Tektronix 7B70 User manual

ced in c
:opyrigh
s and
rny' form
t owner
I the UI
ts resei
an#%.,
nited
ved.
t be
Scans by ArtekMedia O 2006

Scans
BY
Artek Media
Artek Media
1042 Plummer Cir . SW
Rochester,
MN 55902
www
.artekmedia .co m
"High resolution scans of
obsolete technical
manuals"
if your
looking for a quality
scanned technical
manual in
PDF format please
visit
our
WEB site at
www .artekmedia .co
m or drop us an
email at
manuals
@ artekme dia .co m
and we will be happy
to email you
a current list of the
manuals we
have available .
If you don't see
the manual you need
on the list drop us
a line anyway we may
still be able
to point you to
other sources . If you
have an existing
manual you
would like
scanned please
write for details,
This can often be done
very
reasonably in consideration for
adding your
manual to our library .
Typically the scans
in our
manuals are done as
follows ;
1)
Typed text pages are
typically
scanned in black and white
at 300 dpi .
2) Photo pages
are typically scanned in
gray scale mode
at 600 dpi
3) Schematic
diagram pages
are typically scanned
in black and white at
600
dpi unless the
original manual had
colored high
lighting (as is the case
for
some
70's vintage Tektronix
manuals) .
if you purchased
this manual from us
(typically
through our Ebay name
of
ArtekMedia)
thank you very much
. If you received
this from a
well-meaning
"friend"
for free we would
appreciate your treating
this much like
you would
"share
ware" . By that we
mean a donation
of at least
$5-10 per manual is
appreciated
in recognition
of the time (a
manual can take as much
as 40 hours
to
reproduce, book,
link etc .), energy
and quality of effort
that went into preserving
this manual
. Donations via PayPal
go to :
manmanuals@artekmedia .co m
or can
be
mailed to us
the address
above .
Dave & Lynn
Henderson
Artek Media

TABLE OF CONTENTS
SECTION 1 SPEC1FlCATlONS
l ntroduction
Electrical Characteristics
Sweep Rate
Sweep Accuracy
Sweep Length
Sweep Hold-Off Time
External Horizontal Amplifier
Deflection Factor
Frequency Response
Trigger Sensitivity
InternalTrigger Jitter
External Trigger Input
P-PAuto Sensitivity
Environmental Characteristics
Altitude
Physical Characteristics
Finish
Dimensions
Weight
SECTION
2 OPERATIIUG IIUSTRUCTIONS
General
l nstallation
FrontPanel Controls
Test Setup Chart
General Operating Information
Sweep Calibration Check
Simplified Operating Instructions
Normal Sweep
Magnified Sweep
Delayed Sweep
Pushbutton 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
1-1
1-1
1-1
1-1
1-1
1-1
1-1
1-1
1-2
1-2
1-2
1-2
1-2
Scans by ArtekMedia O 2006

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
DetailedCircuit Description
Trigger Input
Trigger Amplifier
l nput Stage
Peak Detector
Slope Comparator
Output Stage
Trigger Generator
Trigger Pulse Generator
Sweep Gate Stage
Triggered Hold-OffStage
Bright Line Auto
External Horizontal Amplifier
Time-BaseGenerator
General
NormalTrigger Mode Operation
Single Sweep Operation
Alternate Operation
Delayed Sweep Operation
Horizontal Preamp
Readout Block
SECTION
4 MAINTENANCE
PreventiveMaintenance
General
Cleaning
Visual Inspection
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
Scans by ArtekMedia O 2006

TABLE OF CONTENTS
SECTION 4 MAINTENANCE (cont)
Troubleshooting
Troubleshooting Aids
Troubleshooting Equipment
Troubleshooting Techniques
Corrective Maintenance
Obtaining Replacement Parts
Soldering Techniques
Component Replacement
Instrument Repackaging
(cont)
Page
SECTION 5 PERFORMANCE CHECK/CALIBRATION
Introduction 5-1
Test Equipment Required 5-1
Short Form Procedure 5-2
PerformanceCheckICalibrationProcedure 5-4
General 5-4
PreliminaryControl Settings 5-4
CheckIAdjust Steps (referto Short-Form Procedure
for index to steps) 5-5
SECTION 6 ELECTRICAL PARTS LIST
Abbreviations and Symbols
Parts Ordering lnformation
lndex of ElectricalParts List
SECTION
7 DIAGRAMSAlUD MECHANICAL PARTS ILLUSTRATIOIUS
Diagrams
Mechanical Parts Illustrations
SECTlOlU 8 MECHAIUICALPARTS LIST
MechanicalParts List lnformation
lndex of MechanicalParts Illustrations
Mechanical Parts List
Accessories
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-12B and other standards of the electronics
industry. Change information, if any,
is located at the rear of this
manual.
iii
Scans by ArtekMedia O 2006

-
RESET
Fig. 1-1. 7870 Time Base.
Scans by ArtekMedia O 2006

SECTION 1
7870 SPECIFICATION
Change information, ifany,affecting thissection willbe foundat the rear of themanual.
Introduction
The 7B70 Time Base Unitis designed specifically for use
with Tektronix 7700-series oscilloscopes. However,
it is
compatible with all 7000-series oscilloscopes. The 7B70
provides calibrated sweeps from 5 secondsldivision to0.02
microsecond/division. The XI0 MAGNIFlER extends the
calibrated sweep to 2 nanosecondsldivision. Sweep rates
may be varied continuously (uncalibrated) betweencalibra-
ted steps. Sweep triggering is to 200 megahertz or vertical
amplifier bandwidth, whichever is less. The 7B70 features
an external horizontal amplifier todisplay signals applied to
the EXT VOLTS INconnector. The sweep free-runsto pro-
vide a bright base line inthe absence of adequate triggering
signal in P-PAUTO and AUTO triggering modes.
The Performance Check Procedure given in Section 5
provides a convenient method of checking performance of
this instrument. The following electrical characteristics
apply over a calibration interval of 1000 hours or six
months (whichever occurs first) at an ambient temperature
of
O'C to +50°C, unless otherwise noted. Warmup time for
given accuracy is 20 minutes.
TABLE
1-1
ELECTRICAL CHARACTERISTICS
Characteristic
Sweep Rate
Calibrated Range
VARIABLE Range
(uncalibrated)
Sweep Accuracy
Over Center
8
Divisions
5 s/div to 1sldiv
0.5 sldiv to
0.02 psldiv
Over any 2 Division
IntervalWithin Cen-
ter
8 Divisions
Exclude Following 1-startof Sweep.
Characteristic Performance
Performance
5 seconds/division to 0.02 micro-
secondldivision ina 1-2-5sequence.
XI0 magnifier extends sweep rate
to2 nanosecondsldivision.
Continuously variable between cali-
brated sweep rates. Extends uncali-
brated sweep rate to at least 12.5
secondsldivision.
Measured in 7700-series oscillo-
scope.
Sweep Length
1 10.5 divisions to 13divisions.
-
Portionsof Magni-
fied Sweep End of Sweep.
+15'~to+35'~
Sweep Hold-OffTime
5 sldiv to5 psldiv
O'C to+50'~
Unmag
3%
2%
External Horizontal
Amplifier
1.5 times the TIMEIDIVISION set-
ting or less.
2psldiv to
0.02 psldiv
Unmag
4%
3%
Mag
3.5%
2.5%
Deflection Factor
EXT
VARIABLE
Fully Clock-
wise
3.5 microsecondsor less.
Mag
5%
4%
5%
VARIABLE
Fully Clock-
wise
7%
25 millivolts/division within 5 milli-
voltsldivision.
250 millivolts/division within 50
millivolts/division.
Scans by ArtekMedia O 2006
VARIABLE
Range Atleast10:I
1-1

TABLE 1-1 (cont) TABLE
1-1 (cont)
Characteristic
ExternalTrigger lnput
1
Performance Characteristic
Frequency
Response
Performance
System -3 dB points in7700-series
oscilloscope.
lnput Rand C
Maximum lnput
Voltage
1megohm within 2%, 20 picofarads
within 2 picofarads.
500 volts (DC
+ Peak AC). 500
volts (P-PAC) at 1kilohertz or less.
Level Range
(ExcludingP-P
AUTO)
EXT
EXT+ 10
DC
I -----
1 100kilohertz
Trigger Sensitivity
1 Triggering 1 Minimum Trig- At least +1.5 volts to-1 5 volts.
Frequency
~an~e' At least +15 volts to-15 volts.
geringSignal
Required
P-P AUTO Operation
Sensitivity
Coupling
1 INT , 7;;v
--
AC , 30 Hz to 20 MHz 0.3 div 0.5 div Internal, 125 millivolts Ex-
ternal, 200 Hz to 20 MHz. Upper
frequency and amplitude limits
same as NORMAL Trigger Sensiti-
vity.
20 MHz to
200 MHz
1 20 MHz Low Frequency Must Trigger on 50 hertz, 2division
Response signal.
AC HF REJ I30Hz to 50 kHz 10.3div
/ 75 mV
DC I DC to 20 MHz 10.3div 1 75 mV
I I
TABLE 1-2
ENVIRONMENTAL CHARACTERISTICS
275 mV
20 MHz to
200 MHz
Thisinstrument will meet the electrical characteristics
given in Table
1- 1 over the following environmental
limits.
1.5 div
'On lnternal 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. Non-operating
1 To 50,000 feet and -55O~.
Characteristic
Altitude
'will not trigger on sine waves of 3
divisions or less internal or 1.5
volts external below 120Hz.
Performance
TABLE
1-3
PHYSICALCHARACTERISTICS
sweep generator produces one Finish
sweep only. Dimensions
Single Sweep
1 Front panel is anodized aluminum.
14.583 inches long by 2.75 inches
wide by 5 incheshigh.
Triggering requirements same as
normal sweep. When triggered,
lnternal Trigger Jitter
Characteristic
1 nanosecond or less at 150 mega-
Performance
hertz. Weight
I
/ Approximately 2.88 pounds.
Scans by ArtekMedia O 2006

- Operating Instructions-7670
SECTION 2
OPERATING INSTRUCTIONS
Change information, if any, affecting thissection will be foundat therear of themanual.
General
The 7B70 plug-in unit operates with a Tektronix
7000-series indicator oscilloscope and a 7A-seriesvertical
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.
Installation
The 7B70 is designed to operate inthe 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 in this manner, there is no retraceblanking
or internal triggering provision and the unit may not meet
the specifications given in Section
1. The instructio,~~in
this manual are written for use of the 7870 inahorizontal
plug-incompartmentof the oscilloscope.
When the 7B70
is used with an oscilloscope which has
two horizontal plug-incompartments, install this unit in the
B (right) compartment. Then, if a delaying-sweep unit is
installed-inthe A (DELAYINGTIME BASE)compartment,
delayed-sweepoperation
is available. The 7B70 will operate
3 I I AND COUPLING. I \6
Release
Latch
I
VARIABLE
c
Fig. 2-1. Location of release latch.
properly in the A compartment for all horizontal modes of
operationexcept delayingsweep.
To install the 7870 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.
2-1) 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 ad-
justment when insertingplug-inunits, the sweep calibration
of the 7B70 should be checked when
it is insertedintothe
indicator to verify measurement accuracy. The procedure
for checking the unit
is given under Sweep Calibration
Check in this section.
FRONT-PANELCONTROLS
General
All controls required for the operation of the 7B70 are
located on the front panel of the unit (see Fig.
2-2). To
make full use of the capabilities of this instrument, the
operator 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 Operating Information.
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.
TRIG'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 vertical unit and indi-
cator oscilloscope.
Scans by ArtekMedia O 2006

Operating Instructions-7B70
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 by the
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) or when the trigger
signal is inadequate, the sweep
free runs at the sweep rate selec.
ted by the TIME/DIV switch to
producea referencetrace.
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-
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 rep-
etition rate is below the 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 TIME/DIV
switch to produce a reference
trace.
NORM: Sweep initiated by the
applied trigger signal at any
point selected by the LEVEL/
SLOPE control over the frequen-
zy 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 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 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
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 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 a sweep is com-
pleted, the RESET-READYlight
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 attenuatesAC
signals below about 30 hertz.
Accepts signals between 30hertz
and 200 megahertz.
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.
Scans by ArtekMedia O 2006

..
OperatingInstructions-7B70
-
TRIGGERING
MOO€ COUPUlG SOURCE
TRtGGERING
CONTROLS
SWEEP
CONTROLS
DISPLAY
SELECTOR
TRIGGERING
CONTROL
Fig.
2-2. Front-Panelcontrols and connectors.
DC: Accepts all trigger signals from
DCto
200 megahertz.
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-
strument.
EXT: Trigger signal obtained from
an external signal applied to the
EXTTRIG INconnector.
EXT
+ 10: Trigger signal obtained
from an external signal applied
to the EXT TRIG INconnector
as in the EXT position. In this
position the external signal is
Scans by ArtekMedia O 2006

OperatingInstructions-7B70
attenuated 10 times before it is Display Mode
appliedto the trigger circuit. TIME BASE Selects sweep rates as determined
EXTTRIG INor lnpur connector for external trigger byTIMEIDIV switch.
EXTVOLTS
IN
signal or amplifier inputsignal. AMPLIFIER Displays signals applied tothe EXT
TRIG IN or EXT VOLTS IN connec-
Sweep Controls
POSITION Controls horizontal position of dis- VARIABLE
play. (amplifier)
FINE Provides more precise control of
horizontal positions.
TIMEIDIV Selects the basic sweep rate of the
output sawtooth. The VARIABLE
control must be in calibrated posi-
tion and MAGNIFIED switch set to
XIfor indicated sweep rate.
VARIABLE Two-position switch actuated by
(TIME/DIV) the VARIABLE knobtoselect cali-
brated or uncalibratedsweep rates.
At the in position, the VARIABLE
control
is inoperativeand 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 TIMEIDIV
switch position can be reduced to
at least the sweep rate of the next
adjacent position, to provide con-
tinuously variable sweep rates from
5 nanosecondsldivision (X10-MAG-
NIFI
ER on) toabout 12.5 seconds1
division, with MAGNIFIER at XI.
MAGNIFIED Push-button switches to select the
horizontal magnification. The
Selected magnification
is indicated
bya lighted button.
X1:Magnified sweep at the basic
sweep rate indicated by TIME1
DIV switch.
SWP CAL
X10: Magnified sweep at a sweep
rate 10 times faster than the
basic sweep rate indicatedby the
TIMEIDIV switch. The portion
of the normal sweep within the
center division of the graticuleis
the portion shown in magnified
form.
Screwdriver adjustment to set am-
plitude of the output sawtooth.
tor. Select TRIGGERING SOLIRCE
and COUPLING.
Varies deflection factor by afactor
of 10.
TEST SETUP CHART
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
it may
be used as a trainingaid for familiarization with this instru-
ment.
GENERAL OPERATING INFORMATION
Sweep CalibrationCheck
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 if nec-
essary. Allow five minutes warmup before performing this
procedure.
1. Connect a one-kilohertz calibrator signal from the
Indicator Oscilloscope Calibrator to the Vertical unit input
connector.
2. Set the TIMEIDIV switch to 1 ms and press the top
TRIGGERIIVGand 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.
5. If necessary, adjust the SWP CAL adjustmentfor one
completecycle per division.
Simplified Operating Instructions
The following information is provided to aid in quickly
obtaining the correct settings for the 7B70 to present a
Scans by ArtekMedia O 2006

Operating Instructions-7B70
7B70 TEST SET-UP CHART
MAGNIFIER
VARIABLE (CAL IN1
EX1 VOLTS IN
TIME BASE
NOTES:
Fig. 2-3. 7B70 Test Setup Chart.
Scans by ArtekMedia O 2006

Operating Instructions-7B70
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. onthe A time-base.
1. Select the TRIGGERING MODE, COLlPLlNG and
2. Set the indicator oscilloscopehorizontal mode to dis-
SOURCE which fit the requirements of the signal to be play the A time base.
displayed.
3. Set the TIMEIDIV switch of the 7670so 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). If the 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. Ifthe light does
not come on at any setting of the LEVELISLOPE control,
the trigger signal is inadequate or the COUPLING and
SOURCE switches are set incorrectly.
4. Set the TIMEIDIV switch and POSITIOIV controlfor
a display which remains on the display area horizontally
(VARIABLE control should be inCAL position 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 MULT dial to
position the intensified zone to the portion of the display
to be delayed.
5. Set the indicator oscilloscopehorizontal mode todis-
play the B time base (7870).
6. Ifa delayed sweep with lessjitter is desired, press the
A time-base B TRIGGERABLE AFTER DELAY push-
button. The triggering controls of the 7670 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
tainedasfollows after a normal-sweepdisplay is obtained as
Sequence which places the
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 push-buttons; P-P AUTO, AC, INT and
1. Adjust the POSITION control to move the area to be TlME BASE. When an adequate trigger signal is applied, 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
TRIG'D 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 following discussions or the instruction
3. Press the X10-MAGNIFIER push-button. manuals for the associated indicator oscilloscope and verti-
cal unit for more information.
4. Use the fine range of 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 7870 is used inan GERING controls are correctly set and an adequatetrigger
Scans by ArtekMedia O 2006

-
OperatingInstructions-7B70
a. II",.
SOURCl
push-buttc
AUTO
m
COUPLING Trigger Mode
push-butt01
MOD
5
The pushbuttons located under the MODE title (see Fig.
push-bu1
)M
2-4) select the mode in which the sweep is triggered. The
1
selected mode is indicated by alightedpushbutton.
sour / :I!
P-P AUTO. When the P-P AUTO pushbutton is pressed,
'6
a triggered display is providedat any settingof the LEVEL1
"i
SLOPE control whenever an adequate trigger signal is
applied. The range of the LEVELISLOPE control in this
ii
mode is between about 10%and 90% of the peak-to-peak
amplitude of the appliedtrigger signal. The LEVELISLOPE
M+D
control can be set so the displayed waveform starts at any
mi
point within this range on either slope. Inthe P-P AUTO
mode, the trigger circuit automatically compensates for
MAQNlFlER
.i. Irma
changes in trigger signal amplitude for signals above the
minimum amplitude requirement.Therefore, ifthe LEVEL1
~BLEGAL IN)
SLOPE control is set so the displayed waveform starts at a
TIME/DIV
certain percentage-point on the leading edge of a low-
amplitude signal, it triggersat the same percentage-pointon
i
the leading edge of a high-amplitudesignal if the LEVEL1
SLOPE control is not changed. This operation is illustrated
Fig. 2-4. View of front panel showing push-buttonsassociated with
iq Fig. 2-5.
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-
quencv ran@. This feature can be used as a general indica-
When the trigger repetitionrate is below about 200 hertz
(or outsidethe frequency range selected bythe 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 atriggered display 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, siyce
it is notnecessary to
this unit
is correctly triggered when operatingas adelayed- reset the LEVELISLOPE control for each observation.
sweep unit
(B).
Also, because of the ease of obtainingatriggered display in
Fig. 2-5. LEVELISLOPE control operation for (P-PI AUTO mode triggering. (A) LEVELISLOPE control set so displayed waveform starts at
about 25% point of a twodivision waveform.
(BI displayed waveform still triggered at about 25% of leading edge, when signal amplitude
increases to produce a six-division display (LEVELISLOPE control at same settingfor both waveformsl.
8 2-7
Scans by ArtekMedia O 2006

Operating Instructions-7B70
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 presented with 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
?8 vertical divi-
sions. The TRIG'D light indicates when the display is trig-
gered.
When the trigger repetition rate is below about 30hertz
(or outside the frequency range selected bythe 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 a triggered display is presented.
When the LEVELISLOPE control is at a setting outsidethe
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 a signal without observing the waveshape (such as in
bandwidth measurements).
NORM. When the NORM push-button is pressed, a trig-
gered display is presented with the correct setting of the
LEVELISLOPE control whenever an adequate trigger signal
is applied. The range of the LEVELISLOPE control inthis
mode is
?8 vertical divisions. The TRIG'D light indicates
when thedisplay 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 a setting out-
side the amplitude range of the trigger signal, when the
trigger repetition rate is outside the frequency range
selected by the COUPI-ING switch or when the trigger sig-
nal is inadequate, there is notrace (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 repetitivetype display may produce an
unstable presentation. A stable display can often be ob-
tained under these circumstances by using thesingle-sweep
feature of this unit. The SINGLE SWP MODE is also useful
tophotograph 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 amplitude, successivesingle-
sweep displays may notstart at the same pointof the wave-
form. To avoid 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
instructionmanual.
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-sweep display, press the
RESET-READY pushbuttonagain.
When using the single-sweep mode to photograph wave-
forms, the graticule must be photographed separately inthe
normal manner to prevent over-exposing the 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 frequencies covered by each position
of the COUPLING switch.
Scans by ArtekMedia O 2006

d
OperatingInstructions-7B70
NORM AC HF
Fig. 2-6. Frequency range of each COUPLING switch position.
AC. In the AC position of the COUPLING switch, the
DC component of the trigger signal
is blocked.Signalswith
low-frequencycomponents 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 a better 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 impossibleto main-
tain astable display. Insuch cases, use DC coupling.
AC LF REJ. In the AC LF REJ position, DC is rejected
and low-frequencytrigger signals below about
30 kilohertz
are attenuated. Therefore, the sweep
is triggered only by
the higher-frequencycomponents of the trigger signal. This
position
is particularly usefulfor providingstabletriggering
if the trigger signal contains line-frequency components.
Also, the AC LF REJ position providesthe best alternate-
male vertical displays at fast weep rates when comparing
two or more unrelated signals (with dual-trace vertical or
slaved triggering operation for dual-verticalunitoperation).
AC HF REJ. The AC HF REJ position passes all low-
frequency signals between about 30 hertz and 50 kilohertz.
DC is rejectedand signals outside the above rangeare atten-
uated. When triggering from complex waveforms, this
position
is useful for providing stable display of the low-
frequency components.
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 a DC level selected by the setting of
the LEVELISLOPEcontrol. When usinginternaltriggering,
the setting of the vertical unit position controls affectsthe
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-
catedby a lightedpushbutton.
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-
Scans by ArtekMedia O 2006
ArtekMedia
Digitally signed by ArtekMedia
DN: cn=ArtekMedia, o=ArtekMedia.com, ou, [email protected], c=US
Date: 2008.11.17 07:49:37 -06'00'

Operating Instructions-7B70
vided by the associated vertical unit or indicator oscillo-
scope; see the instruction manualsfor these instrumentsfor
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
(multiple or sub-multiple) to the line frequency.
It is also
useful for providing a stable display of a line-frequency
component inacomplex waveform.
EXT. An external signal connected to the EXT TRIG
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.An external
trigger signal can be used to provide a triggered display
when the internal signal is too low inamplitude 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-shapingcircuits, 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 inthe circuit
to be examined without resettingthe TRIGGERING con-
trols.
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
LEVELISLOPEcontrol.
Trigger Slope
The LEVELISLOPE control determines whether the
trigger circuit responds on the positive-goingor 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-goingpor-
tion of the waveform (notice positive-goingwaveform 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 displayed waveform 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 is triggered, 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 triggeringover
the selected slope. This is particularly useful in the P-P
AUTO MODE. When the LEVELISLOPE control is set to
the
"0" on either the positive-goingor 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 "On, the displayed waveform starts at a
point correspondingto 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-goingslope, the displayed waveform
starts at a more positive level. Fig. 2-7 illustratesthe opera-
tion of the LEVELISLOPE control at different levels and
slopes of adisplayedwaveform.
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 triggeringslope 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
seconds/division. 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 TI
MEIDIV 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 useful when a specific uncalibrated
sweep rate has been obtained and
it is desired to switch
betweenthis uncalibratedsweep rate and acalibrated sweep
rate.Switching from uncalibratedtocalibrated operation or
vice versa does not affect the setting of the VARIABLE
TIMEIDIV control. The VARIABLE TIMEIDIV control
allows the sweep rate ineach TIMEIDIV switch positionto
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 Indructions-7B70
Fig. 2-7. Effectof LEVELISLOPE control on CRT display (AUTO P-PMODE).
k
2-1 1
Scans by ArtekMedia O 2006
TR16'D \
LEVELJSLOPE
CRT displays
obtainedwith
LEVE
LISLOPE
control in
positive-slope
region TRIG'D
\
LEVELjSLOPE
_ -----__--_------- ---------------
TRIG'D \
LEVELISLOPE
b
CRT displays
obtained with
LEVELISLOPE
control in
negative-dope
region TRlG'D
LEVEL/SLOPE