Tektronix 7B10 User manual

'HBktfDnix
COMMITTED TO EXCELLENCE
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
7B10
TIME BASE
OPERATORS
INSTRUCTION MANUAL
Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97077 Serial Number
070-2317-00
Prodlict Group 42 First Printing SEP 1978
Revised JUN 1985

Copyright -1978 Tektronix, Inc. All rights reserved.
Contents of this publication may not be reproduced in any
form \without the \written permission of Tektronix, Inc.
Products of Tektronix, Inc. and its subsidiaries are covered
by U.S. and foreign patents and/or pending patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and are
registered trademarks of Tektronix, Inc. TELEQUIPMENT
is aregistered trademark of Tektronix U.K. Limited.
Printed in U.S. A. Specification and price change privileges
are reserved.
INSTRUMENT SERIAL NUMBERS
Each instrument has aserial number on apanel insert, tag,
or stamped on the chassis. The first number or letter
designates the country of manufacture. The last five digits
of the serial number are assigned sequentially and are
unique to each instrument. Those manufactured in the
United States have six unique digits. The country of
manufacture is identified as follo\ws;
BOOOOOO Tektronix, Inc., Beaverton, Oregon, USA
100000 Tektronix Guernsey, Ltd., Channel Islands
200000 Tektronix United Kingdom, Ltd., London
300000 Sony/Tektronix, Japan
700000 Tektronix Holland, NV, Heerenveen,
The Netherlands

7B10 Operators
TABLE OF CONTENTS
PAGE
LIST OF ILLUSTRATIONS j|
LIST OF TABLES jj
OPERATORS SAFETY SUMMARY ijj
SECTION 1GENERAL INFORMATION
INTRODUCTION 1_1
OPERATORS MANUAL M
INSTRUCTION MANUAL 1-1
INSTALLATION M
INSTRUMENT PACKAGING 1-1
SPECIFICATION 1-2
STANDARD ACCESSORIES 1-4
SECTION 2OPERATING INSTRUCTIONS
CONTROLS, CONNECTORS AND INDICATORS 2-1
OPERATORS CHECKOUT 2-1
SETUP PROCEDURE 2-1
SWEEP FUNCTIONS 2-1
TRIGGERING FUNCTIONS 2-4
DETAILED OPERATING INFORMATION 2-4
TRIGGERING SWITCH LOGIC 2-4
TRIGGERING MODE 2-4
TRIGGERING COUPLING 2-5
TRIGGERING SOURCE 2-5
TRIGGERING SLOPE 2-7
TRIGGERING LEVEL 2-7
HORIZONTAL SWEEP RATES 2-7
TIME MEASUREMENTS 2-7
SWEEP MAGNIFICATION 2-8
VARIABLE HOLD OFF 2-8
MAINFRAME OPERATING MODES 2-8
APPLICATIONS 2-8
TIME-INTERVAL MEASUREMENTS 2-8
PERIOD AND FREQUENCY MEASUREMENTS 2-8
RISE-TIME AND FALL-TIME MEASUREMENTS 2-9
PULSE WIDTH MEASUREMENTS 2-10
DELAYED-SWEEP MEASUREMENTS 2-11
SECTION 3INSTRUMENT OPTIONS
CHANGE INFORMATION

7B10 Operators
LIST OF ILLUSTRATIONS
FIGURE
NO. page
Frontis-
piece 7B10 Features iv
1-1 Location of release latch 1-1
1-
27B10 dimensional drawing 1-4
2-
1Front-panel controls, connectors, and
indicators 2-2
2-2 Effect of LEVEL control and SLOPE switch on
crt display 2-6
2-3 Area of graticule used for most accurate time
measurements 2-7
2-4 Operation of sweep magnifier 2-8
2-5 Measuring the period and determing the
frequency of adisplayed waveform 2-9
2-6 Measuring the rise time and fall time of a
displayed waveform 2-10
2-7 Measuring the pulse width of adisplayed
waveform 2-10
LIST OF TABLES
TABLE
NO- PAGE
1-1 Electrical Characteristics 1-2
1-2 Environmental Characteristics 1-4
1-3 Physical Characteristics 1-4

7B10 Operators
OPERATORS SAFETY SUMMARY
The following general safety information applies to all operators and service personnel. Specific warnings and cautions
will be found throughout the manual where they apply and should be followed in each instance.
WARNING statements identify conditions or practices which could result in personal injury or loss of life.
CAUTION statements identify conditions or practices which could result in damage to the equipment or other property.
WARNING
GROUND THE INSTRUMENT
To reduce electrical-shock hazard, the mainframe (oscilloscope) chassis must be properly grounded. Refer to
the mainframe manual for grounding information.
DO NOT REMOVE INSTRUMENT COVERS
To avoid electric-shock hazard, operating personnel must not remove the protective instrument covers
Component replacement and internal adjustments must be made by qualified service personnel only.
DO NOT OPERATE IN EXPLOSIVE ATMOSPHERE
To avoid explosion, do not operate this instrument in an explosive atmosphere unless it has been certified for
such operation.
V
sCAUTION
PREVENT INSTRUMENT DAMAGE
Plug-in units should not be installed or removed without first turning the instrument power off, to prevent
instrument damage.

7B10 Operators
2416-1
7BIO Features
The 7B10 Time-Base unit provides calibrated sweep rates from .2 seconds to 2nanoseconds and triggering to 1
gigahertz for 7100-, 77CX3-, 7800-, and 79CXD-series oscilloscopes. AX10 Magnifier increases each sweep rate by a
factor of 10 and aVARIABLE TIME/DIV control provides continuously variable sweep rates between calibrated steps.
Variable hold off and alpha-numeric readout are provided. Also, when operating in the AUTO TRIGGERING MODE, a
bright baseline trace is displayed in the absence of atrigger signal. The 7B10 can be operated as an independent time
base or as adelayed-sweep unit with acompanion delaying time-base unit.
!V

Section 1—7B10 Operators
GENERAL INFORMATION
INTRODUCTION
OPERATORS MANUAL
The Operators Manual contains information necessary to
effectively operate the 7B10 Time Base and is divided
into three sections: Section 1provides abasic description
of the 7B10 with instrument specifications and
accessories, section 2contains operating information for
the instrument, Instrument Option information is located
in section 3of the manual.
INSTRUCTION MANUAL
The Instruction Manual provides both operating and
servicing information for the 7B10 Time Base. The
Instruction Manual is divided into nine sections.
Operating information is covered in the first two sections;
servicing information for use by qualified service
personnel is contained in the remaining seven sections
of the manual. Schematic diagrams are located at the
rear of the manual and can be unfolded for reference
while reading other parts of the manual. The reference
designators and symbols used on the schematics are
defined on the first page of the Diagrams and Circuit
Board Illustrations section. All abbreviations used in this
manual, with the exception of the parts list and
schematic diagrams, comply with the American National
Institute Y1. 1-1 972 publication. The parts lists are
computer printouts and use computer-supplied
abbreviations. Instrument Option information is located
in section 6of the Instruction Manual.
INSTALLATION
The time-base unit is designed to operate in the
horizontal plug-in compartment of the mainframe. This
instrument can also be installed in avertical plug-in
compartment to provide avertical sweep on the crt.
However, when used in this manner, there are no
internal triggering or retrace blanking provisions, and the
unit may not meet specifications.
To install the unit in aplug-in compartment, push it in
until it fits firmly into the compartment. The front panel
of the unit should be flush with the front panel of the
mainframe. Even though the gain of the mainframe is
standardized, the sweep calibration of the unit should be
checked when installed. The procedure for checking the
unit is given under Sweep Functions in the Operators
Checkout procedure in section 2.
To remove the unit, pull the release latch (see Fig. 1-1 )to
disengage the unit from the mainframe, and pull it out of
the plug-in compartment.
INSTRUMENT PACKAGING
If this instrument is to be shipped for long distances by
commercial means of transportation, it is recommended
that it be repackaged in the original manner for
maximum protection. The original shipping carton can be
saved and used for this purpose. If more information is
needed, contact your local Tektronix Field Office or
representative.
Fig. 1-1. Location of release latch.
1-1

General Information—7B10 Operators
SPECIFICATION
This instrument will meet the electrical characteristics listed in Table 1-1, following complete adjustment. The following
electrical characteristics are valid over the stated environmental range for instruments calibrated at an ambient
temperature of +20° to +30° C, and after atwenty-minute warmup unless otherwise noted.
TABLE 1-1
Electrical Characteristics
Characteristics Performance Requirement
SWEEP GENERATOR
Sweep Rates
Calibrated Range 0.2 s/div to 2ns/div in 25 steps, XI 0Magnifier extends
fastest calibrated sweep rate to 0.2 ns/div.
Variable Range Continuously variable uncalibrated sweep rate to at
least 2.5 times the calibrated sweep rate setting.
Sweep Accuracy^ with 7104, 7900 and
7800 Series Mainframes
+15° to +35° C
0.2 s/div to 10 ns/div
5ns/div and 2ns/div
Measured over center 8displayed divisions. ^SWP CAL
is adjusted at 1ms/div within the +20° to +30° Crange.
UNMAG MAG XI
0
2%
3%
3%
4%^
0° to +50° CDerate +15° to +35° Caccuracy by additional 1%.
Excluded Portions of Sweep
7104
7800, 7900 Series
None.
First 5ns.
Sweep Length At least 10.2 div.
MAG Registration 0.5 div or less from graticule center when changing
from MAG XI 0to MAG XI.
Position Range
POSITION Controls fully cw Start of sweep must be to right of graticule center at
1ms/div.
POSITION Controls fully ccw End of sweep must be left of graticule center at 1ms/div.
’Some mainframes limit fastest calibrated sweep rate.
^200 ps/div is measured over any 5divisions withir. the center 8divisions.
1-2 REV MAY 1981

General Information—7B10 Operators
TABLE 1-1 (CONT.)
Electrical Characteristics
Characteristic Performance Requirement
TRIGGERING
Trigger Sensitivity for Repetitive Signals Triggering Frequency Minimum Triggering
Range® Signal Required
Coupling Internal External
AC 30 Hz to 250 MHz 0.5 div 50 mV
250 MHz to 1GHz 1.5 div 150 mV
AC LF REJ'’ 50 kHz to 250 MHz 0.5 div 50 mV
250 MHz to 1GHz 1.5 div 150 mV
AC HF REJ 30 Hz to 30 kHz 0.5 div 50 mV
DC® DC to 250 MHz 0.5 div 50 mV
250 MHz to 1GHz 1.5 div 150 mV
Single Sweep Same as for Repetitive Triggering,
Internal Trigger Jitter 30 ps or less at 1GHz.
Operating in HF SYNC MODE
AC, AC LF REJ, or DC 250 MHz to 1GHz-0.3 div. Internal
75 mV External.
External Trigger Input
LEVEL RANGE At least ±3,5 V(checked on 1kHz sine wave).
Maximum Safe Input
1-Megohm Input 250 V(dc plus peak ac).
50-0hm Input 1Watt average.
Input Rand C
1-Megohm Input 1MQ within 5%, 20 pF within 10%.
50-0hm 50 Qwithin 2%.
Trigger Holdoff Time
Minimum Holdoff Setting
0.2 s/div to 50 ms/div 40 ms, or less
20 ms/div to 2^(s/div 2times TIME/DIV setting, or less
1yus/div to 2ns/div 2.0 IIS, or less
Maximum Holdoff Setting
0.2 s/div to 50 ms/div 400 ms, or greater
20 ms/div to 2yus/div 20 times TIME/DIV setting, or greater
1/fs/div to 0.5 yus/div 20.0 IIS, or greater
0.2 yUs/div to 2ns/div 6.0 ns, or greater
=The triggering frequency ranges given here are limited to the -3 dB frequency of the oscilloscope vertical system when operating in the Internal
mode.
^Will not trigger on sine waves at or below 60 Hz when amplitudes are less than 8divisions Internal or 3volts External.
The triggering frequency range for DC COUPLING applies to frequencies above 30 Hz when operating in the AUTO TRIGGERING MODE.
REV MAY 1981 1-3

General Information—7B10 Operators
TABLE 1-2
Environmental Characteristics
Refer to the Specification section of the associated mainframe manual.
TABLE 1-3
Physical Characteristics
Characteristic Information
Net Weight Approximately 2.6 pounds (1.2 kilogram).
Dimensions See Figure 1-2, dimensional drawing.
STANDARD ACCESSORIES
Operators Manual
Instruction Manual
OVERALL DIMENSIONS
(MEASURED AT MAXIMUM POINTS)
NOTE: TOP FIGURES IN INCHES
LOWER FIGURES IN CENTIMETERS
c1985-5
Fig. 1-2. 7B10 dimensional drawing.
1-4

Section 2—7B10 Operators
OPERATING INSTRUCTIONS
The 7B10 Time-Base unit operates with aTektronix 7100, 7700, 7800, or 7900-series oscilloscope mainframe and a7A-
series amplifier unit to form acomplete oscilloscope system. This section describes the operation of the front-panel
controls and connectors, provides detailed operating information, an operators checkout procedure, and basic
applications for this instrument.
CONTROLS, CONNECTORS, AND
INDICATORS
All controls, connectors, and indicators required for the
operation of the time-base unit are located on the front
panel. Figure 2-1 provides abrief description of all front-
panel controls, connectors, and indicators. More detailed
information is given in the Detailed Operating
Information.
OPERATORS CHECKOUT
The following procedures are provided for checking basic
instrument functions. Refer to the description of the
controls, connectors, and indicators while performing
this procedure. If performing the operators checkout
procedure reveals amalfunction or possible
maladjustment, first check the operation of the
associated plug-in units, then refer to the instruction
manual for maintenance and adjustment procedures.
SETUP PROCEDURE
1. Install the time-base unit being checked in the A
horizontal compartment of the mainframe.
2. Install an amplifier plug-in unit in avertical
compartment.
3. Set the time-base unit controls as follows:
SLOPE (+)
mode auto
COUPLING AC
SOURCE INT
POSITION Midrange
TIME/DIV 1ms
VARIABLE (CAL IN) Calibrated
(Pushed in)
HOLD OFF min (fully
counterclockwise)
mag XI (pushed in)
EXT TRIG IN OUT 50 O
4. Turn on the mainframe and allow at least 20 minutes
warmup.
5. Set the mainframe vertical and horizontal modes to
display the plug-in units used and adjust the intensity
and focus for awell-defined display. See the oscilloscope
mainframe and amplifier unit instruction manuals for
detailed operating instructions.
SWEEP FUNCTIONS
Normal Sweep
Perform the following procedure to obtain anormal
sweep and to demonstrate the function of the related
controls:
1.Perform the preceding Setup Procedure.
2. Connect a0.4-volt, 1-kilohertz signal from the
mainframe calibrator to the amplifier unit input.
3. Set the amplifier unit deflection factor for 4divisions
of display.
4. Adjust the LEVEL control for astable display,
5. Turn the POSITION control and note that the trace
moves horizontally.
6. Turn the FINE control and note that the display can be
precisely positioned horizontally.
7. Check the display for one complete cycle per division.
If necessary, adjust the front-panel SWP CAL screwdriver
adjustment for one complete cycle per division over the
center 8graticule divisions. Be sure that the timing of the
mainframe calibrator signal is accurate to within 025%
(+20° to +30° C).
8. Press to release the VARIABLE (CAL IN) control. Turn
the VARIABLE (CAL IN) control fully counterclockwise
and note that the displayed sweep rate changes to at
least the next slower TIME/DIV switch setting (i.e., 2
milliseconds/division). Press the VARIABLE (CAL IN)
knob in to the calibrated position.
Magnified Sweep
Perform the following procedure to obtain aXI
0
magnified display and to demonstrate the function of the
related controls:
1. Obtain aone cycle per division display as described in
the preceding Normal Sweep procedure.
2. Press to release the MAG button (XI 0). Note that the
unmagnified display within the center division of the
graticule is magnified to about 10 divisions.
3. Press the MAG button (XI ).
2-1

Operating Instructions—7B10 Operators

©©©©©©©
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Operating Instructions—7B10 Operators
TRIGGERING
LEVEL Control—Selects apoint on the trigger signal where triggering occurs.
SLOPE Switch Permits sweep to be triggered on negative or positive-going portions of the trigger signal.
READY Indicator—Illuminates when sweep circuit is armed (SINGLE SWP Mode).
TRIG'D Indicator—Illuminates when the display is triggered.
MODE Pushbuttons—Selects the operating mode of the triggering circuit.
COUPLING Pushbuttons— Selects the method of coupling the trigger signal to triggering circuit.
SOURCE Pushbuttons—Selects source of the trigger signal.
SWEEP
POSITION Control—Provides horizontal positioning.
FINE Control—Provides precise horizontal positioning.
MAG Pushbutton—Selects magnified X10 or unmagnified sweep.
HOLD OFF Control—Permits hold off period to bo varied to improve trigger stability on repetitive complex
waveforms.
TIME/DIV Selector—Selects the sweep rate of the sweep generator.
VARIABLE Control and CAL Switch—Selects calibrated or uncalibrated sweep rates. Uncalibrated sweep rates can
be continuously reduced to at least the sweep rate of the next slower position.
SWP CAL Adjustment—Compensates for basic timing changes duo to the differences in sensitivity of mainframes.
EXTERNAL TRIGGER INPUT
EXT TRIG Button—Selects input impedance.
EXT TRIG IN Connector—Connector (BNC type) provides input for external trigger signals.
2317-03
Fig. 2-1 (cont.). Front-panel controls, connectors, and indicators.

Operating Instructions—7B10 Operators
TRIGGERING FUNCTIONS
Perform the following procedure to obtain atriggered
sweep and to demonstrate the functions of the related
controls:
1. Obtain adisplay as described in the preceding Normal
Sweep procedure.
2. Turn the LEVEL control fully counterclockwise to
obtain afree-running sweep.
3. Slowly turn the HOLD OFF control clockwise and note
that astable display can be obtained at several positions
of the HOLD OFF control. Return the HOLD OFF control
to the fully counterclockwise (MIN) position.
NOTE
The HOLD OFF control varies the sweep hold-
off time which effectively changes the
repetition-rate of the horizontal sweep signal.
However, Its primary function is to obtain a
stable display of complex waveforms which
are otherwise difficult to trigger.
4. Press the AC, AC HF REJ, and DC COUPLING buttons
for both the +and -positions of the SLOPE switch and
check for astable display (LEVEL control may be
adjusted, if necessary, to obtain astable display).
5. Apply the 0.4-volt, 1kilohertz signal from the
mainframe calibrator to the amplifier unit and to the EXT
TRIG IN connector,
6. Press the EXT SOURCE button and set the amplifier
unit deflection factor for a4-division display.
7. Press the AC, AC HF REJ, and DC COUPLING buttons
for both the +and -positions of the SLOPE switch and
check for astable display (LEVEL control may be
adjusted, if necessary).
8. Press the AC COUPLING, INT SOURCE, and NORM
MODE buttons. Adjust the LEVEL control for astable
display.
9. Press the AUTO MODE button and adjust the LEVEL
control for afree-running display.
10. Press the NORM MODE button and check for no
display.
11.Adjust the LEVEL control for astable display and
press the SINGLE SWP MODE button.
12. Note that one trace occurs when the SINGLE SWP
button is pressed again.
13. Disconnect the mainframe calibrator signal from the
amplifier unit input and press the SINGLE SWP button.
Check for no display and note that the READY indicator is
lit.
14.
Note that one trace occurs and that the READY
indicator extinguishes when the mainframe calibrator
signal is reconnected to the amplifier unit input.
DETAILED OPERATING
INFORMATION
TRIGGERING SWITCH LOGIC
The MODE, COUPLING, and SOURCE push buttons of the
TRIGGERING switches are arranged in asequence which
places the most-often used position at the top of each
vertical row of push buttons. With this arrangement, a
stable display can usually be obtained by pressing the top
push buttons: AUTO, AC, INT. When an adequate trigger
signal is applied and the LEVEL control is correctly set,
the unit is triggered as indicated by the illuminated
TRIG'D light. If the TRIG'D light is not on, the LEVEL
control is either at asetting outside the range of the
trigger signal applied to this unit from the vertical unit,
the trigger signal amplitude is inadequate, or its
frequency is below the lower frequency limit of the AC
COUPLING switch position. If the desired display is not
obtained with these buttons pushed in, other selections
must be made. Refer to the following discussions or the
instruction manuals for the associated oscilloscope
mainframe and vertical unit(s) for more information.
TRIGGERING MODE
The MODE push-button switches select the mode in
which the sweep is triggered.
Auto
The AUTO MODE provides atriggered display with the
correct setting of the LEVEL control whenever an
adequate trigger signal is applied (see Trigger Level
discussions). The TRIG'D light indicates when the display
is triggered.
When the trigger repetition rate is outside the frequency
range selected by the COUPLING switch or the trigger
signal is inadequate, the sweep free runs at the rate
indicated by the TIME/DIV switch (TRIG'D indicator off).
An adequate trigger signal ends the free-running
condition and atriggered display is presented. The sweep
also free runs at the rate indicated by the TIME/DIV
switch when the LEVEL control is at asetting outside the
amplitude range of the trigger signal. This type of free-
running display is useful when it is desired to measure
only the peak-to-peak amplitude of asignal without
observing the waveshape (such as bandwidth
measurements),
HF Sync
The HF SYNC mode provides atriggered display with the
correct setting of the LEVEL control whenever ahigh
frequency, (100 MHz or higher) low amplitude signal is
applied. This mode is useful when the incoming signal is
too small to produce stable triggering in the AUTO or
NORMAL modes. The HF SYNC mode increases trigger
sensitivity and provides automatic trigger amplifier
centering for optimum triggering under these conditions.

Operating Instructions—7B10 Operators
Normal
The NORM MODE provides atriggered display with the
correct settings of the LEVEL control whenever an
adequate trigger signal is applied. The TRIG'D light
indicates when the display is triggered.
The normal trigger mode must be used to produce
triggered displays with trigger repetition rates below
about 30 hertz. When the TRIG'D light is off, no trace is
displayed.
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. Under these circumstances, a
stable display can often be obtained 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 asingle-sweep display of arepetitive signal,
first obtain the best possible display in the NORM MODE.
Then, without changing the other TRIGGERING controls,
press the SINGLE SWP RESET button. Asingle trace is
presented each time this button is pressed. Further
sweeps cannot be presented until the SINGLE SWP
RESET button is pressed again. If the displayed signal is a
complex waveform composed of varying amplitude
pulses, successive single-sweep displays may not start at
the same point on the waveform. To avoid confusion due
to the crt persistence, allow the display to disappear
before pressing the SINGLE SWP RESET button 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 by using
aviewing hood as recommended in the mainframe
instruction manual.
When using the single-sweep mode to photograph
waveforms, the graticule may have to 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
SINGLE SWP RESET button 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 signal triggers
the unit. Further information on photographic techniques
is given in the appropriate camera instruction manual.
TRIGGERING COUPLING
The TRIGGERING COUPLING push buttons select the
method in which the trigger signal is connected to the
trigger circuits. Each position permits selection or
rejection of some frequency components of the signal
which triggers the sweep.
AC
AC COUPLING blocks the dc component of the trigger
signal. 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 alow repetition rate or dc
level, one of the other COUPLING switch positions will
provide abetter display.
AC LF REJ
AC LF REJ COUPLING rejects dc, and attenuates low-
frequency trigger signals below about 50 kilohertz.
Therefore, the sweep is triggered only by the higher-
frequency components of the trigger signal. This position
is particularly useful for providing stable triggering if the
trigger signal contains line-frequency components. Also,
the AC LF REJ position provides the best alternate-mode
vertical displays at fast sweep rates when comparing two
or more unrelated signals.
AC HF REJ
AC HF REJ COUPLING passes all low-frequency signals
between about 30 hertz and 30 kilohertz. Dc is rejected
and signals outside the above range are attenuated.
When triggering from complex waveforms, this position
is useful to provide astable display of the low-frequency
components.
DC
DC COUPLING can be used to provide stable triggering
from low-frequency signals which would be attenuated
in the other COUPLING switch positions. DC COUPLING
can be used to trigger the sweep when the trigger signal
reaches adc level set by the LEVEL control. When using
internal triggering, the setting of the vertical unit position
control affects the triggering point.
TRIGGERING SOURCE
The TRIGGERING SOURCE push buttons select the
source of the trigger signal which is connected to the
trigger circuits.
Internal
The INT position connects the trigger signal from the
vertical plug-in unit. Further selection of the internal
trigger signal may be provided by the vertical plug-in unit
or by the mainframe; see the instruction manuals for
these instruments for more information. For most
applications, the internal source can be used. However,
some applications require special triggering which
cannot be obtained in the INT position. In such cases, the
LINE or EXT positions of the SOURCE switches must be
used.
Line
The LINE position connects asample of the power-line
voltage from the mainframe to the trigger circuit. Line
triggering is useful when the input signal is time-related
(multiple or submultiple) to the line frequency. It is also
useful for providing astable display of aline-frequency
component in acomplex waveform.

Operating Instructions—7B10 Operators
CRT DISPLAY
OBTAINED WITH
SLOPE SWITCH
SET TO POSITIVE (+)
TMG'O
LEVEL W
TRIG'O
LEVEL W
CRT DISPLAY
OBTAINED WITH
SLOPE SWITCH
SET TO NEGATIVE (-)
TRIG'O
S(L©(Pll
LEVEL W
Cl qfin-nn
Fig, 2-2. Effect of LEVEL control and SLOPE switch on crt display.

External
The EXT position connects the signal from the EXT TRIG
IN connector to the trigger circuit. The external signal
must be time-related to the displayed waveform for a
stable display. An external trigger signal can be used to
provide atriggered display when the internal signal is
either too low in amplitude for correct triggering or
contains signal components on which triggering is not
desired. It is also useful when signal tracing in
amplifiers, phase-shift networks, wave-shaping circuits,
etc. The signal from asingle point in the circuit can be
connected to the EXT TRIG IN connector through aprobe
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.
The IN 1Mn/OUT 50 Qpushbutton provides a
convenient means of selecting external-trigger input
impedance. Pushing the button in sets the amplifier input
impedance to 1MQ and the OUT position provides 50 Q
input impedance.
Operating Instructions—7B10 Operators
HORIZONTAL SWEEP RATES
The TIME/DIV switch provides calibrated sweep rates
from .2 seconds/division to 2nanosecond/division in a
1-2-5 sequence. The VARIABLE TIME/DIV control must
be in the calibrated position and the MAG switch set to
XI to obtain the sweep rate indicated by the TIME/DIV
switch. However, the mainframe crt readout will display
the appropriate sweep rate.
The VARIABLE TIME/DIV control includes atwo-position
switch to determine if the sweep rate is calibrated, or
uncalibrated. When the VARIABLE control is pressed in,
it is inoperative and the sweep rate is calibrated. When
pressed and released outward, the VARIABLE control is
activated for uncalibrated sweep rates, to at least the
sweep rate of the next slower position.
Acalibrated sweep rate can be obtained in any position
of the VARIABLE control by pressing in the VARIABLE
control. This feature is particularly useful when aspecific
uncalibrated sweep rate has been obtained and it is
desired to switch between calibrated and uncalibrated
displays.
TRIGGERING SLOPE TIME MEASUREMENTS
The TRIGGERING SLOPE switch (concentric with the
TRIGGERING LEVEL control) determines whether the
trigger circuit responds on the positive- or negative-going
portion of the trigger signal. When the SLOPE switch is
in the (+) (positive-going) position, display starts on the
positive-going portion of the waveform (see Figure 2-2).
When several cycles of asignal appear on the display the
setting of the SLOPE switch is often unimportant.
However, if only acertain portion of acycle is to be
displayed, correct setting of the SLOPE switch is
important to provide adisplay that starts on the desired
slope of the input signal.
TRIGGERING LEVEL
The TRIGGERING LEVEL control determines the voltage
level on the trigger signal at which the sweep is
triggered. When the LEVEL control is set in the +region,
the trigger circuit responds at amore positive point on
the trigger signal. When the LEVEL control is set in the -
region, the trigger circuit responds at amore negative
point on the trigger signal. Figure 2-2 illustrates this
effect with different settings of the SLOPE switch.
To set the LEVEL control, first select the TRIGGERING
MODE, COUPLING, SOURCE, and SLOPE. Then set the
LEVEL control fully counterclockwise and rotate it
clockwise until the display starts at the desired point.
In the HF SYNC mode, the trigger LEVEL control varies
the sensitivity of the Trigger Generator. The LEVEL
control is set to provide astable display.
When making time measurements from the graticule, the
area between the second and tenth vertical lines of the
graticule provides the most linear time measurements
(see Fig. 2-3). Position the start of the timing area to the
second vertical line and adjust the TIME/DIV switch so
the end of the timing area falls between the second and
tenth vertical lines.
SECOND-VERTICAL TENTH-VERTICAL
LINE line
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Fig. 2-3. Area of graticule used for most accurate time
measurements.
2-7

Operating Instructions—7B10 Operators
SWEEP MAGNIFICATION
The sweep magnifier can be used to expand the display
be afactor of 10. The center division of the unmagnified
display is the portion visible on the crt in the magnified
form (see Fig. 2-4). The equivalent length of the
magnified sweep is more than 100 divisions; any 10
division portion can be viewed by adjusting the POSITION
and FINE POSITION controls to bring the desired portion
into the viewing area. When the MAG switch is set to
XI 0(OUT) the equivalent magnified sweep rate can be
determined by dividing the TIME/DIV setting by 10; the
equivalent magnified sweep rate is displayed on the crt
readout.
VARIABLE HOLD OFF
The HOLD OFF control improves triggering stability on
repetitive complex waveforms by effectively changing the
repetition rate of the horizontal sweep signal. The HOLD
OFF control should normally be set to its minimum
setting. When astable display cannot be obtained with
the TRIGGERING LEVEL control, the HOLD OFF control
can be carried for an improved display. If astable
display cannot be obtained at any setting of the LEVEL
and HOLD OFF controls, check the TRIGGERING
COUPLING and source switch settings.
1
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Fig. 2-4. Operation of sweep magnifier.
MAINFRAME OPERATING MODES
The time-base unit can be operated either as an
independent time base in any Tektronix 7100-, 7700-,
7800-, or 7900-series oscilloscope mainframes, or as a
delayed-sweep unit in those mainframes that have two
horizontal compartments. Acompanion delaying time
base unit is required for delayed-sweep operation. Refer
to the delaying time-base unit instruction manual for
additional information.
APPLICATIONS
The following information describes procedures and
techniques for making basic time measurements with the
time-base unit installed in aTektronix 7100, 7700, 7600,
or 7900-series oscilloscope. These procedures provide
enough detail to enable the operator to adapt them to
other related time measurements. Contact your Tektronix
Field Office or representative for assistance in making
measurements that are not described in this manual.
TIME-INTERVAL MEASUREMENTS
Since time is afunction of the sweep rate and the
horizontal distance (in divisions) that the sweep travels
across the graticule in acalibrated-sweep oscilloscope
system, the time interval between any two points on a
waveform can be accurately measured. The following
procedures provide methods to measure some of the
more common time-related definable characteristics of a
waveform such as period, frequency, rise time, fall time,
and pulse width. The procedure for each of these
measurements is essentially the same, except for the
points between which the measurements are made. The
time interval between any two selected points on a
displayed waveform can be measured with basically the
same technique.
PERIOD AND FREQUENCY MEASUREMENTS
Perform the following procedure to measure the period
and determine the frequency of adisplayed waveform:
1. Install the time-base unit in amainframe horizontal
compartment (either Aor Bhorizontal in afour-
compartment mainframe).
2. Connect the signal to be measured to the vertical unit
input.
3. Set the mainframe horizontal- and vertical-mode
switches to display the time base and vertical units.
(Check that the time base VARIABLE (CAL IN) control is
pushed in and the HOLD OFF control is in the MIN
position.)
4. Set the TRIGGERING switches and LEVEL control for a
stable display (see General Operating Information for
selecting proper triggering).

Operating Instructions—7B10 Operators
Fig. 2-5. Measuring the period and determining the frequency
of adisplayed waveform.
5. Set the vertical deflection factor and position control
for about a5-division display, vertically centered on the
graticule.
6. Set the TIME/DIV switch and POSITION controls for a
complete cycle displayed within the center 8graticule
divisions as shown in Figure 2-5.
7. Measure the horizontal distance in divisions over 1
complete cycle of the displayed waveform.
Using the formula:
1
Frequency =—\
—
period
Substituting values:
1
Frequency =—=1.43 kilohertz
0.7 ms
RISE-TIME AND FALL-TIME MEASUREMENTS
Perform the following procedure to measure the rise time
and fall time of adisplayed waveform:
1. Install the time-base unit in amainframe horizontal
compartment (either Aor Bhorizontal in afour-
compartment mainframe).
2. Connect the signal to be measured to the vertical unit
input.
3. Set the mainframe horizontal- and vertical-mode
switches to display the time base and the vertical unit.
(Check that the time base VARIABLE (CAL IN) control is
pushed in and the HOLD OFF control is in the MIN
position.)
4. Set the TRIGGERING switches and LEVEL control for a
stable display (see General Operating Information for
selecting proper triggering).
5. Set the vertical deflection factor and position controls
for avertically-centered display with an exact number of
divisions of amplitude.
8.
Multiply the horizontal distance measured in Step 7by
the TIME/DIV switch setting. (Divide the answer by 10 if
sweep magnification is used.)
Example: Assume that the horizontal distance over 1
complete cycle is 7divisions, and the TIME/DIV switch
setting is .1 ms (see Fig. 2-5).
Using the formula:
Horizontal TIME/DIV
Period =distance xsetting
Magnification
Substituting values:
Period =-^=0.7 millisecond
1
9.
Determine the frequency of the displayed waveform
obtained in steps 1through 8by taking the reciprocal of the
period of 1cycle.
Example: Assume that the period of the displayed
waveform is 0.7 millisecond.
6. Set the TIME/DIV switch and POSITION control to
display the rising or falling portion of the waveform
within the center 8graticule divisions as shown in Figure
2-6 (see General Operating Information in this section for
discussion of timing measurement accuracy).
7. Determine rise time or fall time by measuring the
horizontal distance in divisions between the point on the
rising or falling portion of the waveform that is 10% and
the point that is 90% of the total display amplitude (see
Fig. 2-6).
NOTE
The left edge of the oscilloscope graticule is
scribed with 0, 10, 90, and 100% lines for
convenience when measuring rise time or fall
time. To use this feature, adjust the vertical
deflection factor and position controls to fit
the display between the 0and 100% graticule
lines. Then measure the horizontal distance
between the points where the waveform
crosses the 10%, and 90%, graticule lines.
8. Multiply the horizontal distance measured in step 7by
the TIME/DIV switch setting. (Divide the answer by 10 if
sweep magnification is used.)
@2-9

Operating Instructions—7B10 Operators
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PULSE WIDTH MEASUREMENTS
Perform the following procedure to measure the pulse
width of adisplayed waveform:
1. Install the time-base unit in amainframe horizontal
compartment (either Aor Bhorizontal in afour-
compartment mainframe).
2. Connect the signal to be measured to the vertical unit
input.
3. Set the mainframe horizontal- and vertical-mode
switches to display the time base and vertical unit.
(Check that the time base VARIABLE (CAL IN) control is
pushed in and the HOLD OFF control is in the MIN
position.)
4. Set the TRIGGERING switches and LEVEL control for a
stable display (see General Operating information for
selecting proper triggering).
5. Set the vertical deflection factor and position control
for about a5-division pulse vertically centered on the
graticule.
6. Set the TIME/DIV switch and POSITION control for 1
complete pulse displayed within the center 8graticule
divisions as shown in Figure 2-7.
7. Measure the horizontal distance in divisions between
the 50% amplitude points of the displayed pulse (see Fig.
2-7.).
8. Multiply the horizontal distance measured in step 7by
the TIME/DIV switch setting. (Divide the answer by 10 if
sweep magnification is used.)
Fig. 2-6. Measuring the rise time and fall time of adisplayed
waveform.
Example: Assume that the horizontal distance between
the 50% amplitude points is 3divisions, and the
TIME/DIV switch setting is .1 fjs (see Fig. 2-6).
Using the formula:
Horizontal distance TIME/DIV
Rise Time =(divisions) xsetting
Magnification
Substituting values:
_2.5 X0.1 /is
Rise Time =^=0.25 microsecond
PULSE WIDTH
Fig. 2-7. Measuring the pulse width of adisplayed waveform.