Tektronix 7B70 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97005
I BASE
SN B205OOO AND UP
INSTRUCTION MANUAL
Serial Number
070-1579-00 Scans by ArtekMedia O 2006 473

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defective ma
questions with re
All requests for repair and replacement parts shoutd
directed tothe TEKTRONlX FieldOfficeor
repre
in your area. This will assure you the fastest
service. Please include the instr
r and Serial Number w
y Tektronix, Inc., Beaverton, Oregon.
Printed in the United States of America. All rights resewed.
Contents of this publication may notbe reproduced in any
form without permission of Tektronix, Inc.
U.S.A. and Foreign TEKTRONIX productscovered byU.S.
and foreign patents and/or patents pending.
TEKTRONIX
is a registered trademark of Tektronix, Inc.
Scans by ArtekMedia O 2006

7B70 (SN B205000 and Up)
TABLE OF CONTENTS
SECTION 1 SPECIFICATIONS
Introduction
Electrical Characteristics
Sweep Rate
Sweep Accuracy
Sweep Length
Sweep Hold-Off Time
External Horizontal Amplifier
Deflection Factor
Frequency Response
Trigger Sensitivity
Internal Trigger Jitter
External Trigger
l nput
P-P Auto Sensitivity
Environmental Characteristics
Altitude
Physical Characteristics
Finish
Dimensions
Weight
SECTlOlV 2 OPERATING INSTRUCTIOIVS
General
Installation
FrontPanel Controls
Test Setup Chart
General Operating Information
Sweep Calibration Check
Simplified Operating
l nstructions
IVormal Sweep
Magnified Sweep
Delayed Sweep
Pushbuttoll Switch Logic
Triggered Light
Trigger Mode
Trigger Coupling
Trigger Source
Trigger Slope
Trigger Level
Horizontal Sweep Rate
Sweep Magnifier
Horizontal Position Control
Display Mode
Page
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7B7O (SN B205000 and Up)
TABLE OF CONTENTS (cont)
SECTION 2 OPERATING INSTRUCTIONS (cont)
Applications
General
Frequency Comparison
Time Duration Measurements
Determining Frequency
Risetime Measurements
Delayed Sweep Time Measurements
Delayed Sweep Magnification
DisplayingComplex Signals Using Delayed Sweep
Pulse Jitter Measurements
X-Y Phase Measurements
SECTION 3 CIRCUIT DESCRIPTION
l ntroduction
Block Diagram Description
Detailed Circuit Description
Trigger
l nput
Trigger Amplifier
l nput Stage
Peak Detector
Slope Comparator
OutputStage
Trigger Generator
Trigger Pulse Generator
Sweep Gate Stage
Triggered Hold-OffStage
Bright Line Auto
External Horizontal Amplifier
Time-BaseGenerator
General
Normal Trigger Mode Operation
Single Sweep Operation
Alternate Operation
Delayed Sweep Operation
Horizontal Preamp
ReadoutBlock
SECTION4 MAINTENANCE
PreventiveMaintenance
General
Cleaning
Visual
l nspection
Transistor Checks
Recalibration
Page
2-13
2-13
2-13
2-14
2-15
2-15
2-16
2-17
2-18
2-18
2-19
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7B70 (SN B205000 and Up)
TABLE OF CONTENTS
SECTION 4 MAINTENANCE (cont)
Troubleshooting
Troubleshooting Aids
Troubleshooting Equipment
Troubleshooting Techniques
Corrective Maintenance
Obtaining Replacement Parts
Soldering Techniques
Component Replacement
l nstrument Repackaging
(cont)
SECTION 5 PERFORMANCE CHECK/CALIBRATION
l ntroduction
Test Equipment Required
Short Form Procedure
Performance Check/CalibrationProcedure
General
PreliminaryControl Settings
Check/Adjust Steps (refer to Short-FormProcedure
for index to steps)
SECTION 6 ELECTRICAL PARTS LIST
Abbreviations and Sym~bols
Parts Ordering Informatioil
Index of Electrical Parts List
SECTION
7 DIAGRAMS
SECTION 8 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", NllL STD-12B and other standards of the electronics
industry. Change information, if any,
is located at the rear of this
manual.
Page
4-2
4-2
4-3
4-3
4-5
4-5
4-6
4-6
4-8
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7B70 (SN B205000 and Up)
Scans by ArtekMedia O 2006
Fig. 1-1. 7870 Time Base.

7B70 (SN B205000and Up)
SECTION 1
Change information, if any, affecting thissection willbe found at therear of themanual.
Introduction the EXT VOLTS INconnector. The sweep free-runstopro-
vide a bright base line inthe absence of adequatetriggering
The 7870 Time Base Unit
is designed specifically for use signal in P-PAUTO and AUTO triggering modes.
with Tektronix 7700-series oscilloscopes. However, it is
compatible with all 7000-series oscilloscopes. The 7870
provides calibrated sweeps from 5 secondsldivision to 0.02
microsecond/division. The XI0 MAGN l F l ER extends the The Performance Check Procedure given in Section 5
calibrated Sweep to 2 nanoseconds/division. Sweep rates provides a convenient method of checking performance of
may be varied continuously (uncalibrated) betweencalibra- this instrument. The following electrical characteristics
ted steps. Sweep triggering is to 200 megahertz or vertical apply at an ambient temperature of
O'C to +50°c, unless
amplifier bandwidth, whichever is less. The 7B70 features otherwise noted. Warmup time for given accuracy is 20
an external horizontal amplifier todisplay signals applied to minutes.
TABLE
1-1
ELECTRICAL CHARACTERISTICS
Performance
Start of Sweep; 12ns in 7900
Characteristic
Swee~Rate
~ ~.
Calibrated Range
Time Interval 1 +15~~t0+35~~ O~C~O+~O~C
Performance Characteristic
Excluded Divi-
sions
of Mag- I series, 20 ns in 7704A, 50 ns in
5 secondsldivision to 0.02 micro- nified Sweep other 7000 series mainframes.
secondldivision ina 1-2-5sequence. End of Sweep; beyond the 90th
XI0 magnifier extends sweep rate division
to2 nanosecondsldivision.
VARIABLERange
(uncalibrated)
Sweep Accuracy
Over Center
8 1 Unmag Mag Unmag I Mag
Continuously variable betweencali-
Sweep Hold-0ff Time
brated sweep rates. Extends uncali- 5 sldiv to 5psldiv 1.5 times the TIME/DIVISION set-
brated sweep rate to at least 12.5 ting or less.
seconds/division.
0.02 psldiv
Measured in 7000 series mainframe. External Horizontal
Amplifier
5 sldiv to 0.1
1
sldiv and 0.2 , 3% 3.5% 4% 1 5%
psldiv to 0.02
psldiv
Sweep Length
50 msldiv 1 2% 1 2.5% 3% 1 4%
0.5 psldiv
10.0divisions to 13divisions.
Over any 2 div
interval within
center
8 div
Deflection Factor
EXT
VARIABLE
Fully Clock-
wise
25 millivoltsldivision within 5 milli-
volts/division.
VARIABLE
Fully Clock-
I
5%
Scans by ArfekMedia O 2006
250 rnillivoltsldivision within 50
millivolts/division.
1
7% VARIABLE
Range
wise
At least 10:1
1-1

Specification-7B7O (SN B205000 and Up)
TABLE 1-1 (cont)
I
Characteristic 1 Performance
Nominal
1 System -3 dB points in7700-series
Frequency oscilloscope.
Response
AC, AC LF REJ, 16hertz 100kilohertz
AC HF REJ
DC
~ , ----- 100kilohertz
Trigger Sensitivity
Required
20 MHz to
20 MHz to
200 MHz
Coupling
AC
1.5div
0.3 div
1.5 div
I
20 MHz to
200 MHz
INT
30 Hz to 20 MHz 0.3
- div
ACHFREJ
DC
'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.
EXT
75 mV
'will not trigger on sine waves of 3
divisions or less internal or 1.5
volts external below 120 Hz.
-- -
30Hzto50kHz
DCto20MHz
Single Sweep ~riggeringrequirements same as
normal sweep. When triggered,
sweep generator produces one
sweep only.
0.3div
0.3div
TABLE 1-1 (cont)
75mx
75mV
InternalTrigger Jitter
ExternalTrigger lnput
Voltage volts (P-PAC) at 1 kilohertz or less.
1 nanosecond or less at 150 mega-
hertz.
Input Rand C 1megohm within 2%, 20 picofarads
Level Range
(ExcludingP-P
AUTO)
EXT
1 At least +I .5 volts to -1 5 volts.
- -
EXT + 10
P-PAUTO Operation
TABLE
1-2
At least +I5voltsto -15 volts.
Sensitivity
ENVIRONMENTALCHARACTERISTICS
0.5 div Internal, 125 millivolts Ex-
ternal, 200 Hz to 20 MHz. Upper
frequency and amplitude limits
same as NORMAL Trigger Sensiti-
Thisinstrument will meet the electrical characteristics
given in Table
1- 1 over the following environmental
limits.
vity.
Non-o~erating
1 To 50.000 feet and -55'~.
Low Frequency
Response
--
Characteristic
Altitude
TABLE
1-3
Must Trigger on 50 hertz, 2division
signal.
Performance
-
PHYSICALCHARACTERISTICS
Finish Front panel
is anodized aluminum.
Characteristic
Dimensions
Performance
14.583 inches long by 2.75 inches
wide by 5 incheshigh.
I
I
Weight 1 Approximately 2.88 pounds.
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7B70 (SN B205000 and Up)
SECTION 2
OPERA TlNGINSTRUCTIONS
Changeinformation, ifany, affecting thissection willbe found at the rear ofthemanual.
General
The 7B70 plug-in unit operates with a Tektronix
7000-series indicator oscilloscope and a 7A-series vertical
plug-in unit to form a complete oscilloscope system. To
effectively use the 7B70
its operation and capabilities
should be known. This section describes the operation of
the front-panel controls, gives first-time and general opera-
ting information and
lists some basic applications for this
instrument.
l nstallation
The 7B70 is designed tooperateinthe horizontal plug-in
compartments of Tektronix 7000-seriesoscilloscopes. The
7B70 can also be installed inavertical plug-incompartment
to provide a sweep that runs vertically on the CRT. How-
ever, when used inthis 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 7B70 inahorizontal
plug-incompartmentof the oscilloscope.
When the 7B70
is used with an oscilloscope which has
two horizontalplug-incompartments, installthis unit inthe
B (right) compartment. Then, if
a delaying-sweep unit is
installed inthe A (DELAYINGTIME BASE)compartment,
delayed-sweepoperation
is available.The 7870will operate
EXT TRIG IN
OR
EM VOLTS IN
TEKTRONIX O
-6-
7610
TtME BASE
I
ele ease/
Latch
Fig.
2-1. Location of release latch.
properly in the A compartment for all horizontal modes of
operation exceptdelaying sweep.
To install the 7B70 into a plug-in compartment, push
it
in until it fits firmly into the indicator plug-in compart-
ment. To remove, pull the release latch (see Fig.
2-11 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 ad-
justment when insertingplug-in units, the sweep calibration
of the 7870 should be checked when
it is inserted intothe
indicator to verify measurement accuracy. The procedure
for checking the unit is given under Sweep Calibration
Check in this section.
FRONT-PANEL CONTROLS
General
All controls requiredfor the operation of the 7870 are
located on the front panel of the unit (see Fig.
2-2). To
make full use of the capabilities of this instrument, the
opetator should be familiar with the function and use of
each of these controls. A brief description of the front-
panel controls and connector is given here. More detailed
information
is given under General OperatingInformation.
Triggering Controls
LEVELISLOPE 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-goingslope of
the trigger signal as shown by the
negative-goingwaveform.
TR IG'D Light indicates that the sweep is
triggered and will produceadisplay
with correct setting of the POSI-
TION control and the controls on
the associated verticalunit and indi-
cator oscilloscope.
Scans by ArtekMedia O 2006

Operating Instructions-7B70 (SN B205000and Up)
MODE Series of push-button switches to
select the trigger mode. Selected
mode is indicated by lighted but-
ton.
P-P AUTO: Sweep automatically
triggered at point selected bythe
LEV
ELISLOPE control when
the trigger signal repetition-rate
is above about 200 hertz and
within the.frequency range selec-
ted by the COUPLING switch.
Triggered sweep can be obtained
throughout the entire range of
the LEVELISLOPE control.
When the trigger repetition rate
is below the lower frequency
limit (or above upper limit for
AC HF REJ)orwhen the trigger
signal is inadequate, the sweep
free runs at the sweep rateselec.
ted by the TIMEIDIV switch to
produce a reference trace.
AUTO: Sweep initiated by the
applied trigger signal at point
selected by the LEVELISLOPE
control when the trigger signal
repetition rate is above about 30
hertz and within the frequency
range selected by the COU-
PLl
NG 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 rep-
etition rate is below the lower COUPLING
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 TIMEIDIV
switch to produce a reference
trace.
NORM: Sweep initiated by the
applied trigger signal at any
point selected by the LEVEL1
SLOPE control over the frequen-
cy range selected by the COU-
PLl
NG switch. Triggered sweep
can be obtained only over the
amplitude range of the applied
trigger signal. When the LEVEL1
SLOPE control is outside the
amplitude range, the trigger rep-
etition rate is outside the fre-
quency range selected by the
COUPLING switch or the trigger
signal is inadequate, there is no
trace.
SINGLE SWP: Sweep initiated by
the applied trigger signal at any
point selected by the LEVEL1
SLOPE control over the fre-
quency range selected by the
COUPLlNG 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
LEVELISLOPE 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 notrace.
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 theunit is ready
to be triggered. After the unit is
triggered and a sweep 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 30hertz
and 200megahertz.
AC LF REJ: Rejects DC and atten-
uates signals below about 30
kilohertz. Accepts signals
be-
tween 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
DCto200 megahertz.
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OperatingInstructions-7B70 (SN B205000 and Up)
. .
TRIGGERING
AC LF REJ LINE
TRIGGERING
NORM AC HFREJ
CONTROLS
DISPLAY MODE
SWEEP
CONTROLS
TRIGGERING
CONTROL
DISPLAY
SELECTOR
Fig. 2-2. Front-Panel controls and connectors.
SOURCE Series of push-button switches to
select the trigger source. Selected
source
is indicated by lighted but-
ton.
INT: Trigger signal obtained inter-
nally from avertical unit.
LINE: Trigger signal obtained in-
ternally from a sample of the
line voltage applied to this in- EXTTRIG INor
strument. EXTVOLTS IN
EXT: Trigger signal obtained from
an external signal applied to the
EXTTRIG INconnector.
EXT
t 10: Trigger signal obtained
from an external signal applied
to the EXT TRIG IN connector
as in the EXT position. In this
position the external signal
is
attenuated 10 times before it is
appliedtothe trigger circuit.
Input connector for externaltrigger
signal or amplifier input signal.
Scans by ArtekMedia O 2006

Operating Instructions-7B70 (SN B205000and Up)
Sweep Controls
POSITION
tor. Select TRIGGERING SOURCE
and COUPLING.
Controls horizontal position of dis-
play. VARIABLE
(amplifier) Varies deflection factor by afactor
of 10.
Provides more precise control of
horizontal positions.
TEST SETUP CHART
TIMEIDIV Selects the basic sweep rate of the
output sawtooth. The VARIABLE
control must be in calibrated posi-
tion and MAGNIFIEDswitch set to
X1for indicatedsweep rate.
General
Fig. 2-3 shows the front panel of the 7B70. This chart
can be reproduced and used as a test-setup record for
special measurements, applicationsor procedures,or itmay
be used as a training aid for familiarizationwith this instru-
ment.
VARIABLE
(TIMEIDIV) Two-position switch actuated by
the VARIABLE knob toselect cali-
brated or uncalibratedsweep rates.
At the in position, the VARIABLE
GENERAL OPERATING INFORMATION
control is inoperativeand the sweep
rate
is calibrated.When pressed and
released, the knob moves out to
activatethe VARIABLE control for
Sweep Calibration Check
Whenever the 7B70 is inserted into a plug-incompart-
ment other than the one in which
it was calibrated, the
sweep calibration should be checked and readjusted ifnec-
essary. Allow five minutes warmup before performing this
procedure.
NOTE
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
2 nanoseconds/division(X1O-MAG-
Nl F l ER on) to about 12.5 seconds1
division. with MAGlUlFlER at XI.
For accurate sweep timing, apply a signal of known
frequency or timeperiod (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 GAL 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
a Tektronix TimeMark Generator.
Push-button switches to select the
horizontal magnification. The
Selected magnification
is indicated
by a lighted button.
MAGNIFIED
X1:Magnified sweep at the basic
sweep rate indicated by TIME1
DIV switch. 1. Connect
a 1 millisecond time-mark signal from the
Time-MarkGenerator with a 50-ohm BNC coaxial cable and
50-ohm BNC termination to the Input of the associated
vertical unit.
X10: Magnified sweep at a sweep
rate 10 times faster than the
basic sweep rate indicatedbythe
TIMEIDIV switch. The portion
of the normal sweep within the
center division of the graticule
is
the portion shown in magnified
form.
2. Set the TIMEIDIV switch to
1 ms and press the top
TRIGGERING and DISPLAY 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.
Screwdriver adjustment to set am-
plitudeof the output sawtooth.
SWP CAL
5. If necessary, adjust the SWP CAL adjustment for one
complete cycle per division.
Display Mode
TIME BASE Selects sweep rates as determined
by TIMEIDIV switch.
Simplified Operating Instructions
The following information is provided to aid in quickly
obtaining the correct settings for the 7B70 to present
a
AMPLIFIER Displays signals applied tothe EXT
TRIG IN or EXT VOLTS INconnec-
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OperatingInstr~~ctions-7670 (SN B205000and Up)
7B70 TEST SET-UP CHART
TRIGGERING
TR16'0 0 MODE COUPLIIYG SOURCE
NORM AC HFRW
SIROLE
EX1 -m
FINE
POSITION
MAGNIFIER
XI XIO
VARIABLE (CAL IN)
TIME/DIV
DISPLAY MODE
TIME BASE
0
EXT TRIG IN
OR
EXT VOLTS IN
TEKTRONIX El
17~701
TIME BASE
NOTES:
Fig. 2-3. 7870 Test Setup Chart.
Scans by ArtekMedia O 2006

Operating Instructions-7B70 (SN B205000and Up)
display. The operator should be familiar with the complete oscilloscope that has dual time base capabilities and when
function and operation of the unit as described inthis sec- used with a companion delaying-sweepunit (A). Obtain a
tion before usingthis procedure. display as given in steps 1-5 under Normal Sweep. Then
proceedas follows:
Normal Sweep. The following procedure will provide a 1. Press the B STARTS AFTER DELAY push-button
stable display for most normal-sweepapplications. on the A time-base.
1. Select the TRIGGERING MODE, COUPLING and
2. Set the indicator oscilloscopehorizontal modetodis-
SOURCE which fit the requirements of the signal to be play the A time base.
displayed.
3. Set the TIMEIDIV switch of the 7B70 so the intensi-
2. Turn the LEVELISLOPE control to the desired fied zone on the display is the desired length (intensified
slope. zone will be displayed in delayed form). Ifthe intensified
zone is not visible, adjust the indicator intensity controls.
3. If the green TRIG'D light is not on, adjust the
LEVELISLOPE 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 LEVELISLOPE control,
the trigger signal
is inadequate or the COUPLING and
SOURCE switchesare set incorrectly.
4. Set the TIMEJDIV switch and POSITIONcontrol for
a display which remains on the display area horizontally
(VARIABLEcontrol should be inCALposition for calibra-
ted sweep rates).
5. If the display does not start at the correct point on
the waveform, readjust the LEVELISLOPE control for the
desired triggering.
4. Adjust the A time-base DELAY TlME MULTdial to
position the intensified zone to the portion of the display
to be delayed.
5. Set the indicator oscilloscope horizontal modetodis-
play the B time base (7B70).
6. If a delayed sweep with less jitter is desired, pressthe
A time-base B TRIGGERABLE AFTER DELAY push-
button. The triggering controls of the 7B70 must be set to
obtain astable display.
Pushbutton Switch Logic
The TRIGGERING MODE, COUPLING and SOURCE
Magnified Sweep. A magnified-sweepdisplay can be ob- switches and the DISPLAY MODE switch are arranged ina
tained as follows after a normal-sweepdisplay
is obtained as sequence which places the most often-used position at the
given insteps 1-5above. top of each series of pushbuttons. With this arrangement, a
stable normal-sweep display can usually be obtained by
pressing the top plsh-blttbns; P-P
AUTO, AC, INT and
1. Adjust the POSITION control tomovethe area to be TlME BASE. When an adequatetrigger signal isapplied, the
magnified within the center division of the CRT. unit is triggered as indicated by the illuminated TRIG'D
light at any setting of the LEVELISLOPE control. If the
TRIGID light is not on, either the trigger signal applied to
2. If necessary, change the TIMEIDIV switch setting so this unit from the vertical unit is inadequate or
it is below
the complete area to be magnified
is within the center divi- the lower frequency limit of the AC COUPLING switch
sion. position. If the desired display is not obtained with the
pushbuttons pushed in, other selections must be made.
Refer to the followinq discussions or the instruction
3. Press the X10-MAGNIFIER push-button. manuals for the associated indicator oscilloscope and verti-
cal unitfor more information.
4. Use the fine rangeof the POSITION control toestab-
lish precise positioning of the magnified display.
Triggered Light
The TRIG'D light provides a convenient indication of
Delayed Sweep. The following procedure can be used to the condition of the triggering circuits. If the TRIG-
obtain a delayed-sweepdisplay when the 7B70 is used in an GERING controls are correctly set and an adequate trigger
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Operating Instructions-7B70 (SNB205000and Up)
COUPLING Trigger Mode
push-buttons
MODE
The pushbuttons located under the MODE title (see Fig.
push-buttons
2-4) select the mode in which the sweep is triggered. The
selected mode is indicatedby alightedpushbutton.
P-P AUTO. When the P-P AUTO pushbutton
is pressed,
a triggered display
is providedat any settingof the LEVEL1
AUTO AC LF RSJ UNE SLOPE control whenever an adequate trigger signal is
applied. The range of the LEVELISLOPE control in this
MORM ACHFRO
mode is between about 10%and 90% of the peak-to-peak
amplitude of the appliedtrigger signal. The LEVELISLOPE
control can be set so the displayed waveform starts at any
point within this range on either slope. Inthe 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 LEVEL1
SLOPE control is set so the displayed waveform starts at a
certain percentage-point on the leading edge of a low-
amplitude signal, it triggersat the same percentage-pointon
the leading edge of a high-amplitudesignal if the LEVEL/
SLOPE control
is not changed. This operation is illustrated
Fig. 2-4. Exploded view of front panel showing push-buttons in Fig. 2-5.
associated with the MODE. COUPLING and SOURCE switches.
signal is applied, the TRIG'D light is on. Under certain
conditions, the TRIG'D light may be off, indicating that
the sweep is not triggered. The cause might be
a misad-
justed LEVELISLOPE control, incorrectly set COUPLING
or SOURCE switches, low trigger signal amplitude, or a
trigger signal repetition rate outside the acceptable fre-
quency range. This feature can be used as a general indica-
When the trigger repetitionrate is below about 200 hertz
(or outsidethe 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 TIMEIDIV
switch to produce a reference trace (TRIG'D light off).
When an adequate trigger signal is again applied, the free-
running condition ends and atriggereddisplay is presented.
tion of correct triggering. It is particularly useful when
setting up the trigger circuits when a trigger signal
is avail- The P-P AUTO trigger mode
is particularly useful when
able without
a display on the CRT. It also indicates that observing a series of waveforms, since
it is not necessary to
this unit
is correctly triggered when operating as adelayed- reset the LEVELISLOPE control for each observation.
sweep unit
(B).
Also, because of the ease of obtaining atriggered display in
Fig. 2-5. LEVELISLOPE control operation for (P-P) AUTO mode triggering. (A) LEVELISLOPE control set so displayed waveform starts at
about 25% point of a onedivision waveform. (B) displayed waveform still triggered at about
25% of leading edge, when signal amplitude
increasesto produce an eight-divisiondisplay (LEVEL/SLOPE control at same setting for both waveforms).
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Operating Instructions-7B70 (SN B205000and Up)
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 notobtain-
able inthis mode.
AUTO. When the AUTO push-button is illuminated, a
triggered display is presentedwith the correct setting of the
LEVELISLOPE control (see Trigger Level discussion)
whenever an adequate trigger signal is applied. The range of
the LEVELISLOPE control in this mode is
k8 vertical divi-
sions. The TRIG'D light indicates when the display
is trig-
gered.
When the trigger repetition rate
is below about 30 hertz
(or outside the frequency range selected by the COUPLllVG
switch) or when the trigger signal is inadequate, the sweep
free runs at the sweep rate indicated by the TIMEIDIV
switch to produce a reference trace (TRIG'D light off).
When an adequate trigger signal is again applied, the free-
running condition ends and atriggered display is presented.
When the LEVELISLOPE control is at asetting outside the
amplitude range of the trigger signal, the sweep also free
runs at the sweep rate indicated by the TIMEIDIV switch.
This type of free-running display can be useful when
it is
desired to measure only the maximum peak-to-peakampli-
tude of asignal without observingthe waveshape (suchas in
bandwidth measurements).
NORM. When the NORM push-button is pressed, atrig-
gered display is presented with the correct setting of the
LEVELISLOPE control whenever an adequatetrigger signal
is applied. The range of the LEVELISLOPE control inthis
mode is
+8 vertical divisions. The TRIG'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 LEVELISLOPE control is at asetting out-
side the amplitude range of the trigger signal, when the
trigger repetition rate
is outside the frequency range
selected by the COLlPLlNG switch or when the trigger sig-
nal is inadequate, there is no trace (TRIG'D light off).
SINGLE
SWP. When the signal to be displayed is not
repetitive or varies in amplitude, waveshape or repetition
rate, a conventional repetitive type display may produce an
unstable presentation. A stable display can often be ob-
tained under these circumstances by using the single-sweep
feature of this unit. TheSINGLE SWP MODE
is also useful
to photograph non-repetitiveor unstabledisplays.
To obtain a single-sweep display of a repetitive 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. A single 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 a complex waveform
composed of pulses of varying amp1itude, successive single-
sweep displays may not start at the same point of the wave-
form. Toavoid confusion due tothe CRT persistence, allow
the display to decay before pressing the RESET-READY
pushbutton again. Atfast 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 a viewing 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 a signal 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 a sweep. The
light goes out after the random signal triggers the unit. To
prepare the unit for another single-sweepdisplay, press the
R ESET-READY pushbutton again.
When using the single-sweep mode to photograph wave-
forms, the graticule must be photographed separately inthe
normal manner to prevent over-exposingthe film. Be sure
the camera system is well protected against stray light, or
operate the system in a darkened room. For repetitive
waveforms, press the RESET-READY pushbutton only
once for each waveform unless the signal is completely
symmetrical. Otherwise, multiplewaveforms 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 inwhich the trigger signal is
connected to the trigger circuits. The selected coupling is
indicated by a lighted 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 frequenciescovered by each position
of the COUPLllVG switch.
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Operating Instructions-7B70 (SN B205000 and Up)
TRIGGERING
MODE COUPLING SOURCE
P-PkUTO AC
10Hz 100Hz 10kHz 100kHz 10MHz 100MHz
Fig. 2-6. Frequency range of each COUPLING switch position.
AC. In the AC position of the COUPLING switch, the AC HF
REJ. The AC HF REJ position passes all low-
DC component of the trigger signal is blocked. Signalswith frequency signals between about 30 hertz and 50 kilohertz.
low-frequency components below about 30hertz are atten- DC
is rejected and signals outside the above range are atten-
uated. In general, AC COUPLING can be used for most uated. When triggering from complex waveforms, this
applications. However, if the signal contains unwanted fre- position is useful for providing stable display of the !ow-
quency components or if the sweep is to be triggered at a frequency components.
low repetition rate or DC level, one of the remaining
COUPLING switch positions will provide a better display.
DC. DC COUPLING can be used to provide stable trig-
gering with low-frequency signals which would be atten-
The triggering point in the AC position depends Lipon uated in the other modes, or with low-repetition rate
the average voltage level of the trigger signal. If the trigger Signals. It can also be used to trigger -thesweep when the
signal occurs randomly, the average voltage level will vary, trigger signal reaches a DC level selected by the setting of
causing the triggering point to vary also. This shift of the the LEVELISLOPE control. When usinginternal triggering,
triggering point may be enough so
it is impossibleto main- the setting of the vertical unit position controls affects the
tain astable display. Insuch cases, use DC coupling. DC triggering point.
AC LF REJ. Inthe AC LF REJ position, DC is rejected
and low-frequency trigger signals below about 30kilohertz
are attenuated. Therefore, the sweep is triggered only by
the higher-frequency components of the trigger signal. This
position
is particularly usefulfor 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-verticalunit operation).
Trigger Source
The pushbuttons located below the SOURCE title (see
Fig.
2-4) select the source of the trigger signal which is
connected tothe trigger circuits. The selected source is indi-
cated by a lighted 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-
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Date: 2008.11.17 09:04:10 -06'00'

Operating Instructions-7B70 (SN B205000and Up)
vided by the associated vertical unit or indicator oscillo-
scope; see the instruction manualsfor these instruments for
information. For most applications, the INT-SOURCEposi-
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 a sample of the power-linevoltage, towhich the indi-
cator oscilloscope is connected, to the trigger circuit. Line
triggering is useful when the input signal is time-related
(m~.~ltipleor sub-multiple) to the line frequency. It is also
useful for providing a stable display of a line-frequency
component ina complex waveform.
EXT. An external signal connected to the EXT TRlG
IN connector can be used to trigger the sweep inthe EXT-
SOURCE position. The external signal must be time-related
to the displayed waveform for astable display. Anexternal
trigger signal can be used to provide a triggered 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 TRlG 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 inthe circuit
to be examined without resetting the TRIGGERING con-
trols.
EXT + 10. Operation in the EXT + 10 position is the
same as describedfor 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
LEVELISLOPE control.
Trigger Slope
The LEVELISLOPE 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 LEVELISLOPE 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 LEVEL1
SLOPE control on the displayedwaveform is shown in Fig.
2-7. When several cycles of a signal appear in the display,
the selection of the trigger slope
is often unimportant.
However, if only a certain portion of a cycle is to be dis-
played, correct setting of the LEVELISLOPE control is
important to provide a display which starts on the desired
slope of the input signal.
Trigger Level
The LEVELISLOPE control determinesthe voltage level
on the trigger signal at which the display istriggered, as well
as selecting the trigger slope. The center knob of the
LEVELISLOPE control provides about a 3:1 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 LEVELISLOPE con.trol is set to
the
"0" on either the positive-going or negative-goingwave-
form, the sweep is triggered near the zero-volt level of the
trigger signal. As the LEVELISLOPE control is rotated
away from the "O", 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 LEVELISLOPE control is turned clockwise from the
"0" on the positive-going slope, the displayed waveform
starts at a more positive level. Fig. 2-7 illustrates the opera-
tion of the LEVELISLOPE 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 LEVELISLOPE control so the displayed wave-
form starts at the desired point. The triggering slope can be
changed at any time by rotating the LEVELISLOPE con-
trol to the corresponding point on the other slope wave-
form.
Horizontal Sweep Rate
The TIMEIDIV switch provides 26 calibrated sweep
rates ranging from 0.02 microsecond1division to five
secondsldivision. The VARIABLE TIMEIDIV control must
be in the calibrated position and the MAGNIFIER at XI
for the indicated sweep rate. The VARIABLE TIMEIDIV
control incorporates a two-position switch to determine if
the sweep rate is calibrated or uncalibrated. When the
VARIABLE knob is in the inward position, the VARI-
ABLE TIMEIDIV 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. A calibrated
sweep rate can be obtained at any position of the VARI-
ABLE TIMEIDIV control by pressing in the VARIABLE
knob. This feature is useflil when a specific uncalibrated
sweep rate has been obtained and
it is desired to switch
betweenthis uncalibrated sweep rate and acalibrated sweep
rate. Switchingfrom uncalibrated to calibrated operation or
vice versa does not affect the setting of the VARIABLE
TI
MEIDIV control. The VARIABLE TIME/DIV control
allows the sweep rate ineach TIMEIDIV switch position to
be reduced to at least the sweep rate of the next adjacent
switch position. This provides an overall uncalibrated vari-
Scans by Artekhledia O 2006

Operating Instructions-7B70 (SN B205000and Up)
CRT displays
obtainedwith
LEVELISLOPE
control in
positiveslope
region
CRT displays
obtained with
LEVELISLOPE
control in
negativeslope
region
L
TRIG'D \
k
A\
1
....
Y
TRIG'D
I 1
L
At
1
...**
I'
___________-_____-_-__---- ___---
TRWD \
L
At
1 a**e*
N'
TRIG'D \
L
Al
I
....+
n
-
Fig. 2-7. Effect of LEVELISLOPE control on CRT display (AUTO P-P MODE).
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