Tektronix 7B71 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97005
TEKTRONIX®
DELAYING
TIME BASE
SN B2050D0 AND UP
INSTRUCTION MANUAL
Serial Number 'JtXiiD ~~ ^
070-1580-00 373

WARRANTY
All TEKTRONIX instruments are warranted against
defective materials and workmanship for one year. Any
questions with respect to the warranty should be taken up
with your TEKTRONIX Field Engineer or representative.
All requests for repair and replacement parts should be
directed to the TEKTRONIX Field Office or representative
in your area. This will assure you the fastest possible
service. Please include the instrument Type Number or Part
Number and Serial Number’ with all requests for parte or
service. .j, ** || ''
'''-s.’
Specifications and price change privileges reserved.
Copyright ©1973 by Tektronix, Inc., Beaverton, Oregon.
Printed in the United States of America. All rights reserved.
Contents of this publication may not be reproduced in any
form without permission of Tektronix, Inc.
U.S.A. and Foreign TEKTRONIX products covered by U.S.
and foreign patents and/or patents pending.
TEKTRONIX is aregistered trademark of Tektronix, Inc.

7B71 (SN B205000and Up)
TABLE OF CONTENTS
Page
SECTION 1SPECIFICATIONS
Introduction 1-1
Electrical Characteristics 1-1
Sweep Rate 1-1
Sweep Accuracy 1-1
Sweep Length 1-1
Sweep Hold-Off Time 1-1
Variable Time Delay 1-1
Delay Time Range 1-1
Differential Delay Time Measurement Accuracy 1-1
Jitter 1-2
Trigger Sensitivity 1-2
Internal Trigger Jitter 1-2
External Trigger Input 1-2
Level Range 1-2
P-P Auto Sensitivity 1-2
Environmental Characteristics
Altitude 1-2
Physical Characteristics
Finish 1-2
Dimensions 1-2
Weight 1-2
SECTION 2OPERATING INSTRUCTIONS
General 2-1
Installation 2-1
Front Panel Controls 2-1
Test Setup Chart 2-4
General Operating Information 2-4
Sweep Calibration Check 2-4
Simplified Operating Instructions 2-6
Normal Sweep 2-6
Magnified Sweep 2-6
Delayed Sweep 2-6
Pushbutton Switch Logic 2-6
Triggered Light 2-7
Trigger Mode 2-7
Trigger Coupling 2-9
Trigger Source 2-10
Trigger Slope 2-10
Trigger Level 2-10
Horizontal Sweep Rate 2-12
Sweep Magnifier 2-12
Horizontal Position Control 2-13

7B71 (SN B205000and Up)
TABLE OF CONTENTS (cont)
Page
SECTION 2OPERATING INSTRUCTIONS (cont)
Applications 2-13
General 2-13
Measurement Techniques 2-13
Time Duration Measurements 2-14
Determining Frequency 2-15
Risetime Measurements 2-15
Delay Sweep Time Measurements 2-16
Delayed Sweep Magnification 2-17
Displaying Complex Signals Using Delayed Sweep 2-18
Pulse Jitter Measurements 2-18
SECTIONS CIRCUIT DESCRIPTION
Introduction 3-1
Block Diagram Description 3-1
Detailed Circuit Description 3-1
Trigger Input 3-1
Input Source 3-1
Trigger Amplifier 3-2
General 3-2
External Input Amplifier 3-2
Input Stage 3-2
Peak Detector 3-3
Slope Comparator 3-3
Output Stage 3-4
Trigger Generator 3-4
Trigger Pulse Generator 3-4
Sweep Gate Stage 3-4
Triggered Hold-Off Stage 3-4
Bright Line Auto 3-5
Time-Base Generator 3-5
General 3-5
Normal Trigger Mode Operation 3-5
Single Sweep Operation 3-8
Alternate Operation 3-8
Delayed Sweep Operation 3-8
Delay Pickoff 3-9
Horizontal Preamp 3-9
Readout Block 3-9
SECTION 4MAINTENANCE
Preventive Maintenance 4-1
General 4-1
Cleaning 4-1
Visual Inspection 4-1
Transistor and Integrated Circuit Checks 4-1
Recalibration 4-1

7B71 (SIM B205000 and Up)
TABLE OF CONTENTS (cont)
SECTION 4MAINTENANCE (cont) Page
Troubleshooting 4-2
Troubleshooting Aids 4-2
Troubleshooting Equipment 4-2
Troubleshooting Techniques 4-2
Corrective Maintenance 4-6
General 4-6
Obtaining Replacement Parts 4-6
Soldering Techniques 4-7
Component Replacement 4-7
Instrument Repackaging 4-10
SECTION 5PERFORMANCE CHECK/CALIBRATION
Introduction 5--|
Test Equipment Required 5-1
Short-Form Procedure and Index 5-2
Performance Check/Calibration Procedure 5-4
General 5-4
Preliminary Control Settings 5-5
Check/Adjust Steps (refer to Short-Form Procedure 5-5
for index to steps)
SECTION 6ELECTRICAL PARTS LIST
Abbreviations and Symbols
Parts Ordering Information
Index of Electrical Parts List
SECTION 7DIAGRAMS
SECTIONS MECHANICAL PARTS LIST
CHANGE INFORMATION
Abbreviations and symbols used in this manual are based on or
taken directly from IEEE Standard 260 "Standard Symbols for
Units", MIL STD-1 2B and other standards of the electronics
industry. Change information, if any, is located at the rear of this
manual.

TRiGGERING
WOOE COUPlfPiG SOURCE
P-PAOTO AC iNT
rmc'D I
LEVEl/SLOPE
SiNGlE
FINE
POSITION R^T MAGNIFIER
READY-
VARJABiE (CAL IN)
time/div ORDLYTIME
BDELAY MODE
(A INTER DURING 8}
II INDEPENDENT
BSTARTS
AFTER DELAY
8TRIGGERABLE
AFTER DELAY
DELAY TIME MULT
DELAYING TIME BASE
7B71
Fig. 1-1. 7B71 Delaying Time Base.
7B71 (SN B205000and Up)

7B71 (SN B205000and Up)
SECTION 1
7B71 SPECIFICATION
Change information,if any,affecting this section will be found at the rear of the manual.
Introduction
The 7B71 Time Base Unit is designed specifically for use
with Tektronix 7700-Series Oscilloscopes. However, it is
compatible with all 7000-Series Oscilloscopes. The 7B71
provides calibrated sweeps from 5seconds/division to 0.02
microseconds/division (2 nanoseconds/division with X10
MAGNIFIER). Sweep rates may be varied continuously
(uncalibrated) between calibrated steps. Sweep triggering is
to 200 megahertz or vertical amplifier bandwidth, which-
ever is less. The delaying sweep feature of the 7B71, in
delayed sweep operation, gives continuous sweep delay
from 0to 10 times the setting of the TIME/DIV OR DLY
TIME selector. The sweep free-runs providing abright base-
line in the absence of adequate triggering signal in P-P
AUTO and AUTO triggering modes.
The Performance Check procedure given in Section 5of
this manual provides aconvenient method of checking per-
formance of this instrument. The following electrical
characteristics apply at an ambient temperature of 0°C to
+50 C, unless otherwise noted. Warmup time for given
accuracy is 20 minutes.
TABLE 1-1
Electrical Characteristics
Characteristic Performance
Sweep Rate
Calibrated Range 5seconds/division to 0.02 micro-
seconds/division in a1-2-5 se-
quence. X10 magnifier extends
sweep rate to 2nanoseconds/
division.
VARIABLE Range
(uncalibrated)
Continuously variable between cali-
brated sweep rates. Extends uncali-
brated sweep rate to at least 12.5
seconds/division.
Sweep Accuracy Measured in 7000 series mainframe
Time Interval +15°Cto +35°C 0°C to +50°C
Over Center Unmag Mag Unmag Mag
8div
5s/div to 0.1
s/div and 0.2
ys/div to 0.02
ys/div
3% 3.5% 4% 5%
50 ms/div to
0.5 ys/div
2% 2.5% 3% 4%
Over any 2div
interval within
center 8div
5% 7%
a
Characteristic Performance
Excluded Divisions
of Magnified Sweep Start of Sweep; 12 ns in 7900
series, 20 ns in 7704A, and 50 ns in
other 7000 series mainframes.
End of Sweep; beyond the 90th
division
Sweep Length 10 divisions to 13 divisions.
Sweep Hold-Off Time
5s/div to
5ys/div
1.5 times the TIME/DIVISION set-
ting or less.
2ys/div to
0.02 ys/div
3.5 microseconds or less.
Variable Time Delay
Delay Time Range 0to 10 times DELAY TIME/DIV
setting from 5s/div to 1ys/div.
Differential Delay
Time Measurement
Accuracy
(+15°Cto +35° C)
5s/div to 1s/div
±(1.5% of measurement +0.3% of
full scale).
1-1

Specification-7871 (SN B205000 and Up)
TABLE 1-1 (cont)
Characteristic Performance
0.5 s/div to 1/Js/div ±(1 %of measurement +0.3% of full
scale). Full scale is 10 times the
DELAY TIME/DIV setting. Accu-
racy applies over the center 8major
DTM divisions.
Jitter 1part or less in 50,000 of 10 times
the TIME/DIV setting.
Trigger Sensitivity Triggering
Frequency
Range*
Minimum Trig-
gering Signal
Required
Coupling INT EXT
AC 30 Hz to
20 MHz 0.3 div 75 mV
20 MHz to
200 MHz 1.5 div 375 mV
AC LF REJ2 30 kHz to
20 MHz 0.3 div 75 mV
20 MHz to
200 MHz 1.5 div 375 mV
AC HF REJ 30 Hz to
50 kHz 0.3 div 75 mV
DC DC to
20 MHz 0.3 div 75 mV
i
20 MHz to
200 MHz 1.5 div 375 mV
Single Sweep Triggering requirements same as
normal sweep. When triggered,
sweep generator produces one
sweep only.
Internal Trigger Jitter 1nanosecond
hertz.
or less at 150 mega-
External Trigger Input
Maximum Input
Voltage
500 volts (DC +Peak AC). 500
volts (P-P AC) at 1kilohertz or less.
On Internal Triggering Only; the specified upper —3 dB frequency
of the Vertical System replaces upper limit frequencies in the
above table when the number in the table is greater than the —3 dB
frequency of the Vertical System.
2Will not trigger on sine waves of 3divisions or less internal or 1.5
volts external below 120 Hz.
TABLE 1-1 (cont)
Characteristic Performance
Input Rand C1megohm within 2%, 20 picofarads
within 2picofarads.
Level Range
(Excluding
P-P AUTO)
EXT
EXT+ 10
At least +1 .5 volts to —1 .5 volts.
At least +15 volts to —15 volts.
P-P AUTO operation
Sensitivity 0.5 div Internal, 125 millivolts
External 200 Hz to 20 MHz. Upper
frequency and amplitude limits
same as NORMAL Trigger Sensi-
tivity.
Low Frequency
Response
Must Trigger on 50 hertz, 2division
signal.
TABLE 1-2
Environmental Characteristics
This instrument will meet the electrical characteristics given
in Table T1 over the following environmental limits.
Characteristic Performance
Altitude
Non-operating To 50,000 feet and -55" C.
TABLE 1-3
Physical Characteristics
Finish Front panel is anodized aluminum.
Dimensions Fits single plug-in compartment of
7000-series oscilloscope.
Weight Approximately 2.88 pounds.
1-2

7B71 (SN B205000and Up)
SECTION 2
OPERATING INSTRUCTIONS
Change information, if any, affecting this section will be found at the rear of the manual.
General
The 7B71 delaying sweep plug-in unit operates with a
Tektronix 7000-series indicator oscilloscope and a7A-series
vertical plug-in unit to form acomplete oscilloscope
system. To use the 7B71 effectively, its operation and
capabilities should be known. This section describes the
operation of the front-panel controls, gives first-time and
general operating information and lists some basic applica-
tions for this instrument.
Installation
The 7B71 is designed to operate in the horizontal plug-in
compartments of Tektronix 7000-series oscilloscopes. The
7B71 can also be installed in avertical plug-in compartment
to provide asweep that runs vertically on the CRT. How-
ever, when used in this manner, there is no retrace blanking
or internal triggering provision and the unit may not meet
the specifications given in Section 1. The instructions in
this manual are written for use of the 7B71 in ahorizontal
plug-in compartment of the oscilloscope.
When the 7B71 is used with an oscilloscope which has
two horizontal plug-in compartments, install this unit in the
A(DELAYING TIME BASE) compartment. Then, if a
delayed-sweep unit is installed in the B(right) compart-
ment, delayed-sweep operation is available. The 7B71 will
operate properly in the Bcompartment for all horizontal
modes of operation except delaying sweep.
To install the 7B71 into aplug-in compartment, push it
in until it fits firmly into the indicator plug-in compart-
ment. To remove, pull the release latch (see Fig. 2-1) to
disengage the unit from the indicator and pull it out of the
plug-in compartment. Even though the horizontal gain of
the indicator oscilloscope is standardized to minimize
adjustment when inserting plug-in units, the sweep calibra-
tion of the 7B71 should be checked when it is inserted into
the indicator to verify measurement accuracy. The pro-
cedure for checking the unit is given under Sweep Calibra-
tion Check in this section.
FRONT-PANEL CONTROLS
General
All controls required for the operation of the 7B71 are
located on the front panel of the unit (see Fig. 2-2). To
Release
Latch
Fig. 2-1. Location of release latch.
make full use of the capabilities of this instrument, the
operator should be familiar with the function and use of
each of these controls. Abrief description of the front-
panel controls and connector is given here. More detailed
information is given under General Operating Information.
Triggering Controls
LEVEL/SLOPE Selects the amplitude point and
slope of trigger signal on which the
sweep is triggered. When the indica-
tor line on the outer ring is to the
left of center, the sweep is triggered
on the positive-going slope of the
trigger signal, as shown by the
positive-going waveform. To the
right of center, the sweep is trig-
gered on the negative-going slope of
the trigger signal as shown by the
negative-going waveform.
TRIC'D Light indicates that the sweep is
triggered and will produce adisplay
with correct setting of the POSI-
TION control and the controls on
the associated vertical unit and indi-
cator oscilloscope.
[A] 2-1

MODE COUPUNG SOURCE
PPAUTO AC INT
LEVEL/SLOPE
INOEPENDEN1
Operating lnstructions-7B71 (SN B205000 and Up)
TRIC'D 0TRIGGERING
TRIGGER
CONTROLS
AUTO ACIFREJ tIN£
NORM ACHFREJ EXT
SINGLE
SWP -I DC EXT ^10
FINE
POSITION
.ARIAIU fCAL IN
ime/divor dly time
BDELAY MODE
lA INTER DURING I-
SWEEP
CONTROLS
BSTARTS 1,.
AFTER DEUY /50
BTRIGGERABLE
AFTER DEUY
DELAY
CONTROLS DEUY TME MULT
TRIGGER
CONTROL
Fig. 2-2. Front-Panel controls and connectors.
MODE Series of push-button switches to
select the trigger mode. Selected
mode is indicated by lighted
button.
P-P AUTO: Sweep automatically
triggered at point selected by the
LEVEL/SLOPE control when
the trigger signal repetition rate
is above about 200 hertz and
within the frequency range
selected by the COUPLING
switch. Triggered sweep can be
obtained throughout the range
of the LEVEL/SLOPE control.
When the trigger repetition rate
is below the lower frequency
limit (or above upper limit for
AC HF REJ) or when the trigger
signal is inadequate, the sweep
free runs at the sweep rate
selected by the TIME/DIV
switch to produce areference
trace.
2-2 lA]

Operating Instructions—7B71 (SN B205000 and Up)
AUTO: Sweep initiated by the
applied trigger signal at point
selected by the LEVEL/SLOPE
control when the trigger signal
repetition rate is above about 30
hertz and within the frequency
range selected by the COU-
PLING switch. Triggered sweep
can be obtained only over the
amplitude range of the applied
trigger signal. When the LEVEL/
SLOPE control is outside the
amplitude range, the trigger
repetition rate is below the COUPLING
lower frequency limit (or above
upper limit for AC HF REJ) or
the trigger signal is inadequate,
the sweep free runs at the sweep
rate selected by the TIM E/D IV
switch to produce areference
trace.
NORM: Sweep initiated by the
applied trigger signal at any
point selected by the LEVEL/
SLOPE control over the fre-
quency range selected by the
COUPLING switch. Triggered
sweep can be obtained only over
the amplitude range of the
applied trigger signal. When the
LEVEL/SLOPE control is out-
side the amplitude range, the
trigger repetition rate is outside
the frequency range selected by
the COUPLING switch or the
trigger signal is inadequate, there
is no trace.
RESET-READY: Push-button to
reset the Sweep Generator for
the next sweep in the single-
sweep mode. The RESET-
READY button remains lighted
to indicate that the unit is ready
to be triggered. After the unit is
triggered and asweep is com-
pleted, the RESET-READY light
goes out until the button is
pressed again.
Series of push-button switches to
select the trigger coupling. Selected
coupling is indicated by lighted
button.
AC: Rejects DC and attenuates AC
signals below about 30 hertz.
Accepts signals between 30 hertz
and 200 megahertz.
AC LF REJ: Rejects DC and
attenuates signals below about
30 kilohertz. Accepts signals
between 30 kilohertz and 200
megahertz.
AC HF REJ: Accepts signals be-
tween about 30 hertz and 50
kilohertz. Rejects DC and atten-
uates signals outside this fre-
quency range.
DC: Accepts all trigger signals from
DC to 200 megahertz.
SINGLE SWP: Sweep initiated by SOURCE
the applied trigger signal at any
point selected by the LEVEL/
SLOPE control over the fre-
quency range selected by the
COUPLING switch. Triggered
sweep can be obtained only over
the amplitude range of applied
trigger signal. After the first
sweep is displayed, further
sweeps cannot be presented until
the RESET-READY push-
button is pressed. When the
LEVEL/SLOPE control is out-
side the amplitude range, the
trigger repetition rate is outside
the frequency range selected by
the COUPLING switch, the trig-
ger signal is inadequate or when
the RESET-READY light is off,
there is no trace.
Series of push-button switches to
select the trigger source. Selected
source is indicated by lighted
button.
INT: Trigger signal obtained inter-
nally from avertical unit.
LINE: Trigger signal obtained
internally from asample of the
line voltage applied to this
instrument.
EXT: Trigger signal obtained from
an external signal applied to the
EXT TRIG IN connector.
EXT ^10: Trigger signal obtained
from an external signal applied
to the EXT TRIG IN connector
as in the EXT position. In this
2-3

Operating lnstructions-7B71 (SIM B205000 and Up)
EXT TRIG IN
Sweep Controls
POSITION
FINE
TIME/DIV OR
DLY TIME
VARIABLE
MAGNIFIER
position the external signal is SWP CAL
attenuated 10 times before it is
applied to the trigger circuit.
Screwdriver adjustment to set
amplitude of the output sawtooth.
Input connector for external trigger
signal.
Controls horizontal position of
display.
Provides more precise control of
horizontal positions.
Selects the basic sweep rate of the
output sawtooth and selects basic
delay time (to be multiplied by the
DELAY TIME MULT dial setting).
The VARIABLE control must be in
calibrated position and MAGNI-
FIED switch set to XI for indicated
sweep rate.
Two-position switch actuated by
the VARIABLE knob to select cali-
brated or uncalibrated sweep rates.
At the in position, the VARIABLE
control is inoperative and the sweep
rate is calibrated. When pressed and
released, the knob moves out to
activate the VARIABLE control for
uncalibrated sweep rates. The
sweep rate in each TIME/DIV
switch position can be reduced to
at least the sweep rate of the next
adjacent position, to provide con-
tinuously variable sweep rates from
2nanoseconds/division (X10-
MAGNIFIER on) to about 12.5
seconds/division, with MAGNI-
FIER at XI.
Series of push-button switches to
select the delay logic to the com-
panion delayed-sweep unit (B).
Selected delay mode is indicated by
alighted button.
INDEPENDENT: The 7B71 and
the companion delayed-sweep
unit (B) operate independently
as normal time-base units.
BSTARTS AFTER DELAY; The
companion delayed-sweep unit
(B) produces asweep immediate-
ly following the delay time
selected by the TIME/DIV OR
DLY TIME switch and the
DELAY TIME MULT dial.
BTRIGGERABLE AFTER
DELAY: The companion delayed-
sweep unit (B) produces asweep
after the first trigger pulse is
received following the delay
time selected by the TIME/DIV
OR DLY TIME switch and the
DELAY TIME MULT DIAL.
LT Provides variable delay for the
delay pulse to the companion
delayed-sweep unit (B) from 0to
10 times the basic delay time selec-
ted by the TIME/DIV OR DELAY
TIME switch.
TEST SETUP CHART
Delay Controls
BDELAY MODE
(A INTEN
DURING B)
DELAY TIME MU
Push-button switches to select the
horizontal magnification. The
Selected magnification is indicated
by alighted button.
XI: Magnified sweep at the basic
sweep rate indicated by TIME/
DIV switch.
General
Fig, 2-3 shows the front panel of the 7B71. This chart
can be reproduced and used as atest-setup record for
special measurements, applications or procedures, or it may
be used as atraining aid for familiarization with this
instrument.
X10: Magnified sweep at asweep
rate 10 times faster than the
basic sweep rate indicated by the
TIME/DIV switch. The portion
of the normal sweep within the
center division of the graticule is
the portion shown in magnified
form.
GENERAL OPERATING INFORMATION
Sweep Calibration Check
Whenever the 7B71 is inserted into aplug-in compart-
ment other than the one in which it was calibrated, the
sweep calibration should be checked and readjusted if
necessary. Allow five minutes warmup before performing
this procedure.
2-4

Operating lnstructions-7B71 (SN B205000 and Up)
7B71 TEST SET-UP CHART
NOTES:
Fig. 2-3. 7B71 Test Setup Chart.

Operating lnstructions-7B71 (SN B205000 and Up)
NOTE
For accurate sweep timing, apply asignal of known
frequency or time period (time-mark signal, calibrator
square wave, 60 hertz line etc.) to the associated
vertical amplifier unit and adjust the TIME/DIV OR
DLY TIME switch and the SWP CAL control to
calibrate the signal to the oscilloscope graticule. Be
sure that the sweep timing signal is accurate within
0.
5.. The following sweep calibration procedure uses
aTektronix Time-Mark Generator.
1. Connect a1millisecond time-mark signal from the
Time-Mark Generator with a50-ohm BNC coaxial cable and
50-ohm BNC termination to the Input of the associated
vertical unit.
2. Set the TIME/DIV switch to 1ms and press the top
TRIGGERING and BDELAY MODE pushbuttons.
3. Set the Vertical unit to display at least two divisions
of the signal vertically.
4. Check the CRT display for one complete cycle per
division.
5. If necessary, adjust the SWP CAL adjustment for one
complete cycle per division.
Simplified Operating Instructions
The following information is provided to aid in quickly
obtaining the correct settings for the 7B71 to present a
display. The operator should be familiar with the complete
function and operation of the unit as described in this
section before using this procedure.
Normal Sweep. The following procedure will provide a
stable display for most normal-sweep applications.
1. Select the TRIGGERING MODE, COUPLING and
SOURCE which fit the requirements of the signal to be
displayed.
2. Turn the LEVEL/SLOPE control to the desired slope.
3. If the green TRIG'D light is not on, adjust the
LEVEL/SLOPE control throughout the range of the selec-
ted slope until the TRIG'D light comes on. If the light does
not come on at any setting of the LEVEL/SLOPE control,
the trigger signal is inadequate or the COUPLING and
SOURCE switches are set incorrectly.
4.
Set the TIME/DIV switch and POSITION control for
adisplay which remains on the display area horizontally
(VARIABLE control should be in CAL position for cali-
brated sweep rates)
.
5.
If the display does not start at the correct point on
the waveform, readjust the LEVEL/SLOPE control for the
desired triggering.
Magnified Sweep. Amagnified-sweep display can be
obtained as follows after anormal -sweep display is obtained
as given in steps 1-5 above.
1.
Adjust the POSITION control to move the area to be
magnified within the center division of the CRT.
2.
If necessary, change the TIME/DIV switch setting so
the complete area to be magnified is within the center divi-
sion.
3. Press the X10-MAGNIFIER push-button.
4. Use the fine range of the POSITION control to
establish precise positioning of the magnified display.
Delayed Sweep. The following procedure can be used to
obtain adelayed-sweep display when the 7B71 is used in an
oscilloscope that has dual time base capabilities and when
used with acompanion delayed-sweep unit (B). Obtain a
display as given in steps 1-5 under Normal Sweep. Then
proceed as follows:
1.
Press the BSTARTS AFTER DELAY push-button.
2. Set the indicator oscilloscope horizontal mode to dis-
play the Atime base (7B71).
3. Set the time/division switch of the companion
delayed-sweep unit (B) so the intensified zone on the dis-
play is the desired length (intensified zone will be displayed
in delayed form). If the intensified zone is not visible,
adjust the indicator intensity controls.
4.
Adjust the DELAY TIME MULT dial to position the
intensified zone to the portion of the display to be delayed.
5.
Set the indicator oscilloscope horizontal mode to dis-
play the Btime base (delayed sweep unit).
6.
If adelayed sweep with less jitter is desired, press the
7B71 BTRIGGERABLE AFTER DELAY push-button.
The triggering controls of the companion delayed-sweep
unit (B) must be set to obtain astable display. See the
instruction manual for that unit for further information.
Pushbutton Switch Logic
The TRIGGERING MODE, COUPLING and SOURCE
switches and the BDELAY MODE switch are arranged in a
2-6 m

Operating lnstructions-7B71 (SN B205000 and Up)
sequence which places the most often-used position at the
top of each series of pushbuttons. With this arrangement, a
stable display can usually be obtained by pressing the top
push-buttons; P-P AUTO, AC, INT and INDEPENDENT.
When an adequate trigger signal is applied, the unit is trig-
gered as indicated by the illuminated TRIC'D light at any
setting of the LEVEL/SLOPE control. If the TRIC'D light
is not on, either the trigger signal applied to this unit from
the vertical unit is inadequate or it is below the lower fre-
quency limit of the AC COUPLINC switch position. If the
desired display is not obtained with the pushbuttons
pushed in, other selections must be made. Refer to the
following discussions or the instruction manuals for the
associated indicator oscilloscope and vertical unit for more
information.
Triggered Light
The TRIC'D light provides aconvenient indication of the
condition of the triggering circuits. If the TRICCERINC
controls are correctly set and an adequate trigger signal is
applied, the TRIC'D light is on. Under certain conditions,
the TRIC'D light may be off, indicating that the sweep is
not triggered. The cause might be amisadjusted LEVEL/
SLOPE control, incorrectly set COUPLINC or SOURCE
switches, low trigger signal amplitude, or atrigger signal
repetition rate outside the acceptable frequency range. This
feature can be used as ageneral indication of correct trig-
gering. It is particularly useful when setting up the trigger
circuits when atrigger signal is available without adisplay
on the CRT. It also indicates that this unit is correctly
triggered when operating as a delaying-sweep unit (A).
Trigger Mode
The pushbuttons located under the MODE title (see Fig.
2-4) select the mode in which the sweep is triggered. The
selected mode is indicated by alighted pushbutton.
P-P AUTO. When the P-P AUTO pushbutton is pressed,
atriggered display is provided at any setting of the LEVEL/
SLOPE control whenever an adequate trigger signal is
applied. The range of the LEVEL/SLOPE control in this
mode is between about 10% and 90% of the peak-to-peak
amplitude of the applied trigger signal. The LEVEL/SLOPE
control can be set so the displayed waveform starts at any
point within this range on either slope. In the P-P AUTO
mode, the trigger circuit automatically compensates for
changes in trigger signal amplitude for signals above the
minimum amplitude requirement. Therefore, if the
LEVEL/SLOPE control is set so the displayed waveform
starts at acertain percentage-point on the leading edge of a
low-amplitude signal, it triggers at the same percentage-
point on the leading edge of ahigh-amplitude signal if the
LEVEL/SLOPE control is not changed. This operation is
illustrated in Fig. 2-5.
When the trigger repetition rate is below about 200 hertz
(or outside the frequency range selected by the COUPLING
switch), or when the trigger signal is inadequate, the sweep
free runs at the sweep rate indicated by the TIME/DIV
switch to produce areference trace (TRIG'D light off).
When an adequate trigger signal is again applied, the free-
running condition ends and atriggered display is presented.
MODE COUPLING SOURCE
pushbuttons pushbuttons pushbuttons
TRIG'D H
LEVEL/SLOPE
FINE
POSITION
BDELAY MODE
(A INTEN DURING B)
Hindependent
\TRIGGERING /
MODE COUPLING SOURCE
PPAUTO AC INT
SINGLE
SWP ‘
READY-
OC EXIT 10
BB
MAGNIFIER
XI fi X10
CAL IN
TIME/DIV OR DLY TIME
ms'
Fig. 2-4. Exploded view of front panel showing push-buttons
associated with the MODE, COUPLING and SOURCE switches.
The P-P AUTO trigger mode is particularly useful when
observing aseries of waveforms, since it is not necessary to
reset the LEVEL/SLOPE control for each observation.
Also, because of the ease of obtaining atriggered display in
this mode, the P-P AUTO trigger mode can be used for
most applications and the remaining modes used only for
special applications or when stable triggering is not obtain-
able in this mode.
AUTO. When the AUTO push-button is illuminated, a
triggered display is presented with the correct setting of the
LEVEL/SLOPE control (see Trigger Level discussion)
whenever an adequate trigger signal is applied. The range of
the LEVEL/SLOPE control in this mode is ±8 vertical divi-
sions. The TRIG'D light indicates when the display is
triggered.
When the trigger repetition rate is below about 30 hertz
(or outside the frequency range selected by the COUPLING
switch) or when the trigger signal is inadequate, the sweep
free runs at the sweep rate indicated by the TIME/DIV
switch to produce areference trace (TRIG'D light off).
When an adequate trigger signal is again applied, the free-
running condition ends and atriggered display is presented.
2-7

Operating lnstructions-7B71 (SN B205000 and Up)
Fig. 2-5. LEVEL/SLOPE control operation for (P-P) AUTO mode triggering. (A) LEVEL/SLOPE control so displayed waveform starts at
about 25% point of atwo-division waveform. (B) displayed waveform still triggered at about 25% of leading edge, when signal amplitude is
increased, to produce asix-division display (LEVEL/SLOPE control at same setting for both waveforms).
When the LEVEL/SLOPE control is at asetting outside the
amplitude range of the trigger signal, the sweep also free
runs at the sweep rate indicated by the TIME/DIV switch.
This type of free-running display can be useful when it is
desired to measure only the maximum peak-to-peak ampli-
tude of asignal without observing the waveshape (such as in
bandwidth measurements).
NORM. When the NORM push-button is pressed, a
triggered display is presented with the correct setting of the
LEVEL/SLOPE control whenever an adequate trigger signal
is applied. The range of the LEVEL/SLOPE control in this
mode is ±8 vertical divisions. The TRIC'D light indicates
when the display is triggered.
The NORM trigger mode must be used to produce trig-
gered displays with trigger repetition rates below about 30
hertz. When the LEVEL/SLOPE control is at asetting out-
side the amplitude range of the trigger signal, when the
trigger repetition rate is outside the frequency range selec-
ted by the COUPLING switch or when the trigger signal is
inadequate, there is no trace (TRIC'D light off).
SINGLE SWP. When the signal to be displayed is not
repetitive or varies in amplitude, waveshape or repetition
rate, aconventional repetitive type display may produce an
unstable presentation. Astable display can often be obtain-
ed under these circumstances by using the single-sweep
feature of this unit. The SINGLE SWP MODE is also useful
to photograph non-repetitive or unstable displays.
To obtain asingle-sweep display of arepetitive signal,
first obtain the best possible display in the NORM MODE.
Then without changing the other TRIGGERING controls,
press the SINGLE SWP pushbutton. When ready to view
the single-sweep display, press the RESET-READY push-
button. Asingle trace is presented each time the RESET-
READY pushbutton is pressed (as long as the repetitive
signal remains connected to the system and TRIGGERING
controls are correctly set) and further sweeps cannot be
presented until the RESET-READY pushbutton is pressed
again. If the displayed signal is acomplex waveform com-
posed of pulses of varying amplitude, successive single-
sweep displays may not start at the same point of the wave-
form. To avoid confusion due to the CRT persistence, allow
the display to decay before pressing the RESET-READY
pushbutton again. At fast sweep rates, it may be difficult to
view the single-sweep display. The apparent trace intensity
can be increased by reducing the ambient light level or
using aviewing hood as recommended in the indicator
instruction manual.
Non-repetitive, random signals can be displayed in the
single-sweep mode by first obtaining the best possible dis-
play in the NORM MODE with asignal which is about the
same amplitude and frequency as the random signal. Then
without changing the other TRIGGERING controls, press
the SINGLE SWP pushbutton. When ready for the random
signal, press the RESET-READY pushbutton. The RESET-
READY pushbutton remains lighted to indicate that the
unit has been reset and is ready to produce asweep. The
light goes out after the random signal triggers the unit. To
prepare the unit for another single-sweep display, press the
RESET-READY pushbutton again.
When using the single-sweep mode to photograph wave-
forms, the graticule must be photographed separately in the
normal manner to prevent over-exposing the film. Be sure
2-8 [A]

Operating Instructions—7B71 (SN B205000 and Up)
the camera system is well protected against stray light, or
operate the system in adarkened room. For repetitive
waveforms, press the RESET-READY pushbutton only
once for each waveform unless the signal is completely
symmetrical. Otherwise, multiple waveforms may appear on
the film. For random signals, the camera lens can be left
open until the random signal triggers the unit (RESET-
READY pushbutton lighted). Further information on
photographic techniques is given in the camera instruction
manual.
Trigger Coupling
The pushbuttons located below the COUPLING title
(see Fig. 2-4) select the method in which the trigger signal is
connected to the trigger circuits. The selected coupling is
indicated by alighted pushbutton. Each position permits
selection or rejection of the frequency components of the
trigger signal which trigger the sweep. Fig. 2-6 graphically
illustrates the band of frequencies covered by each position
of the COUPLING switch.
AC. In the AC position of the COUPLING switch, the
DC component of the trigger signal is blocked. Signals with
low-frequency components below about 30 hertz are atten-
uated. In general, AC COUPLING can be used for most
applications. However, if the signal contains unwanted fre-
quency components or if the sweep is to be triggered at a
low repetition rate or DC level, one of the remaining
COUPLING switch positions will provide abetter display.
The triggering point in the AC position depends upon
the average voltage level of the trigger signal. If the trigger
signal occurs randomly, the average voltage level will vary,
causing the triggering point to vary also. This shift of the
triggering point may be enough so it is impossible to main-
tain astable display. In such cases, use DC coupling.
AC LF REJ. In the AC LF REJ position, DC is rejected
and low-frequency trigger signals below about 30 kilohertz
are attenuated. Therefore, the sweep is triggered only by
the higher-frequency components of the trigger signal. This
position is particularly useful for providing stable triggering
if the trigger signal contains line-frequency components.
Also, the AC LF REJ position provides the best alternate-
mode vertical displays at fast sweep rates when comparing
two or more unrelated signals (with dual-trace vertical or
slaved triggering operation for dual-vertical unit operation).
AC HF REJ. The AC HF REJ position passes all low-
frequency signals between about 30 hertz and 50 kilohertz.
DC is rejected and signals outside the above range are atten-
uated. When triggering from complex waveforms, this posi-
tion is useful for providing stable display of the low-
frequency components.
200 MHz
kHz 10 MHz 100 MHz
CAL IN
TiME/DIV OR DLY TIME
SINGLE
SWP
RESET
B
READY-
MAGNIFIER ^
XI Sxio
TRIGGERING
MODE COUPUNfi SOURCE
P-PAUTO AC
AUTO
10 kHz 100 DC 10 Hz 100 Hz
Fig. 2-6. Frequency range of each COUPLING switch position.
[A] 2-9

Operating lnstructions-7B71 (SN B205000 and Up)
DC. DC COUPLING can be used to provide stable trig-
gering with low-frequency signals which would be atten-
uated in the other modes, or with low-repetition rate
signals. It can also be used to trigger the sweep when the
trigger signal reaches aDC level selected by the setting of
the LEVEL/SLOPE control. When using internal triggering,
the setting of the vertical unit position controls affects the
DC triggering point.
Trigger Source
The pushbuttons located below the SOURCE title (see
Fig. 2-4) select the source of the trigger signal which is
connected to the trigger circuits. The selected source is indi-
cated by alighted pushbutton.
INT. In the INT position of the SOURCE switch, the
trigger signal is derived from the associated vertical unit.
Further selection of the internal trigger signal may be pro-
vided by the associated vertical unit or indicator oscillo-
scope; see the instruction manuals for these instruments for
information. For most applications, the INT-SOURCE posi-
tion can be used. However, some applications require
special triggering which cannot be obtained in the INT-
SOURCE position. In such cases LINE- or EXT-SOURCE
must be used.
LINE. The LINE position of the SOURCE switch con-
nects asample of the power-line voltage, to which the indi-
cator oscilloscope is connected, to the trigger circuit. Line
triggering is useful when the input signal is time-related
(multiple or sub-multiple) to the line frequency. It is also
useful for providing astable display of aline-frequency
component in acomplex waveform.
EXT. An external signal connected to the EXT TRIG
IN connector can be used to trigger the sweep in the EXT-
SOURCE position. The external signal must be time-related
to the displayed waveform for astable display. An external
trigger signal can be used to provide atriggered display
when the internal signal is too low in amplitude for correct
triggering or contains signal components on which it is not
desired to trigger. It is also useful when signal tracing in
amplifiers, phase-shift networks, wave-shaping circuits, etc.
The signal from a single point in the circuit under test can
be connected to the EXT TRIG IN connector through a
probe or cable. The sweep is then triggered by the same
signal at all times and allows amplitude, time relationship or
waveshape changes of signals at various points in the circuit
to be examined without resetting the TRIGGERING
controls.
EXT ^10. Operation in the EXT 10 position is the
same as described for EXT except that the external signal is
attenuated 10 times. Attenuation of high-amplitude exter-
nal trigger signals is desirable to broaden the range of the
LEVEL/SLOPE control.
Trigger Slope
The LEVEL/SLOPE control determines whether the
trigger circuit responds on the positive-going or negative-
going portion of the trigger signal. When the indicator line
on the outer ring of the LEVEL/SLOPE control is to the
left of center, the display starts on the positive-going por-
tion of the waveform (notice positive-going waveform to
left of control. To the right of center, the display starts on
the negative-going portion of the waveform (notice
negative-going waveform). The effect of the LEVEL/
SLOPE control on the displayed waveform is shown in Fig.
2-7. When several cycles of asignal appear in the display,
the selection of the trigger slope is often unimportant.
However, if only acertain portion of acycle is to be dis-
played, correct setting of the LEVEL/SLOPE control is
important to provide adisplay which starts on the desired
slope of the input signal.
Trigger Level
The LEVEL/SLOPE control determines the voltage level
on the trigger signal at which the display is triggered, as well
as selecting the trigger slope. The center knob of the
LEVEL/SLOPE control provides about a3:1 reduction in
relation to the outer indicator ring, to allow precise level
selection. This control can also be turned throughout the
complete 360° rotation to allow continuous triggering over
the selected slope. This is particularly useful in the P-P
AUTO MODE. When the LEVEL/SLOPE control is set to
the '0"on either the positive-going or negative-going wave-
form, the sweep is triggered near the zero-volt level of the
trigger signal. As the LEVEL/SLOPE control is rotated
away from the “0”, the displayed waveform starts at a
point corresponding to the position of the indicator line on
the associated slope waveform (within amplitude range of
trigger signal except in P-P AUTO MODE which provides
triggered display throughout entire slope). For example if
the LEVEL/SLOPE control is turned clockwise from the
“O" on the positive-going slope, the displayed waveform
starts at amore positive level. Fig. 2-7 illustrates the opera-
tion of the LEVEL/SLOPE control at different levels and
slopes of adisplayed waveform.
Before setting the triggering level, select the TRIG-
GERING SLOPE, MODE, COUPLING and SOURCE. Then
adjust the LEVEL/SLOPE control so the displayed wave-
form starts at the desired point. The triggering slope can be
changed at any time by rotating the LEVEL/SLOPE con-
trol to the corresponding point on the other slope
waveform.
2-10

Operating lnstructions-7B71 (SN B205000 and Up)
CRT displays
obtained with
LEVEL/SLOPE
control in
negative-slope
region
Fig. 2-7. Effect of LEVEL/SLOPE control on CRT display (AUTO P-P MODE).
2-n

Operating Instructions—7B71 (SIM B205000 and Up)
Horizontal Sweep Rate
The TIME/DIV switch provides 26 calibrated sweep
rates ranging from 0.02 microsecond/division to five
seconds/division. The VARIABLE TIME/DIV control must
be in the calibrated position and the MAGNIFIER at XI
for the indicated sweep rate. The VARIABLE TIME/DIV
control incorporates atwo-position switch to determine if
the sweep rate is calibrated or uncalibrated. When the
VARIABLE knob is in the inward position, the VARI-
ABLE TIME/DIV control is inoperative and the sweep rate
is calibrated. When pressed and released, the VARIABLE
knob moves outward to activate the VARIABLE TIME/
DIV control for uncalibrated sweep rates. Acalibrated
sweep rate can be obtained at any position of the VARI-
ABLE TIME/DIV control by pressing in the VARIABLE
knob. This feature is useful when aspecific uncalibrated
sweep rate has been obtained and it is desired to switch
between this uncalibrated sweep rate and acalibrated sweep
rate. Switching from uncalibrated to calibrated operation or
vice versa does not affect the setting of the VARIABLE
TIME/DIV control. The VARIABLE TIME/DIV control
allows the sweep rate in each TIME/DIV switch position to
be reduced to at least the sweep rate of the next adjacent
switch position. This provides an overall uncalibrated vari-
able sweep rate range from 20 nanoseconds/division (from
2nanoseconds/division with MAGNIFIER at X10) to about
12.5 seconds/division.
When making time measurements from the graticule, the
area between the second-division and tenth-division vertical
lines of the graticule provides the most linear time measure-
ment (see Fig. 2-8). Therefore, the first and last division of
the display area should not be used when making accurate
time measurements. Position the start of the timing area to
the second-division vertical line (second line from the left)
and adjust the TIME/DIV switch so the end of the timing
area falls between the second-division and tenth-division
vertical lines.
Sweep Magnifier
The sweep magnifier expands the sweep ten times. The
center division of the unmagnified display is the portion
visible on the screen in magnified form (see Fig. 2-9).
Equivalent length of the magnified sweep is more than 100
divisions; any 10-division portion can be viewed by
adjusting the horizontal POSITION control to bring the
desired portion onto the viewing area. The dual-range
feature of the horizontal POSITION control is particularly
useful when the MAGNIFIER is set to X10 (see Horizontal
Position Control discussion which follows).
To use sweep magnification, first move the portion of
the display which is to be expanded to the center of the
graticule. Then press the X10-MAGNIFIER pushbutton;
the XI 0button lights to indicate that the horizontal sweep
rate is magnified. Whenever the X10-MAGNIFIER push-
Fig. 2-8. Area of graticule used for accurate time measurements.
4'00m\ 1aops
(B) Magnified Waveform
Fig. 2-9. Operation of sweep magnifier.
2-12 0