Tektronix 7B52 User manual

INSTRUCTION
MANUAL
Serial Number ___ __ _
7852
DUAl.
TIME BASE
Tektronix, I nc . • P. O . Box 500 • Beaverton, Or egon 97005 • Phone [phone] • Cables, T ektronix
070 -' 043- 00
670

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SECTION 1
SECTION 2
SECTION 3
SECTION 4
7B52
TABLE OF CONTENTS
SPECIFICATION Page Preventive Maintenance
4-1
Introduction
1-1
General 4-1
Electrical Characteristics
1-1
Cleaning
4-1
Main Sweep (Table 1-1) 1-1
Transistor FET, and Integrated
Dly'd Sweep (Table 1-2)
1-1
Circuit Checks 4-1
Triggering (Table 1-3) 1-2 Recalibration
4-1
Mixed Sweep, Variable Time Delay Troubleshooting 4-2
(Table 1-4) 1-2 Introduction 4-2
Amplifier (Table 1-5) 1-3 Troubleshooting Aids 4-2
Environmental Characteristics Troubleshooting Equipment 4-3
(Table 1-6) 1-3 Troubleshooting Techniques 4-3
Corrective Maintenance 4-4
OPERATING INSTRUCTIONS Obtaining Replacement Parts 4-4
Soldering Techniques 4-5
General
2-1
Component Replacement 4-5
Installation
2-1
Front Panel Controls and Connectors 2-2 SECTION 5 PERFORMANCE CHECK/CALIBRATION
Test Set-up Chart 2-9
First-Time Operating Instructions 2-9 Introduction
5-1
Sweep Calibration Check 2-9 Test Equipment Required
5-1
Simplified First-Time Operation 2-9 Short Form Procedure 5-2
General 5-5
CIRCUIT DESCRIPTION Procedure 5-5
Introduction 3-1
Simplified Block Diagram 3-1
SECTION 6 ELECTRICAL PARTS LIST
Main Sweep Mode
3-1
Abbreviations and Symbols
Delayed Sweep Mode
3-1
Parts Ordering Information
Mixed Sweep Mode 3-3 Index of Electrical Parts List
External Horiz Input 3-3
Circuit Description 3-4 SECTION 7 DIAGRAMS AND MECHANICAL PARTS
Introduction 3-4 ILLUSTRATIONS
Main Trigger Generator 3-5
Main Sweep Generator 3-7 Diagrams
Delayed Trigger Preamp 3-10 Mechanical Parts Illustrations (on
Delayed Trigger Generator 3-f1 reverse side
of Diagrams)
Delayed Sweep Generator 3-11
Horizontal Preamp 3-13 SECTION 8 MECHANICAL PARTS LIST
Time/Div Readout Switching 3-14 Mechanical Parts List Information
Index of Mechanical Parts Illustrations
MAINTENANCE Mechanical Parts List
Introduction 4-1
Accessories
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.

MAIN TRIGGERING
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Fig. 1·1. 7B52 DU IlI Time Base.
7852
®
ArtekMedia
Digitally signed by ArtekMedia
DN: cn=ArtekMedia, o=ArtekMedia.com,
ou, [email protected], c=US
Date: 2008.11.16 23:08:46 -06'00'

I'
7B52
SECTION 1
SPECIFICA TION
Change information, if any, affecting this section will be found at the rear of this manual.
Introduction
The 7B52 Dual Time Base is designed specifically for use
with
the 7503 Indicator Oscilloscope; however, it is com-
patible with
all 7000-Series Indicator Oscilloscopes. The
7B52 features calibrated sweeps from 5 s/div
to 50 ns/div
(0.5 s/div to 5 ns/div with X10 Magnification), triggering to
100 MHz, and four display modes. Other features include
lighted pushbutton switches, 0 to 10 times continuous
sweep delay, bright base line
in AUTO mode in absence of
adequate triggering signals, and an AMPL position for
X-Y
operation.
Display modes include MAIN SWEEP, INTENSIFIED
SWEEP, DELAYED SWEEP, and MIXED SWEEP. In the
MIXED mode, the Main Sweep is displayed to a point selec-
ted by the DELAY TIME MULT, after which the sweep
rate
is determined by DLY'D SWEEP setting. This mode
permits sweep magnification
of any point on the normal
(Main) sweep selected by the DELAY TIME MUL T control.
ELECTRICAL CHARACTERISTICS
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 OoC to +50o C, unless otherwise noted. Warmup time for
given accuracy
is 20 minutes. The instrument must be
operating
in a calibrated indicator oscilloscope for given
accuracy.
TABLE
1-1
MAIN SWP Electrical Characteristics
Characteristic Performance Requirement
Differential Sweep Measured
in 7500-Series
Accuracy1 Oscilloscope
Time Interval +15°C to +35°C
OoC to +50oC
Center 8 Unmag
Mag
2 Unmag
Mag
2
Divisions
50 ms/Div to 2% 2.5% 3% 4%
.5 ]..Is/Div
lThe term "Differential Sweep" refers to Sweep display measured
over
the center 8 divisions of the graticule.
2Measure Mag accuracies between first and ninth segment of un·
magnified sweep.
®
TABLE 1-1 (cont)
Characteristic Performance Requirement
5 s/Div
to
3%
3.5%
4%
5%
.1 s/Div and
.2
]..Is/Div to
.05 ]..Is/Div
Any two Divi-
5% of
7% of
sions within Cen· measurement measurement
ter 8 Divisions
Sweep Rate MAIN
Continuously variable between cali-
VARIABLE Range brated sweep rates. Extends sweep
rate
to at least 12.5 siD iv .
Sweep Length 10.4 Divisions within 0.3 Division
at 1 ms/Div. (Adjusted at this rate.)
10.0 to 13.0 Divisions at all other
sweep rates.
Sweep Holdoff Time
5 s/Div
to
1 times
the TIME/DIV switch
10 ]..Is/Div
setting or less.
5 ]..Is/Div to 2.5 ]..Is or less
.05
]..Is/Div
Normal/Mag Within 0.5 Division.
Registration
TABLE 1-2
DLY'D
SWP Electrical Characteristics
Characteristic Performance Requirement
Differential Sweep Measured in 7500-Series
Accuracyl Oscilloscope
Time Interval +15°C
to +35°C
OoC to+50oC
Center 8 Unmag
Mag2
Unmag Mag
2
Divisions
50 ms/Div to 3%
3.5% 4%
5%
.5 ]..Is/Div
1-1

Specification-7B52
TABLE 1·2 (cont) TABLE 1·3 (cont)
Characteristic Performance Requirement
.5 s/Div
to 4% 4.5% 5% 6%
.1 s/Div and
.2 l1s/Div to
.05 l1s/Div
--
Any two Divi·
6% of
8% of
sions within Cen· measurement measurement
ter 8 Divisions
Sweep Length 10.4 Divisions
within 0.3 Division
at 1 ms/Div.
10.0 to
13 Divisions at all other
sweep rates.
Sweep Holdoff Time Determined by MAIN SWP TIME/
DIV switch setting.
TABLE 1·3
Triggering Electrical Characteristics
Characteristic Performance Requirement
Trigger Sensitivity Triggering Minimum
Coupling3 Frequency Signal
Range Required
INT EXT
AC
30 Hz-l0MHz
0.3 Div 150 mV
10 MHz-lOO MHz 1.5 Div 750 mV
AC LF REJ4 30 kHz-l0 MHz 0.3 Div - - - - --
(Main Only) 150 kHz-l0
MHz - - -- -- 150 mV
10 MHz-l00MHz 1.5 Div 750 mV
AC HF REJ 30Hz-50kHz
0.3 Div 150 mV
(Main Only)
DC
DC-l0MHz
0.3 Div 150 mV
10 MHz-l00MHz 1.5 Div
750mV
Single Sweep
Triggering requirements
same
as
(Main Only) Main Sweep. When triggered,
sweep
generator produces 1 sweep.
Internal Trigger 1 ns or less at 75 MHz.
Jitter
3 0n Internal Triggering Only, the specified upper -3 dB frequency
of the Vertical System replaces any frequencies in the above table
when the number in the table is greater than the upper -3 dB
frequency of the indicator oscilloscope Vertical Amplifier.
4WiII not trigger on sine waves of 3 Divisions or less internal, or 1.5
volts external, below 120 Hz.
'·2
Characteristic Performance Requirement
External Trigger
Input
Maximum Input
Voltage
Input Resistance
I nput Capacitance
Level
Range
EXT
EXT -7- 10
(Main Only)
500 volts (DC plus peak AC). 500
volts (peak-to-peak AC to 1 kHz or
less).
1 megohm within 2%.
20 picofarad within 2 picofarad.
At least +3.5 volts to -3.5 volts.
At least +35 volts to -35 volts.
Auto Bright Base Line Sweep free-runs in absence of trig-
(Main Only) gering signal in
AUTO.
TABLE 1-4
Mixed Sweep, Variable Time Delay
Electrical Characteristics
Characteristic
Mixed
Sweep
Sweep Accuracy
Variable Time Delay
Differential Delay
Accuracy
Center 8 Divi-
sions
5 s/Div
to
1 s/Div
.5 s/Div
to
1 l1s/Div
Performance Requirement
2% plus measured MAIN SWP error.
Exclude following portions of
Mixed Sweep; first 0.5 Divisions of
Main Sweep and 0.2 Division or 0.1
l1s, whichever is greater, after tran-
sition of Main Sweep to Dly'd
Sweep.
Within 2%
Within 1%
Multiplier Linearity Within 0.2% of full scale (1 minor
division).
Jitter
1 part or less in 20,000 of 10 times
the
TIME/DIV switch setting.
®

TABLE 1-5
Amplifier Electrical Characteristics
Characteristic Performance Requirement
Deflection Factor
EXT, Xl0 MAG
10 millivolts/division within 10%.
EXT
100 millivolts/division within 10%.
EXT 710 1 volt/division within 10%.
Frequency Response System
-3 dB points in 75-Series
Oscilloscope
Lower -3 dB Upper -3 dB
AC
40 Hz
2 MHz
AC LF REJ 16 kHz 2
MHz
AC HF REJ 40 Hz 100 kHz
DC
DC
2 MHz
®
Specification-7B52
TABLE 1-6
ENVIRONMENTAL CHARACTERISTICS
This instrument will meet the electrical characteristics
given over
the following environmental limits.
Characteristic
Altitude
Non-Operating
Transportation
Performance Requirement
To 50,000 feet and -55°C.
Qualified under National Safe Tran-
sit
Committee test procedure lA,
category II.
1-3

NOTES

7B52
SECTION 2
OPERA TING INSTRUCTIONS
Change information, if any, affecting this section will be found at the rear of this manual.
General
The 7B52 Dual Time Base Unit is designed specifically
for use w it h Te ktronix 7500-Series Indic ator Oscilloscopes
having one
ho rizontal plug·in compartment; however, it is
com patibl e wi th all Tektronix 700 0 -Ser ie s Indicator
Oscilloscopes.
To effectively use the 7B52, its operation
and capabi
liti es should be known. Thi ssection describes the
operation
of the front·pan el contr ols, gives first· time and
general operating
information, lists some basic applications
and tells
how to make the instrument compatible with all
7000 ·Series oscilloscopes.
Installation
The 7B52 is designed to operate in the horizontal plug·in
compartment of the oscilloscope, The 7B52 can also be
install ed in a verti cal plug·in compartment to provide a
sweep that runs vertically on the
CRT , Ho wever, when used
in this manner, there is no retrace blanking or internal trig·
gering provisions, and the unit may not meet the specifica·
tions given in Section 1. The instructions in this manual are
written for use of the 7B52 in the horizontal plug·in
compartment.
Before proceeding
with installation, it is necessary to set
two internal 7852 switches which provide proper triggering
Trig ge r ab te
A lt er
DT
MA I NfRAME DELAYING
Run s
A
fter
DT
, I
I_~
Independe nt
o
DE L AYED TR I GGER SOURCE
~
MA IN AUX
Fig. 2· t.L ocation of DELAYED TRIGGER SOURCE an d MAIN ·
FRAME DELAYING MO DE switches.
signals from within or to the indicator oscilloscope main·
frame. The DELAYED TRIGGER SOURCE and MA IN·
FRAME DELAY ING MODE switches perform these
functions; see Fig, 2·' . Table 2·' lists the SOURCE and
MODE switch positions for using the 7852 in any
7000·Seri es Indicator Oscilloscope.
TABLE 2·'
I ndicator Oscilloscope and Horizontal
Plug·ln Compartment Used
Switch 7503
7504·7704 7504·7704
Position A HOR IZ B
HORIZ
DElAYED
TRIGGER
SOURCE
MAIN
Horizontal
A Hor izontal B Horizontal
Trig Selector Trig Selector Trig Selector
AUX
L eft Vertical B Hor izontal A Horizontal
Signal Trig Selector Trig Selector
MAIN·
FRAME
DElAYING
MODE
Independent Normal Normal Normal
(Rear))
Runs After
......
Delaying Swp .
.....
(Center)2 (8 H orizonta l
Runs
After
Delay
In terval)
Triggerable
......
Delaying Swp
.. ....
After (Front)2
(B Horizontal
Triggerable
After Delay
Interval)
) Sw it ch must be in this p osit ion to obtain intensified sweep,
2 Fun ctional only when 7B52 is placed in A HORtZ compartment of
7504 or 7704.
2-1

Operating In struct io n s-7 8 52
To install the 7852 into a plug-in compartment, push it
in until it fits firmly i nto the compartment. To remove, 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. Even though the horizontal gain
of the inc:li-
cator oscilloscope is standardized to minimize adjustment
when inserting plug·ins. the sweep calibration
of the 7852
should be checked. The procedure for checki ng the unit is
given under Sweep Calibration Check in the First-Time
Operating Instructions
of this section.
REl.EASE
l.ATCH
.," TWIll.
,.-
~~
DUAL TIME BASE
Fig. 2·2. L oe. t io n of re le s$fI l atc h.
FRONT· PANEl C ONTROLS and CONNECTORS
General
All controls required for the operation of the 7652 are
located on the front panel
of the unit (see Fig. 2·3) with
the exception of the internal DELAYED TRIGGER
SOURCE and
MA IN -FRAME DE L AY I NG MODE sw itches.
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 detailed description of the front·
panel controls and connectors
is given here.
Main Triggering Controls
LEVEL/SLOPE
2·2
The LEVEL/SLOPE control deter-
mines whether the trigger ci rcuit
responds on the positive-going
or
negative-going portion of the trigger
signal. When the indicator line on
the
outer ring of the lEVEL!
SLOPE control is to the left of
center, the display starts on the
positive-going portion of the wave-
form (notice positiveijoing wave-
form symbol to l eft of control). To
the right
of center, the display
starts on the negativeijoing portion
TRIG'D LAMP
of the waveform (notice negative·
going waveform symbol). When
several cycles of a signal appear in
the display. the se lection of the
trigger slope
is often unimportant.
However.
if only a certain portion
of a cycle is to be displayed, correct
setti
ng of the LEVEL/SLOPE con·
trol is important to provide a dis·
play which starts on the desired
slope
of the input signal.
The lEVELISLOPE control deter ·
mines the voltage level on the trig.
ger signal
at which the display is
triggered, as well as selecting the
tr
igger slope. The center knob of
the LEVEL/SLOPE control pro·
vides about a 3:1 reduction in rela·
tion to the outer indicator ring, to
allow precise level selection. This
control can also be turned through-
out the complete 3600 rotation to
allow continuous triggering over the
selected slope. When the
lEVEL!
SL OPE control is set to the line on
either the positive-going
or nega-
t ive-going waveform symbol the
sweep
is triggered near the zero-volt
Ievei of the trigger signal lAC
coupled only). As the LEVEL!
SLOPE control is rotated ;may
from the zero line, the displayed
waveform starts
at a point carre·
sponding to the position of the
ind icator tine on the associated
slope waveform symbol. For
example, if the LEVEL/SLOPE
control is turned clockwise from
the zero line
on the positiveijoing
slope symbol. the displaved wave·
form starts at a more positive level.
Before setting the triggering
level, select the TRIGGERiNG
MODE, COUP
LI NG and SOURCE.
Then adj ust the lEVEL/SLOPE
control SO the displayed waveform
starts at the desired point. The trig-
gering slope can be changed at any
time by rotating the LEVEL!
SLOPE
control to the corre-
sponding point on the other sl ope
waveform symbol.
The TRIG'D lamp provides a con-
venient indication of the condition
of the trigger circuits. If the MAIN
®

TR IGGERING MOOE. COU ·
PliNG . and SOURCE switches are
correctly set and a suitable trigger
s
ignal is app li ed, the TRIG'O lamp
is on. Under certain conditions, the
TR IG'O lamp may be off, indio
cating that the sweep is not trig.
gered. The cause might be a mis·
adjust ment of the LE VELISL OPE
control, incorrectly set COUP LI NG
or SOURCE switches, lOIN trigger
MAIN
TRI GGERING
CONT ROLS
DISPLAY
MOOE
CONTR
OLS
DELAY
CONTRO L
_.•
llvtL/SlO"!
MAIN TRIGGERINO
_. -
-K M
• • •
-
•
DUAL TIME BASE
Fij. 2-3. Front"'an.1 contro ls and connector, .
Operating Instru ctions-7852
signal amplitude, or a trigger signal
repetition rate outside the accept·
able frequency range. This feature
can be used
as a general indication
of correct triggering.
It is partic·
ularly useful when se tt ing up the
trigger circuits when a trigger signal
is available wi thout a display on the
CRT. It also indicates that this unit
is correctly triggered when oper·
ating as a OL Y'O SWEEP.
SWEEP
CONTRO LS
OlY1l
TRIGGERING
CON TROL S
INPUT
CONNECTORS
2·3

Operating Instructions-7B52
MODE
AUTO
NORM
2·4
The pushbuttons located under the
MODE ·title select the mode in
which the sweep is triggered. The
selected mode in which the sweep is
triggered. The selected mode is indi-
cated by a lighted pushbutton.
When the AUTO pushbutton is
illuminated, a triggered display is
presented with the correct setting
of the LEVEL/SLOPE control
whenever an adequate trigger signal
is applied. The range of the
LEVEL/SLOPE control in this
mode
is ±S vertical divisions. 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
DL'Y TIME switch to produce a
reference trace (TRIG'D light off).
When an adequate trigger signal is
again applied, the free-running con-
dition ends and a triggered display
is proesented. When the LEVEL/
SLOPE control is at a setting out-
side the amplitude range of the
trigger signal, the sweep also free-
runs at the sweep rate indicated by
the TIME/DIV or DL'Y TIME
switch. This type of free-running
display can be useful to measure
only the maximum peak-to-peak
amplitude of a signal without ob-
serving the waveshape (such as in
bandwidth measurements).
When
the NORM pushbutton is
pressed, a triggered display is pre-
sented with the correct setting of
the LEVEL/SLOPE control when-
ever an adequate trigger signal is
applied. The range of the LEVEL/
SLOPE control in this mode is ±S
vertical divisions.
The TRIG'D light
indicates when the display is trig-
gered.
The NORM trigger mode must be
used to produce triggered displays
with trigger repetition rates below
SINGLE
SWP
30 hertz. When the LEVEL/SLOPE
control
is at a setting outside the
amplitude range of the trigger sig-
nal, when the trigger repeition rate
is
outside the frequency range
selected by the COUPLING switch,
or when the trigger signal is inade-
quate, there is no trace (TRIG'D
light
is off).
Non-repetitive, random signals can
be displayed in the single-sweep
mode
by first obtaining the best
possible display 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 pushbutton again.
When using
the single-sweep mode
to photograph waveforms, the grati-
cule must
be photographed sepa-
rately
in the normal manner to
prevent over-exposing the film. Be
sure the camera system is well pro-
tected 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 camera lens can be left
open until the random signal trig-
gers the unit (RESET-READY
pushbutton lighted). Further infor-
mation on photographic techniques
is given in the camera instruction
manual.
When the signal to be displayed is
not repetitive or varies in ampli-
tude, waveshape or repetition rate,
a conventional repetitive type dis-
play may produce an unstable pre-
®

®
sentation. A stable di sp lay can
often be obtained under t he se cir·
cumstances by using the single.
s wee p feature of this unit. The
SI NGLE SWP MODE is also use ful
to photograph non-repetitive or un·
stable displays.
To obt ain a single·sweep display of
a repetitive signal, first o bt ain the
best possible display in the NORM
MO DE. Th en wit h out changing the
ot her TRIGG ER ING contro l s, pr ess
the SI NG LE SWP pushbutton.
When ready to view the
si ngle·
sweep display press the RES ET ·
READY PUSH BUTTON. A single
trace is presented eac h time the
RESET ·R EADY pushbutton is
pressed (as long as the repetitive s ig .
nal remains connected to the
system and TR
IGGERING controls
are correctly set) and further
sweeps cannot be presented until
the RESET-READY push button is
pressed again. If the displayed sig·
nal is a complex wave
form com·
posed of pulses of varying ampli·
tude, successive single-sweep dis·
MAIN TR' (I(lnl NG
OU"l T IM( .....
DC 10 Hz
CO UPLING
AC
30 kHz
100 Hz 10kHl
Operating Instruction s -7B52
plays may not start at the same
point of the waveform. To avoid
confusion due
to the CR T persist·
ence, a
llow the displ ay to decay be·
fore pressing the RESET ·REA DY
pushbutton again. At fast sweep
rates, it may be difficult to view the
single·sweep display. The apparent
trace i
nt ensity can be increased by
reducing the
am bient light l eve l or
using a viewing hood as recom·
mended in the indicator instruction
manual.
The pushbuttons located below the
COUPLING title selects the method
in which the trigger signal
is con·
nected to t he trigger circuits. The
selected coupli ng is indicated by a
lighted pushbutton. Each position
permits selection
or rejection of the
frequency components of the
tr ig·
ger signa l which trigger the sweep.
Fig. 2-4 graphically illustrates the
band
of frequencies covered by
eac h position of the COU PLING
switch.
In the AC position of the CO U·
PLi NG switch, the DC component
50 kHz
100 kHz 10 MHz
100 MHz
Fig. 2·4. Frequency range of each CO UPLING switch pOsition.
2-5

Operating Instructions-7B52
AC LF REJ
AC HF REJ
DC
2-6
of the trigger signal is blocked. Sig-
nals with low-frequency compo·
nents below
about 30 hertz are
attenuated. In general, AC
COUPLING can be used for most
applications. However, if
the signal
contains unwanted frequency com-
ponents or if the sweep is to be trig-
gered 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 posi-
tion depends upon the average volt-
age 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 dis-
play. In such cases, use DC
coupling.
In the AC LF REJ position, DC is
rejected and low-frequency trigger
signals below
about 30 kilohertz are
attenuated. Therefore, the sweep is
triggered only by the higher-
frequency components of the trig-
ger signal. This position is partic-
ularly useful for providing stable
triggering if the trigger signal con-
tains line-frequency components.
Also, the AC LF REJ position pro-
vides the best alternate mode verti-
cal displays
at fast sweep rates
when comparing
two or more un-
related signals (with dual-trace ver-
tical
or slaved triggering operation
for dual-vertical unit operation).
The AC HF REJ position passes all
low-frequency signals between
about 30 hertz and 50 kilohertz.
DC is rejected and signals outside,
the above range are attenuated.
When triggering from complex
waveforms, this position
is useful
for providing a stable display of the
low-frequency components.
DC COUPLING can be used to pro-
vide stable triggering with low-
frequency signals which would be
SOURCE
INT
LINE
EXT
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 con-
trol. When using internal triggering,
the setting of the vertical unit posi-
tion control affects the DC trig-
gering point.
The pushbuttons located below
the
SOU RCE title select the source of
the trigger signal which is con-
nected to the trigger circuits. The
selected source is indicated by a
lighted pushbutton.
In the I NT position of the
SOURCE switch, the trigger signal
is derived from the associated verti-
cal unit.
Further selection of the
internal trigger signal may be pro-
vided by the associated vertical unit
or indicator oscilloscope; see the
instruction manuals for these
instruments for information. For
most applications, the INT-
SOU
RCE position can be used.
However, some applications require
special triggering which cannot be
obtained
in the INT-SOURCE posi-
tion. In such cases LlNE- or EXT-
SOURCE must be used.
The LINE position
of the SOURCE
switch connects a sample of the
power·line voltage, to which the
indicator 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 compo-
nent in a complex waveform.
An external signal connected
to the
MAIN TRIG IN connector can be
used
to trigger the sweep in the
EXT-SOURCE position. The exter-
nal signal must be time-related
to
the displayed waveform for a stable
display. An external trigger signal
can be used to provide a triggered
display when
the internal signal is
®

EXT710
Sweep Controls
TIME/DIVor
DL'Y TIME
DLY'D SWEEP
MAIN VARIABLE
®
too low in amplitude for correct
triggering or contains signal compo-
nents on which it is not desired to
trigger. It is also useful when signal
t racing in amplifiers, phase-sh itt
networks, wave-shaping circuits,
etc. The signal from a single point
in the circuit under test can be con-
nected to the MAIN TRIG IN con-
nector through a probe or cable.
The sweep is then triggered by the
same signal at all times and allows
amplitude, time relationship or
waveshape changes of signals at
various points in the circuit to be
examined without resetting the
TRIGGERING controls.
Operation in the EXT 7 10 position
is the same as described for EXT
except that the external signal is
attenuated 10 times. Attenuation
of high-amplitude external trigger
signals is desirable to broaden the
range of the LEVEL/SLOPE
control.
The TIME/DIV or DL'Y TIME
switch provides 25 calibrated sweep
rates ranging from .05 ps/div to five
seconds/div. The MAIN VARI-
ABLE control must be in the CAL
position (locked in) and the X 10
MAG switch must be off (locked
in) for the indicated sweep rate.
The DL Y'D SWEEP switch provides
22 calibrated sweep rates ranging
from .05 ps to .5 second.
With DISPLAY MODE switch at
INTEN or DLY'D SWP, pullout on
the DL Y'D SWEEP switch and
rotate clockwise.
The MAIN VARIABLE control
incorporates a two-position switch
to determine whether the sweep
rate is calibrated or uncalibrated.
When the knob is in the inward
position, the MAIN VARIABLE is
inoperative and the sweep rate is
calibrated. When pressed and re-
leased, the MAIN VARIABLE knob
POSITION
SWPCAL
X10 MAG
Operating I nstructions-7B52
moves outward to activate the
MA IN V A R IABLE control for
uncalibrated rates. A calibrated rate
may be obtained at any position of
the MAIN VARIABLE control by
pressing in and locking. This feature
is useful when a specific uncali-
brated sweep rate has been ob-
tained and it is desired to switch
between this uncalibrated sweep
rate and a calibrated sweep rate.
The MAIN VARIABLE control
a Ilows the sweep rate in each
TIME/DIV switch position to be
reduced
to at least the sweep rate
of the next adjacent switch posi-
tion. This provides an overall un-
calibrated variable sweep range
from 50 ns/div to about 12.5
seconds/d ivision.
The POSITION control provides
horizontal positioning of the CRT
display.
The SWP CAL control is a screw-
driver
adjustment to set the ampli-
tude of the output sawtooth wave-
form.
The X10 MAG switch expands the
sweep ten times. The center divi-
sion
of the unmagnified display is
the portion visible on the CRT in
magnified form. Equivalent length
of the magnified sweep is 100
divisions.
Display Mode Controls
MAIN SWP
INTEN
The MAl N SWP selects sweep rates
as
determined by the TIME/DIV
switch.
This is one of the delayed sweep
functions. In INTEN mode, a por-
tion of the main sweep is intensi-
fied
during the time that delayed
sweep is in operation as determ ined
by DLY'D SWEEP. (MAIN FRAME
DELAYING MODE switch must be
in Independent position.)
2-7

Operating Instructions-7B52
DLY'D SWP
MIXED SWP
Delay Control
One of the delayed sweep func-
tions. In DLY'D SWP, the delayed
sweep is displayed at the end of
each delay period as determined by
the DL'Y TIME and DELAY TIME
MUL T control settings.
Main
and delayed sweep function.
In MIXED SWP position, the main
sweep is displayed on the CRT to
the point determined by the DE-
LAY TIME MUL T control, fol-
lowed
by the delayed sweep.
DELAY TIME MUL T The DELAY TIME MUL T (DTM)
provides variable delay
of 0 to 10
times the basic delay time selected
by the DL'Y TIME switch.
Dly'd Triggering Controls
DL Y'D LEVEL Two position switch actuated by
the LEVEL control. At the 'IN'
position, the LEVEL, SLOPE, COU-
PLING, and SOURCE switches are
inoperative. However, the DL Y'D
Sweep will run after Dry time as
determined by the DL'Y TIME
switch and setting of the DELAY
TIME MUL T control. In the 'OUT'
position, the LEVEL, SLOPE, COU-
PLING, and SOURCE switches are
operative. In this condition, the
Dly'd Sweep is triggerable.
SLOPE
COUPLING
2-8
Pushbutton switch to select either
positive
or negative slope of de-
layed trigger.
Pushbutton switch
to select either
AC (in) or DC (out) cOl!pling.
AC: Rejects
DC and attenuates AC
signals below about 20 Hz. Accepts
signals between 30 Hz and 100
MHz.
DC: Accepts all triggers between
DC and 100 MHz.
SOURCE
I nput Connectors
MAIN TRIG IN
AMPL IN
DLY'D TRIG IN
Amplifier
Pushbutton switch to select trigger
source.
I NT (in): Trigger signal obtained
from vertical unit.
EXT (out): Trigger signal obtained
from DL Y'D TRIG IN connector.
BNC input connector for external
triggering signal.
BNC
input connector for external
signal.
TIME/DIV or DL'Y TIME
switch must be in AMPL and the
MAIN TRIGGERING SOURCE
switch must be set for EXT or EXT
-;- 10.
BNC
input connector for exter-
nal
dly'd triggering signal. DL Y'D
LEVEL control must be out and
the
DL Y'D SOURCE switch must
be set for EXT.
In some applications, it is desirable
to display one signal vs. another
(X-Y) rather than against time. The
AMPL position of the TIME/DIV
or DL'Y TIME switch, in conjunc-
tion with a signal applied to the
AMPL IN connector, provides a
means of applying this signal to the
horizontal amplifier. The correct
MAIN TRIGGERING COUPLING
and SOURCE switches must be
selected to correspond to the the
signal applied to the AMPL IN
connector.
Two modes of external hoirzontal
operation are provided. When the
MAl N TR IGGERING SOURCE
switch is set to EXT or EXT -;- 10
positions, external horizontal de-
flection
is provided by the signal
applied
to the AMPL IN connector.
The signal coupling provided
by the
COUPLING switch can be used to
select or reject components of the
external horizontal signal.
®

General
The external horizontal deflection
factor is approximately 100 mV/div
in EXT and 1 V/div in EXT 7 10
positions of the SOURCE switch.
TEST SETUP CHART
Fig. 2-5 shows the front panel of the 7B52. This chart
can be reproduced and used as a gest setup record for
special measurements, applications, or produces; or it may
be used as a training aid for familiarization with this
instrument.
FIRST-TIME OPERATING INSTRUCTIONS
Sweep Calibration Check
Whenever the 7B52 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. Set the two
internal switches (see Installation this section), install the
7B52 into the plug-in compartment of an indicator oscillo-
scope, and allow at least 20 minutes warmup before pro-
ceeding with the following:
1. Connect a 1 kHz calibrator signal from the indicator
oscilloscope Cal Out connector via a 50 ohm BNC coaxial
cable
to the Input connector on the Vertical plug-in unit.
2.
Set the 7B52 TIME/DIV or DL'Y TIME switch to 1
ms, press the DISPLAY MODE MAIN SWP switch and press
the MAIN TRIGGERING AUTO, AC, and INT switches.
3.
Set the Vertical plug-in unit for a CRT display ampli-
tude of 2 to 4 divisions using DC coupling.
4. Rotate the LEVEL/SLOPE control for a triggered
display.
5. Check the CRT display for one complete cycle of
calibrator signal for each major division. (See Fig. 5-2 of
PERFORMANCE CHECK/CALIBRATION procedure.)
6. Adjust
SWP CAL (a front-panel screwdriver adjust-
ment) for exactly 1 complete cycle of calibrator signal for
each major division
on the CRT. Use only the center 8
graticule divisions.
First-Time Operation
Use the following first time operating procedure to be-
come acquainted with the 7B52. For a complete descrip-
®
Operating Instructions-7B52
tion of each control and connector, refer to CONTROLS
and CONNECTORS in this section.
1.
Complete parts 1 through 6 of the Sweep Calibration
Check.
2. Rotate the LEVEL/SLOPE control and note that the
CRT display is triggered on the positive slope of the display
with LEVEL/SLOPE on +, free-runs with LEVEL/SLOPE
control at top and bottom, and triggers on the negative
slope of the display with LEVEL/SLOPE on -. Also, check
that the TRIG'D lamp is on with triggered display.
3. Press the MAIN TRIGGERING NORM switch and
repeat part 2. Note that the CRT display is the same,
except when the LEVEL/SLOPE control is at the top and
at the bottom. At these two positions, there should be no
CRT display.
4. Press the MAIN TRIGGERING SINGLE SWP switch
and
rotate the LEVEL/SLOPE control 360
0•
Note that
there is no CRT display. Return the LEVEL/SLOPE con-
trol to 0/+.
5. Observing the CRT, press the MAIN TRIGGERING
READY switch. Note that there is one sweep each time the
READY switch is pressed.
6. Disconnect
the Calibrator signal from the Vertical
unit Input connector and press the MAIN TRIGGERING
READY switch.
Note that no sweep occurs, but the
READY switch light is on.
7. Observing the CRT, connect the Calibrator signal to
the Vertical unit Input connector. Note that one sweep
occurs and
at the end of the sweep the READY light is out.
8. Press the MAIN TRIGGERING AUTO switch and
rotate the. LEVEL/SLOPE control for a triggered display.
Rotate the POSITION control throughout its range. Note
that the display moves left and right across the CRT. Posi-
tion the start of the CRT display to the fifth vertical grati-
cule line (see Fig. 5-2
in PERFORMANCE CHECK/
CALIBRATION procedure).
9. Press in the X10 MAG switch and release. Note that
the display still starts near the fifth vertical line on the
CRT. Rotate the POSITION control to start the display on
the zero vertical line. Note that the display now consists of
one cycle of the Calibrator signal rather than 10 cycles. The
rate of the displayed signal is the resultant of dividing the
TIME/DIV switch setting by 10.
2-9

Operating Instruction s- 7B52
7852 TEST SET-UP CHART
NOTES:
2-10
MAIN TIUOGE'UNO
TNl' D0 ItDD I -.. .
LfVEL/a L (N01! 0
..
0
......
0
......
0
K
0
f©Jt~
, __ . -0 ."' J
POS ITION sw, 0
g '" -Z?~
O ~U
DELAY nME MUll
......
'"
0
-
0
on
0
on• •
0
DUAL TIME BASE
Fig. 2- 5. 7852 Test Setup Chill.t.
®

10. Lock the X10 MAG switch in (off).
11. Pull
out on the DL Y'D SWEEP switch and rotate
clockwise
to .1 ms. Press the DISPLAY MODE INTEN
switch. Note that a normal sweep (Main Sweep) with an
intensified portion (Dly'd Sweep) is displayed on the CRT.
Rotate the DELAY TIME MUL T (DTM) control and note
that the intensified portion of the display is controlled by
the DTM.
12. Release the DL Y'D LEVEL control and rotate it
from one end
of rotation to the other (it is assumed that
the DLY'D SLOPE, COUPLING, and SOURCE switches are
locked in: +, AC, and INT). Note that rotation of the
DL Y'D LEVEL control controls the triggering of the inten-
sified portion. Rotate
the DTM, and observe that one com-
plete revolution is required to move the intensified sweep
one division on the CRT
as compared with rotating the
DTM in part 11. Lock in the DL Y'D LEVEL control and
set
the DTM to 5-00.
13. Note
the starting position of the intensified portion.
It should start at the fifth vertical line on the CRT. Note
the length of the intensified p'ortion. It should be one divi-
sion,
or one complete cycle of Calibrator signal. The
starting position of the intensified sweep is determined by
the resultant of multiplying the DL'Y TIME switch setting
(same as TIME/DIV) and
the DTM dial setting. The length
of the intensified portion is determined by the setting of
the DL Y'D SWEEP switch setting.
14. Press
the DISPLAY MODE DLY'D SWP switch.
Note
that the CRT display now consists of one cycle of
Calibrator signal. This is also the intensified portion ob-
served
in part 13, and gives the same result as obtained in
part 9. The advantage of this mode over the one used in
part 9 is that any cycle of the Calibrator signal may be
viewed
in a magnified form by merely rotating the DTM
control. (Rotate the DTM to verify.) Return the DTM to
5-00.
®
Operating I nstructions-7B52
15. Press the DISPLAY MODE MIXED switch. Note
that the CRT display now consists of 5 complete cycles of
normal sweep (Main Sweep) and 1/2 cycle of Dly'd sweep.
Note also
that the 1/2 cycle starts at the fifth vertical line.
Under the above conditions, the first 5 cycles of Calibrator
signal are presented
at a rate of 1 ms (setting of TIME/DIV
switch), the Dly'd sweep starts 5 ms after the Main sweep
(DTM dial setting times the DL'Y TIME switch setting),
and
the Dly'd sweep is running at a rate of .1 ms (setting of
DLY'D SWEEP switch).
NOTE
See the Specification section for any deviation in the
settings listed above.
16. Rotate the DTM and note that, again, any portion
of the Calibrator signal may be viewed.
17. Disconnect
the Calibrator signal from the Vertical
Unit Input connector and reconnect it to the AMPL (MAIN
TRIG
IN) connector. Set the TIME/DIV or DL'Y TIME
and DLY'D SWEEP switches to AMPL and press the MAIN
TRIGGERING EXT switch. Note that the CRT display
now consists of two dots separately by approximately 4
major divisions.
18. Press
the MAIN TRIGGERING EXT + 10 switch.
Note
that the CRT display now consists of two horizontal
dots separately by approximately .4 divisions.
This completes
the First-Time Operation. It should be
remembered different signal inputs require different 7B52
control settings, but the procedure for viewing these signals
is essentially the same as given in this procedure.
2-11

7852
SECTION 3
CIRCUIT DESCRIPTION
Change information, if any,affecting this section willbe found at the rear of this manual.
Introduction
This section of the manual contains a description of the
circuitry used in the 7B52 Dual Time Base. The description
begins with a discussion of
the major circuit functions using
a simplified block diagram.
SIMPLIFIED BLOCK DIAGRAM
The Simplified Block Diagram, Fig. 3-1, shows inter-
connection of the basic circuit blocks in the 7B52. In some
cases, such as the Main Sweep Trigger, the block includes a
number
of separate circuits. The individual circuits are
discussed
in detail later in this section.
Main Sweep Mode
When the DISPLAY MODE switch is set to select MAIN
SWP, operation is as follows:
Main Sweep Trigger. This block includes circuitry for
selecting the trigger source, type of coupling, triggering
mode, and point
on the trigger signal where triggering
occurs. Also, regardless of the trigger signal shape or ampli-
tude (within specification), this circuitry provides a fast-
rise, uniform-amplitude pulse to the Main Sweep Start
Multi. Termination of the pulse (or gate) occurs at the rise
of Main Sweep Holdoff.
Main Sweep Start Multi. This circuit is activated by the
positive gate from the Main Sweep Trigger block. The out-
put signal coupled to the Main Sawtooth Generator is a
positive gate with
the same duration as the sweep. This gate
is also coupled to the Sweep Gate Out block. A negative-
going gate (coincident with the positive gate) is coupled to
the Delayed Sweep Lockout Multi and the Delayed Sweep
Start Control blocks.
Main Sawtooth Generator. The main sweep signal is
developed by the Main Sawtooth Generator. When a posi-
tive gate from the Main Sweep Start Multi is applied, a
sawtooth waveform
is generated. The sawtooth duration is
determined by the positive gate duration. Rate of change of
the sawtooth is set by Ct and Rt, selected by the TIME/
DIV switch.
®
Sweep Stop Comparator. One side of this comparator is
driven by the main sweep sawtooth signal, and the other
side
is set by the Main Swp Stop adjustment. When the
sawtooth waveform passes through the setting of the Main
Swp Stop adjustment, the output of the Sweep Stop Com-
parator switches to a positive level. This positive step is
applied to the Main Sweep Holdoff and via a small capaci-
tance to the Main Sweep Start Multi. This resets the Main
Sweep Start Multi so that it is ready to receive another
trigger signal.
Main Sweep Holdoff. This circuit develops a gate which
is used to prevent generation of a trigger signal until the
sweep circuits have stabilized after a sweep. The positive
step from
the Sweep Stop Comparator initiates the positive
holdoff gate. The duration of the holdoff gate is variable,
depending on the setting of the TIME/DIV switch. Holdoff
timing capacitors are separate from sweep timing capaci-
tors. Holdoff is longer for slower sweep rates.
Output from the Main Sweep Holdoff is coupled to the
Main Sweep Trigger and the Delayed Sweep Trigger blocks.
A trigger signal cannot be generated during the holdoff
interval. The holdoff serves
to reset the trigger circuits so
that they are ready to receive an input trigger signal after
holdoff.
Horiz Output. The Horiz Output block includes the Ext
Horiz Amp, Position Amp, Horiz Display Selector, and
Horiz
Out Amp circuits.
With
the DISPLAY MODE switch set to MAIN SWP, this
block selects the signal from the Main Sawtooth Generator,
amplifies the signal, and converts the single-ended input to
a push-pull output signal. A DC positioning level is also
applied to this block.
Delayed Sweep Mode
To generate the delayed sweep, the Main Sawtooth
Generator must first be gated on (see Main Sweep Mode).
Delay Pickoff. This circuit supplies a positive gate which
starts when
the main sawtooth signal passes through the
level selected by the DELAY TIME MUL T control. The
gate ends with
the main sawtooth signal. The output signal
is coupled to the Delay Gate Amp.
3-1