Tektronix 7B53N User manual

TABLE OF
CONTENTS
Introduction
Simplified Block Diagram
Discussion
Main Sweep Mode
Delayed Sweep Mode
Mixed Sweep Mode
3-1
3-1
3-1
3-3
7B53N
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 .
SECTION 1 SPECIFICATION
Page
SECTION 3 CIRCUIT DESCRIPTION
(cont)
Page
Introduction
1-1
Circuit Operation
3-3
Table 1-1
Electrical 1-1
General
Main Trigger
Preamp
3-3
3-4
Main
Sweep Triggering 1-1
Main Trigger
Generator 3-5
Delayed
Sweep Triggering 1-3
Main
Sweep Generator 3-8
Main Sweep Generator
1-4
Delayed Trigger Preamp
3-11
Delayed Sweep Generator
1-4
Delayed Trigger
Generator 3-12
Mixed Sweep, Variable
Time Delay 1-5
Delayed Sweep
Generator 3-13
Amplifier
Output
Signals 1-5 1-6
Horizontal Preamp
3-16
Table 1-2
Environmental Characteristics 1-7
SECTION 4
MAINTENANCE
Table
1-3 Physical 1-7
Introduction 4-1
SECTION 2
OPERATING INSTRUCTIONS
Preventive Maintenance
4-1
Troubleshooting 4-2
General
2-1
Corrective
Maintenance 4-6
Installation 2-1
Controls and Connectors
2-2
SECTION 5
CALIBRATION
General
2-2
Main
Triggering Controls
2-2
Introduction
5-1
Sweep
Controls
2-4
Tektronix Field
Service 5-1
Delayed Trigger Controls
2-4
Using This
Procedure 5-1
Front-Panel Connectors
2-5
Test
Equipment Required
5-1
Sweep Calibration
2-6
Preliminary Control Settings
5-2
Simplified
Operating Instructions 2-6
Part 1 Performance Check
5-4
Main
Sweep
2-6
Index to Part I-Performance
Check 5-4
Magnified Display
2-6
Preliminary
Procedure for
Delayed Sweep Display
2-6
Performance Check
5-4
Mixed Sweep Display
2-7 Trigger
System Check
5-5
General
Operating Instructions 2-7
Horizontal System Check
5-11
Pushbutton Switch
Logic
2-7
Output Signals Check
5-17
Triggered Light
2-7
Part 11 Adjustment
5-18
Main Trigger Mode
2-7
Index to Part
11-Adjustment 5-18
Main Trigger Coupling 2-8
Preliminary Adjustment
Procedure 5-18
Main Trigger Source
2-9
Trigger System Adjustment 5-19
Main Trigger Slope
2-10
Horizontal System Adjustment
5-25
Main Trigger
Level
2-10
Output Signals
5-29
Selecting
Sweep Rates
2-10
Time Measurement
2-10
SECTION 6 ELECTRICAL
PARTS LIST
Sweep Magnifier
2-12 Abbreviation
and Symbols
Main Sweep Operation
2-12
Parts
Ordering Information
Delayed Sweep
Operation 2-12
Index to Electrical Parts List
MixedSweep
Operation
2-13
Electrical Parts List
Delayed
Sweep Triggering
2-13
Delayed Gate Output
2-14
SECTION 7 DIAGRAMS AND
CIRCUIT BOARD
Applications
2-14
ILLUSTRATIONS
General
2-14
Comparison
Measurement Symbols
and Reference Designators 7-1
Techniques 2-14 Diagrams
Time Duration Measurements
2-15 Circuit Board Illustrations
Determining Frequency
2-16
Risetime
Measurements
2-16 SECTION 8
MECHANICAL PARTS LIST
Delayed Sweep
Measurements 2-17
Mechanical Parts List Information
Delayed Sweep
Magnification 2-18
Index of Mechanical Parts List
Triggered
Delayed Sweep
and Illustrations
Magnification
2-19
Mechanical
Parts List
Pulse Jitter Measurements
2-19
Accessories
SECTION 3 CIRCUIT DESCRIPTION

Introduction
The 7B53N
is a dual time base unit designed for use in
Tektronix 7000-Series Oscilloscopes without a readout
system
; however it is compatible with all 7000-Series
Oscilloscopes
. The 7B53N features calibrated sweeps from
5 seconds/division to 50 nanoseconds/division (5
nanoseconds/division
with X10 magnification) . The Main or
Delayed sweep rates may be varied continuously (uncali-
brated) between calibrated steps . Sweep triggering is pro-
vided to at least 100
megahertz, Separate trigger
controls
are provided
to select the desired triggering
for the main
and
delayed sweeps .
O
SECTION l
SPECIFICATION
TABLE 1-1
ELECTRICAL
MAIN SWEEP TRIGGERING
7B53N
Four display modes are provided . These include separate
display of the main sweep, an
intensified display, delayed
sweep, and mixed sweep
. The 7B53N can also be used as an
amplifier for X-Y
operation .
This instrument will meet the electrical characteristics
listed under Performance Requirement
in Table 1-1, fol-
lowing complete calibration
. The following electrical char-
acteristics apply over an ambient temperature range of 0 ° C
to +50 ° C, except as otherwise indicated . Warmup time for
given accuracy is 20 minutes .
Characteristic Performance Requirement Supplemental Information
Source
Internal from associated vertical unit . Selected by SOURCE switch .
Internal from AC power source .
External
External divide by ten .
Coupling AC Selected by COUPLING switch .
AC
low-frequency reject .
AC high-frequency reject .
DC
Polarity Sweep can be triggered from positive- Selected by LEVEL/SLOPE control .
going
or negative-going portion of trigger
signal .
Internal Trigger Sensitivity
AC 0 .3 division of deflection, minimum, 30 The specified upper -3 dB frequency
hertz to 10 megahertz ; increasing to 1 .5
of
the vertical system supersedes
the
divisions at
100
megahertz .
frequency limits given in the Internal
Trigger Sensitivity table when the
number in the table is greater
than the
upper -3 dB frequency of the vertical
unit .

Specification-7B53N
Performance
Requirement
0 .3
division of deflection, minimum,
30
kilohertz
to 10 megahertz ; increasing
to
1 .5
divisions at 100 megahertz
.
0 .3 division of
deflection, minimum, 30
hertz to 50
kilohertz .
0 .3 division
of deflection, minimum, DC
to 10
megahertz ; increasing to 1 .5
divi-
sion
at 100 megahertz .
100 millivolts, minimum, 30
hertz
to 10
megahertz
; increasing to 500
millivolts at
100 megahertz .
100
millivolts, minimum, 150 kilohertz
to 10 megahertz ; increasing to 500 milli-
volts at 100 megahertz .
100
millivolts, minimum, 30 hertz to 50
kilohertz .
100 millivolts, minimum, DC to 10
mega-
hertz ; increasing to 500 millivolts at
100
megahertz .
Stable display presented with signal
amplitudes given
under Internal and Ex-
ternal
Trigger Sensitivity above 30 hertz .
Presents
a
free-running sweep for lower
frequencies or in absence of a trigger
signal .
Main Sweep Generator produces only one
sweep when triggered . Further
sweeps are
locked out
until RESET button is
pressed . Trigger sensitivity same as given
for internal and external sensitivity .
1 nanosecond or less at
75 megahertz .
AC LF REJ
AC
HF REJ
DC
External Trigger Sensitivity
AC
AC
LF REJ
AC HF
REJ
DC
Auto Triggering
Single Sweep
Characteristic
Internal Trigger
Jitter
External Trigger Input
Input R and C
Maximum
Safe Input Voltage
TABLE 1-1 (cont)
Supplemental
Information
SOURCE switch set to EXT .
Trig-
gering signal requirements
increased 10
times for EXT=10 position
.
Approximately 1 megohm paralleled
by 20 pF .
500 volts (DC +
Peak AC)
.
500 volts
peak-to-peak AC at 1 kilohertz or less .

Level Range
EXT
TABLE 1-1 (cont)
Characteristic

I

Performance
Requirement
EXT
-
10
At least
+and
-1 .5 volts .
At least + and
-15 volts .
DELAYED SWEEP TRIGGERING
Specification-71353N
Supplemental
Information
Source
Internal from associated
vertical unit Selected by Delayed
Triggering
SOURCE switch .
External
Coupling
AC
Selected by Delayed Triggering
COUPLING switch .
DC
Polarity
Sweep can be triggered from positive- Selected by
Delayed Triggering SLOPE
going or negative-going portion of trigger
switch .
signal .
Internal Trigger Sensitivity
AC
0 .3 division of deflection,
minimum, 30
hertz to 10 megahertz
; increasing to 1 .5
divisions at 100 megahertz .
DC
0 .3 division of deflection, minimum,
DC
to 10 megahertz, increasing
to 1 .5 divi-
sions at 100
megahertz .
External Trigger Sensitivity
AC
100 millivolts, minimum, 30 hertz to 10 Delayed Triggering SOURCE switch
megahertz ; increasing to 500 millivolts at
set to EXT .
100 megahertz .
DC
100 millivolts, minimum, DC to
10 mega-
hertz ; increasing to
500 millivolts at 100
megahertz
.
Internal
Trigger
Jitter 1 nanosecond or less at 75 megahertz
.
External Trigger Input
Maximum
Safe Input Voltage
500 volts (DC + Peak AC) . 500 volts
peak-to-peak AC at 1 kilohertz or
less .
Input R and C
1 megohm paralleled by 20 picofarads .
Level Range
At least
+and
-1 .5 volts .

Specification-71353N
TABLE 1-1 (cont)
MAIN SWEEP
GENERATOR
DELAYED
SWEEP GENERATOR
Characteristic
Performance Requirement Supplemental Information
Sweep Accuracy
Measured in 7400- and 7500-Series
Oscilloscopes
Time Interval
+15 ° C to
+35
° C 0° C to +50 ° C
Over Center 8
Divisions Unmagnified Magnified Unmagnified
Magnified
50 milliseconds/division to
Within 2%
Within 2 .5% Within 3% Within 4%
0 .5 microsecond/division
5 seconds/division to
0 .1
second/division and 0 .2
Within 3%
Within
3.5%
Within 4% Within 5%
microsecond/division to
0 .05 microsecond/division
Sweep Linearity
Over
any 2 division portion with-
in center
eight divisions (all Within 5%
Within 7%
sweep rates)
VARIABLE Sweep Rate
Range Continuously variable between calibrated Extends
sweep rate to at least 12 .5
sweep rates .
seconds/division . VARIABLE control
internally switchable between Main
and Delayed Sweeps .
Sweep Hold-Off
Time
5 seconds/division
to 10 micro- 1 .5 times the TIM E/D IV setting or less
seconds/division
5 microseconds/division
to 0 .5 2 .5 microseconds or less
microsecond/division
Normal-Mag Registration Within 0 .5 division
Sweep Accuracy
Time Interval
Measured in
Oscilloscopes .
+15 ° C
7400-Series or
to +35 ° C
7500-Series
0 0 C
to
50 °
C
Over Center 8 Divisions
Unmagnified Magnified Unmagnified Magnified
50 milliseconds/division to
Within 3% Within 3.5% Within 4% Within 5%
0 .5 microsecond/division
0 .5 second/division to 0 .1
second/division and 0 .2
Within 4% Within
4
.5% Within 5%
Within
6%
microsecond/division to
0 .5 microsecond/division

Within 2% ± measured Main Sweep
error
Within
2%
Within 1%
Within 0 .2% of full scale (1 minor divi-
sion)
Less than 1 part in 20,000 of the maxi-
mum available
delay
time (10 times
the
Main
Sweep TIME/DIV switch setting) .
Sweep Accuracy
DELAY TIME MULT
Delay Accuracy over
center
eight
divisions
5 seconds/division to 1
second/division
0 .5
second/division to 1
microsecond/division
Multiplier Linearity
Delay Time Jitter
TABLE 1-1 (cont)
MIXED SWEEP, VARIABLE TIME
DELAY
AMPLIFIER
Specification-71353N
Exclude the following portions of
Mixed Sweep :
First
0 .5
division after start of MAIN
sweep display and 0 .2 division or 1
microsecond (whichever is greater)
after transition of MAIN to
DLY'D
sweep
10 millivolts/division within 10% .
100 mill
ivolts/division within 10% .
1
volt/division within 10% .
Deflection
Factor
EXT, MAG X10
EXT, MAG off
EXT= 10, MAG
off
Characteristic
Performance Requirement Supplemental Information
Sweep Linearity
Over any 2 division portion with-
in center eight divisions (all
Within 6%
Within 8%
sweep rates)
VARIABLE
Sweep Rate Range Continuously
variable between calibrated Extends sweep rate to at least
1 .25
sweep rates .
seconds/division . VARIABLE control
internally switchable between Main
and Delayed Sweeps .
Sweep Hold-Off Time
Determined
by the Main Sweep TIME/
DIV setting .

Specification-71353N
Performance Requirement Characteristic
TABLE 1-1 (cont) .
OUTPUT SIGNALS
Supplemental
Information
Delayed Sweep Gate
Available at front-panel DLY'D TRIG
IN connector
when operating in a
Waveshape
Rectangular pulse
delayed sweep mode with the Delayed
Triggering SOURCE switch set to INT .
Amplitude +3 .5 volts within 40°% with baseline at 0
to -1 volt .
Polarity
Positive-going
Duration For the time of the
delayed
sweep
Output
Resistance Approximately 1 kilohm
Loading
At
least
10
kilohms shunted by 100
picofarads or less .
Composite Sweep Gate Coupled to associated indicator
oscilloscope
by way of
pin
A1
on
In-
Waveshape Rectangular pulse .
terface
circuit
board .
Polarity
Positive-going
Duration
DISPLAY MODE
MAIN
SWP
Coincident with the main sweep interval .
INTEN Coincident with the main sweep interval
.
DLY'D
SWP Coincident with the delayed sweep in-
terval .
MIXED Coincident with the main sweep interval
plus the delayed sweep interval
.
Nominal
Frequency Response
System -3 dB points in 7400-Series or
7500-Series Oscilloscope .
AC
Lower -3 dB
40 hertz
Upper -3 dB
2 megahertz
AC LF REJ 16 kilohertz 2megahertz
AC HF REJ
40 hertz 100 kilohertz
DC DC
2 megahertz

Performance Requirement
Rectangular
pulse
Positive-going
Coincident
with the delaying
sweep (all
DISPLAY MODES)
Sawtooth signal with slope
determined by
setting of TIME/DIV OR
DL'Y TIME
switch
.
Sawtooth signal with slope
determined by
setting of
DELAYED SWEEP Time/
Division
switch .
Composite Sawtooth
signal with slope
determined by the
setting of TIME/DIV
OR DL'Y TIME
switch during the main
sweep portion of display, and by the
setting of DELAYED SWEEP
Time/
Division switch during delayed
sweep por-
tion of
display .
Negative-going
Coincident with the main sweep
interval
Ramp duration coincident with the de-
layed sweep interval ; total duration
coin-
cident with the
delaying sweep interval .
Ramp duration coincident
with the main
sweep interval plus the
delayed sweep in-
terval ; total duration
coincident with the
delaying sweep
interval .
Auxiliary Gate
Waveshape
Polarity
Duration
Composite Sawtooth
Waveshape
DISPLAY
MODE
MAIN SWP
O
Polarity
Characteristic
INTEN
DLY'D SWP
MIXED
Duration
DISPLAY MODE
MAIN SWP
INTEN
DLY'D
SWP
MIXED
TABLE
1-1 (cont)
TABLE
1-2

TABLE 1-3
ENVIRONMENTAL
CHARACTERISTIC
Refer to the Specification
for the associated oscillo-

Size
scbpe .

Weight
Specification-7B53N
Supplemental Information
Coupled
to associated
indicator oscil-
loscope
by way of B5 on
Interface
board .
Coupled to
associated indicator
oscilloscope
by way of pins A3 and 133
on
Interface board
PHYSICAL
Fits all 7000-series plug-in compartments .
3 .25 pounds . (1
.48 kilograms)

General
Installation
SECTION
z
OPERATING
INSTRUCTIONS
The 7B53N
Dual Time Base 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 71353N, its
operation and
capabilities should be known
.
This
section
describes the
operation of the front-panel controls,
gives
simplified
operating instructions
and general operating
information, and lists some
basic applications for this
instrument .
The 7B53N is designed to operate in
the horizontal plug-
in compartment of the
indicator oscilloscope . This instru-
ment can also be
installed in the vertical plug-in compart-
ment to
provide a sweep that runs vertically
on the CRT .
However,
when used in this manner, there
are
no
retrace
blanking
or internal triggering provisions, and the unit
may
not meet
the specifications given in
Section 1 . The instruc-
tions in this manual are written
for use of the 7B53N in the
horizontal plug-in
compartment .
The
7B53N can be operated in an
indicator oscilloscope
with four
plug-in compartments
either independently, in
the Alternate or Chopped
Horizontal Modes, or as
a
delayed sweep
unit . However, when the 7B53N is
operated
as a delayed
sweep unit, it must be triggered for
a CRT
display . It cannot
delay another time base unit,
but it can
delay its
own internal delayed sweep .
Before
proceeding with
installation, it is necessary to
check
the setting of the internal
Variable Selector
switch
on the right side of the
instrument (see Fig . 2-1
for location) . The
Variable Selector switch determines
whether the
front-panel VARIABLE control operates
in
conjunction with
the main or
delayed sweeps (see
controls
and connectors discussion
in this section for
VARIABLE control operation)
.
To install the 7B53N in
a plug-in compartment, push it
in until it fits firmly into
the compartment . The front-panel
of the 7B53N
should be flush with the front-panel
of the
indicator oscilloscope
. Even though
the gain of the indica-
tor oscilloscope is standardized
to minimize adjustment
when inserting plug-in units,
the sweep calibration of the
7B53N should
be checked when it is installed
. The pro-
cedure
for checking the unit is given
under Sweep Calibra-
tion Check in
this section .
7B53N
Fig . 2-1 . Location of Variable Selector switch .
To
remove the 7B53N, pull the release
latch (see Fig .
2-2) to disengage the unit from
the indicator oscilloscope
and pull it out of the plug-in
compartment .
Fig . 2-2 . Location
of
release
latch .

Operating Instructions-71353N
General
To make full use of
the capabilities of this
instrument, the operator
should be familiar with the
function and use of
each of the controls . A brief
description of the
controls and connectors is given here .
More detailed
information is given under General
Operating
Information . Fig . 2-3 shows the
front-panel
and
external controls and connectors of
the 7B53N .
Main Triggering
Controls
LEVEL/SLOPE

Selects the amplitude point
and
r signal
on which the
gered
. When the indi
the outer ring is to the
the sweep is triggered
ive-going slope of the
trigger signal, as shown by the
g waveform . To the
ter, the sweep is trig-
negative-going slope of
signal as shown
by the
negative-going
waveform .
2-2
CONTROLS
AND CONNECTORS
slope of trigg
sweep is tri
cator
line on
left
of cente
on the posi
positive-goi
right of ce
gered on th
the trigger
TRIG'D

Lamp indicates that the sweep is
triggered and will produce a display
with correct setting of
the
POSITION
control and the controls
on the associated vertical unit and
indicator oscilloscope .
MODE

Four pushbutton
switches to select
the desired trigger mode .
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 outside
the fre-
quency
range selected by the
COUPLING switch, or the trig-
ger signal is inadequate,
the
sweep
free-runs at the sweep rate
selected
by the TIME/DIV OR
DL'Y TIME switch .
COUPLING
NORM : Sweep
initiated by the
applied trigger signal at point se-
lected by the LEVEL/SLOPE
control over the frequency range
selected by the
COUPLING
switch .
Triggered sweep can be
obtained only over the ampli-
tude
range of the applied trigger
signal . There is no trace
when
the LEVEL/SLOPE control
is
outside the amplitude
range, the
trigger repetition
rate is outside
the frequency
range selected by
the
COUPLING switch, or the
trigger signal is inadequate .
SINGLE SWP : After a
sweep is dis-
played, further
sweeps cannot be
presented until
the RESET but-
ton is
pressed . Display is trig-
gered as for NORM operation,
using the MAIN TRIGGERING
controls .
RESET-READY : Pushbutton
to
reset the Sweep
Generator for
the
next sweep in
the SINGLE
SWP mode . The
RESET-READY
button remains
illuminated to
indicate that
the unit 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 .
Four pushbutton switches to select
trigger coupling .
AC :
Rejects DC and attenuates AC
signals below about 30 hertz .
Accepts signals between 30
hertz
and 100 megahertz .
AC LF
REJ : Rejects DC and atten-
AC HF REJ : Accepts signals
be-
tween about 30 hertz
and 50
kilohertz
. Rejects DC and atten-
uates
signals from 50 kilohertz
to 100
megahertz .
O
uates signals below about 30
kilohertz . Accepts signals
be-
tween 30 kilohertz
and 100
megahertz .

SOURCE
O
INT : Trigger signal obtained in-
ternally from vertical unit by
way of associated indicator
oscilloscope .
Fig . 2-3 . Front-panel controls and connectors
.
DC : Accepts all trigger signals from
DC to
100 megahertz .
Four pushbutton switches
to select
the trigger
source .
Operating Instructions-71353N
LINE : Trigger signal obtained in-
ternally from a sample of the
line voltage applied to associated
indicator oscilloscope .
EXT : Trigger signal obtained
from
an external signal applied to the
MAIN TRIG IN connector .
EXT =10 : Trigger signal obtained
from an external signal applied
2- 3

Operating Instructions-71353N
Sweep Controls
POSITION
X10 MAG
SWP CAL
TIME/DIV OR
DL'Y TIME
VARIABLE
2- 4
to the
MAIN
TRIG
IN con-
nector . In this position the ex-
ternal signal is attenuated 10
times before it is applied to the
trigger circuit .
Controls the horizontal position of
trace .
Increases sweep rate of both the
main and delayed sweeps ten times
by horizontally expanding the
center
division of
display .
Light
indicates when magnifier is on .
Screwdriver adjustment to set hori-
zontal gain of unit . Used to set the
basic timing of the 7B53N
and
to
compensate for differences in CRT
deflection factor when changing
indicator oscilloscopes .
Combination switch selects the
sweep
rates for both the main and
delayed sweep generators
. The clear
plastic flange indicates the sweep
rate of the main sweep circuit for
main sweep display only and indi-
cates the basic delay time .(to be
multiplied by the DELAY TIME
MULT dial setting) for delayed or
mixed sweep operation . The
DELAYED
SWEEP knob, when
pulled out and rotated clockwise,
selects the sweep rate of the de-
layed sweep circuit for mixed or
delayed sweep operation . The
VARIABLE control
must be in the
CAL position and the X10 MAG
switch must be off for indicated
sweep rate .
Two position switch actuated by
the VARIABLE knob to select cali-
brated or uncalibrated sweep rates .
In the CAL position (pushed in) 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 uncali-
brated sweep
rates
.
The sweep rate
in each TIME/DIV
switch position
DISPLAY MODE
DELAY TIME MULT
Delayed Trigger
Controls
LEVEL
can be reduced at least to the sweep
rate of
the next slower position .
The VARIABLE control can be
switched to either the main or de-
layed sweeps by means of the inter-
nal Variable Selector switch (see In-
stallation in this section) .
Four pushbutton switches to select
the desired display mode .
MAIN SWP : Sweep rates deter-
mined by the TIME/DIV OR
DL'Y TIME switch .
INTEN : In this mode, a portion of
the main sweep
is intensified
during the time that the delayed
sweep is in operation, as deter-
mined by the DLY'D SWEEP
Time/Division switch .
D LY'D SWP : The DLY'D SWP
mode is a function of the
delayed sweep . In this mode, the
delayed sweep is displayed at a
rate determined by the DLY'D
SWP Time/Division switch at the
end of each delay period, as
determined by the TIME/DIV
OR DL'Y TIME switch and the
DELAY TIME MULT dial set-
tings .
MIXED : The MIXED mode is a
combination of the main and
delayed
sweeps . The main
sweep
is displayed on the CRT to a
point determined by the
DELAY TIME MULT dial ; the
remainder of the sweep is at the
rate determined by the delayed
sweep .
Provides variable delay of 0 to 10
times the basic
delay
time selected
by the TIME/DIV OR DL'Y TIME
switch .
Dual function control to determine
the mode and level for delayed
sweep
display
.
O

SLOPE
COUPLING
SOURCE
IN - RUNS AFTER DLY TIME :
The delayed sweep runs immedi-
ately
following the delay time
selected by the
TIME/DIV OR
DL'Y TIME switch
and the DE-
LAY TIME MULT dial . Delayed
SLOPE, COUPLING, SOURCE,
and LEVEL functions inoperative .
OUT-DLY'D SWP TRIGGER-
ABLE
:
When the
LEVEL con-
trol is pressed
and released the
delayed sweep is triggerable . The
LEVEL control can now be ro-
tated to select the amplitude
point on the trigger signal at
which the delayed sweep is trig-
gered . In the OUT-DLY'D
SWEEP TRIGGERABLE posi-
tion the delayed SLOPE,
COUPLING, and SOURCE func-
tions are activated .
Two position switch to select the
portion
of trigger signal which
starts the delayed sweep .
+ :
The delayed sweep can be trig-
gered
from
positive-going
por-
tion of trigger signal .
- : The
delayed sweep can be trig-
gered from negative-going por-
tion
of trigger signal .
Two position switch to
determine
the method of coupling delayed
trigger signal to the delayed trigger
circuit
.
AC : Rejects DC and attenuates AC
signals
below about 30
hertz
.
DC : Accepts trigger signals from
DC to 100 megahertz .
Two position switch to select
source of the delayed trigger . Also
determines the function of the
DLY'D TRIG IN connector .
INT :
The delayed trigger
signal is
obtained from the vertical ampli-
fier unit by way of the associ-
ated indicator oscilloscope .
Also
Front-Panel
Connectors
MAIN TRIG IN
DLY'D TRIG IN
Operating Instructions-71353N
connects the Delayed Gate Out
signal to the DLY'D TRIG
IN
connector for external use .
EXT
:
The delayed trigger signal is
obtained from an external signal
applied to the DLY'D TRIG IN
connector .
Front-panel BNC
connector serving
two different input functions,
depending upon the setting of the
TIME/DIV OR DL'Y TIME switch
and the MAIN TRIGGERING
SOURCE switch .
MAIN TRIG IN : External trigger
input for Jhe Main Triggering cir-
cuit . The SOURCE switch for
MAIN TRIGGERING must
be
set
to EXT or EXT =10 and
TIME/DIV OR DL'Y TIME
switch set to any position except
AMPL .
AMPL : When the
TIME/DIV OR
DL'Y
TIME switch is set to
AMPL and the MAIN TRIG-
GERING SOURCE switch is set
to the EXT or EXT =10 posi-
tion,
this connector serves
as an
External
Horizontal Input .
Front-panel BNC
connector serving
two different functions depending
upon the setting of the Delayed
Triggering
SOURCE switch .
DLY'D TRIG IN : When the
Delayed Trigger SOURCE switch
is set to EXT, this
connector
serves
as
an
external trigger in-
put for the delayed triggering
circuit .
Delayed Gate Output : When the
Delayed Trigger SOURCE switch
is set to INT the DLY'D TRIG
IN connector serves as a
Delayed
Gate
Output . The
Delayed Gate
signal is
a rectangular positive-
going pulse with approximately
3 .5 volts amplitude and pulse
width coincident with the
delayed sweep .
2-5

Operating
Instructions-71353N
Sweep Calibration Check
Whenever the 7B53N is inserted into a plug-in compart-
ment of an indicator oscilloscope other than the one in
which
it was originally calibrated, the sweep calibration
must be checked, and readjusted if
necessary . Install the
7B53N into the plug-in compartment
of the indicator
oscilloscope and allow at least
20 minutes warmup before
proceeding with
the following :
For accurate sweep timing, apply a signal
of known fre-
quency or time period (time-mark
signal, calibrator square-
vyave, 60-hertz line,
etc .) to the associated vertical amplifier
unit and
adjust
the
TIME/DIV OR DL'Y TIME switch and
the
SWP CAL control to calibrate that signal to the oscillo-
scope graticule . The following method, using
a Tektronix
2901 Time Mark Generator, is
recommended .
1 . Connect a 1 millisecond time-mark signal from
the
time-mark
generator through a 50-ohm BNC coaxial cable
to the Input of
the associated vertical unit .
2 . Set the 7B53N TIME/DIV OR
DL'Y TIME switch to
1 ms and press the
VARIABLE control to the CAL posi-
tion . Press the
MAIN TRIGGERING AUTO, AC, and INT
switches .
3 . Set the vertical unit
for
a
CRT display amplitude of
two to four
divisions using DC coupling .
4 . Rotate the LEVEL/SLOPE control for a triggered
display .
5 .
Check the CRT display for one marker each major
graticule division over center eight divisions .
6 . Adjust
SWP CAL (front-panel screwdriver adjust-
ment), for one
marker each major division . Use the
POSITION control as necessary to align the
display with
the vertical graticule lines .
The following information is provided to aid in quickly
obtaining the correct settings for the 7B53N to present a
display . The operator
should be familar with the complete
function
and operation of the unit described in this section
before
using this procedure .
Main Sweep
The
following procedure will provide a stable display for
most main sweep applications :
2-6
SIMPLIFIED
OPERATING INSTRUCTIONS
1 . Select the MODE, COUPLING,
and SOURCE push-
button of the MAIN
TRIGGERING switches which fit the
requirements
of the signal to be displayed .
2 . Press the MAIN SWP
pushbutton of the DISPLAY
MODE switch .
3 . Turn the LEVEL/SLOPE control to the
desired
slope .
4 . If the green
TRIG'D light is not on, adjust the
LEVEL/SLOPE
control throughout the range of
the
selected 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 not adequate
or the
COUPLING and SOURCE switches
are set incorrectly .
5 . Set
the TIME/DIV or DL'Y TIME switch
and
POSITION
control for a display which remains on the
dis-
play area horizontally (VARIABLE
control should be in
CAL position for calibrated sweep
rates) .
6 .
If the display does not start at the correct
point on
the waveform, readjust the LEVEL/SLOPE
control for the
desired triggering .
Magnified Display
A magnified-sweep
display can be obtained as follows
after anormal-sweep
display is obtained :
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 or
DELAY TIME
switch setting so the complete
area to be magnified is
within the center graticule
division .
3 . Press and release the X10 MAG
switch . Light indi-
cates when magnifier is on (the
indicator oscilloscope Inten-
sity may need to be
increased to view magnified display) .
4 . Use the POSITION control to establish precise
positioning of the magnified display .
Delayed Sweep Display
The following procedure is recommended for use of
INTEN and DLY'D SWP DISPLAY MODES . Obtain a dis-
play as previously given under Main Sweep, then proceed as
follows :
O

1 . Press the X10 MAG switch in (off) and press the
Delayed Triggering LEVEL control to the IN-RUNS
AFTER DLY TIME position .
2 .
Press the
INTEN pushbutton of the DISPLAY MODE
switch
.
Pull out the DLY'D
SWEEP Time/Division switch
and rotate
clockwise to obtain the amount of magnification
desired . Note that a normal sweep (Main Sweep) with an
intensified portion (Delayed Sweep) is displayed on the
CRT . The indicator
oscilloscope Intensity may have to be
decreased to
view the intensified display .
3 . Rotate the DELAY
TIME MULT dial and note that
the intensified portion of the display is controlled by the
DELAY TIME MULT .
4 . Press the DLY'D SWP button of the
DISPLAY
MODE switch .
Note the magnified display, as determined
by the
DLY'D SWEEP Time/Division switch . The Intensity
may need to be increased to see the delayed sweep display .
5 . For a delayed
sweep with less jitter, press in and
release
the Delayed
Triggering LEVEL control . Delayed
triggering
SLOPE, COUPLING, and SOURCE switches
should be set to +, AC, and INT respectively .
Rotate the
Delayed
Triggering LEVEL control for a stable delayed
sweep display .
Mixed Sweep Display
The
procedure that follows can be used for basic
mixed
sweep
operation . Obtain a display as
previously given under
Main sweep . Then
proceed as follows :
1 . Press the MIXED pushbutton of the
DISPLAY
MODE switch and press and Delayed
Triggering LEVEL
control to the
IN-RUNS AFTER DLY TIME position .
2 . Pull out the DLY'D SWEEP
Time/Division switch
and turn clockwise to set the
sweep rate for the delayed
portion of display .
3 . Adjust DELAY TIME
MULT dial to vary the point at
which the display
switches from the Main to Delayed sweep
rate .
4 . If less jitter
is desired for the delayed sweep portion
of
the
mixed sweep display, press in and release the De-
layed Triggering LEVEL control . Delayed Triggering
SLOPE, COUPLING,
and SOURCE switches should be set
to +, AC, and INT respectively . Rotate the Delayed
Triggering LEVEL control to trigger the delayed sweep
portion of display .
GENERAL OPERATING INSTRUCTIONS
Pushbutton Switch Logic
Operating
Instructions-71353N
The MODE, COUPLING, and SOURCE pushbuttons of
the
MAIN TRIGGERING switches and the DISPLAY
MODE pushbuttons are arranged in a 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 pushbuttons :
AUTO, AC, INT, and MAIN SWP
.
When an adequate
trigger
signal is applied, the unit is triggered
as indicated by the
illuminated TRIG'D light, with the correct setting of the
LEVEL/SLOPE control . If the TRIG'D light is not on, the
LEVEL/SLOPE control is at a setting outside the range of
the trigger signal applied to this unit from the vertical unit ;
the trigger signal is inadequate, or its frequency is
below the
lower frequency limit
of the AC COUPLING switch posi-
tion . If the desired display is
not obtained with these push-
buttons
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 TRIG'D light provides
a convenient indication of
the condition of
the triggering circuits . If the MAIN
TRIGGERING controls
are correctly set and an adequate
trigger
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 mis-
adjusted LEVEL/SLOPE control,
incorrectly set
COUPLING or SOURCE switches,
low trigger signal ampli-
tude, or a trigger
signal repetition rate outside the accept-
able frequency range . This light can be used as a general
indication of correct triggering . It is particularly
useful
when setting up the trigger circuits
when a trigger signal is
available without a display on the
CRT
.
Main Trigger Mode
The pushbuttons
located under the MODE title select
the mode in which the main
sweep is triggered .
AUTO . When the AUTO
pushbutton is pressed, a trig-
gered display
is presented with the correct setting of the
LEVEL/SLOPE
control (see Trigger Level discussion)
whenever an adequate trigger signal is applied . 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 or
DELAY TIME switch (TRIG'D light off)
. When an ade-
quate trigger signal
is again applied, the free-running con-
2- 7

Operating Instructions-71353N
dition ends and a
triggered display is presented . When the
LEVEL/SLOPE
control is at a setting outside the
amplitude
range of the trigger
signal, the sweep also free runs at
the
sweep rate
indicated by the TIME/DIV or
DELAY TIME
switch . This type
of free-running display can be useful
when
it is
desired to measure only the maximum
peak-to-
peak amplitude
of a signal without
observing the waveshape
(such as in bandwidth measurements)
. When the display is
of a much greater
amplitude than can be displayed on the
CRT, the sweep
will be triggered in all positions of the
LEVEL/SLOPE control
and will not free-run .
NORM . When the NORM
pushbutton is pressed, a trig-
gered display is
presented with the correct setting of the
LEVEL/SLOPE
control whenever an adequate trigger signal
is applied
. 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
LEVEL/SLOPE control is at a setting out-
side the amplitude
range of the trigger signal, when
the
trigger
repeitition rate is outside the frequency
range
selected by the COUPLING switch, or
when the trigger
signal is inadequate, there is no
trace (TRIG'D light is off) .
SINGLE SWEEP . 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
obtained under these
circumstances by using the single-
sweep feature
of this unit . The single-sweep mode is also
useful to
photograph non-repetitive or unstable
displays .
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 MAIN TRIGGERING
switches, press
the SINGLE SWP pushbutton . When ready
to view
the single-sweep display, press the RESET-READY
pushbutton . 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
MAIN
TRIGGERING switches are correctly set) ; further
sweeps cannot be presented until the
RESET-READY push-
button is pressed again
.
If the displayed
signal is a complex
waveform composed of pulses of
varying amplitude,
successive single-sweep displays
may not start at the same
point of the
waveform . To avoid confusion due to the CRT
persistence,
allow the display to disappear 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 a viewing hood as recommended
in the indicator oscilloscope instruction
manual .
Non-repetitive, random signals can be displayed in the
single-sweep mode by first obtaining , the best possible dis-
2- 8
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 MAIN TRIGGERING controls,
press the SINGLE-SWP pushbutton . When ready for the
random signal, press the RESET-READY pushbutton . The
RESET-READY pushbutton remains illuminated
to indi-
cate that the unit
has been reset and is ready to produce a
sweep .
The light goes out after the single sweep has been
displayed . To prepare the unit for another single-sweep dis-
play, press the RESET-READY pushbutton .
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
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, multiple
waveforms may appear on
the film . For random signals, the
lens can be left open until
the random
signal triggers the unit (RESET-READY push-
button illuminated) . Further information on photographic
technique is given in the appropriate camera
instruction
manual .
RESET-READY . The RESET-READY
pushbutton re-
sets the main sweep generator for the
next sweep when
operating in the SINGLE SWP MODE . See the
preceeding
Single Sweep
discussion for more information .
Main Trigger
Coupling
The MAIN TRIGGERING pushbuttons
located below
the COUPLING title select the method
in which the trigger
signal is connected to the
trigger circuits . Each position
permits selection or
rejection of the frequency components
of the trigger signal which trigger the sweep . Fig . 2-4 graph-
ically 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
attenuated . In general, AC COUPLING can be used for
most applications . However, if the signal contains unwanted
frequency 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 of the COU-
PLING
switch
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 maintain a stable display . In
such cases, use DC coupling .
O

AC LF REJ . In the AC LF REJ position of the
COU-
PLING switch, DC is
rejected and low-frequency trigger
signals
below about 30 kilohertz are attenuated . Therefore,
the sweep is triggered only by the higher-frequency com-
ponents 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 .
AC HF
REJ . The AC HF REJ position of the COU-
PLING switch passes all low-frequency signals between
about 30 hertz and 50
kilohertz .
DC is rejected
and signals
outside the above range are attenuated . When triggering
from complex waveforms, this position is useful to provide
a stable display of the low-frequency components .
DC . The
DC position of the COUPLING switch can be
used to provide stable triggering with low-frequency signals
which would be attenuated 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 LEVEL/SLOPE control . When using
internal triggering, the setting of the vertical unit position
controls affects the DC triggering point .
Fig . 2-4 . Frequency range of each COUPLING switch position .
Main Trigger Source
Operating Instructions-71353N
The
MAIN TRIGGERING pushbuttons located below
the SOURCE title select the source of the trigger signal
which is connected to the main trigger circuits .
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 I NT position of the
SOURCE switch can be used . However, some applications
require special triggering
which cannot be obtained in the
INT position of the SOURCE switch . In such cases LINE or
EXT positions of the SOURCE switch must be used
.
LINE . The LINE position of the SOURCE switch con-
nects a sample of the power-line voltage from the indicator
oscilloscope 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 pro-
viding a stable display of a line-frequency component in a
complex waveform .
EXT . An external signal connected to the MAIN TRIG
IN connector can be used to trigger the sweep in the EXT
2-
9