Tektronix 475 oscilloscope, DM44 digital multimeter Operators manual

 Tektronix, Inc.
Р.О. Вох 500
Beaverton, Oregon
070-2039-00
97077
Copyright
Tektronix
COMMITTED TO EXCELLENCE
PLEASE CHECK FOR CHANGE
INFORMATION AT THE REAR
OF THIS MANUAL.
475
OSCILLOSCOPE
AND
DM44 DIGITAL
MULTIMETER
OPERATORS
INSTRUCTION MANUAL
First Printing JUL 1976
Serial Number Revised OCT 1981
© 1976 Tektronix, Inc. All rights
reserved. Contents of this publication may not be
reproduced in any form without the written
permission of Tektronix, Inc.
Products of Tektronix, Inc. and its subsidiaries
are covered by U.S. and foreign patents and/or
pending patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and Wy
are registered trademarks of Tektronix, Inc.
TELEQUIPMENT is a registered trademark of
Tektronix U.K. Limited.
Printed in U.S.A. Specification and price change
privileges are reserved.
APPLICATIONS AND MEASUREMENTS (cont)
TABLE OF CONTENTS
LIST OF ILLUSTRATIONS
LIST OF TABLES
BEFORE OPERATING
INTRODUCTION
SAFETY INFORMATION
OPERATING VOLTAGE
Line Voltage Selection
Regulating Range Selection
OPTIONS
CONTROLS, CONNECTORS, AND
INDICATORS
VERTICAL
DISPLAY
DM44
TRIGGER
HORIZONTAL, CALIBRATOR, AND POWER
REAR PANEL
LEFT SIDE PANEL
RIGHT SIDE PANEL
REV A JAN 1981
rage
Iv
Y
Co PO ГО ГО — — =
= = В В
12
14
14
14
BASIC OSCILLOSCOPE DISPLAYS
NORMAL SWEEP DISPLAY
MAGNIFIED SWEEP DISPLAY
DELAYED SWEEP DISPLAY
MIXED SWEEP DISPLAY
X-Y DISPLAY
SINGLE SWEEP DISPLAY
DM44 DISPLAYS AND MEASUREMENTS
RESISTANCE
VOLTS
TEMPERATURE
Accuracy Check
TIME AND 1/TIME
APPLICATIONS AND MEASUREMENTS
PRELIMINARY
Signal Ground
Input Coupling Capacitor Precharging
475/DM44 Operators
TABLE OF CONTENTS (cont)
Page
OPERATOR'S ADJUSTMENTS AND CHECKS 29
Trace Rotation
Probe Compensation
Vertical Gain Check
Basic 475 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
FREQUENCY 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
475/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
Basic 475 Delayed or Mixed Sweep Time
Measurements
TIME DIFFERENCE BETWEEN REPETITIVE
PULSES (BASIC 475)
TIME DURATION MEASUREMENTS
(BASIC 475)
FREQUENCY MEASUREMENTS (BASIC 475)
TIME DIFFERENCE BETWEEN TWO PULSES
FROM DIFFERENT SOURCES (BASIC 475)
RISETIME (BASIC 475)
MIX (BASIC 475)
Page
16
16
17
17
18
18
19
20
20
22
24
24
27
28
28
28
28
Page
42
43
44
45
45
46
48
48
49
50
51
52
53
REV A JAN 1981
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig
Fig.
Fig.
Fig.
TABLE OF CONTENTS (cont)
DM44 Delayed or Mixed Sweep Time
Measurements
TIME DIFFERENCE BETWEEN REPETITIVE
PULSES (DM44)
TIME DURATION MEASUREMENTS (DM44)
FREQUENCY MEASUREMENTS (DM44)
TIME DIFFERENCE BETWEEN TWO PULSES
FROM DIFFERENT SOURCES (DM44)
RISETIME (DM44)
MIX (DM44)
OPERATOR'S SPECIFICATIONS
475 OSCILLOSCOPE
VERTICAL
TRI
GGERING
DIFFERENTIAL TIME MEASUREMENT
(BASIC 475)
DIFFERENTIAL TIME MEASUREMENT
(DM44)
HORIZONTAL
X-Y
CALIBRATOR
REV A ЗАМ 1981
10.
11.
12.
13.
14.
15.
16.
LIST OF
Regulating range selector and line
fuse.
Vertical controls, connectors, and
indicators.
Display and DM44 controls,
connectors, and indicators.
Trigger controls, connectors, and
indicators.
Trigger controls, connectors, and
indicators.
Horizontal, calibrator, and power
controls, connectors, and indicators.
Page
54
56
57
58
58
60
61
62
62
62
63
63
64
64
64
64
OPERATOR'S SPECIFICATIONS (cont)
Z AXIS INPUT
OUTPUTS
AC POWER SOURCE
ENVIRONMENTAL
DM44 DIGITAL MULTIMETER
RESISTANCE
TIME
1/TIME
TEMPERATURE
DC VOLTAGE
ACCESSORIES
STANDARD ACCESSORIES
OPTIONAL ACCESSORIES
OPTIONS
OPTION 1
OPTION 4
OPTION 7
475/DM44 Operators
Page
10
Rear panel and left side panel controls,
connectors, and indicators.
Resistance.
Volts.
Temperature,
Probe compensation.
Basic 475 timing check.
DM44 timing check.
Peak-to-peak voltage of a waveform.
Instantaneous voltage measurements.
Algebraic addition.
15
21
23
25
29
30
31
32
33
35
ТУ;
18.
19.
20.
Fig.
Fig.
Fig.
Fig.
21.
22.
23.
24.
25.
Fig.
Fig.
Fig.
Fig.
Fig.
26.
Fig.
ig. 27.
Fig.
28.
29.
Fig.
Fig.
Fig. 30.
Fig. 31.
Fig. 32.
475/DM44 Operators
ILLUSTRATIONS
Common-mode rejection.
Time duration,
Risetime.
Time difference between two pulses
from different sources,
Phase difference.
High-resolution phase difference.
Pulse jitter.
Delayed sweep magnification.
Time difference between repetitive
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,
Page
65
65
65
65
66
66
66
66
66
66
68
68
68
69
69
69
69
Page
36
38
39
40
43
43
44
46
49
50
51
53
56
57
59
60
LIST OF TABLES
Page Page
TABLE 1 Regulating Ranges 2 TABLE 4 Centigrade to Fahrenheit Conversion 26
TABLE 2 Resistance Ranges 20 TABLE 5 DM44 Delayed Sweep Displays 54
TABLE 3 Volts Ranges 22
@ 475/DM44 Operators у
T
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46: M
2039-15 2039-12
475 Oscilloscope with DM44 Digital Multimeter. Basic 475 Oscilloscope.
475/DM44 Operators @
BEFORE OPERATING
INTRODUCTION
The Tektronix 475 Oscilloscope is a dual-channel
portable instrument. The dual-channel dc-to-200 MHz
vertical system provides calibrated deflection factors from
2 millivolts to 5 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.
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 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.
@ 475/DM44 Operators 1
OPERATING VOLTAGE
LARGA
S CAUTION
LIO
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.
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 pull 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.
Line Voltage Selection
This instrument operates from either a 115-volt or a
230-volt 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 adapter 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
The Regulating Range Selector assembly (located on
the rear panel) is set for one of the line voltage ranges
shown in Table 1. Italso contains the line fuse for overload
protection.
TABLE 1
Regulating Ranges
Range Selector
Switch Position
Regulating Range
115-Volts
Nominal
230-Volts
Nominal
LO (Switch bar in
lower holes)
99 to 121 volts
198 to 242 volts
M (Switch bar in
middle holes)
104 to 126 volts
207 to 253 volts
HI (Switch bar in
upper holes)
Fuse Size
108 to 132 volts
1.5 A 3AG
Fast-blow
216 to 264 volts
0.75 A 3AG
Fast-blow
2 475/DM44 Operators
OPTIONS
Options are available to alter oscilloscope performance
to meet particular applications. A number in either MOD
slot (see Item 53, Controls, Connectors, and Indicators)
indicates a modified oscilloscope.
LINE FUSE
1739-1
Fig. 1. Regulating range selector and line fuse.
@ 475/DM44 Operators 3
CONTROLS, CONNECTORS AND INDICATORS
5 2 +
VERTICAL
oD ооо 1. CH 1 and CH 2 VOLTS/DIV—Selects the vertical
deflection factor ina 1-2-5 sequence (VAR control mustbe
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
® DO VOLTS/DIV switch, and extends the maximum vertical
deflection to at least 12.5 volts per division (5 volt
position).
10
4. UNCAL Lamp—Indicates when the VAR
20333 VOLTS/DIV control is out of the calibrated detent and the
Fig. 2. Vertical controls, connectors, and indicators. vertical deflection factor is uncalibrated.
4 475/DM44 Operators @
5. POSITION—Positions the display vertically. In the
X-Y mode, the CH 1 POSITION control positions on the X
axis (harizontally) and the CH 2 POSITION control
positions on the Y-axis (vertically).
6. CH 1 OR X and CH 2 OR Y— Input connectors for
application of external signals to the inputs of the vertical
amplifier. In the X-Y mode of operation, the signal
connected to the CH 1 OR X connector provides horizon-
tal deflection and the signal connected to the CH 2 OR YY
connector provides vertical deflection,
7. AC-GND-DC—Selects the method used to couple a
signal to the input of the vertical amplifier. In the AC
position, signals are capacitively coupled to the vertical
amplifier, The dccomponentofthe 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 display of the signals of both
channels. Display 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 plus 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 at a
repetition rate of approximately 250 kHz. Useful at sweep
rates slower than about 50 microseconds/division, or
when a dual-trace, single-sweep display is required.
CH 2: Channel 2 only is displayed. It must be selected
in X-Y 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 displayed on
the crt.
10. INVERT—Channel 2 display is inverted in the
INVERT (button in) position.
@ 475/DM44 Operators 5
Fig. 3. Display and DM44 controls, connectors, and indicators.
475/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) inputs for voltage and resistance
Only.
19. Probe Connector—Input connector for the
temperature probe.
20. Readout—Negative polarity indication is
automatic for negative dc voltage and temperature with no
polarity 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 Vto 1.2 kV dcin5ranges
(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 theother
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 orthe other will light to indicate intervals
per ms (1/ms lamp) or intervals per us (1/us lamp). No
@ 475/DM44 Operators 7
lamp lit indicates intervals per second. If the duration of
one event is being measured, the Readout and Scale
Factor Lamps indicate frequency. The 1/ms lamp in-
dicates kHz, the 1/us lamp indicates MHz, and no lamp lit
indicates Hz.
24. A 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 control
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 control move only the reference
point. The procedure for making this modification is
located 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.
Fig. 4. Trigger controls, connectors, and indicators.
8 475/DM44 Operators @
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, shape or time causing an unstable conven-
tional display. It can also 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), Asweep is reset at the end
of B sweep to provide the fastest possible sweep repetition
@ 475/DM44 Operators
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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.
23. COUPLING—Determines method used to couple
signals to the trigger generator circuit.
AC: Signalsarecapacitivelycoupledtotheinputofthe
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 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: All 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.
10 475/DM44 Operators @
32. SOURCE—Determines the source of the trigger EXT: Signals connected to the External Trigger Input
signal coupled to the input of the trigger circuit. connectors are used for triggering. External signals must
be time-related to the displayed signal for a stabledisplay.
It is useful when the internal signal is too small or contains
undesired signals that could cause unstable triggering. It
NORM: Trigger source is displayed signal(s). It does is useful when operating in CHOP mode.
not indicate time relationship between CH 1 and CH 2
signals. However, stable triggering of non-time-related
signals usually can be obtained by setting VERT MODE to
ALT, SOURCE to NORM and COUPLING to LF REJ.
Carefully adjust LEVEL for a stable display. à |
EXT — 10 (A Trigger circuit only): External trigger
signal is attenuated by a factor of 10.
CH 1: À 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,
STARTS AFTER DELAY (B Trigger circuit only): B
Sweep runs immediately after the delay time selected by
the DELAY-TIME POSITION control. When making
СН 2: À sample of the signal available in Channel 2is differential time measurements you must use this mode to
used as a trigger signal. CH 1 signal is unstable if it is not obtain valid measurements. On instruments equipped
time-related. with a DM44 you must use this mode to obtain valid
measurements when using the TIME or 1/TIME functions.
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 33. External Trigger Inputs—Input connectors for ex-
waveform. ternal trigger signals.
@ 475/DM44 Operators 11
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-Y 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-
ly for À sweep and B Sweep.
36} {35 41 36. X10 MAG—Increases displayed sweep rate by a
2039.7 factor of 10. It extends fastest sweep rate to 1
nanosecond/division. The magnified sweep is the center
Fig. 6. Horizontal, calibrator, and power controls, connectors, division of the unmagnified display (0.5 division either side
and indicators. of the center graticule line).
12 475/DM44 Operators @
37. VAR—Provides continuously variable sweep rates
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 rateiscalibrated 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 control 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 DM44 is in the TIME
or 1/TIME function, this control operates in conjunction
with the À TIME control. The DELAY TIME POSITION
control moves both the reference point and the time-
measurement point. The À TIME control moves only the
time-measurement point. With the time-measurement
point to the left of the reference point the Readout
NOTE
You can modify your instrument to make the DELAY
TIME 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 combination 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
indicates a negative time difference.
switch. B sweep is inoperative.
@ 475/DM44 Operators
MIX: The first part of the horizontal 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/DIV) switch and the
DELAY-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 Holder—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 for externally 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.
14 475/DM44 Operators a
13
CH 1 GAIN
5 mV
CH 2 GAIN
5mV
CH 2 GAIN
2mV
2039-8
Fig. 7. Rear panel and left side panel controls, connectors, and indicators.
@ 475/DM44 Operators 15
These instructions permit the operator to obtain the most commonly used basic displays.
NORMAL SWEEP DISPLAY Display
INTENSITY Fully counterclockwise
1. Set the controls as follows:
Vertical Trigger
VERT MODE CH 1 (Both A and B if applicable)
VOLTS/DIV Position determined by SLOPE +
amplitude of signal to LEVEL 0
be applied SOURCE NORM
VOLTS/DIV VAR Calibrated detent COUPLING AC
AC-GND-DC AC TRIG MODE (A only) AUTO
Vertical POSITION Midrange A TRIG HOLDOFF NORM
100 MHz-20 MHz BW Not limited (yellow band
not visible) 2. Pull the POWER switch (on). Connect the signal to
INVERT Button out the CH 1 input connector.
Horizontal | 3. Adjust the INTENSITY control for the desired
display brightness. If the display is not visible with the
MES Statin Locked together at 7 me INTENSITY control at midrange, pressthe BEAM FINDER
A TIME/DIV VAR Calibrated detent pushbutton and adjust the CH 1 VOLTS/DIV switch to
HORIZ DISPLAY A reduce the vertical display size. Center the compressed
X10 MAG Off (button out) display with the vertical and horizontal POSITION con-
POSITION Midrange trols; release the BEAM FINDER pushbutton.
16
475/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 control 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
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 Normal Sweep Display.
2. Setthe HORIZ DISPLAY switch to A INTEN and the
B Trigger SOURCE switch to STARTS AFTER DELAY.
3. Pull out on the B TIME/DIV knob and turn cw until
the intensified zone is the desired length. Adjust the
INTENSITY control as needed to make the intensified
Zone distinguishable from the rest of the display. If your
instrument is equipped with a DM44, set the FUNCTION
switch to a function other than TIME or 1/TIME for a single
delayed sweep. Dual delayed displays are discussed in
to determine the magnified sweep rate.
step 6.
@ 475/DM44 Operators
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 yourinstrument 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 displays. 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
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 function 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 atthe 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.
475/DM44 Operators @
17
20
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 display 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.
@ 475/DM44 Operators
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 frequency 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.
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
wll a lL J
>
Q CAUTION
O ALIAS
The meter may be damaged by attempting to
measure voltage if the meter is in the resistance
mode of operation (OHMS FUNCTION button push-
ed in) and the applied voltage is in excess of 120 V
rms.
1. Push in the OHMS FUNCTION button and the
MQ RANGE button. See Fig. 8.
TABLE 2
Resistance Ranges
RANGE READOUT MEASUREMENT
20 MQ 20.00—02.00 20 MQ—2 MQ
2 MQ) 2.000—0.200 2 MQ—200 kQ2
200 kQ | 200.0—20.00 200 кО—20 КО
20 kQ 20.00—02.00 20 kQQ—2 КО
2 kQ 2.000—0.200 2 kQQ—200 0
200 Q 200.0—000.0 2000—0Q —
A blinking readout on any range, when connected to
2. Connect the + and COM leads to the unknown
resistance.
3. Reduce the range, using the following table, until a
proper readout is obtained.
20
any unknown resistance, indicates an overrange condi-
tion and a need to select a higher range.
A blinking readout, when meter leads are disconnected
Is normal.
475/DM44 Operators @
RESISTANCE
INPUT
RANGE SELECTION
(465/DM-0-2)2039-9
VOLTS
LALALA Fy
| CAUTION
RANAS
The maximum safe input voltage is £1200 V (dc +
peak ac) between the + and COM inputs or between
the + input and chassis.
The maximum COM floating voltage is +500 V (dc +
peak ac) to chassis.
The meter may be damaged by attempting to
measure voltage if the meter is in the resistance
mode of operation and the applied voltage is in
excess 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.
1. Push in the VOLTS FUNCTION button and the
1.2 kV RANGE button. See Fig. 9.
2. Connect the COMMON lead to the reference point
(usually a ground or test point) and the HIGH lead to the
unknown voltage to be measured and observe the reading.
22
475/DM44 Operators
Fig. 8. Resistance.
475/DM44 Operators 21
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
2 V ranges.
A blinking readout on any range indicates an
overrange condition and a need to select a higher
range.
TABLE 3
Volts Ranges
RANGE READOUT MEASUREMENT
1.2 kV 1.200—0.200 1.2 kV—200 V
200 V 200.0—020.0 200 V—20 V
20 V 20.000—02.00 20 V—2 V
2V 2.000—0.200 2V—2V
200 mV 0.200—0.000 2 v-0 Y
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VOLTAGE
INPUT
FUNCTION SELECTION
REFERENCE
RANGE SELECTION
(465/DM-0-3)2039-10
Fig. 9. Volts.
@ 475/DM44 Operators 23
TEMPERATURE NOTE
all lll all al ll Seal al
Q CAUTION )
dr AT ES
The maximum safe voltage on the measurement
surface is +400 V (dc + peak ac) above chassis
ground.
The sensor tip is fragile and may break if droppedor
subjected to excessive stress. Force exerted on the
sensor tip should not exceed 20 pounds.
If the reading exceeds —55°C or +150° C, remove
the probe at once to prevent probe damage.
1. Push in the TEMP (°C) FUNCTION button. See
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
fahrenheit.
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
removed from the device by the probe, etc.
These items and other probe information are in the
probe manual, which should be reviewed.
Accuracy Check
The DM44 is calibrated to its original probe, giving
accurate readings within 2°C for examples that follow.
The DM44 should be recalibrated to any replacement
probe.
In the following checks, use an accurate thermometer
to verify water temperature. Anything in solution affects
the melting temperature and the boiling point is affected
by changes in altitude and barometric pressure.
Low Temperature
Allow a container (preferably insulated) of crushed ice
to melt until there are only a few pieces of ice remaining.
24 475/DM44 Operators a
APPLY SILICONE GREASE
TO THE SURFACE TO BE
MEASURED (WHEN POSSIBLE).
- y A e
E
WS
Ad
Г
к
а
Ге,
LA %
a,
К
Г
PROBE
TEMPERATURE
SENSOR TIP
5
al
E
fhe
Pe
o.
E
PL RT
+
o
=
Co
pr ot
ol
Po aly
FAA NE
Ly je Pa a
Ay i
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rl
wt
a
i лож
A... X
Sn ur y a
aL E
Fo
Fi
Lu a
SEALED PORTION
THIS
(465/DM-0-4)2039-11
Fig. 10. Temperature.
@ 475/DM44 Operators 25
TABLE 4
CENTIGRADE TO FAHRENHEIT CONVERSION
= OÙ - 40 - 30 - 20 -10 0
CENTIGRADE
FAHRENHEIT
CENTIGRADE
FAHRENHEIT
CENTIGRADE
FAHRENHEIT
CENTIGRADE
FAHRENHEIT
-50 -40 -30 -20 -0 0 10 20 30
0 10 20 30 40 50
40 50 60 70 80 90 100 110 120
90 60 70 80 90 100
130 140 150 160 170 180 190 200 210
100 NO 120 130 140 190
220 230 240 250 260 270 280 290 300
26
475/DM44 Operators @
te he A
2 CAUTION
LOTA o
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.
@ 475/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 for
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
Signal Ground
ИИ nl nl ll all Ll
2 CAUTION
O Pa
Avoid cross-grounding because instrument damage
may occur.
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 a common 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
by 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, especially if the dc
level difference is more than 10 times the VOLTS/DIV
setting.
1. Before connecting the probe tip to a signal source,
set the Input Coupling switch to GND.
2. Touch the probe tip to oscilloscope chassis ground.
Wait several seconds for the Input Coupling capacitor to
discharge.
3. Connect the probe tip to the signal source.
4. Wait several seconds for the Input Coupling
capacitor to charge.
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.
28 475/DM44 Operators a
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.
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.
Trace Rotation Adjustment E.
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- PENSATED
driver adjustment located below the crt graticule) to align (OVERSHOOT)
the trace with the center horizontal graticule line.
UNDER COM-
PENSATED
(ROLLOFF)
Probe Compensation
Miscompensation is one of the greatest sources of
operator error. Most attenuator probes are equipped with pd Add
adjustments to ensure optimum measurement accuracy.
Probe compensation is accomplished as follows: Fig. 11. Probe compensation.
@ 475/DM44 Operators 29
Vertical Gain Check B TIME/DIV 5 us
Obtain a Normal Sweep Display presentation of the HORIZ DISPLAY pik AFTER DELAY
calibrator square-wave voltage. Set the appropriate B NCTIÓN TUNE
VOLTS/DIV switch to the 50 mV position and the Input FUNC |
A TIME To move the time-
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 475 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 475 Timing Check to verify the
accuracy of the horizontal deflection system.
Leave controls set as for the Basic 475 Timing Check
except as follows:
measurement point to the
right of the reference
point.
9.8 TO 10.2
6.53 TO 6.79
1738-14
Fig. 12. Basic 475 timing check.
30 475/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 B). Verify the readout
is 16.49 to 16.84 and the ms lamp is lit.
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
ETT with the center vertical graticule line (see Fig. 14, Point B).
Measure the vertical deflection from peak-to-peak (Point
Fig. 13. DM44 timing check. A to Point B).
@ 475/DM44 Operators 31
Multiply the vertical deflection just measured by the
CEREAL ME 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) witha VOLTS/DIV
switch setting of .5.
VERTICAL
DEFLECTION
Using the formula:
— verti
Volts goes) VOLTS/DIV
Peuk-to-heak 7 deflection X settin
MEASURE AMPLITUDE Р (divisions) 9
ГНОМ АТОВ
(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 will subtract the trace thickness from
the measurement.
Substituting the given values:
Volts Peak-to-Peak = 4.6 X 0.5 V = 2.3 volts.
INSTANTANEOUS VOLTAGE
MEASUREMENTS—DC
Obtain a Normal Display. Make sure the VAR
VOLTS/DIV control is in the calibrated detent.
475/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. If the
waveform moves 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, if the
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
4.6 divisions (see Fig. 15), the waveform is above the
reference line, and the VOLTS/DIV switch is set to 2.
и NEGATIVE REFERENCE LINE
== =
VERTICAL
DEFLECTION MEASURE
AMPLITUDE
АТОВ
OR
NEGATIVE
AMPLITUDE
сто В
А
Fig. 15. Instantaneous voltage measurement.
Using the formula:
465/DM-0-7
Instan- vertical VOLTS/
taneous = distance X polarity X DIV
Voltage (divisions) setting
Substituting: =4.6 X (+1) X2 V = 9.2 volts.
@ 475/DM44 Operators
If 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 divisions 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).
34
The following general precautions should be observed
when using the ADD made.
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-level value. Apply a negative
dc level (or a positive level usingthe CH 2 INVERT switch),
of the value determined, to Channel 2 input. See Fig. 16B.
The ADD mode puts the resultant display within the
operating range of the POSITION controls.
475/DM44 Operators @
33
Ss
LVEVIVED
1 | | | | vi
-— oy
an
—
“=
POSITIVE LEVEL |
+ | | т т Y
r
T
+
+
Í
1
| |
| Т | OV RI |
WITH 3 DIVISIONS OF
POSITIVE DC LEVEL. NEG
ov
| | | 1 — т : — ER A | 1 J
| NEGATIVE OFFSET
q + | 4. 3 = i | Ç + T | .- " A
CE] Ty Ш
| | pa т
| - | — L ar EEE | | | | | : = | |
(A) CHANNEL 1 SIGNAL (8) CHANNEL 2 DISPLAY (C) RESULTANT DISPLAY
WITH 3 DIVISIONS OF
ATIVE OFFSET.
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.
@
475/DM44 Operators
EXAMPLE: The signal applied to the CH 1 input
contains unwanted line frequency components (see Fig.
174). 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
35
CH 1 SIGNAL
WITH UNWANTED
LINE FREQUENCY 100 ="
COMPONENT
CH 2 SIGNAL
FROM LINE
FREQUENCY
SOURCE
(INVERTED)
SIGNAL WITH
LINE FREQUENCY
COMPONENT
CANCELED
`
(A) CH 1 AND CH 2 SIGNALS.
(B} RESULTANT SIGNAL. 1738-19
36
Fig. 17. Common-mode rejection.
475/DM44 Operators
VOLTS/DIV and VAR VOLTS/DIV controls so the CH 2
display is about the same amplitude as the undesired
portion of the CH 1 display (see Fig. 17A).
3. Set the VERT MODE switch to ADD. Slightly
readjust the CH 2 VAR VOLTS/DIV control for maximum
cancellation of the undesired signal component (see Fig.
178).
AMPLITUDE COMPARISON
MEASUREMENTS
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
to set the reference signal to an exact number of divisions.
The unknown signal can then be quickly and easily
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
establishing a vertical conversion factor and an arbitrary
deflection factor. The amplitude of the reference signal
must be known before a vertical conversion factor can be
established.
@
Determine the vertical conversion factor using this
formula:
reference signal amplitude (volt)
Vertical vertical VOLTS/DIV
Conversion = deflection X switch
Factor (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 ofan 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 following formula:
EXAMPLE: The reference signal amplitude measured is
30 volts with a VOLTS/DIV switch setting of 5and 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
fn 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.
Sigal Arbitrary Vertical
де’ ii de 7 deflection X deflection TIME-DURATION MEASUREMENTS
pu factor (divisions)
о Obtain a Normal Sweep display. Be sure the VAR
TIME/DIV control is set to the calibrated detent. Set the
Sianal Vertical VOLTS/DIV Vertical TIME/DIV switch for a single event and position the
A tas Conversion X switch X deflection display to place the time measurement points to the center
IRAE Factor setting (divisions) horizontal graticule line (see Fig. 18).
@ 475/DM44 Operators 37
HORIZONTAL
DISTANCE
1738-20
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 set to 2 ms with the magnifier off.
Using the formula:
horizontal
Time _
Buratión — distance X
(divisions)
magnification
Time/Div
setting
Substitute the given values:
Time
= 8.3 X 2 ms = 16.6 milliseconds
Duration
FREQUENCY MEASUREMENTS
Time Duration measurements can be used todetermine
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
time duration a 16.6 ms = ВО Пепе
Frequency =
38 475/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 ii waveform,
Falltime 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 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%
mes
| | “TT |
SIÓN ® 7 | MEASURE
AMPLITUDE "7 TIME FROM
| 1 ATOB
| | | I
| | 5 | E
FH —
Lu LME | Ld
HORIZONTAL
=e DISTANCE 465/DM-0-13
Fig. 19. Risetime.
Using the time duration formula to find risetime:
Time horizontal
: TIME/DIV
Duration = distance X
} EI setting
(risetime) (divisions)
Substituting the given values:
and 90% points is 5 divisions (see Fig. 19) and the
TIME/DIV switch is set to 1 us. Risetime = 5 À 1 us = 5 microseconds.
@ 475/DM44 Operators 39
TIME-DIFFERENCE BETWEEN
TWO PULSES FROM
DIFFERENT SOURCES
CHANNEL 1 (REFERENCE) CHANNEL 2
50%
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 the setting of
the 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).
AMPLITUDE
LEVEL
MEASURE
TIME FROM
ATOB
— a! HORIZONTAL La
| DIFFERENCE |
465/DM-0-14
Fig. 20. Time difference between two pulses from different
sources.
Using the formula:
; horizontal
‘ue = mia X difference
Difference setting (divisions)
magnification
Substituting the given values:
Time _ 60usX45 _ 22 5 microseconds
Difference 10
40 475/DM44 Operators a
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
compared with, or adjusted to, an exact number of
divisions.
Other unknown signals may be measured without
disturbing the setting of the VAR TIME/DIV control by
establishing a horizontal conversion factor and an ar-
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 deflection to make an accurate measurement.
Do not readjust the VAR TIME/DIV control. Measure the
horizontal deflection in divisions and calculate the time
duration using the formula:
bitrary deflection factor. The time duration of the Time arbitrary horizontal
reference signal must be known before a horizontal Durati = deflection X deflection
conversion factor can be established. UE factor (divisions)
or
Determine the horizontal conversion factor using the Time horizontal TIME/DIV horizontal
formula: Duran = conversion X switch X deflection
factor setting (divisions)
reference signal time duration
conds
mii EXAMPLE: The reference signal frequency measured is
Horizontal Horizontal TIME/DIV 455 hertz (time duration: 2.19 milliseconds) with a
Conversion = deflection X switch TIME/DIV switch setting of .2 ms, and the VAR TIME/DIV
Factor (divisions) setting control adjusted to provide a horizontal deflection of eight
@ 475/DM44 Operators 41
divisions. Substituting these values in the horizontal
conversion factor formula:
Horizontal
. _ 2.19 ms _
8 X 0.2 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:
Time Duration = 1.37 X 50 us X 7 = 480 us
This answer can be converted to frequency by taking
the reciprocal of the time duration (see applications on
Determining Frequency).
PHASE DIFFERENCE
MEASUREMENTS
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.
42
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° B 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.
475/DM44 Operators @
CHANNEL 1 CHANNEL 2
(REFERENCE) J IARI
- T ]
(NTT TTT]
ZI
MEASURE
TIME FROM
ATOB
| HORIZONTAL
Py DIFFERENCE
| E LLL E 4 $1 —
|
DIVISIONS
ae ——.
(360°) 465/DM-0-15
Fig. 21. Phase difference.
Using the formula:
rizontal
Phase jag 120 sweep rate
= difference X "e
Difference divisions (degrees/div)
Substituting the given values:
Phase Difference = 0.6 X 45° = 27”.
HIGH RESOLUTION PHASE
DIFFERENCE MEASUREMENTS
Make more accurate phase measurements by in-
creasing the sweep rate (without changing the À 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
== ———— 7
MEASURE
TIME FROM
ATOB
| HORIZONTAL I
™* DIFFERENCE >
465/DM-0-16
Fig. 22. High-resolution phase difference.
@ 475/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 ac
(divisions) (degrees/div)
Substituting the given values:
Phase Difference = 6 X 45° = 27°.
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. Setthe HORIZ DISPLAY switch
to B DLY'D.
MEASURE
TIME FROM
ATOB
1738-34
Fig. 23. Pulse jitter.
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 by the B
TIME/DIV switch setting to obtain pulse jitter time.
44 475/DM44 Operators @
DELAYED OR MIXED
SWEEP MAGNIFICATION
The delayed sweep features of the 475 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 an
amount of time selected by the ATIME/DIV switch and the
DELAY-TIME POSITION control before the display is
presented at the sweep rate selected by the B TIME/DIV
switch. 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.
@ 475/DM44 Operators
INTENSI
TO BE
ZONE
[Al A INTENSIFIED DISPLAY
[BI B DELAYED DISPLAY
1738-31
46
Fig. 24. Delayed sweep magnification.
4. Set the HORIZ DISPLAY switch to A INT and the B
Trigger SOURCE switch to STARTS AFTER DELAY,
Instrument equipped with DM44. 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 display
to be magnified.
6. Set the B TIME/DIV switch to a setting which
intensifies the full portion to be magnified. The startof the
intensified zone remains as positioned above (see Fig. 24).
7. Set the HORIZ DISPLAY switch to B DLY'D to
magnify the portion 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.
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 us is:
Apparent
Magnification A TIME/DIV setting
(Delayed B TIME/DIV setting
Sweep)
Substituting the given values:
Apparent 1X 107
Magnification 1X10”
The apparent magnification is 100 times.
Triggered Delayed Sweep Magnification
The delayed sweep magnification method just describ-
ed may produce too much jitter at high apparent
magnification ranges. Operating the B Sweep in a
triggered mode provides a more stable display since the
delayed display is triggered at the same point each time.
475/DM44 Operators @
1. Set up the display as 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. (If 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.
If the condition cannot be remedied with the B Triggering
controls or by increasing the display amplitude (lower
VOLTS/DIV setting), trigger 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 made and magnification factors
are calculated as in the STARTS AFTER DELAY mode
previously given.
@ 475/DM44 Operators 47
BASIC 475 DELAYED OR MIXED SWEEP TIME MEASUREMENTS
The delayed sweep modes can be used to make more accurate time measurements.
TIME DIFFERENCE BETWEEN
REPETITIVE PULSES (BASIC 475)
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 dial 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 POSITION dial to move the pulse (or rising
portion) to some vertical reference line (see Fig. 25B).
Note the setting of the DELAY TIME POSITION dial. Turn
the DELAY TIME POSITION dial clockwise to move the
second pulse 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 controls. Note the setting of the
DELAY TIME POSITION dial.
Determine the time difference using the following
formula:
Time Difference =
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
№” dial _ | X (A TIME/DIV
PONS ng setting)
48 475/DM44 Operators @
TIME
DIFFERENCE
INTENSIFIED
ZONE
[Al A DISPLAY
VERTICAL
REFERENCE LINE
iB) B DLY'D DISPLAY 1738-23
Fig. 25. Time difference between repeltitive 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 475)
Obtain a Delayed Sweep Display. Set the À 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 the display to place the time
measurement points to the center horizontal graticule line
(see Fig. 26).
Use the DELAY 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.
@ 475/DM44 Operators 49
—— Time = Time
INTENSIFIED Difference Duration
a NE E \ second first delay time
JANE | | | dial — dial | X (A TIME/DIV
(A fr | 1 (B) y setting setting setting)
+ ++ ++ 4 + + +
| 3 |
| A Л Substituting the given values:
+
pe as ——
| || i LL
! HORIZONTAL
DISTANCE
++
—
| I
/ | MEASURE \ | 1/ |
SE TIME | JE
* FROM A TO B |
i
|
465/DM-0-9
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:
Time Duration = (9.53 — 1.20) X 2 ms = 16.66 ms
FREQUENCY MEASUREMENTS
(BASIC 475)
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, Fig. 26) is 16.66 milliseconds.
Using the formula:
1
Frequency =— :
q y time duration
Substituting the given values:
60 hertz
1
Frequency = gee ms.
50 475/DM44 Operators @
TIME DIFFERENCE BETWEEN TWO
PULSES FROM DIFFERENT SOURCES
(BASIC 475)
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.
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 DISPLAY switch to À 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).
E
CHANNEL 1 (REFERENCE) CHANNEL 2 i Egle
= г pr — —
4 + + | | +CH2 SIGNAL.
50% a CH1 SIGNAL
AMPLITUDE —— —— —— —t———++—
LEVEL MEASURE М
неон gr ere —— TIME
INTENSIFIED | | FROM ATO EB |}. LA 4 A | | |
A CH1 SIGNAL A FORCH1 |
TR 11 = — 1 ~] | BFORCH?
| Sr = 1
E A Er bh
| |
| : L 1 E ri | == L ==
|
HORIZONTAL
—— DIFFERENCE i RE
Fig. 27. Time difference between two pulses from different sources.
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 move 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 dial 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. Usethe 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
1 = dial = dial X (A TIME/DIV
difference ,
setting setting setting)
52
475/DM44 Operators
475/DM44 Operators
51
Substituting the given values:
Time Difference = (7.10 — 2.60) X 50 us = 225 us
RISETIME (BASIC 475)
Risetime measurements use the same methods as time-
duration measurements, except the measurements are
made between the 10% and 90% points of the waveform.
Falltime 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 five-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
@
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
ee signal and the 190% graticule line (see Fig. 28, Point B). Time — Riseti _
Note the DELAY TIME POSITION dial setting. Différence — "me =
Substitute the DELAY 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 values:
Г | 7 EST TIT TT Ti Risetime = (7.50 — 2.50) X 1 us = 5 ms.
| T : | JA Se MIX (BASIC 475)
| For the MIX mode of operation, the same general
SIGNAL xa E) TE procedures can be used. With the first part of the display at
: РВОМ АТО В 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
] 0-11 39- :
oil DLY'D mode is the most accurate and therefore
recommended mode of making differential time
Fig. 28. Risetime. measurements.
@ 475/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 VERT
FUNCTION | DISPLAY MODE DISPLAY OBTAINED
СН 1, СН 2, | One intensified zone, DELAY TIME POSITION moves intensified zone.
OR ADD
A INT
ALT or Two intensified zones, one on each channel display. Intensified zones
VOLTS CHOP are coincident in time. DELAY TIME POSITION moves both intensified
OHMS, zones.
OR TEMP CH 1, CH 2,
OR ADD One mixed display. Position of transition point determined by DELAY
TIME POSITION.
MIX
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.
54 475/DM44 Operators @
TABLE 5 (cont)
DM44 Delayed Sweep Displays
DM44 HORIZ VERT
_FUNCTION DISPLAY MODE DISPLAY OBTAINED
CH 1, CH 2 | Two intensified zones. DELAY TIME POSITION moves both intensified
OR ADD zones. A TIME moves only one intensified zone.
A INT? ALT Two intensified zones. Reference point appears 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 display).
TIME + ant чат я | te on
on SHOR WO pairs of intensified zones, one pair on each channel display. The pairs
are coincident in time with each other. DELAY TIME POSITION moves all
ИМЕ four intensified zones. A TIME moves two intensified zones.
CH 1, CH 2, | Two mixed displays, one on each channel display. DELAY TIME POSITION
OR ADD moves transition point of both displays. A TIME moves transition point of
— | CH 2 display only.
ALT Two mixed displays, one on each channel display. DELAY TIME 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 overlap.
‘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.
@ 475/DM44 Operators
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.
23A. 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 DLY'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 on screen. The Readout and Scale Factor Lamps
now indicate the time difference between the pulses.
56 475/DM44 Operators
TIME
DIFFERENCE
NTENSIFIED
ZONES
(A) A DISPLAY
VERTICAL
REFERENCE LINE
A AND B
SUPERIMPOSED
(B) B DLY'D DISPLAY (1738-23)2039-30
Fig. 29. Time difference between repetitive pulses.
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 À INTEN
B SOURCE STARTS AFTER DELAY
A TIME/DIV To display a single
event.
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
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-
@
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 DLY'D. Slightly
readjust the A TIME control to superimpose the displayed
waveform portions (see Fig. 30B). The DELAY. TIME
POSITION control 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:
1/ms Lamp 1/us Lamp Multiplier a
OFF OFF Hz
a ON OFF kHz
OFF ON MHz
58
INTENSIFIED
ES
(A) A SWEEP DISPLAY
i
SUPERIMPOSE
PORTIONS OF
WAVEFORM
(B) BDLY'D DISPLAY
2039-31
Fig. 30. Time duration and frequency measurements.
475/DM44 Operators
57
A blinking display 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
1 0.25 DIV
2 0.5 DIV
5 1.0 DIV
TIME DIFFERENCE BETWEEN
TWO PULSES FROM
DIFFERENT SOURCES (DM44)
Set controls as follows:
A SOURCE
VERT MODE
HORIZ DISPLAY
B SOURCE
B TIME/DIV
VAR TIME/DIV
475/DM44 Operators
CH1
ALT
A INT
STARTS AFTER DELAY
3 or 4 positions more
cw than A 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
Adjust the A TIME control
to move the time-
measurement point to the desired spot on the CH 2 display
(see Fig. 314, Point B).
Set the HORIZ DISPLAY switch to B DLY'D. Slightly
readjust the DELAY TIME POSITION and A TIME controls
to superimpose the waveforms (see Fig. 31B).
The
Readout and Scale Factor Lamps indicate the time
time-measurement point appears on the CH 2 display. difference.
CHANNEL 1 (REFERENCE) ii 2
N y Q cH 2 SIGNAL
50% CH 1 SIGNAL
AMPLITUDE —— — AA ——
LEVEL MEASURE
TIME
INTENSÍFIED | РВОМ АТО В a A E MN, |
ZONES
| LL CH1 SIGNAL |) > SUPERIMPOSE
— A LEADING EDGES
a : = EN E dd
|
| i 3 L + il td
HORIZONTAL
i DIFFERENCE '
(465/DM-0-10)2039-32
Fig. 31. Time difference between two pulses from different sources.
@ 475/DM44 Operators 59
RISETIME (DM44) 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 control to move the time measure-
ment point to the 90% graticule line (see Fig. 32, Point B).
Set controls as follows: The Readout and Scale Factor Lamps indicate the
risetime.
FUNCTION TIME
HORIZ DISPLAY A INTEN
B SOURCE STARTS AFTER DELAY
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 display is exactly 5 divisions.
Vertically position the display so the bottom touches the
0% graticule line and the top touches the 100% graticule
line.
Г | т (TTT
a | / } IN [
| | \
SIGNAL Eo « | MEASURE
ate) oros
LAT
| | | $ | | | |
INTENSIFIED ZONES
HORIZONTAL | ë
DISTANCE
(465/DM-0-11)2039-29
Fig. 32. Risetime.
60 475/DM44 Operators @
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 ATIME/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.
@ 475/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.
475 OSCILLOSCOPE
VERTICAL
Deflection Factor Accuracy: Within 3% in the calibrated
position.
Frequency Response: Dc to at least 200 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: 1.75 nanoseconds or less (calculated from
0.35 — bandwidth in MHz).
Maximum Input Voltage: Dc-coupled 250 V (dc + peak
ac) or 500 V p-p ac at 1 kHz or less; ac-coupled, 500 V (dc
+ peak ac) or 500 V p-p ac 1 kHz or less.
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: 0.5 пА 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 400 mV/DIV. Bandwidth is dc to at least
62 475/DM44 Operators e
20 MHz, with CH 2 OUT connected to CH 1 input. AC-
coupled, using a 50 Q, 42-inch BNC cable, terminated in
50 ©) 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,
fromdcto 25 MHz; increasing to 1.5 divinternal or 150 mV
external at 100 MHz.
EXT — 10 Signal: Amplitude requirements are mul-
tiplied by 10.
@
Accuracy for Measurements Less than One Major Dial
Division: Within 0.01 major dial divisions from +15°C to
+35° C. Within +£0.02 major dial divisions from —15°C to
ТОО
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
475/DM44 Operators
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 + a
-20 V, 40 М р-р.
Trigger View
nd
Deflection Factor: About 50 mV/div in EXT and about
500 mV/div in EXT — 10.
Risetime: 5 ns or less.
Trigger Centering Point: Within 1.0 division of screen
center.
DIFFERENTIAL TIME
MEASUREMENT (BASIC 475)
Accuracy for Measurements Greater than One Ma
jor
Dial Division: Within +£1% from +15°C to +35° C. Within
+1.5% from —15°C to +55°C.
475/DM44 Operators
Calibrated Delay Time (VAR control to CAL):
Continuous from 0.2 us to at least 5 seconds after the start
of A (delaying) sweep.
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 Amplifiers:
Within 3° from dc to 50 kHz.
Deflection Accuracy: Within 4%.
CALIBRATOR
Output Voltage: 0.3 V within 1% and within 0.3% from
+20°C to +30°C.
Output Current: 30 mA within 2% from +20°C to
+30° C.
Repetition Rate: About 1 kHz.
63
Z AXIS INPUT
Sensitivity: Noticeable intensity modulation, at normal
intensity settings, by a 5 V p-p signal. A positive-going
AC POWER SOURCE
Requlating Ranges:
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/divinto 1 MO; toat 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.
Output Resistance: About 500 ohms.
115 V 230 V
_ High 108 V to 132 V
Low 99 V to 121 V
Medium | 104 V to 126 V
198 V to 242 V
207 V to 253 V
216 V to 264 V
Line Frequency: From 48 Hz to 440 Hz.
Maximum Power Consumption: 100 watts at 115 Y,
60 Hz, medium range.
ENVIRONMENTAL
Operating Temperature: -15°C to +55°C.
Operating Altitude: To 15.000 feet. Maximum operating
temperature decreases 1°C/1,000 feet, above 5,000 feet.
Humidity (Operating and Storage): 5 cycles (120 hours)
referenced to MIL-E-16400F,
@ 475/DM44 Operators 65
DM44 DIGITAL MULTIMETER
RESISTANCE
Maximum Safe Input Voltage: 120 V rms between + and
COM inputs.
Resistance Accuracy: 200 QQ range—within 0.25% +1
count, plus probe resistance; 2 k(2, 20 k(2, 200 k(2, and 2
MQ ranges—within 0.25% +1 count; 20 MQ) range—within
0.3% +1 count.
Temperature Dependence: 20 k(2, 200 kQ and 2 MQ)
ranges—250 ppm/°C; 200 Q, 2 kQ2 and 20 M() ranges—
350 ррт/° С,
Resolution: 0.1 À.
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.
66 475/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 Surfaces:
+100 V (dc + peak ac) above chassis ground.
Temperature (Storage and Operating): Probe Body and
Cable, —55°C to +105°C. Probe Sensor Tip, —55°C to
+150°C.
DC VOLTAGE
Maximum Safe Input Voltage: +1200 V (dc + peak ac)
between + and chassis.
Common Floating Voltage: +500 V (dc + peak ac) to
chassis.
REV. A, JAN. 1978
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.
(e)
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.
475/DM44 Operators
ACCESSORIES
STANDARD ACCESSORIES
INCLUDED
2 10X Probe Packages 010-6106-03
1 Accessory Pouch, Snap (w/o DM) 016-0535-02
1 Accessory Pouch (DM) 016-0594-00
1 Accessory Pouch, Zipper 016-0537-00
1 Operator's Manual 070-2039-00
1 Service Manual (475) 070-1862-00
2 Fuses, 1.5 A 3AG fast-blow 159-0016-00
2 Fuses, 0.75 A 3AG fast-blow 159-0042-00
1 Filter, Blue Plastic (installed) 337-1674-00
1 CRT Filter, Clear Plastic 337-1674-01
1 Adapter, Ground Wire 134-0016-01
1 Pair, Test Leads (DM) 003-0120-00
1 Service Manual (DM44) 070-2036-00
1 P6430 Temperature Probe (DM44) 010-6430-00
OPTIONAL ACCESSORIES
C-5A Option 2 low cost fixed focus camera— Order
C-5A Option 2.
68 475/DM44 Operators
Protective Cover—Waterproof, blue vinyl—Order 016-
0554-00.
Folding Polarized Viewing Hood—Order 016-0180-00.
Folding Viewing Hood, light-shielding—Order 016-
0592-00.
Folding Viewing Hood, light-occluding—Order 016-
0566-00.
Mesh Filter—Improves contrast and EMI filter—Order
378-0726-01.
SCOPE-MOBILE Cart—Occupies less than 18 inches
aisle space, has storage area in base— Order 200.
Test Lead Set—1 black lead with banana plug and
grounding clip, 1 red lead with banana plug and probe.
Includes retractable hook tip and Cl tester probe cover.
May be used with other miniature probe tip accessories.
Order 012-0427-00.
REV. A, JAN, 1978
67
OPTIONS
Your instrument may contain the following options:
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.
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).
475/DM44 Operators 69