Tektronix 71310 User manual

7eI~ronbc
Tektronix, Inc .
P
.O .
Box 500
Beaverton, Oregon

97077

Serial Number
COMMITTED TO EXCELLENCE
PLEASE CHECK
FOR CHANGE INFORMATION
ATTHE REAR OF THIS
MANUAL .
71310
TIME BASE
OPERATORS
INSTRUCTION MANUAL
070-2317-00

First Printing SEP 1978
Product Group 42

Revised OCT 1983

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 a registered
trademark of Tektronix U .K . Limited .
Printed in U .S .A . Specification and price change privileges
are reserved .
INSTRUMENT SERIAL NUMBERS
Each instrument has a serial numberon a panel 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 follows :
13000000

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

TABLE OF CONTENTS
PAGE
LIST OF
ILLUSTRATIONS
....................... . . . . . . . . . . . ii
LIST OFTABLES ......................... . . . . . . ...... . . . . . ii
OPERATORS SAFETY SUMMARY .................. . . . . . . .
. iii
SECTION 1 GENERAL
INFORMATION
INTRODUCTION . . ....................................
1-1
OPERATORS MANUAL .............................
1-1
INSTRUCTION MANUAL .......................... . .
1-1
INSTALLATION ... . . . . . . .............................. 1-1
INSTRUMENTPACKAGING ............................ 1-1
SPECIFICATION . . ... . . . . . . ........................... 1-2
STANDARD
ACCESSORIES ........................... 1-4
SECTION 2 OPERATING INSTRUCTIONS
CONTROLS, CONNECTORS AND INDICATORS .......... 2-1
OPERATORS CHECKOUT ............................. 2-1
SETUP
PROCEDURE
...............................
2-1
SWEEP FUNCTIONS .......................... . . . . . 2-1
TRIGGERING
FUNCTIONS ..........................
2-4
DETAILED OPERATINGINFORMATION
............ . . . . . 2-4
TRIGGERING SWITCH LOGIC
..................... . . 2-4
TRIGGERING MODE ....................... . . . . . . . . 2-4
TRIGGERING COUPLING ......................... . . 2-5
TRIGGERING SOURCE ........................... . . 2-5
TRIGGERING SLOPE ....................... . . . . . . . . 2-7
TRIGGERINGLEVEL ............................. . . 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 3 INSTRUMENT OPTIONS
CHANGE INFORMATION

713110 Operators
LIST
OF ILLUSTRATIONS
FIGURE
NO .

PAGE
Frontis-
piece

71310 Features ................................. . .
iv
1-1

Location of release latch ........................
1-1
1-2

71310 dimensional drawing .....................
1-4
2-1

Front-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 a displayed 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 a displayed
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

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 .
GROUND THE INSTRUMENT
DO NOT REMOVE INSTRUMENT
COVERS
WARNING
7B10
Operators
To reduce
electrical-shock
hazard, the mainframe (oscilloscope)
chassis must be properly grounded . Refer to
the mainframe manual for grounding
information .
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 .
PREVENT INSTRUMENT DAMAGE
Plug-in units should not be installed or removed without first turning the instrument power off,
to
prevent
instrument damage .

71310 Operators
71310 Features
2416-1
The 71310 Time-Base unit
provides calibrated sweep rates from
.2 seconds to 2
nanoseconds and triggering to 1
gigahertz for 7100-, 7700-, 7800-,
and
7900-series oscilloscopes .
A
X10
Magnifier increases each sweep rate by a
factor of 10 and a
VARIABLE 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 a trigger signal . The 71310 can be operated as an independent time
base or as a
delayed-sweep unit with a companion delaying time-base unit .

INTRODUCTION
OPERATORS MANUAL
GENERAL INFORMATION
The Operators Manual contains information
necessary to
effectively operate the 71310 Time Base and is divided
into three sections : Section 1 provides a basic description
of the 71310 with instrument specifications and
accessories, section
2 contains operating information for
the instrument, Instrument Option
information is located
in section 3 of the manual .
INSTRUCTION MANUAL
The Instruction Manual
provides both operating and
servicing information for the 71310
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 .1-1972 publication . The
parts lists are
computer printouts and use computer-supplied
abbreviations . Instrument Option information is located
in section
6 of 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 a vertical plug-in
compartment to provide a vertical 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 a plug-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 .
Section 1-71310 Operators
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 .
INSTRUMENTPACKAGING
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 .

General
Information-71310 Operators
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 a twenty-minute warmup unless otherwise noted .
SPECIFICATION
TABLE 1-1
Electrical Characteristics
Characteristics

I

Performance
Requirement
SWEEP GENERATOR
'Some
mainframes limit fastest calibrated sweep rate .
2 200 ps/div is measured over any 5 divisions within the center 8 divisions .
REV MAY 1981
Sweep
Rates
Calibrated Range 0 .2 s/div to 2 ns/div in 25 steps .
X10 Magnifier 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 Measured over center 8 displayed
divisions
. 2 SWP CAL
7800 Series Mainframes is adjusted at 1 ms/div
within the +20
°
to +30 ° C range .
+15° to +35°
C UNMAG MAG X10
0 .2
s/div to 10 ns/div 2% 3%
5
ns/div and 2 ns/div 3% 4% 2
0°
to +50° C Derate +15° to +35° C accuracy by
additional 1% .
Excluded Portions of Sweep
7104 None .
7800, 7900 Series
First
5 ns .
Sweep Length
At least 10 .2 div .
MAG Registration
0 .5 div or less from graticule center when changing
from MAG X10 to MAG X1 .
Position Range
POSITION
Controls fully cw Start of sweep must be to
right
of
graticule center at
1 ms/div .
POSITION Controls fully ccw End of
sweep
must be
left
of
graticule center at 1 ms/div .

REV MAY
1981
Characteristic
TABLE 1-1 (CONT .)
Electrical Characteristics
TRIGGERING
General Information-7B10 Operators
Performance Requirement
'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 8 divisions Internal or 3 volts External .
5 The
triggering frequency range for DC COUPLING
applies to frequencies above 30 Hzwhen operating in the AUTO TRIGGERING MODE .
Trigger Sensitivity for Repetitive Signals Triggering Frequency Minimum Triggering
Range 3 Signal Required
Coupling Internal External
AC 30 Hz to 250 MHz 0 .5 div 50 mV
250 MHz to 1 GHz 1 .5 div 150 mV
AC LF REJ ° 50 kHz to 250 MHz 0 .5 div 50 mV
250 MHz to 1 GHz 1 .5 div 150 mV
AC
HF REJ
30 Hz to 30 kHz 0 .5 div 50 mV
DC 5 DC to 250 MHz 0 .5 div 50 mV
250 MHz
to
1 GHz
1 .5
div
150 mV
Single Sweep Same as for Repetitive Triggering
.
Internal Trigger Jitter 30 ps or less at 1 GHz .
Operating in HF SYNC MODE
AC, AC LF REJ, or DC 250 MHz to 1 GHz-0
.3 div . Internal
75 mV External .
External Trigger Input
LEVEL RANGE
At least ±3 .5 V
(checked on 1 kHz sine wave) .
Maximum Safe
Input
1-Megohm Input 250 V (dc plus peak ac) .
50-Ohm Input 1 Watt average .
Input R and C
1-Megohm Input
1
Mfg within 5%, 20 pF within 10% .
50-Ohm 50 0 within 2% .
Trigger Holdoff Time
Minimum Holdoff Setting
0
.2 s/div
to 50 ms/div 40
ms, or less
20
ms/div to 2 ps/div
2 times TIME/DIV setting, or less
1 ps/div to 2 ns/div 2 .0 ps, or less
Maximum Holdoff Setting
0 .2 s/div to 50 ms/div
400 ms, or greater
20 ms/div to 2 ps/div 20
times TIME/DIV setting, or greater
1 ps/div to 0 .5
ps/div 20
.0 ps, or greater
0 .2
ps/div to 2 ns/div 6
.0 /is, or greater

General Information-7B10 Operators
Net Weight
TABLE 1-2
Environmental
Characteristics
Refer
to the Specification section of the
associated mainframe manual .
TABLE 1-3
Physical Characteristics
Characteristic

I

Information
Approximately 2 .6 pounds (1 .2 kilogram) .
Dimensions

See Figure 1-2, dimensional drawing .
STANDARD ACCESSORIES
1 ea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... . .
. . . . Operators Manual
1 ea . . . . . . . . . . . . .... . . . .
. . . . . .. .
.
.. .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Instruction Manual
a o 0
000
a R0
0 t]
5.0
(12 .7)
NOTE :

TOPFIGURES IN INCHES
LOWER FIGURES IN CENTIMETERS
OVERALL DIMENSIONS
(MEASURED
AT MAXIMUM POINTS)
1 .2
~
(3 .0)

(31 .7)
14 .5
(36 .9)
(2 .21
r
F
C 1985-5
Fig . 1-2 . 71310
dimensional drawing .

OPERATING
INSTRUCTIONS
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 a brief 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 a malfunction 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 a vertical
compartment .
3 . Set the time-base unit controls as follows
:
SLOPE . . . . . . . . . . . . . . . . . .. .
. . . . . . . . . . . . . . . . . . (+)
MODE
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AUTO
COUPLING
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AC
SOURCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INT
POSITION
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Midrange
TIME/DIV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 ms
VARIABLE (CAL IN) . . . . . . . . . . . . . . . . . . .
Calibrated
(Pushed
in)
HOLD OFF . . . . . . . . . . . . . . . . . . . . . . . . . . . MIN
(fully
counterclockwise)
MAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . X1 (pushed in)
EXT
TRIG IN . . . . . . . . . . . . . . . . . . . . . . . . OUT
50
0
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 a well-defined display . See the
oscilloscope
mainframe and amplifier unit instruction
manuals for
detailed operating instructions .
SWEEP FUNCTIONS
Normal Sweep
Magnified Sweep
3 . Press the MAG button (X1) .
Section 2-71310 Operators
The 71310 Time-Base unit operates with a Tektronix 7100,
7700, 7800, or 7900-series oscilloscope mainframe and a 7A-
series
amplifier
unit to form a complete 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
.
Perform the following procedure
to obtain a normal
sweep and to demonstrate the function
of the related
controls :
1
.
Perform the preceding Setup Procedure .
2 . Connect a 0
.4-volt,
1-kilohertz signal from the
mainframe
calibrator to the amplifier unit input .
3 . Set the amplifier unit deflection
factor for 4 divisions
of display .
4 . Adjust the LEVEL control for a stable 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 8 graticule divisions
. Be sure that the timing of the
mainframe calibrator signal
is accurate to within 0 .25%
(+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 .
Perform
the
following
procedure to obtain a X10
magnified display and to
demonstrate the function of the
related controls :
1 . Obtain a one cycle per division
display as described in
the preceding Normal Sweep procedure .
2 . Press to release the MAG
button (X10) . Note that the
unmagnified display within the center
division of the
graticule is magnified to about
10 divisions .

Operating
Instructions-781 Q Operators
2-2
Fig .
2-1
.
Front-panel controls, connectors, and indicators
.

O LEVEL Control-Selects a point on the trigger signal where triggering
occurs .
O
SLOPE Switch-Permits sweep to be triggered on negative or positive-going
portions of the trigger signal .
O
READY Indicator-Illuminates when sweep circuit is armed (SINGLE SWP Mode) .
O TRIG'D Indicator-Illuminates when
the display is triggered .
O
MODE Pushbuttons-Selects the operating
mode of the triggering circuit .
O
COUPLING Pushbuttons-Selects the method
of coupling the trigger signal to triggering circuit .
O]

SOURCE Pushbuttons-Selects source of the trigger signal .
O POSITION Control-Provides horizontal positioning .
O
FINE Control-Provides precise horizontal positioning .
TRIGGERING
SWEEP
MAG Pushbutton-Selects magnified X10 or unmagnified sweep .
HOLD OFF Control-Permits
hold off period to be varied to improve trigger
stability on repetitive complex
waveforms
.
~Z
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
due to the differences in sensitivity of mainframes .
EXT TRIG Button-Selects
input impedance .
EXTERNAL TRIGGER INPUT
EXT TRIG IN Connector-Connector (BNC
type) provides input for external trigger signals
.
Fig . 2-1 (cont .)
.
Front-panel controls, connectors, and indicators .
Operating Instructions-7810 Operators
2317-03
2-3

Operating Instructions-7810 Operators
TRIGGERING FUNCTIONS
Perform the following procedure
to obtain a triggered
sweep and to demonstrate the functions
of the related
controls :
1 . Obtain a display as described in the preceding Normal
Sweep procedure .
2 . Turn the LEVEL control fully counterclockwise
to
obtain a free-running
sweep .
3 . Slowly turn the HOLD OFF control clockwise
and note
that a stable 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
a
stable
display (LEVEL control may be
adjusted, if necessary,
to obtain a stable display) .
5 . Apply the 0 .4=volt, 1 kilohertz 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 a 4-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 a stable display (LEVEL control may be
adjusted,
if
necessary)
.
8 . Press the AC COUPLING, INT
SOURCE, and NORM
MODE buttons . Adjust the LEVEL control for
a stable
display .
9
.
Press the AUTO MODE button and
adjust the LEVEL
control for a free-running display .
10 . Press the NORMMODE button and check for no
display .
11 . Adjust the LEVEL
control
for
a stable 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 .
2-
4
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
TRIGGERINGSWITCH LOGIC
The MODE, COUPLING, and SOURCE push buttons
of the
TRIGGERING switches are arranged in a sequence 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
a setting 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 a triggered 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 a triggered display is presented . The
sweep
also free runs at the rate indicated by the TIME/DIV
switch when the LEVEL control is at a setting 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 a signal without
observingthe waveshape (such as bandwidth
measurements) .
HF Sync
The HF SYNC mode provides a triggered display with the
correct setting of the LEVEL control whenever a high
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 underthese conditions
.

Normal
The NORMMODE provides a triggered
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 a single-sweep display of a repetitive signal,
first obtain the best possible display in the NORM MODE .
Then, without changing the other
TRIGGERING controls,
press the SINGLE SWP RESET button .
A single 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 do component of the trigger
signal .
Signals with low-frequency components
below
about 30 hertz are
attenuated . In general, AC COUPLING
AC LF REJ
AC
HF REJ
DC
TRIGGERING SOURCE
Internal
Line
Operating Instructions-7B10 Operators
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 do
level, one of the other
COUPLING switch positions will
provide a better display .
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 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 a stable display of the
low-frequency
components .
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 a do level set by the LEVEL control .
When using
internal triggering, the setting of the vertical unit
position
control affects the triggering point .
The TRIGGERING SOURCE push
buttons select the
source of the trigger signal which
is connected to the
trigger circuits .
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 .
The LINE position connects a
sample 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 a stable display of a
line-frequency
component in
a complex waveform .
2- 5

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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 a triggered display when the internal signal
is
either too low in amplitude for correct triggering or
contains signal componentson which triggering is not
desired . It is also useful when signal tracing in
amplifiers, phase-shift networks, wave-shaping circuits,
etc . The signal from a single point in the circuit can be
connected to the
EXT TRIG
IN connector through a probe
or cable . The sweep is then triggered by the same signal
at
all
times
and
allows
amplitude,
time relationship, or
waveshape changes of signals at various
points in the
circuit to be examined without resetting
the TRIGGERING
controls .
The IN 1
Mfg/OUT
50
f2
pushbutton provides a
convenient means of
selecting
external-trigger input
impedance . Pushing the button in sets the amplifier input
impedance to
1 Mfgand the
OUT position provides 50 f2
input
impedance .
TRIGGERING SLOPE
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 a signal appear
on the display the
setting
of
the SLOPE switch
is often unimportant .
However, if only a certain portion of a
cycle is to be
displayed, correct setting
of
the
SLOPE switch is
important to provide a display 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 a more positive point on
the
trigger
signal . When the LEVEL control is set in the -
region, the trigger circuit
responds at a more 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 a stable display .
TIME MEASUREMENTS
Operating
Instructions-71310 Operators
HORIZONTAL SWEEP RATES
The TIME/DIV switch provides calibrated sweep
rates
from .2 seconds/division to 2 nanosecond/division
in a
1-2-5
sequence . The VARIABLE TIME/DIV control must
be in the calibrated position and the MAG switch
set to
X1 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 a
two-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 .
A calibrated sweep rate can be obtained in any
position
of the
VARIABLE
control by pressing in the VARIABLE
control
.
This
feature
is particularly useful when a specific
uncalibrated
sweep rate has been obtained and it is
desired to switch between
calibrated and uncalibrated
displays
.
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-71310 Operators
SWEEP MAGNIFICATION
The sweep magnifier can be used to
expand
the display
be a factor 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
X10 (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 a stable display cannot be obtained with
the TRIGGERING LEVEL control, the HOLD OFF control
can be carried for an improved display . If a stable
display cannot be obtained at
any
setting of the LEVEL
and HOLD OFF controls, check the TRIGGERING
COUPLING and source switch settings .
(SPLAY
AY
c 1960-16
2-8
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
.
A companion
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
a
Tektronix 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 a function of the sweep rate and the
horizontal distance (in divisions) that the sweep travels
across the graticule in a calibrated-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 a displayed waveform :
1 . Install the time-base unit in a mainframe horizontal
compartment (either A or B horizontal in a four-
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) .
I
UNMAGNIFIED
HERNMENNUM
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Fig . 2-5 . Measuring the period and determining the frequency
of a displayed waveform .
5 . Set the vertical deflection factor and
position control
for about a 5-division display, vertically centered
on the
graticule .
6 . Set the TIME/DIV switch and POSITION controls for a
complete cycle displayed within the center 8 graticule
divisions as shown in Figure 2-5 .
7 . Measure the horizontal distance in divisions over 1
complete cycle of the displayed waveform .
8 . Multiply the horizontal distance
measured in Step 7 by
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 7 divisions, and the
TIME/DIV switch
setting is .1 ms (see Fig . 2-5) .
Using the formula :
Horizontal TIME/DIV
Period = distance

x setting
Substituting values :
Magnification
Period
=
7
x0
.1
ms
=
0
.
7 millisecond
1
9 . Determine the frequency of the displayed
waveform
obtained in steps 1 through 8 by taking the reciprocal of
the
period of 1 cycle .
Example : Assume that
the period of the displayed
waveform is 0 .7 millisecond .
Using the formula :
Frequency =

1
Substituting values :
Frequency =
Operating
Instructions-7810
Operators
period
1
0 .7 ms
= 1 .43 kilohertz
RISE-TIME AND FALL-TIME MEASUREMENTS
Perform the following procedure to measure the rise time
and fall
time of
a
displayed waveform :
1 . Install the time-base unit in a mainframe
horizontal
compartment (either A or B horizontal in a four-
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 a vertically-centered display with an exact number
of
divisions of amplitude .
6 . Set the TIME/DIV switch and POSITION control to
display the
rising
or falling portion of the waveform
within the center 8 graticule 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 0 and 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 7 by
the TIME/DIV switch setting . (Divide the answer
by10 if
sweep magnification is used .)
2-9
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MEASURE HORIZONTAL DISTANCE FROM
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c 1985-10

Operating Instructions-7B10 Operators
Fig . 2-6 . Measuring the rise time and fall time
of a displayed
waveform .
Example : Assume that the horizontal distance between
the 50% amplitude points is 3 divisions, and the
TIME/DIV
switch setting is .1 Ns (see Fig . 2-6) .
Using the formula :
Horizontal distance

TIME/DIV
Rise Time =

(divisions)

x

setting
Magnification
Substituting values :
2 .5 x 0 .1 ,us
Rise Time =

1

= 0 .25 microsecond
2-10
PULSE WIDTH MEASUREMENTS
Perform the following procedure to measure the pulse
width
of a displayed waveform :
1 . Install the time-base unit in a mainframe
horizontal
compartment (either A or B horizontal in
a four-
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 a 5-division pulse vertically
centered on the
graticule .
6 . Set the TIME/DIV switch and POSITION control
for 1
complete pulse displayed within the center 8 graticule
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
7 by
the TIME/DIV switch setting . (Divide the
answer by 10 if
sweep magnification is used .)
Fig .
2-7 . Measuring the pulse width of a displayed
waveform .
RISE TIME
log
9
Oro
RON
MEN
NO
1
1
MMM''1W
EMNISIMASM
MMM
MEASURE HORIZ ONTAL
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MEASURE HORIZONTAL DISTANCE FROM
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PULSE WIDTH
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MEASURE HORIZONTAL DISTANCE FROM
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