt U eg E INPUT RESISTANC VOLTS PN gt CAUTION The maximum safe input voltage is 1200 V dc peak ac between the and COM inputs or between the input and chassis 3 Reduce the range using Table 3 until a proper readout is obtained NOTE When no voltage is applied in the 20 V to 1 2 kV ranges the readout is 0000 and individual readout elements may blink Also noise picked up by the meter leads may increase the readout inthe 2 Vand The maximum COM floa
19. 33 External Trigger Inputs Input connectors for ex ternal trigger signals get 475A DM44 Operators fi Fig 6 Horizontal calibrator and power controis connectors and indicators HORIZONTAL CALIBRATOR AND POWER 34a A AND B TIME DIV AND DELAY TIME A TIME DIV switch clear plastic skirt selects the sweep rate of the A Sweep circuit for A sweep only operation and selects the basic delay time to be used by the DELAY TIME POSITION control for delayed sweep operation B TIME DIV switch pull out and rotate to unlock selects the sweep rate for the B Sweep circuit for delayed sweep operation only A VAR control must be in the calibrated detent for calibrated A Sweep rates When both TIME DIV switches are fully counterclockwise to the X V position the horizontal X axis display is the CH 1 input 34b DM44 A AND B TIME DIV AND DELAY TIME The controls operate in the same manner as 37a above The A TIME DIV switch also controls the TIME lamps and decimal point location when the DM44 is in the TIME or 1 TIME MODE 35 FINE POSITION Positions the display horizontal iv for A sweep and B Sweep 36 X10 MAG Increases displayed sweep rate by a factor of 10 It extends fastest sweep rate to 1 nanosecond division The magnified sweep is the center division of the unmagnified display 0 5 division either side of the center graticule fine 12 475A DM44 Operators e 37 VAR Provides continuously variable sweep rates
20. 500 V p p ac at 1 kHz or less ac coupied 500 V dc peak ac or 500 V p p ac 1 kHz or less 62 475A DMA4 Operators Positive Going Step Aberrations Less than 3 3 not to exceed 3 peak to peak excluding the ADD mode Common Mode Rejection Ratio ADD Mode with CH 2 inverted At least 10 1 at 20 MHz for common mode signals of 6 divisions or less with GAIN adjusted for best CMRR at 50 kHz Input Gate Current 0 5nA or less 0 1 div at 5 mV DIV from 15 C to 30 C Channel Isolation At least 100 1 at 25 MHz CHOP Mode Repetition Rate Approximately 250 kHz Cascaded Operation CH 2 OUT into CH 1 sensitivity Approximately 2 5 mV DIV Bandwidth is dc to at least 50 MHz with CH 2 OUT connected to CH 1 input AC coupled using a 50 0 42 inch BNC cable terminated in 50 0 at CH 2 Input TRIGGERING Sensitivity Ac Coupled Signal 0 3 div internal or 50 mV external from 60 Hz to 25 MHz increasing to 1 5 div internal or 150 mV external at 100 MHz LF REJ Coupled Signal 0 5 div internal or 100 mV external from 50 kHz to 25 MHz increasing to 1 5 div internal or 300 mV external at 100 MHz Attenuates signals below about 50 kHz HF REJ Coupled Signal 0 5 div internal or 50 mV external from 60 Hz to 50 kHz Attenuates signals below about 50 Hz and above about 50 kHz DC Coupled Signal 0 3 div internal or 50 mV external from dc to 25 MHz increasing to 1 5 div internal or 150 mV external at
21. DE FAHRENHEIT 50 0 50 100 TABLE 4 CENTIGRADE TO FAHRENHEIT CONVERSION 40 30 20 10 0 50 40 30 20 0 0 0 20 A 10 20 30 40 JU 40 50 60 70 80 90 100 10 120 60 70 80 90 00 130 140 150 160 170 180 190 200 210 mo 20 0 140 150 09 230 240 250 260 270 280 290 300 475A DM44 Operators CAUTION CAUTION To prevent possible probe damage be sure only the sealed portion of the probe is immersed see Fig 10 Put the probe tip into the water avoiding the side or bottom of the container Wait for the readout to stabilize indicating the probe has reached the water temperature The readout should be 2 C to 2 C There should be ice remaining after the test to verify that inserting the probe did not raise the water temperature 475A DM44 Operators High Temperature Bring water to a slow boil to prevent splattering Put the probe tip into the water avoiding the side or bottom of the container Wait for the readout to stabilize indicating the probe has reached the water temperature The readout should be between 98 C and 102 C far clean water at sea level TIME AND 1 TIME See DM44 DELAYED OR MIXED SWEEP TIME MEASUREMENTS in this manual 27 APPLICATIONS AND MEASUREMENTS Refer to Basic Oscilloscope Displays as needed to obtain correct displays PRELIMINARY CAUTION NON Ol EA all Mh Avoid cross grounding because instrument damage may occur Signal Ground
22. DIV switch and the DELAV TIME POSITION control REAR PANEL 45 A GATE Provides a positive going rectangular pulse coincident with the A Sweep time which can be used to trigger the signal source with TRIG MODE switch set to AUTO 46 B GATE Provides a positive going rectangular pulse coincident with the B Sweep time which can be used to trigger the signal source after a selected delay time providing that A Sweep is triggered internally 47 CH 2 VERT SIGNAL OUT Provides a sample of the signal applied to the CH 2 input connector 48 EXT Z AXIS Permits intensity modulation of the crt display Does not affect display waveshape Signals with fast rise and fall provide the most abrupt intensity change Signals must be time related to the display for a stable display Useful for adding time markers in un calibrated modes of operation 49 Line Fuse Hoider Contains the line fuse and the regulating range selector See Table 1 for change informa tion 50 Regulating Range Selector Shown in Medium regulating range See Table 1 for change information 51 PROBE POWER Power source for active probe systems 52 Line Cord Makes the connection between the oscilloscope and the power source The cord may be conveniently stored by wrapping it around the feet on the rear panel 53 MOD SLOTS A number in either slot indicates the instrument contains an option or other modifications LEFT SIDE PANEL Access
23. E control to superimpose the displayed waveform portions see Fig 30B The DELAY TIME POSITION contro may need to be slightly readjusted to keep the display on screen The Readout and Scale Factor Lamps indicate the time duration FREQUENCY MEASUREMENTS DM44 To measure frequency use the same procedure as for Time Duration Measurements except set the FUNCTION switch to 1 TIME With the display superimposed the Readout and Scale Factor Lamps indicate the frequency The Scale Factor Lamps indicate the scale factor as follows 58 475A DM44 Operators A blinking displav indicates an over range condition This occurs on measurements as follows A Time Div Set To Decade Spacing Between Intensified Multiples of Zones Less Than TIME DIFFERENCE BETWEEN TWO PULSES FROM DIFFERENT SOURCES DM44 Set controls as follows A SOURCE CH 1 VERT MODE ALT HORIZ DISPLAY A INT B SOURCE STARTS AFTER DELAY B TIME DIV 3 or 4 positions more cw than A TIME DIV VAR TIME DIV Detent position Connect the reference signal to the CH 1 input and the comparison signal to the CH 2 input Connect the signals to the inputs with cables or probes having equal time delays Adjust the DELAY TIME POSITION control to move the reference point to the desired spot on the reference CH 1 display see Fig 31A Point A In the ALT vertical mode the reference point appears on the CH 1 display while the time measurement point
24. ETITIVE PULSES BASIC 475A TIME DURATION MEASUREMENTS BASIC 475A 48 48 49 FREQUENCY MEASUREMENTS BASIC 475A 50 TIME DIFFERENCE BETWEEN TWO PULSES FROM DIFFERENT SOURCES BASIC 475A 51 RISETIME BASIC 475 MIX BASIC 475A 52 53 TABLE OF CONTENTS cont DM44 DELAYED OR MIXED SWEEP TIME MEASUREMENTS Page 54 TIME DIFFERENCE BETWEEN REPETITIVE PULSES DM44 56 TIME DURATION MEASUREMENTS DM44 57 FREQUENCY MEASUREMENTS DM44 58 TIME DIFFERENCE BETWEEN TWO PULSES FROM DIFFERENT SOURCES DM44 RISETIME DM44 MIX DM44 OPERATOR S SPECIFICATIONS 475A OSCILLOSCOPE VERTICAL TRIGGERING DIFFERENTIAL TIME MEASUREMENT BASIC 475A DIFFERENTIAL TIME MEASUREMENT DM44 HORIZONTAL X Y CALIBRATOR 58 60 64 62 62 62 63 63 64 64 64 64 OPERATOR S SPECIFICATIONS cont Z AXIS INPUT OUTPUTS AG POWER SOURCE ENVIRONMENTAL DM44 DIGITAL MULTIMETER RESISTANCE TIME 1 TIME TEMPERATURE DC VOLTAGE ACCESSORIES STANDARD ACCESSORIES OPTIONAL ACCESSORIES OPTIONS OPTION 4 OPTION 7 475A DM44 Operators Page 65 65 65 65 66 66 66 66 66 66 68 68 68 69 69 69 Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig 10 11 12 13 14 15 16 LIST OF ILLUSTRATIONS Regulating range selector and line fuse Vertical controls connectors and indicators Display and D
25. M44 controls connectors and indicators Trigger controls connectors and indicators Trigger controls connectors and indicators Horizontal calibrator and power controis connectors and indicators Rear pane and left side panei controls connectors and indicators Resistance Volts Temperature Probe compensation Basic 475A timing check DMAA timing check Peak to peak voltage of a waveform Instantaneous voltage measurements Algebraic addition Page 15 21 23 25 29 30 31 32 33 35 Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig Fig 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 475A DM44 Operators Common mode rejection Time duration Risetime Time difference between two pulses from different sources Phase difference High resolution phase difference Pulse jitter Delaved sweep magnification Time difference between tepetitive pulses Time duration Time difference between two pulses from different sources Risetime Time difference between repetitive pulses Time duration and frequency measurements Time difference between two pulses from different sources Risetime i Page 36 38 39 40 43 43 44 46 49 50 51 53 56 57 59 kol 60 LIST OF TABLES Page Page TABLE 1 Regulating Ranges 2 TABLE 4 Centigrade to Fahrenhei
26. ON LINE FUSE i i i I Fig 1 Regulating range selector and line fuse e 475A DM44 Operators 3 CONTROLS CONNECTORS AND INDICATORS Fig 2 Vertical controls connectors and indicators VERTICAL 1 CH 1 and CH 2 VOLTS DIV Selects the vertical deflection factor in a 1 2 5 sequence VAR control must be in the calibrated detent for the indicated deflection factor 2 VOLTS DIV Readout Consists of two small lamps for each channel located beneath the skirt of each VOLTS DIV knob One or the other lamp will light up to indicate the correct deflection factor when a probe with a scale switching connector is used A probe without this connector lights the X1 lamp 3 VAR Provides continuously variable uncalibrated deflection factors between the calibrated settings of the VOLTS DIV switch and extends the maximum vertical deflection to at least 25 volts per division 10 volt position 4 UNCAL Lamp indicates when the VAR VOLTS DIV control is out of the calibrated detent and the vertical deflection factor is uncalibrated 475A DM44 Operators 5 POSITION Positions the display vertically In the X Y mode the CH 1 POSITION control positions on the X axis horizontally and the CH 2 POSITION control positions on the Y axis vertically 6 CH 1 OR X and CH 2 OR Y lnput connectors for application of external signals to the inputs of the vertical amplifier in the X Y mode of o
27. RSA UNDER COM PENSATED IROLLOFFI 465 DM 0 5 Fig 11 Probe compensation 475A DM44 Operators 29 Vertical Gain Check Obtain a Normal Sweep Display presentation of the calibrator square wave voltage Set the appropriate VOLTS DIV switch to the 50 mV position and the Input Coupling switch to DC Make sure the VAR VOLTS DIV control is in the calibrated detent Check that the vertical deflection is 5 8 to 6 2 divisions Basic 475A Timing Check 60 Hertz Line Only Obtain a Normal Display Set the A TIME DIV switch to 5 ms position Set the A Trigger SOURCE switch to LINE Push the TRIG VIEW switch and hold itin This displays a sample of the line voltage Use the A Trigger LEVEL control to vertically position the top of the display to within the display area Use the horizontal position control to position the left peak to the left graticule edge see Fig 12 Verify the horizontal distance between the first and the fourth peaks is 9 8 to 10 2 divisions If the fourth peak is not visible verify the horizontal distance between the first and the third peaks is 6 53 to 6 79 divisions DM44 Timing Check 60 Hertz Line Only Perform the Basic 475A Timing Check to verify the accuracy of the horizontal deflection system Leave controls set as for the Basic 475A Timing Check except as follows 8 TIME DIV HORIZ DISPLAV B SOURCE FUNCTION A TIME 5 us A INTEN i STARTS AFTER DELAY TIME To move the time measur
28. SITION dial to move the pulse or rising portion to some vertical reference line see Fig 258 Note the setting of the DELAY TIME POSITION dial Turn the DELAY TIME POSITION dial clockwise to move the second puise to the same vertical reference line if several pulses are displayed return to A INTEN to locate the correct pulse Do not change the settings of the horizon tal POSITION and FINE controis Note the setting of the DELAY TIME POSITION dial Determine the time difference using the following formula second first delay time dial dial x A TIME DIV setting setting setting EXAMPLE Assume the first dial setting is 1 31 and the second dial setting is 8 81 with the A TIME DIV switch set to 0 2 us see Fig 25 Using the formula Time Difference delay time A TIME DIV en Ea x setting setting setting 48 475A DM44 Operators DIFFERENCE A A DISPLAY B B DLY D DISPLAY Fig 25 Time difference between repetitive pulses Substituting the given values Time Difference 8 81 1 31 X 0 2 us The time difference is 1 5 microseconds TIME DURATION MEASUREMENTS BASIC 475A Obtain a Delayed Sweep Dispiay Set the A TIME DIV switch to display a single event Be sure the VAR TIME DIV control is in the calibrated detent For the most accurate measurement set the B TIME DIV switch to the fastest sweep speed that gives a usable visible inten sified zone Vertically position
29. STANCE CONTROLS CONNECTORS AND VOLTS INDICATORS 4 TEMPERATURE VERTICAL 4 Accuracy Check DISPLAY 7 TIME AND 1 TIME DM44 7 TRIGGER 8 HORIZONTAL CALIBRATOR AND POWER 12 APPLICATIONS AND MEASUREMENTS REAR PANEL 14 PRELIMINARY LEFT SIDE PANEL 14 Signal Ground RIGHT SIDE PANEL 14 input Coupling Capacitor Precharging 475A DM44 Operators Page 16 16 17 7 18 18 19 20 20 22 24 24 27 28 28 28 28 APPLICATIONS AND MEASUREMENTS cont TABLE OF CONTENTS cont Page OPERATOR S ADJUSTMENTS AND CHECKS 29 Trace Rotation Probe Compensation Vertical Gain Check Basic 475A Timing Check DM44 Timing Check External Horizontal Gain Check PEAK TO PEAK VOLTAGE MEASUREMENTS AC INSTANTANEOUS VOLTAGE MEASUREMENTS DC ALGEBRAIC ADDITION COMMON MODE REJECTION AMPLITUDE COMPARISON MEASUREMENTS TIME DURATION MEASUREMENTS FREQUENCV MEASUREMENTS RISETIME MEASUREMENTS TIME DIFFERENCE BETWEEN TWO PULSES FROM DIFFERENT SOURCES TIME COMPARISON MEASUREMENTS 29 29 30 30 30 31 31 32 34 35 36 37 38 39 40 41 475A DM44 Operators APPLICATIONS AND MEASUREMENTS cont PHASE DIFFERENCE MEASUREMENTS HIGH RESOLUTION PHASE DIFFERENCE MEASUREMENTS PULSE JITTER MEASUREMENTS DELAYED OR MIXED SWEEP MAGNIFICATION Magnified Sweep Starts After Delay Triggered Delay Sweep Magnification Page 42 43 44 45 45 46 BASIC 475A DELAYED OR MIXED SWEEP TIME MEASUREMENTS TIME DIFFERENCE BETWEEN REP
30. UREMENTS if comparisons of an unknown signal with a reference signal are repetitious e g on an assembly line test it is possible to obtain more accurate easily read measurements if the VAR VOLTS DIV control is adjusted SIGNAL WITH c to set the reference signal to an exact number of divisions LINE FREQUENCY COMPONENT The unknown signal can then be quickly and easily re compared with or adjusted to an exact number of divisions Other unknown signals may be measured without disturbing the setting of the VAR VOLTS DIV control by EEE establishing a vertical conversion factor and an arbitrary defiection factor The amplitude of the reference signal must be known before a vertical conversion factor can be Fig 17 Common mode rejection established 36 475A DM44 Operators Determine the vertical conversion factor using this formula Vertical reference signal amplitude volt Conversion Factor vertical VOLTS DIV deflection X switch divisions setting Determine the arbitrary deflection factor using the formula Arbitrary Vertical VOLTS DIV Deflection Conversion X switch Factor Factor setting To measure the amplitude of an unknown signal set the VOLTS DIV switch to a setting that provides sufficient vertical deflection to make an accurate measurement Do not readjust the VAR VOLTS DIV control Measure the vertical deflection in divisions and calculate the amplitude of the unknown signal using the followi
31. Use either the CHOP or ALT mode Setthe A TRIGGER SOURCE switch to CH 1 The reference signal should precede the comparison signal in time Use coaxial cables or probes that have equal time delay to connect the signals to the input connectors If the signals are of opposite polarity set the INVERT pushbutton to invert the Channel 2 display signals may be of opposite polarity due to 180 phase difference if so take this into account in the final calculation Set the CH 1 and CH 2 VOLTS DIV switches and the CH 1 and CH 2 VAR controls so the displays are equal in amplitude Set the TIME DIV switch for about a one cycle waveform Position the display and turn the A VAR TIME DIV control for 1 reference signal cycle in exactly eight divisions see Fig 21 Each division of the graticule represents 45 of the cycle 360 8 divisions 45 division The sweep rate can be stated in terms of degrees as 45 division Measure the horizontal difference between correspon ding points on the waveforms and multiply the distance measured in divisions by 45 division sweep rate to obtain the amount of phase difference EXAMPLE The horizontal difference is 0 6 division with a sweep rate of 45 division as shown in Fig 21 42 475A DM44 Operators CHANNEL 1 CHANNEL 2 NC LAGGING MEASURE ATOB 465 DM 0 15 Fig 21 Phase difference Using the formula horizontal Phase sweep rate difference X D
32. VOLTAGE Maximum Safe Input Voltage 1200 V dc peak between and chassis Common Floating Voltage 500 V de eda a chassis DC Voltage Accuracy Within 0 1 of reading 1 count Temperature Dependence 44 ppm C Resolution 100 uV Recycle Time At least 3 measurements second Response Time Within 0 5 second Normal Common Mode Rejection Ratio Normal Mode At least 60 dB at 50 Hz and 60 Hz Common Mode At least 100 dB at dc 80 dB at 50 Hz and 60 Hz Input Impedance 10 MQ a 475A DM44 Operators 67 mh mk kek DSG mio mb A kk ID ACCESSORIES STANDARD ACCESSORIES INCLUDED 10X Probe Packages 010 6106 03 Accessory Pouch Snap w o DM 016 0535 02 Accessory Pouch DM 016 0594 00 Accessory Pouch Zipper 016 0537 00 Operators Manual 070 2163 00 Service Manual 475A 070 2162 00 Fuses 1 5 A 3AG fast blow 159 0016 00 Fuses 0 75 A 3AG fast blow 159 0042 00 Filter Blue Plastic installed 337 1674 00 CRT Filter Clear Plastic 337 1674 01 Adapter Ground Wire 134 0016 01 Pair Test Leads DM 003 0120 00 Service Manual DM44 070 2036 00 P6430 Temperature Probe DM44 010 6430 00 OPTIONAL ACCESSORIES C 5A Option 2 low cost fixed focus camera Order C 5A Option 2 68 f77 Folding Viewing Hood 475A DM44 Operators Protective Cover Waterproof blue vinvi Order 016 0554 00 J Folding Polarized Viewing Hood Order 016 0180 00 Folding Viewing Hood
33. amp in dicates kHz the 1 us lamp indicates MHz and no lamp lit indicates Hz 24 TIME Used in conjunction with the DELAY TIME POSITION control in the TIME and 1 TIME func tions The A TIME control moves only the time measurement point The DELAY TIME POSITION contro moves both the reference point and the time measurement point With the time measurement point to the left of the reference point the Readout indicates a negative time difference NOTE You can modify your instrument to make the DELAY TIME POSITION contro move only the reference point The procedure for making this modification is focated in the Maintenance section of the DM44 Service manual TRIGGER 25 TRIG MODE Determines the mode of trigger operation for A Sweep AUTO Sweep is initiated by the applied trigger signal In the absence of an adequate trigger signal or if the trigger repetition rate is less than about 20 hertz the sweep free runs and provides a bright reference trace NORM Sweep is initiated by the applied trigger signal In the absence of an adequate trigger signal there is no trace When the trigger rate is too low for AUTO use NORM SINGL SWP When this pushbutton is pushed the A Sweep operates in the single sweep mode After a single sweep is displayed further sweeps cannot be presented until the SINGLE SWP button is again pushed It is useful when the signal to be displayed is not repetitive or varies in amplitude
34. appears on the CH 2 display CHANNEL 1 REFERENCE CHANNEL 2 AMPLITUDE MEASURE TIME i INTENSIFIED FROM A TO B ZONES e is x eee VD Pee Ji an t E f HORIZONTAL I DIFFERENCE 1 Adjust the A TIME control to move the time measurement point to the desired spot on the CH 2 display see Fig 31A Point B Set the HORIZ DISPLAY switch to B DLV D Slightly readjust the DELAY TIME POSITION and A TIME controis to superimpose the waveforms see Fig 31B The Readout and Scale Factor Lamps indicate the time difference MR AL ee ch2 2 i CH 1 SIGNAL JV superimpose 1 LEADING EDGES TEONE 465 DM 0 10 2039 32 Fig 31 Time difference between two pulses from different sources 475A DM44 Operators 59 RISETIME DM44 Set controls as follows FUNCTION TIME HORIZ DISPLAY A INTEN B SOURCE STARTS AFTER DELAV B TIME DIV 3 or 4 positions more cw than A TIME DIV A TIME To move the time measurement point to the right of the reference point Set the A TIME DIV switch to a setting that displays several events Set the VOLTS DIV and VAR VOLTS DIV so the amplitude of the displav is exactly 5 divisions Vertically position the display so the bottom touches the 0 graticule line and the top touches the 100 graticule line 60 475A DM44 Operators Adjust the DELAY TIME POSITION control to move the reference point to the 10 graticule line see Fig 32 Point A Adjust the A TIME cont
35. ay to be magnified 6 Set the B TIME DIV switch to a setting which intensifies the full portion to be magnified The start of the intensified zone remains as positioned above see Fig 24 7 Set the HORIZ DISPLAY switch to B DLY D to magnify the partion of A sweep that is intensified see Fig 24 8 Time measurements can be made from the display in the conventional manner The sweep rate is determined by the setting of the B TIME DIV switch 9 The apparent sweep magnification can be calculated by dividing the A TIME DIV switch setting by the B TIME DIV switch setting e 475A DM44 Operators 45 EXAMPLE The apparent magnification of a display with an A TIME DIV switch setting of 1 ms and a B TIME DIV switch setting of 1 ys is Apparent Magnification A TIME DIV setting Delayed B TIME DIV setting Sweep Substituting the given values A A INTENSIFIED DISPLAY TITTA KEEN HITAN HA Fl Triggered Delayed Sweep Magnification i es The delayed sweep magnification method just describ NERONA 3 i ed may produce too much jitter at high apparent JR S magnification ranges Operating the B Sweep in a triggered mode provides a more stable display since the Fig 24 Delayed sweep magnification delayed display is triggered at the same point each time Apparent __ 116 Magnification 1x 10 The apparent magnification is 100 times 46 475A DM44 Operators gt 1 Set up the display as
36. ction other than TIME or 1 TIME for a single mixed display Dual mixed displays are discussed in step 4 3 Set the HORIZ DISPLAY switch to MIX The display now contains two sweep rates The first portion of the display is at the A sweep rate while the latter portion of the display is at the B sweep rate The start of the B sweep rate portion can be changed by adjusting the DELAY TIME POSITION control 4 if your instrument is equipped with a DM44 mixed sweep displays of two signals can be obtained at the same time The DM44 will indicate the time difference between the beginning of the B sweep portions of the two displays To obtain two mixed sweep displays set the FUNCTION switch to TIME and the VERT MODE switch to ALT The DELAY TIME POSITION control positions both mixed displays The A TIME control positions only the CH 2 mixed display X Y DISPLAY 1 Preset the instrument controls as given in step 1 of Normal Sweep Display then turn the instrument power on Allow several minutes for instrument warm up 2 Set the TIME DIV switches to X Y and the VERT MODE switch to CH 2 Apply the vertical signal to the CH 2 OR Y input connector and the horizontal signal to the CH 1 OR X input connector 3 Advance the INTENSITY control until the display is visible If the display is not visible with the INTENSITY control at midrange press the BEAM FINDER pushbutton and adjust the CH 1 and CH 2 VOLTS DIV switches until the displa
37. ds division or when a dual trace singie sweep display is required CH 2 Channel 2 only is displayed it must be selected in X V operation 9 100 OR 20 MHz BW TRIG VIEW Three purpose switch that limits the bandwidth of the vertical amplifier system to approximately 100 MHz first detent or 20 MHz second detent when pulled or when pressed causes the signal applied to A Trigger Generator to be dispiayed on the crt 10 INVERT Channel 2 display is inverted in the INVERT button in position 475A DM44 Operators 5 ero BANA AR ti EN Fig 3 Display and DM44 controls connectors and indicators 6 475A DM44 Operators DISPLAY 11 Internal Graticule Eliminates parallax Risetime amplitude and measurement points are indicated at the left hand graticule edge 12 BEAM FINDER Compresses the display to within the graticule area independently of display position or applied signals and provides a visible viewing level 13 INTENSITY Controls brightness of the crt dis play 14 FOCUS Adjusts for optimum display definition 15 SCALE ILLUM Controls graticule illumination 16 ASTIG Used in conjunction with the FOCUS control to obtain a well defined display It does not require readjustment in normal use 17 TRACE ROTATION Adjusts trace to align with the horizontal graticule lines DM44 18 Input Connectors Two banana jacks provide red and COM black input
38. ed to make the intensified zone distinguishable from the rest of the displav If vour instrument is equipped with a DM44 set the FUNCTION switch to a function other than TIME or 1 TIME fora single delayed sweep Dual delayed displays are discussed in step 6 475A DM44 Operators 17 4 Adjust the DELAY TIME POSITION control to move the intensified zone to cover the portion of the display to be displayed in delayed form 5 Set the HORIZ DISPLAY switch to B DLY D The intensified zone noted in steps 3 and 4 is now displayed in delayed form The delayed sweep rate is indicated by the dot on the B TIME DIV knob 6 If your instrument is equipped with a DM44 delayed displays of two signals can be obtained at the same time The DM44 will indicate the time difference between the beginning of the delayed dispiays To obtain two delayed displays set the FUNCTION switch to TIME and the VERT MODE switch to ALT The DELAY TIME POSITION control positions both delayed displays The ALT DELAY control positions only the CH 2 delayed display 7 For a delayed display with less jitter set the B Trigger SOURCE switch to the same position as the A Trigger SOURCE switch and adjust the B LEVEL control for a stable display MIXED SWEEP DISPLAY 1 Obtain a normal sweep display 18 475A DM44 Operators 2 Pullout on the B TIME DIV knob and turn cw to the desired sweep rate If your instrument is equipped with a DM44 set the FUNCTION switch to a fun
39. ement point to the right of the reference point 9 8 TO 10 2 LIL H HEC E ER A E 1738 14 Fig 12 Basic 475A timing check 30 475A DM44 Operators Push the TRIG VIEW button and hold it in Use the DELAY TIME POSITION control to move the reference point to the center horizontal graticule line see Fig 13 Point A Use the ALT DELAY control to move the time measurement point to the center horizontal graticule line on the next cycle see Fig 13 Point 8 Verify the readout is 16 49 to 16 84 and the ms lamp is lit 1738 15 Fig 13 DM44 timing check External Horizontal Gain Check If X Y operation is to be used Use steps 1 through 3 of the Basic Oscilloscope Displays procedure for obtaining a Normal Sweep Display of the calibrator square wave voltage waveform then set the TIME DIV switch to X Y With the calibrator signal connected to the CH 1 OR X input connector and the CH 1 VOLTS DIV switch set to 50 mV the crt display should be two dots separated horizontally by 5 75 to 6 25 divisions PEAK TO PEAK VOLTAGE MEASUREMENTS AC Obtain a Normal Display Make sure the VAR VOLTS DIV control is in the calibrated detent Vertically position the display so the lower portion coincides with a horizontal graticule line see Fig 14 Point A Horizontally position the display so one of the upper peaks coincides with the center vertical graticule line see Fig 14 Point B Measure the vertical defiection
40. f CH 2 display only AG Two mixed displays one on each channel display DELAY TIME F POSI tion moves transition point of both displays ALT DELAY moves tran MIX sition point of CH 2 display only CHOP Four mixed displays two on each channel display Not generally used since mixed displays OVER Your instrument may be modified to make the DELAY TIME POSITION and A TIME controls operate Independently The instructions for making this modification are located in the Maintenance section of the DM44 Service manual e 475A DM44 Operators 55 TIME DIFFERENCE BETWEEN REPETITIVE PULSES DM44 Set the controls as follows FUNCTION TIME HORIZ DISPLAY A INTEN B SOURCE STARTS AFTER DELAY A TIME DIV To display 2 pulses B TIME DIV 3 or 4 positions more cw than A TIME DIV A TIME To move the time measurement point to the right of the ref erence point VAR TIME DIV Detent position Position the display approximately as shown in Fig 29A Use the DELAY TIME POSITION control to move the reference point to the first pulse Both intensified zones will move when the DELAY TIME POSITION control is adjusted Use the A TIME control to move the time measurement point to the second pulse Set the HORIZ DISPLAY switch to B DLV D Slightly readjust the A TIME control to superimpose the waveforms see Fig 29B The DELAY TIME POSITION control may need to be slightly readjusted to keep the display
41. for externaily available adjustments see Fig 7 RIGHT SIDE PANEL LINE VOLTAGE SELECTOR SWITCH located on the right side Selects either 115 V or 230 V nominal line voltage 14 475A DM44 Operators CH 2 GAIN 10mYV CH 2 GAIN SmV 2039 2163 01 Fig 7 Rear panel and left side panel controls connectors and indicators 475A DM44 Operators 15 BASIC OSCILLOSCOPE DISPLAYS These instructions permit the operator to obtain the most commonly used basic displays NORMAL SWEEP DISPLAY 1 Set the controls as follows Vertical VERT MODE CH 1 VOLTS DIV Position determined by amplitude of signal to be applied VOLTS DIV VAR Calibrated detent AG GND DC AC Vertical POSITION Midrange 100 MHz 20 MHz BW Not limited yellow band not visible INVERT Button out Horizontal TIME DIV Switches Locked together at 1 ms A TIME DIV VAR Calibrated detent HORIZ DISPLAY A X10 MAG Off button out POSITION Midrange Display INTENSITY Fully counterclockwise Trigger _ Both A and B if applicable SLOPE HE LEVEL 0 SOURCE NORM COUPLING AC TRIG MODE A only AUTO A TRIG HOLDOFF NORM 2 Pull the POWER switch on Connect the signal to the CH 1 input connector 3 Adjust the INTENSITY control for the desired display brightness If the display is not visible with the INTENSITY control at midrange press the BEAMFINDER pushbutton and adjust the CH 1 VOLTS DIV switch to reduce the vertical display size
42. given in steps 1 through 6 under Magnified Sweep Starts After Delay 2 Set the B Trigger SOURCE switch to the same position as the A Trigger SOURCE switch 3 Adjust the B LEVEL control so the intensified zone on the trace is stable lf an intensified zone cannot be obtained see step 4 4 Inability to intensify the desired portion indicates that the signal does not meet the triggering requirements H the condition cannot be remedied with the B Triggering controls or by increasing the display amplitude lower VOLTS DIV setting tigger B Sweep externally 5 When the correct portion is intensified set the HORIZ DISPLAY switch to B DLY D Slight readjustment of the B LEVEL control may be necessary for a stable display 6 Measurements are mace and magnification factors are calculated as in the STARTS AFTER DELAY moce previously given 475A DM44 Operators 47 BASIC 475A DELAYED OR MIXED SWEEP TIME MEASUREMENTS The delayed sweep modes can be used to make more accurate time measurements TIME DIFFERENCE BETWEEN REPETETIVE PULSES BASIC 475A Obtain a Delayed Sweep Display For the most accurate measurement set the B TIME DIV switch to the fastest sweep speed that gives usable visable intensified zones With the HORIZ DISPLAY switch set to A INTEN use the DELAY TIME POSITION dia to move the intensified zone to the first pulse see Fig 25A Set the HORIZ DISPLAY switch to B DLY D Adjust the DELAY TIME PO
43. he TIME DIV switch if sweep magnification is used divide this answer by 10 EXAMPLE The TIME DIV switch is set to 50 us the MAG switch to X10 and the horizontal difference between waveforms is 4 5 divisions see Fig 20 40 475A DM44 Operators e CHANNEL 1 REFERENCE CHANNEL 2 I gne HORIZONTAL DIFFERENCE Fig 20 Time difference between two pulses from different sources Using the formula horizontal pa X difference Time ES divisions Difference magnification Substituting the given values Time 6005 X45 _ po 5 microseconds Difference 10 TIME COMPARISON MEASUREMENTS If comparisons of an unknown signal with a reference signal are repetitious e g on assembly line test it is possible to obtain more accurate easily read measurements if the VAR TIME DIV control is adjusted to set the reference signal to an exact number of divisions The unknown signal can then be quickly and easily pared with or adjusted to an exact number of unknown signals may be measured without g the setting of the VAR TIME DIV control by ing a horizontal conversion factor and an ar bitrary deflection factor The time duration of the reference signal must be known before a horizontal conversion factor can be established Determine the horizontal conversion factor using the formuta reference signal time duration Horizontal seconds Conversion Factor Horizontal TIME DIV defiection X switch
44. horizontally as much as possible Horizontally position the display so the 10 point on the waveform intersects the second vertical graticule line see Fig 19 Measure the horizontal distance between the 10 and 90 points and multiply the distance measured by the setting of the TIME DIV switch EXAMPLE The horizontal distance between the 10 and 90 points is 5 divisions see Fig 19 and the TIME DIV switch is set to 1 ys MEASURE TIME FROM HORIZONTAL DISTANCE 465 0M 0 13 Fig 19 Risetime Using the time duration formula to find risetime Time i horizontal TIME DIV Duration distance X Satin risetime divisions g Substituting the given values Risetime 5 X 1 us 5 microseconds 475A DM44 Operators 38 TIME DIFFERENCE BETWEEN TWO PULSES FROM DIFFERENT SOURCES Obtain a Normal Sweep Display Make sure the VAR TIME DIV control is in the calibrated detent Set the A Trigger SOURCE switch to CH 1 Connect the reference signal to CH 1 and the comparison signal to CH 2 Connect the signals to the input connectors using probes or cables with equal time delay Set the VERT MODE switch to either CHOP or ALT In general CHOP is more suitable for low frequency signals and the ALT position is more suitable for high frequency signals Center each of the displays vertically see Fig 20 Measure the horizontal difference between the two signals Multiply the measured difference by thesetting of t
45. ifference Baty degrees div divisions Substituting the given values Phase Difference 0 6 X 45 27 TIME FROM HIGH RESOLUTION PHASE DIFFERENCE MEASUREMENTS Make more accurate phase measurements by in creasing the sweep rate without changing the A VAR TIME DIV control by using the X10 MAG mode Delayed sweep magnification may also be used see Fig 22 CHANNEL 1 REFERENCE CHANNEL 2 MEASURE TIME FROM Bi i ki i t 4 i HORIZONTAL PT DIFFERENCE Ti 465 DM 0 16 Fig 22 High resolution phase difference 475A DM44 Operators 43 EXAMPLE If the sweep rate were increased 10 times with the magnifier the magnified sweep rate would be 45 10 4 5 division Fig 22 shows the same signals as used in Fig 21 but with the X10 MAG switch set to X10 With a horizontal difference of 6 divisions the phase difference is horizontal magnified Phase difference X sweep rate Difference ae divisions degrees div Substituting the given values PULSE JITTER MEASUREMENTS Be sure the VAR TIME DIV switch is in the calibrated detent Set the B TIME DIV switch to intensify the full rising portion of the pulse Set the HORIZ DISPLAY switch to B DLY D MEASURE TIME FROM 1738 34 Fig 23 Pulse jitter 14 Pulse jitter is shown by horizontal movement of the pulse and includes the inherent jitter of the Delayed Sweep see Fig 23 Multiple the distance b
46. ination current loop square wave voltage output that permits the operator to compensate voltage probes and check vertical gain current probes and oscilloscope operation It is not intended to verify time base calibration 42 POWER Turns instrument power on and off 43 LOW LINE Lamp Indicates that the applied line voltage is below the lower limit of the regulating range selected by the Regulating Range Selector 44 HORIZ DISPLAY Determines the mode of opera tion for the horizontal deflection system A Horizontal deflection provided by A Sweep at a sweep rate determined by the setting of the A TIME DIV switch B sweep is inoperative 475A DM44 Operators 13 MIX The first part of the horizontai sweep is displayed at a rate set by the A TIME DIV switch and the latter part of the sweep at a rate set by the B TIME DIV switch Relative amounts of the display allocated to each of the two sweep rates are determined by the setting of the DELAY TIME POSITION control A INTEN The sweep rate is determined by the A TIME DIV switch An intensified portion appears on the display during the B Sweep time which is about 10 times the B TIME DIV switch setting This switch position provides a check of the duration and position of the B Sweep delayed sweep with respect to the A Sweep delaying sweep B DLYD The sweep rate is determined by the B TIME DIV switch with the delay time determined by the setting of the DELAY TIME A TIME
47. ions of vertical deflection between the reference line and the other voltage level Substitute this value in the formula just given ALGEBRAIC ADDITION In the ADD position of the VERT MODE switch the waveform displayed is the algebraic sum of the signals applied to the CH 1 and CH 2 inputs CH 1 CH 2 if the CH 2 INVERT switch is pushed the waveform displayed is the difference of the signals applied to the CH 1 and CH 2 inputs CH 1 CH 2 The total deflection factor in the ADD mode is equal to the deflection factor indicated by either VOLTS DIV switch when both VOLTS DIV switches are set to the same position The following general precautions should be observed when using the ADD mode 1 Do not exceed the input voltage rating of the oscilloscope 2 Do not apply signals that exceed an equivalent of about eight times the VOLTS DIV switch settings For example with a VOLTS DIV switch setting of 0 5 the voltage applied to that channel should not exceed about four volts Large voltages may distort the display A common use of the ADD mode is to provide a dc offset for a signal riding on a dc level EXAMPLE The Channel 1 signal is on a 3 division positive dc level using the center line as zero volts See Fig 16A Multiply 3 divisions by the VOLTS DIV switch setting to determine the dc ievel value Apply a negative dc level or a positive level using the CH 2 INVERT switch of the value determined to Channel 2 input
48. ng VERT MODE to ALT SOURCE to NORM and COUPLING to LF REJ Carefully adjust LEVEL for a stable dispiay CH 1 A sample of the signal available in Channel 1 is used as a trigger signal CH 2 signal is unstable if it is not time related CH 2 Asample of the signal available in Channel 2 is used as a trigger signal CH 1 signal is unstable if itis not time related LINE A Trigger circuit only A sample of the power line frequency is used as a trigger signal It is useful when the input signal is time related multiple or submultiple to the line frequency or when it is desirable to provide a stable display of a line frequency component in a complex waveform EXT Signals connected to the External Trigger Input connectors are used for triggering External signais must be time related to the displayed signal for a stable display It is useful when the internal signal is too small or contains undesired signals that could cause unstable triggering lt is useful when operating in CHOP mode EXT 10 A Trigger circuit only External trigger signal is attenuated by a factor of 10 STARTS AFTER DELAY B Trigger circuit only B Sweep runs immediately after the delay time selected by the DELAV TIME POSITION control When making differential time measurements you must use this mode to obtain valid measurements On instruments equipped with a DM44 you must use this mode to obtain valid measurements when using the TIME or 1 TIME functions
49. ng formula Sianal Arbitrarv Vertical Kr RE deflection X deflection p factor divisions or Vertical VOLTS DIV Vertical Signal i Conversion X switch X deflection Amplitude ie Factor setting divisions EXAMPLE The reference signal amplitude measured is 30 volts with a VOLTS DIV switch setting of 5 and the VAR VOLTS DIV control adjusted to provide a vertical deflec tion of 4 divisions Substituting these values in the vertical conversion factor formula vertical 30 Conversion 4X5 1 5 Factor Then with a VOLTS DIV switch setting of 1 the peak to peak amplitude of an unknown signal 5 divisions high can be determined by using the signal amplitude formula Signal Amplitude 1 V X 1 5 X 5 7 5 volts TIME DURATION MEASUREMENTS Obtain a Normal Sweep display Be sure the VAR TIME DIV contro is set to the calibrated detent Set the TIME DIV switch for a single event and position the display to place the time measurement points to the center horizontal graticule line see Fig 18 A 475A DM44 Operators 37 ju a ba kr ka s SE a HORIZONTAL DISTANCE Fig 18 Time duration Measure the horizontal distance between the time measurement points Multiply the distance measured by the setting of the TIME DIV switch If sweep magnification is used divide this answer by 10 EXAMPLE The distance between the time measure ment points is 8 3 divisions see Fig 18 and the TIME DIV switch is se
50. oincident in time DELAY TIME POSITION moves both intensified OHMS o ZONES _ pe z ona en u Gen pe Sort OR TEMP CH 1 GH 2 OR ADD One mixed display Position of transition point determined by DELAY TIME POSITION ALT OR Two mixed displays one on each channel display Transition points are CHOP coincident in time Position of transition points determined by DELAY TIME POSITION in the B DLY D mode the intensified zones that are displayed in the A INTEN mode will be displayed at the B sweep rate 54 475A DM44 Operators TABLE 5 cont DM44 Delayed Sweep Displays DM44 HORIZ VERT _ FUNCTION DISPLAY MODE DISPLAY OBTAINED l l i RS 6 ik i CH 1 CH 2 Two intensified zones DELAY TIME POSITION moves both intensified OR ADD zones A TIME moves only one intensified zone Two intensified zones Reference point appears c on CH 1 display Measurement point appears on CH 2 display DELAY TIME POSITION moves both intensified zones A TIME moves only the measurement point on the CH 2 MPA Two pairs of flere fed zones one pair on each chanel disser The pairs are coincident in time with each other DELAY TIME POSITION moves all four intensified zones A TIME moves two intensified zones OR CHOP 1 TIME CH 1 CH 2 Two mixed displays one on each channel display DELAY TIME POSITION OR ADD moves transition point of both displavs A TIME moves transition point o
51. on screen The Readout and Scale Factor Lamps now indicate the time difference between the pulses PoE TIME gt DIFFERENC ETT I He me T tH ER AMR o LINTENSIFIEDS zad all J ZONES ia i mala A A DISPLAY VERTICAL REFERENCE LINE HE m LES A AND B MTE SUPERIMPOSED A B BDLY D DISPLAY 1738 23 2039 30 I Fig 29 Time difference between repetitive pulses 56 475A DM44 Operators To find the pulse repetition rate superimpose the waveforms as above and set the FUNCTION switch to 1 TIME The Readout and Scale Factor Lamps now indicate the repetition rate TIME DURATION MEASUREMENTS DM44 Set controls as follows FUNCTION TIME HORIZ DISPLAY A INTEN B SOURCE STARTS AFTER DELAY A TIME DIV To display a single 3 or 4 positions more cw than A TIME DIV To move the time a measurement point to m eel pf the right of the ref a u erence point i 5 SUPERIMPOSE VAR TIME DIV Detent position KV Sa B BDLY D DISPLAY Jasons Use the DELAY TIME POSITION control to move the reference point to a horizontal graticule line see Fig 30A Point A Use the A TIME control to move the time Fig 30 Time duration and frequency measurements a 475A DM44 Operators 57 measurement point to near the same horizontal graticule line on the next cycle of the waveform see Fig 30A Point B Set the HORIZ DISPLAY switch to B DLYD Slightly readjust the A TIM
52. ove the CH 1 pulse or rising portion to some vertical reference line see Fig 27B Note the DELAY TIME POSITION dial setting Use the DELAY TIME POSITION dial to move the CH 2 pulse or rising portion to the same reference line Again note the DELAY TIME POSITION dial setting Substitute the DELAY TIME POSITION dia settings in the time difference formula to find the time difference EXAMPLE The A TIME DIV switch is set to 50 us and the B TIME DIV switch is set to 2 us Use the DELAY TIME POSITION dial to move the CH 1 pulse to the reference line The DELAY TIME POSITION dial setting is 2 60 Use the DELAY TIME POSITION dial to move the CH 2 pulse to the reference line The DELAY TIME POSITION dial setting is 7 10 To find the time difference use the formula Time second first delay time A dial dial X A TIME DIV difference setting setting setting Substituting the given values Time Difference 7 10 2 60 X 50 us 225 us RISETIME BASIC 475A Risetime measurements use the same methods as time duration measurements except the measurements are made between the 10 and 90 points of the waveform Falitime is measured between the 90 and 10 points on the trailing edge of the waveform Use a sweep speed setting that displays several cycles or events if possible and be sure the VAR TIME DIV control is in the calibrated detent Set the VOLTS DIV switch and the VAR control or signal amplitude for exactly a fi
53. oves to below the center of the crt the voltage is negative Set the input coupling switch to GND and position the baseline to a convenient reference line Forexample ifthe voltage to be measured is positive then position the baseline to the bottom graticule line Switch the Input Coupling Switch to DC Measure the divisions of vertical deflection between the reference line and the desired point on the waveform see Fig 15 Multiply the veritcal deflection by the VOLTS DIV switch setting Include the attenuation factor of the probe if the probe does not have a scale factor switching connector EXAMPLE The vertical distance measured is 4 6 divisions see Fig 15 the waveform is above the reference line and the VOLTS DIV switch is set to 2 VERTICAL MEASURE AMPLITUDE DEFLECTION Zt 18 EE NEGATIVE AMPLITUDE Fig 15 instantaneous voltage measurement Using the formula Instan vertical VOLTS taneous distance X polarity X DIV Voltage divisions setting Substituting 4 6 X 1 X2 V 9 2 volts 475A DM44 Operators 33 H a negative voltage is to be measured position the trace to the top graticule line and measure from C to B see Fig 15 The ground reference line can be checked at any time by switching to the GND position This method can also be used to measure one voltage with respect to another Position one of the voltage levels to a convenient reference line Measure the divis
54. peration the signal connected to the CH 1 OR X connector provides horizon tal deflection and the signal connected to the CH 2 ORY connector provides vertical deflection 7 AC GND DC Selects the method used to couplea signal to the input of the vertical amplifier In the AC position signals are capacitively coupled to the vertical amplifier The dc componentof the input signal is blocked in the GND position the input of the vertical amplifier is disconnected from the input connector and grounded to allow the input coupling capacitor to precharge Inthe DC position all components of the input signal are passed to the input amplifier 8 VERT MODE Selects mode of operation for ver tical amplifier system CH 1 Channel 1 only is displayed ALT Provides dual trace displav of the signals of both channels Displav is switched between channels at the end of each sweep Useful at sweep rates faster than about 50 microseconds division ADD Signals applied to the CH 1 and CH 2 input connectors are algebraically added and the algebraic sum is displayed on the crt The INVERT switch in Channel 2 allows the display to be CH 1 pius CH 2 or CH 1 minus CH 2 Useful for common mode rejection to remove an undesired signal or for dc offset CHOP Provides dual trace display of the signals of both channels Display is switched between channels ata repetition rate of approximately 250 kHz Useful at sweep rates slower than about 50 microsecon
55. pter may be required for the line cord plug Be sure to use the correct line fuse for the line voltage selected see Table 1 Regulating Range Selection Tne Regulating Range Selector assembly located on the rear panel is set for one of the line voltage ranges shown in Table 1 It also contains the line fuse for overload protection To change the regulating range 1 Disconnect the instrument from the power source 2 Loosen the two captive screws that hold the cover on the selector assembly then puil to remove the cover 3 Pull out the range selector switch bar see Fig 1 Select a range from Table 1 which is centered about the average line voltage Slide the bar to the desired position and plug it in Push the cover on and tighten the screws TABLE 1 Regulating Ranges Regulating Range Ni 115 Volis 230 Volts Nominal Nominal Range Selector Switch Position lower holes CM Switch bar in middle holes Hi Switch bar in upper holes Fuse Size _99 to 121 volts 198 to 242 volts 104 to 126 volts 207 to 253 volts 216 to 264 volts 0 75 A 3AG 108 to 132 volts 1 5 A JAG 2 475A DM44 Operators OPTIONS Options are available to alter oscilloscope performance to meet particular applications A number in either MOD slot see Hem 53 Controls Connectors and Indicators indicates a modified oscilloscope SELECTOR SWITCH BAR SHOWN IN MEDIUM POSITI
56. rol to move the time measure ment point to the 90 graticule line see Fig 32 Point B The Readout and Scale Factor Lamps indicate the risetime INTENSIFIED ZONES i i AMPLITUDE TT HORIZONTAL gt DISTANCE 465 DM 0 11 2039 29 Fig 32 Risetime MIX DM44 For the MIX mode of operation the same general procedures can be used With the first part of the display at a sweep rate set by the A TIME DIV switch and the second part of the display at a sweep rate set by the B TIME DIV switch it is not necessary to switch display modes to ensure location of the correct pulse However inaccuracies are introduced into the measurement by the transition from A to B sweeps The B DLY D mode is the most accurate and therefore the recommended mode of making differential time measurements 475A DM44 Operators 61 OPERATOR S SPECIFICATIONS Refer to the service manual for complete specifications Specifications given are for an operating range of 0 C to 40 C unless otherwise stated 475A OSCILLOSCOPE VERTICAL Deflection Factor Accuracy Within 3 in the calibrated position Frequency Response Dc to at least 250 MHz for CH 1 and CH 2 AC coupled low frequency response is 10 Hz or less Use of a 10X probe extends frequency response to 1 Hz Risetime 1 4 nanoseconds or tess calculated from 0 35 bandwidth in MHz Maximum Input Voltage Dc coupled 250 V dc peak ac or
57. s for voltage and resistance oniv 19 Probe Connector input connector for the temperature probe 20 Readout Negative polaritv indication is automatic for negative dc voltage and temperature wit no polaritv indication for positive measurement A blinking display indicates overrange The decimal point is position ed by the FUNCTION and RANGE controls for multimeter operation and by the oscilloscope A TIME DIV switch in the TIME or 1 TIME modes 21 RANGE Selects from 2 V to 1 2 kV dc in 5 ranges 1200 volts is the maximum safe input in the 1 2 kV dc mode from 200 ohms to 20 megohms in 6 ranges 22 FUNCTION Selects VOLTS OHMS TEMP C 1 TIME or TIME functions of the DM44 23 Scale Factor Lamps Two lamps In the TIME function the Readout and Scale Factor Lamps indicate the time difference between the two intensified zones on the crt display One lamp or the other will light to indicate ms or us No lamp lit indicates seconds In the 1 TIME function the Readout and Scale Factor Lamps indicate the number of measured intervals per unit of time One lamp or the other will light to indicate intervals per ms 1 ms lamp or intervals per us 1 us lamp No 475A DM44 Operators 7 Fig 4 Trigger controls connectors and indicators 475A DM44 Operators lamp lit indicates intervals per second H the duration of one event is being measured the Readout and Scale Factor Lamps indicate frequency The 1 ms l
58. t Conversion 26 TABLE 2 Resistance Ranges 20 TABLE 5 DM44 Delayed Sweep Displays 54 TABLE 3 Volts Ranges 22 475A DM44 Operators v 475A Oscilloscope with DM44 Digital Multimeter 475A DM44 Operators 2163 02 BEFORE OPERATING INTRODUCTION The Tektronix 475A Oscilloscope is a dual channel portable instrument The dual channel dc to 250 MHz vertical system provides calibrated deflection factors from 5 miltivolts to 10 volts division The sweep trigger circuits are capable of stable triggering over the full bandwidth capabilities of the vertical deflection system The horizon tal deflection system provides calibrated sweep rates from 0 5 second to 0 01 microsecond division along with delayed sweep features for accurate relative time measurements A X10 magnifier extends the calibrated sweep rate to 1 nanosecond division The instrument operates over a wide variation of line voltages and frequencies Maximum power consumption is about 100 watts z The Tektronix DM44 Digital Multimeter measures 0 ohm to 20 megohms 0 dc volt to 1200 dc volts or or using the temperature probe 55 C to 150 C The measurement is displayed on a 3 1 2 digital display while the oscilloscope operates normally The digital multimeter and oscilloscope combine to provide a digital readout of the time between any two points on the oscilloscope display Both time measure ment points are
59. t to 2 ms with the magnifier off Using the formula horizontal i Time Time Div A distance X i Duration Nan setting divisions magnification Substitute the given values Time Duration FREQUENCY MEASUREMENTS Time Duration measurements can be used to determine the frequency of a recurrent signal as follows 1 Measure one cycle of the waveform as described in Time Duration Measurements 2 Take the reciprocal of the time duration to deter mine the frequency EXAMPLE The frequency of the signal shown in Fig 18 which has a time duration of 16 6 milliseconds is 1 1 nene time duration u 16 6 ms 60 hertz 38 475A DM44 Operators RISETIME MEASUREMENTS Risetime measurements use the same methods as time duration measurements except the measurements are made between the 10 and 90 points of the waveform Failtime is measured between the 90 and 10 points on the trailing edge of the waveform Obtain a Normal Sweep Display Set ASLOPE to Use a sweep speed setting that displays several cycles or events if possible and be sure the VAR TIME DIV control is in the calibrated detent Set the VOLTS DIV switch and VAR control or signal amplitude for exactly a five divi sion display Set vertical positioning so the display bottom touches the 0 graticule line and the display top touches the 100 graticule line Set the TIME DIV switch for a single event display with the risetime spread
60. the display to place the time measurement points to the center horizontal graticule line see Fig 26 Use the DELAV TIME POSITION dial to move the start left hand edge of the intensified zone to just touch the intersection of the signal and the center horizontal graticule line see Fig 26 Point A Note the DELAY TIME POSITION dial setting Use the DELAY TIME POSITION dial to move the start of the intensified zone to the second time measurement point see Fig 26 Point B Note the DELAY TIME POSITION dial setting 475A DM44 Operators 49 ozone NAME IA i INTENSIFIED HORIZONTAL DISTANCE Fig 26 Time duration Substitute the DELAY TIME POSITION dial settings into the time difference formula to obtain the time duration EXAMPLE The A TIME DIV switch is set to 2 ms and the B TIME DIV switch is set to 1 ms The DELAY TIME POSITION dial setting at Point A Fig 26 is 1 20 The DELAY TIME POSITION dial at Point B Fig 26 is 9 53 To find the time duration use the formula 56 475A DM44 Operators Time Time Difference Duration second first delay time dial dial X A TIME DIV setting setting setting Substituting the given values Time Duration 9 53 1 20 X 2 ms 16 66 ms FREQUENCY MEASUREMENTS BASIC 475A The frequency of a recurrent signal can be calculated by taking the reciprocal of the time duration of one event EXAMPLE The time duration of one event Point A to Point B
61. ting voltage is 500 V dc 2 V ranges peak ac to chassis A blinking readout on any range indicates an The meter may be damaged by attempting to overrange condition and a need to select a higher measure voltage if the meter is in the resistance range mode of operation and the applied voltage is in exc ss of 120 V rms if the reading exceeds 1200 V or the readout blinks indicating overrange disconnect the lead atonce to prevent possible meter damage TABLE 3 Volts nae RANGE READOUT MEASUREMENT p By the ad en button and the WAR SET 200 0 200 _ 1 2 kV 200 V pa SMYKA pe an 200V 2000 0200 200V 250V 2 Connect the COMMON lead to the reference point u Den A usually a ground or test point and the HIGH lead to the 2 V 1 2 000 0 200 VEV 200 mV 0 200 0 000 2 V 0 V unknown voltage to be measured and observe the reading a na A sE 22 475A DM44 Operators BLACK VOLTAGE INPUT FUNCTION SELECTION REFERENCE RANGE SELECTION 465 DM 0 3 2039 10 Fig 9 Volts 475A DM44 Operators 23 TEMPERATURE NOTE Temperature accuracy is affected by several factors such as the angle of contact between the probe and the device to be measured a thermal gradient heat eu removed from the device by the probe ete CAUT CAUTION These items and other probe information are in the probe manual which should be reviewed The maximum safe voltage
62. ues am A TT N t MIX BASIC 475A if ME a zus H MEASURE For the MIX mode of operation the same general SIGNA gt AE TIME procedures can be used With the first part of the display at AMPLITUDE Tr tt LL ETEN jf FROMATOB a sweep rate set by the A TIME DIV switch and the second part of the display at a sweep rate set by the B TIME DIV switch it is not necessary to switch display modes to ensure location of the correct pulse HORIZONTAL However inaccuracies are introduced into the DISTANCE measurement by the transition from A to B sweeps The B 465 0M 0 11 2039 29 3 DLYD mode is the most accurate and therefore recommended mode of making differential time Fig 28 Risetime measurements 475A DM44 Operators 53 DM44 DELAYED OR MIXED SWEEP TIME MEASUREMENTS Most measurements of time time duration frequency time difference and risetime are more easily performed using the TIME function of the DM44 and the delayed sweep mode of the oscilloscope Table 5 lists the DM44 and oscilloscope operating modes and the crt display obtained in these modes TABLE 5 _DM44 Delayed Sweep Displays DM44 HORIZ FUNCTION DISPLAY MODE DISPLAY OBTAINED A TOH1 CH2 One intensified zone DELAY TIME POSITION moves intensified zone OR ADD REN ee N p n E ler My ALT or Two intensified zones one on each channel display intensified zones VOLTS CHOP are c
63. ve division display Set vertical positioning so the display bottom touches the 0 graticule line and the display top touches the 100 graticule line see Fig 28 Set the A TIME DIV switch for a single event display with the risetime spread horizontally as much as possible Horizontally position the display so the 10 point of the waveform intersects the second vertical graticule line see Fig 28 Set the B TIME DIV switch to the fastest sweep speed that provides a usable visible intensified zone Use the DELAY TIME POSITION dial to move the start of the intensified zone left hand edge to just touch the intersection of the signal and the 10 graticule line see 52 475A DM44 Operators Fig 28 Point A Note the DELAY TIME POSITION dial EXAMPLE The A TIME DIV switch is set to 1 us The setting DELAY TIME POSITION dial setting at point A Fig 28 is 2 50 The DELAY TIME POSITION dial setting at point B Use the DELAY TIME POSITION dial to move the start Fig 28 is 7 50 To find the risetime use the formula of the intensified zone to just touch the intersection of the signal and the 90 graticule line see Fig 28 Point B Time ar ii Note the DELAV TIME POSITION dial setting Difference Isetime Substitute the DELAV TIME POSITION dial settings in second first delay time the time difference formula to find the risetime dial dial X A TIME DIV setting setting setting INTENSIFIED ZONES Substituting the given val
64. y is reduced in size both vertically and horizon tally Center the compressed display with the POSITION controls CH 2 POSITION vertically CH 1 POSITION horizontally release the BEAM FINDER pushbutton Adjust the FOCUS control for a well defined display SINGLE SWEEP DISPLAY 1 Obtain a Normal Sweep Display For random signals set the trigger circuit to trigger on a signal that is approximately the same amplitude and DT as the random signal 2 Push the SINGL SWP button on the A TRIG MODE switch The next trigger pulse starts the sweep and displays a single trace If no triggers are present the READY lamp lights indicating the A Sweep Generator circuit is set and waiting to be triggered 3 After the sweep is complete the circuit is locked out and the READY lamp is out Press the SINGL SWP button to prepare the circuit for another single sweep display 475A DM44 Operators 19 DM44 DISPLAYS AND MEASUREMENTS Except for the TIME and 1 TIME functions the DM44 is independently usable anytime the oscilloscope is turned on The TIME and 1 TIME functions are discussed in the Oscilloscope Applications and Measurements section of this manual under Delayed or Mixed Sweep Measurements RESISTANCE TABLE 2 Resistance Ranges tt rrr A MEASUREMENT 20 00 02 00 20M0 2 MQ TO NN CAUTION N RANGE LON LON MO LOS MO The meter may be damaged by attempting to ZM 2 000 0 2
65. y the B TIME DIV switch setting to obtain pulse jitter time 44 475A DM44 Operators DELAYED OR MIXED SWEEP MAGNIFICATION The delayed sweep features of the 475A can be used to provide higher apparent magnification than is provided by the X10 MAG switch The sweep rate of the delayed sweep B sweep is not actually increased the apparent magnification is the result of delaying the B sweep in an mount of time selected by the A TIME DIV switch and the ELAV TIME POSITION control before the display is nted at the sweep rate selected by the B TIME DIV The following method uses the STARTS AFTER DELAY position of the B Trigger SOURCE switch to allow the delayed portion to be positioned with the DELAY TIME POSITION control If there is too much jitter in the delayed display use the Triggered B Sweep mode of operation Magnified Sweep Starts After Delay 1 Connect the signal to either input connector Set the VERT MODE switch to display the channel used 2 Set the VOLTS DIV switch to produce a display about four divisions in amplitude 3 Set the A TIME DIV switch to a sweep rate which displays the complete waveform 4 Set the HORIZ DISPLAY switch to A INT and the B Trigger SOURCE switch to STARTS AFTER DELAY instrument equipped with DMAA Verify that the FUNC TION switch is not set to TIME or 1 TIME 5 Position the start of the intensified zone with the DELAY TIME POSITION control to the part of the displ

Tektronix 475A User's Manual

Contents

Download Pdf Manuals

Related Search

Related Contents