Tektronix 432 Service manual

OPERATORS
HANDBOOK
This
Operators
Handbook
supplements the
complete Instruction Manual provided for this
instrument . For
more
detailed
information
,
refer to the Instruction Manual .
TEXTHINK
TEKTRONIX®
070-1104-00
P.O. Box 500
432
OSCILLOSCOPE
Beaverton
, Oregon
97005
671

Introduction
General
Operating Voltage
Operating
Position
Controls and Connectors
Basic
Operation
User's
Calibration
Trace Rotation
STEP ATTENuator BALance
Probe
Compensation
Vertical GAIN
ASTIGmatism
i
TABLE
OF
CONTENTS
Page
1
1
2
2
9
10
10
10
10
11
Basic
Timing
432
Applications
DC
Voltage
Level
Measurement
Peak - To - Peak Voltage Measurement - AC
Comparison
Measurements
Time - Duration Measurements
Frequency
Measurement
Risetime Measurements
Time - Difference Measurements
Multi - Trace Phase Difference Measurements
X - Y Phase Measurement
Common -
Mode
Rejection
Page
11
12
13
14
17
19
19
20
21
24
Copyright
© 1971
by Tektronix
, Inc. ,
Beaverton ,
Oregon .
Printed in the
United
States of
America . All
rights reserved . Con
tents
of this
publication may not
be reproduced
without
permission of the
copyright owner .
25

INTRODUCTION
432
OSCILLOSCOPE
General
The Tektronix 432 Oscilloscope is a solid - state portable
instrument that combines small size and light weight with
the
ability
to
make
precision
waveform measurements
. The
instrument contains two vertical signal inputs , both of
which
are
capable of 25 -
megahertz
bandwidth ; trigger
cir
cuitry to
permit
obtaining
stable CRT
displays ; and a
hori
zontal deflection system that provides calibrated sweep
rates from 5 seconds to 0.2 microsecond / division ( 20
nanoseconds / division magnified ) .
To effectively use the 432 Oscilloscope , the operation
and
capabilities
of the
instrument
must be
known .
This
Operator's Handbook is intended to give the necessary
information
to allow
a user to
become
familiar with
the
instrument's
power
requirements ,
functions of
controls and
connectors ,
and methods
of
making
several
different
measurements
of
electrical
phenomena .
Also
included is
a
rudimentary
procedure
for
checking
basic
instrument
cali
bration .
Operating
Voltage
The
432
can be
operated on
all
nominal line
voltages
from
100 volts
to 240 volts
AC , 50 to
400 Hertz . It
can
432
also
be
operated
from a 100
volts to 250
volts DC
power
source . No
range
switching or
selection is
necessary
.
CAUTION
This
instrument is
designed for
operation from
a
power
source
with its
neutral
at
or
near
earth
(
ground )
potential ( for both
AC and DC
power
sources
)
with a separate
safety -
earth conductor
. It
is
not
intended
for
operation from two
phases
of
a
multi -
phase AC
system , or
across
the
legs of a
single
phase , three - wire AC system .
The
432 is
designed
to be
used
with
a
three
-
wire
AC
power
system
. If
a
three-
to
two -
wire
adapter is
used to
connect this
instrument to a
two - wire AC
power system ,
be
sure to
connect
the
ground
lead of the
adapter
to
earth
(
ground
) .
Failure to
complete the
ground
system may allow
the
chassis
of
this
instrument to be
elevated above
ground
potential
and
pose
a
shock
hazard
.
When
operating
the
instrument
from
an
external
DC
power
source ,
polarity
of the
external
voltage is
unimpor
1

tant . Again , it
is
imperative
to
complete
the
ground system
to prevent accidental elevation of the instrument chassis
and posing a shock hazard .
Operating
Position
The handle of the 432 can be positioned for carrying or
as a tilt - stand for the instrument . To position the handle ,
press in at both pivot points and turn the handle to the
desired position . Fourteen positions are provided for con
venient carrying or viewing . The instrument can also be set
on the
rear
feet
for
operation or
storage .
2
432
CONTROLS AND CONNECTORS
General
The major controls and connectors for operation of the
432 are located on the front panel of the instrument . Sev
eral auxiliary functions are provided on the rear panel . To
make full use
of the
capabilitites of this
instrument
, the
operator should be familiar with the function and use of
each of these controls and connectors . A brief description
of each control and connector is given here . Some of the
more important instrument specifications are included here
also .
(

A
TYPE 432 OSCILLOSCOPE
TEKTRONIX , INC . , BEAVERTON , OREGON , U.S.A.
SERIAL
8
5
6
1. POSITION - positions the display vertically .
2. STEP ATTEN BAL - balances the input amplifier in the 1 mV ,
2
mV , 5 mV , and
10 mV
positions of the
VOLTS
/ DIV switch
.
3. GAIN - sets the gain of the input amplifier .
4.
VOLTS / DIV -
selects vertical
deflection factor
in a 1-2-5
sequence (
variable
control must be
in the CAL
position for
indicated deflection ) . Calibrated position accuracy within 3 % .
5. Variable - provides continuously variable uncalibrated deflec
tion factors between the calibrated settings of the VOLTS /
DIV switch .
6. AC / DC - in the AC
ition ( button in ) of this push - push
switch
, signals
are capacitively
coupled
to
the vertical ampli
OUT : 1 MHz BW
POSITION
432
AC
STEP ATTEN
BAL
BOTH
IN :
PRECHARGE
OUT OC
GAIN
GND
2
3
5
CH
1
8
all
my
CH 1
IMD 24 of
ALT
VOLTS
/ DIV
CH
1
CH
2
PROBE CAL
08V 1kHz
ADD
N >
5
AA
09
07
AW
OL
CHOP
CH
2
CH 2
1MD
24pf
4EP
ATTEN
BAL
3
GAIN
BOTH IN PRECHARGE
AC
OUT
INVERT
POSITION
OUT
GND
fier
. The DC
component of the
input signal is
blocked . Low
frequency -3 dB point is about 10 hertz . In the DC position
( button out ) , all components of the input signal are passed to
the input
amplifier
.
7. GND - in the GND position ( button in ) of this push - push
switch , the input of the vertical amplifier is disconnected
from the input connector and grounded . Allows precharging
of
the input
coupling
capacitor . When the button
is out
coupling is
determined by
the AC - DC button
.
8. CH 1 and CH 2 - input connectors for application of external
signals to the inputs of the vertical amplifier . Input impedance
is
1 megohm
paralleled by
approximately 24
picofarads . Mini
mum bandwidth : 5 mV and up - 25 megahertz ; 2 mV - 22
megahertz ; 1 mV - 20 megahertz .
3

4
TYPE 432
OSCILLOSCOPE
TEKTRONIX , INC . , BEAVERTON , OREGON , U.S.A.
SERIAL
8000005
9. 5 MHz
BW - in
the out
position
of
this push -
push
switch , the
bandwidth of the
complete vertical
amplifier
system
is
limited
to approximately 5 megahertz .
10. PROBE
CAL 0.6 V 1
kHz -
provides
a
0.6 volt
calibrator
signal to permit probe compensation , adjustment of amplifier
gain , and checking basic horizontal timing .
Vertical Mode
Switch
11. CH
1 -
Channel 1
only
is
displayed
.
12. ALTernate - dual - trace display of signals of both channels .
Display
switched between
channels at the end
of each
sweep .
OUT
: 1 MHz BW
POSITION
AC
STEP
ATTEN
BAL
BOTH IN PRECHARGE
OUT DC
GAIN
432
GND
20
50
CH
1
11
CAL
12
CH 1
1MD 24 of
ALT
VOLTS / DIV
CH 1
CH
2
10
PRO CAL
0.8 KM₂
ADD
13
10
A
*
Og
oz
CAL
Au
OL
CHOP
15. CH 2 -
Channel 2 only is
displayed
.
CH 2
14
CH 2
1Mp
24pF
15
STEP
ATTEN
BAL
GAIN
BOTH IN PRECHARGE
AC
OUT
: INVERT
POSITION
OUT DC
GND
13. ADD - Signals applied to the CH 1 and CH 2 input connectors
are algebraically added , and the algebraic sum is displayed on
the CRT . The INVERT switch in Channel 2 allows the display
to
be CH 1 plus CH
2 or CH 1 minus
CH 2 .
16
14. CHOP - dual - trace display of signals on both channels . Display
is switched at a repetition rate of approximately 100 kilo
hertz
.
16. INVERT - Channel 2 display is inverted in the INVERT
( button out )
position
.
(
A
)

17
BEAM
FINDER
17. BEAM FINDER - compresses an overscanned display to with
in the graticule area , independently of display position or
applied signals .
18. POWER / INTENSITY - a combination control that turns on
instrument power when pulled , and controls brightness of the
display
when rotated
.
19. POSITION - positions the display horizontally .
20. TIME /
DIVision
-
selects
the
sweep
rate of
the sweep
genera
tor ( variable control must be in the CAL position for indi
cated sweep rate ) . Calibrated position accuracy within 3 % .
POWER PULL OUT
INTENSITY
18
OUT : 1 MHz BW
POSITION
19
432
STEP ATTEN
BAL
GAIN
21
20
POSITION
CAL
RESET
READY
TIME / DIV
CAL
152
EXT
HORIZ
VOLTS
/
DIV
CH
1 CH 2
PROBE
CAL
0.6V
1kHz
MAG
PUSH
TURN
20
$
MAG
ONLY
MODE
BOTH
IN SINGLE
AUTO
NORM
22
CAL
TRIGGER
SOURCE
BOTH
IN LINE
CM 1
COMP
BOTH OUT EXT
LF
REJ
LEVEL
L
STEP ATTEN
BAL
IN 1.10
HF
REJ
COUPLING
OUT
OC
GAIN
EXT
ATTEN
OUT
11
AC
OUT
:
INVERT
POSITION
The extreme counterclockwise position of the switch selects
External
Horizontal
mode of
operation
.
21. MAGnifier - a six - position , push - to - turn switch ( concentric
with the TIME /
DIV switch ) that
provides sweep
magnifica
tion up to a maximum of 50 times . Extends fastest sweep rate
to 0.02 microsecond / division .
22. Variable - provides uncalibrated sweep rates between the cali
brated settings selected by the TIME / DIV switch . The sweep
rate in each TIME / DIV switch position can be reduced to at
least the sweep rate of the next adjacent position to provide
continuously variable sweep rates .
LO
5

6
23. COUPLING - determines method of coupling trigger signal to
trigger
circuit .
AC - in the in position of this push - push switch , DC is
rejected and signals below about 20 hertz are attenuated .
Accepts signals between about 20 hertz and 25 megahertz .
DC - when both the AC and the LF REJ push - push
switches are in the out position , signals are directly
coupled
to the trigger
circuit . Accepts
all signals
from DC
to 25
megahertz .
BEAM
FINDER
LF REJ - rejects DC and attenuates signals below approxi
mately 30 kilohertz . Accepts signals between about 30
kilohertz and 25 megahertz .
HF REJ - attenuates signal above approximately 50 kilo
hertz . Accepts signals between DC and approximately 50
kilohertz .
POWER PULL OUT
INTENSITY
OUT
: 1 MHz BW
POSITION
STEP
ATTEN
BAL
GAIN
432
POSITION
CAL
RESET
READY
TIME / DIV
CAL
MAG
PUSH
TURN
EXT
HORIZ
150
VOLTS /
DIV
CH
1 CH
2
PROBE CAL
0.6V
1kHz
us
MAG
ONLY
MODE
BOTH
IN SINGLE
AUTO
CAL
24. SOURCE - selects source of trigger signal .
NORM
24
CH
1
R
SCOJACE
BO
IN
COMP
BOTH OUT EXT
LF HF
BE
REJ
REJ
LEVEL
LOPE
EFAT
23
IN
1.10
EXT
ATTEN
OUT : 11
AC
COPLINGUJT
DC
25
OUT
: INVERT
POSITION
DYS
CH
1 - A
push - push
switch
that in
the CH
1 position
( button in ) selects Channel 1 as an internal trigger source .
COMPosite - a push - push switch that in the COMP position
( button in ) allows the internal trigger source to be deter
mined by the vertical mode of operation .
LINE
- when both the
CH 1 and COMP
switches are pushed
in
, a portion of
the line
frequency is used
as a trigger
signal .
EXTernal - when the
CH 1 and COMP
switches are
both
out
,
signals applied to
the EXT TRIG
input
connector
are
used for
triggering
.
25. EXT ATTENuator - in the 1:10 position ( button in ) of this
push - push switch , external : trigger signals are attenuated by a
factor of ten . In the 1 : 1 position ( button out ) of this switch ,
external trigger
signals are not
attenuated .

BEAM
FINDER
26. SLOPE - selects slope of trigger signal which starts the sweep .
+
-sweep can
be
triggered from
positive - going
portion of
trigger signal .
OUT : 1 MHx BW
POSITION
-sweep can
be
triggered from
negative
-
going portion of
trigger
signal .
generator .
27. LEVEL - selects the amplitude point on the trigger signal at
which the sweep is triggered .
28. MODE - determines the operating mode for the sweep
POWER PULL OUT
INTENSITY
AUTOmatic - in the AUTO position ( button in ) of this
pushbutton switch
, the sweep is initiated
by the applied
trigger signal . In the absence of an adequate trigger signal ,
the sweep free runs and provides a bright reference trace .
432
STEP ATTEN
BAL
GAIN
29
POSITION
CAL
RESET
READY
TIME / DIV
CAL
MAG
PUSH
TURN
1.52
25
EXT
HORIZ
1
PROBE CAL
0.6V 1kMz
02-05
VOLTS
/ DIV
CH 1
CH
2
MAG
ONLY
MODE
BOTH IN SINGLE
AUTO
NORM
CAL
28
TRIGGER
SOURCE
BOTH IN LINE
CH 1
27
COMP
BOTH
OUT
EXT
LF
REJ
LEVEL SLOKE
HF
REJ
COUPLING
OUT
DC
STEP ATTEN
BAL
IN
10
EXT
ATTEN
OUT
11
GAIN
AC
+
26
OUT
: INVERT
POSITION
NORMal - in the NORM position ( button in ) of this push
button switch , the sweep is initiated by the applied trigger
signal . In the absence of an adequate trigger signal , there is
no trace .
BOTH IN : SINGLE sweep - when both the AUTO and
NORM switches are pushed in , the sweep operates in the
Single Sweep Mode . After a sweep is displayed , further
sweeps
cannot be
presented
until the
RESET
button is
pressed .
29. RESET - when the RESET button is pressed ( in the SINGLE
SWEEP mode ) , a single display will be presented ( with correct
triggering ) . After the sweep is completed , the RESET button
must be pressed again before another sweep can be displayed .
If there is not an adequate trigger signal present when the
RESET button is pressed , the sweep generator circuit will
remain armed as indicated by the READY light .
7

8
ASTIG
definition
.
30
)
POSITIVE GOING
INPUT
DECREASES
INTENSITY
32
31
Z AXIS
50
k
30. ASTIGmatism - adjusts CRT beam for optimum display
5 V P - P CAUSES
NOTICEABLE
MODULATION AT
NORMAL INTENSITY
31. Ground Post - connects to oscilloscope chassis . Provides a
common ground return for signal source to insure measure
ment
reliability .
32. Z AXIS - input connector for external blanking signals . A five
volt peak to peak signal will cause noticeable modulation at
normal intensity . A positive - going signal decreases intensity .
33. EXTernal TRIGger - input connector for external trigger
TRACE ROTATION
35
432
EXT
TRIG
( 33 )
1
MS
34
EXT HORIZ
50 k
≈.5 V /
DIV
signals .
Nominal input
signal
level
required for
correct
trigger
operation
is
between 35 and
40
millivolts at
frequencies
below
about five
megahertz
, increasing to
125
millivolts at
megahertz
.
34.
EXTernal
HORIZontal
- input
connector for
external
horizon
tal
signal
when
TIME / DIV
switch is set
to EXT
HORIZ .
Input
impedance
is
approximately 50
kilohms with
a
sensitivity of
approximately
0.5 volt /
division .
35.
TRACE ROTATION
-
adjusts trace to
align with
horizontal
graticule
lines
.
(
A
)

BASIC OPERATION
General
The
following procedure
is given
as a
method of
obtain
ing
a basic
display
on
the CRT of
the 432.
Calibrated
measurements can be made in most applications using this
procedure . Specific techniques required to make more
involved measurements are given in the Applications
section . The
following
procedure is
intended for
use until
the
user
becomes familiar with
instrument
operation .
( A )
1. Set the instrument controls as follows :
POWER /
INTENSITY
POSITION ( horizontal
and vertical )
Sweep
MODE
TIME
/ DIV
TRIGGER
SOURCE
TRIGGER
COUPLING
SLOPE
LEVEL
Vertical Mode
Input
Coupling
VOLTS / DIV
Pushed in and rotated fully
counterclockwise .
Set to mid -
range
AUTO
1
ms
(
unmagnified
)
COMP
AC
+
Mid -
range
CH
1
DC
.1 V
All
remaining
pushbuttons
should be out
.
432
2. Connect the instrument to a power source that meets
the
requirements
of the
instrument
( see
Operating
Voltage
section ) .
3.
Turn on the
instrument
power and
allow
several
minutes
warmup
.
4.
Advance
the
INTENSITY
control until
the free
running
trace
is visible
at the
desired
viewing
level .
5.
Connect the
signal to
be observed
to the CH 1
input
connector .
6.
If
display is
not now
visible
with the
INTENSITY
control at
mid -
range , press the
BEAM FINDER
pushbutton
and
adjust the VOLTS
/ DIV switch
until display
is reduced
in
size
vertically ; then center
the
compressed
display with
the
vertical and
horizontal
POSITION controls ; release
the
BEAM FINDER pushbutton .
7.
Set the
VOLTS / DIV
switch and
vertical POSITION
controls for a display which remains within the display area
vertically
.
8.
Set the LEVEL
control for
a stable display
.
9

9.
Set the
TIME / DIV
and horizontal
POSITION
controls for a display which remains within the display area
horizontally .
10. To magnify the display , position the area of interest
to
the center
vertical graticule line . Push
in the TIME /
DIV
knob , and turn clockwise until the desired amount of
magnification
is
achieved .
USER'S CALIBRATION
General
To insure measurement accuracy , certain portions of the
instrument calibration should be checked before making
the measurement . The following is a procedure for checking
the basic measurement capabilities of the 432. See the
Calibration section of the Instruction Manual for more
detailed
calibration information
.
Trace
Rotation
Use steps 1-4 of the Basic Operation procedure to obtain
a free - running trace . Adjust the TRACE ROTATION
adjustment ( located on the rear panel ) to align the trace
with the horizontal graticule lines .
10
432
STEP ATTENuator BALance
Use
steps 1-4
of the Basic
Operation
procedure to
obtain
a
vertically
centered
free -
running
trace .
Rotate the
Channel
1
VOLTS / DIV
switch from 10
mV to 1 mV
( CH 1 vertical
mode of
operation
) .
Adjust the
Channel 1
STEP ATTEN
BAL
adjustment
(
located on front panel
) for no
trace shift
when switching from 10 mV to 1 mV . Repeat this pro
cedure for Channel 2 .
Probe
Compensation
Variations in total input capacitance and resistance
occur with different combinations of oscilloscopes and
probes
.
Therefore , most
attenuator
probes are
equipped
with adjustments to insure optimum measurement
accuracy .
Probe compensation
is
accomplished
as
follows :
Connect the probe to one of the oscilloscope's input
connectors . Use steps 1-9 of the Basic Operation procedure
to obtain a display about three divisions in amplitude with
one
cycle of
the
calibrator signal
displayed each
two divi
sions . Check the waveform presentation for overshoot or
rolloff , and readjust compensation for flat tops on the
waveforms if necessary . See Fig . 1 .
Vertical GAIN
Use
steps 1-4 of
the Basic
Operation procedure
to obtain
a
free -
running trace .
Connect the
PROBE CAL
0.6 V
1 kHz

Fig . 1.
Probe
compensation .
A
Correct
Over Com
pensated
( Overshoot )
Under
Com
pensated
( Rolloff )
output signal to the CH 1 input connector ( if the signal is
connected through a 10X probe that does not have a scale
factor switching connector , reduce the setting of the
VOLTS
/ DIV
switch from .1 V
to 10 mV ) .
Adjust
the
Channel 1 GAIN
adjustment
(
located on
front panel ) for
exactly 6 divisions of vertical deflection . Repeat this
procedure
for Channel
2 .
432
ASTIGmatism
Use steps 1-9 of the Basic Operation procedure to obtain
a stable display of the calibrator waveform . Set the INTEN
SITY
control
for
normal
brightness
of
the
display (
approxi
mately mid - range ) . Adjust the ASTIG adjustment ( located
on rear panel ) so the vertical and horizontal portions of the
calibrator waveform are equally focused .
Basic
Timing
Use steps 1-9 of the Basic Operation procedure to obtain
a stable display of the calibrator waveform . Set the TIME /
DIV
switch to .5 ms /
div .
Check
the
display
for
one cycle
of
calibrator waveform for each two horizontal divisions . For
a more complete timing check , refer to the calibration pro
cedure given in the Instruction Manual .
APPLICATIONS
General
The following information describes the procedures and
techniques for making basic measurements with a 432
Oscilloscope . These
applications
are
not
described in detail ,
since each
application must be
adapted
to the
requirements
of the
individual
measurements . This
instrument
can
also be
used for many applications which are not described in this
handbook . Contact your local Tektronix Field Office or
11

representative for
assistance in
making
specific
measure
ments
with
this
instrument .
DC
Voltage
Level
Measurement
To
measure
a DC
voltage level
, use the
following
procedure :
1.
Connect the
voltage
source
to either input
connector
.
2.
Set the
instrument
for the
vertical
mode
that
will
display the
channel being
used
.
3. Set the VOLTS / DIV switch to display about five or
six divisions of deflection if possible .
4.
Set the
input coupling to
GND
.
5.
Set the
Sweep
MODE
switch to
AUTO .
6. Position the trace to the bottom line of the graticule
or
other
reference line
. If the
voltage to be
measured
is
negative
with
respect to
ground ,
position the
trace to the
top
line of the
graticule .
Do not
move
the
vertical
POSI
TION
control after this
reference has
been established
.
12
432
NOTE
To
measure a
voltage level with
respect to
another
voltage
rather than
ground ,
make the
following
changes
in
step 6 :
Set the
input
coupling
to
DC
and
apply the reference voltage to the input connector .
Then
position
the
trace to
this
reference
line
.
7.
Set
the
input
coupling to
DC .
The
ground
reference
line can be checked at any time by switching the input
coupling
to
GND .
8.
Measure
the
distance
in
divisions
between
the
refer
ence
line and
the free -
running trace .
NOTE
This
technique
can
also
be
used to
make
instan
taneous DC
voltage level
measurements on
a wave
form ,
rather
than fixed DC
levels .
9. Establish the polarity of the voltage . If the trace is
above the reference line , the voltage is positive ; below the
line
,
negative ( when
the
INVERT
switch is pushed
in if
using
Channel
2 ) .

10. Multiply the distance measured in step 8 by the
VOLTS
/ DIV
switch
setting
. Also
multiply
by
the
attenu
ation factor of the probe , if any , when using a probe that
does not
have a scale
factor
switching connector .
Example . Assume that the vertical distance measured is
5.2 divisions , the trace is above the reference line , and a
VOLTS
/ DIV
switch
setting of 50 mV .
Using
the
formula :
DC
Voltage
=
vertical
distance
(
Divisions
)
X polarity X
Substituting the given values :
DC
Voltage
5.2 X
+1 X
.05
The DC
voltage
is +0.26
volts .
VOLTS / DIV
setting
Peak - To - Peak Voltage Measurements - AC
To make a
peak - to -
peak
voltage
measurement , use
the
following
procedure
:
1.
Connect the signal to
either input
connector
.
432
2. Set the vertical mode to display the channel being
used
.
3. Set the
VOLTS
/
DIV
switch to
display about five
divisions of the
waveform
.
4. Set the
Input
Coupling
to AC
.
NOTE
For low - frequency signals below about 100 hertz , use
DC
coupling .
5. Set the Triggering controls to obtain a stable display .
Set the TIME / DIV switch to a position that displays several
cycles of the
waveform
.
6. Turn the vertical POSITION control so the lower por
tion of the
waveform
coincides
with one
of the
graticule
lines below the center horizontal line , and the top of the
waveform is on the viewing area . Move the display with the
horizontal
POSITION
control
, so
one of the
upper peaks
lies near the center vertical line ( see Fig . 2 ) .
7.
Measure
the
divisions
of
vertical
deflection from peak
to peak . Make sure the Variable VOLTS / DIV control is in
the
CAL
position
.
13

TA
Vertical
deflection
Position
to
center
line
14
1
++++
++++++++
Fig
. 2.
Measuring peak - to - peak
voltage of a
waveform .
NOTE
This technique may also be used to make measure
ments
between two points
on the
waveform rather
than
peak to
peak .
8. Multiply the distance measured in step 7 by the
VOLTS / DIV switch setting . Also multiply by the attenua
432
tion factor of the probe , if any , when using a probe that
does not have a scale factor switching connector .
Example
. Assume
a
peak - to -
peak vertical
deflection of
4.6 divisions ( see Fig . 2 ) and a VOLTS / DIV switch setting
of .5
V.
Using
the formula
:
vertical
deflection
X VOLTS
/ DIV
(
divisions
)
setting
Volts
Peak to Peak
Substituting the
given
values :
=
Volts
Peak to
Peak
=
4.6
X 0.5
V
The
peak - to -
peak
voltage is 2.3
volts
.
Comparison
Measurements
In
some applications
it
may be
desirable
to
establish
arbitrary
units
of
measurement
other
than
those
indicated
by
the
VOLTS / DIV
switch
or
TIME
/ DIV
switch
. This
is
particularly useful when comparing unknown signals to a
reference
amplitude or
repetition rate . One
use for the
comparison
-
measurement
technique
is to
facilitate
calibra

tion of equipment ( e.g. , on an assembly - line test ) where the
desired amplitude or repetition rate does not produce an
exact number of divisions of deflection . The adjustment
will be easier and more accurate if arbitrary units of
measurement are established so that correct adjustment is
indicated by an exact number of divisions of deflection .
Arbitrary sweep rates can be useful for comparing harmonic
signals to a fundamental frequency , or for comparing the
repetition rate of the input and output pulses in a digital
count - down circuit . The following procedure describes how
to establish arbitrary units of measure for comparison
measurements . Although the procedure for establishing
vertical and horizontal arbitrary units of measurement is
much the same , both processes are described in detail .
Vertical
Deflection
Factor . To
establish an
arbitrary ver
tical deflection factor based upon a specific reference
amplitude
, proceed
as
follows :
1.
Connect the
reference signal to
the input
connector
.
Set the TIME / DIV switch to display several cycles of the
signal .
2. Set the VOLTS / DIV switch and the Variable
VOLTS / DIV control to produce a display an exact number
of graticule divisions in amplitude . Do not change the Var
(
A )
432
iable VOLTS / DIV control after obtaining the desired
deflection . This display can be used as a reference for
amplitude comparison measurements .
3. To establish an arbitrary vertical deflection factor so
the amplitude of an unknown signal can be measured
accurately at any setting of the VOLTS / DIV switch , the
amplitude of the reference signal must be known . If it is
not
known , it can
be
measured
before the
Variable
VOLTS / DIV control is set in step 2 .
4. Divide the amplitude of the reference signal ( volts )
by the product of the vertical deflection established in step
2
(
divisions
) and
the setting of
the VOLTS / DIV
switch .
This is the vertical conversion factor .
Vertical
Conversion
Factor
=
reference
signal
amplitude ( volts )
vertical
deflection
X
( divisions )
VOLTS / DIV
switch
setting
5. To measure the amplitude of an unknown signal , dis
connect
the
reference signal and
connect the
unknown
signal to the input connector . Set the VOLTS / DIV switch
to a setting that provides sufficient vertical deflection to
15

make an
accurate measurement . Do not readjust the
Variable VOLTS / DIV control .
6. Measure the vertical deflection in divisions and calcu
late the amplitude of the unknown signal , using the
following
formula
.
Signal
Amplitude
=
VOLTS / DIV
switch
setting
Example . Assume a reference signal amplitude of 30
volts , a VOLTS / DIV switch setting of 5 , and the Variable
VOLTS / DIV control is adjusted to provide a vertical deflec
tion of four divisions .
vertical vertical
X
conversion
X
deflection
factor (
divisions )
Substituting these values in the vertical conversion factor
formula
(
step 4 ) ;
Vertical
Conversion
Factor
=
30 V
4 X 5 V
1.5
Then with a
VOLTS / DIV
switch setting of 1
, the peak
to - peak amplitude of an unknown signal which produces a
vertical deflection of five divisions can be determined by
using the signal amplitude formula ( step 6 ) :
16
432
Signal
Amplitude =
1 V X 1.5
X 5 = 7.5
volts
Sweep Rates . To establish an arbitrary horizontal sweep
rate based upon a specific reference frequency , proceed as
follows :
1. Connect the reference signal to the input connector .
Set the VOLTS / DIV switch for four or five divisions of
vertical deflection .
2. Set the TIME / DIV switch and the Variable TIME /
DIV control so one cycle of the signal covers an exact
number of
horizontal
divisions . Do not change
the
Variable
TIME / DIV control after obtaining the desired deflection .
This display can be used as a reference for frequency
comparison measurements .
3. To establish an arbitrary sweep rate so the repetition .
rate of an unknown signal can be measured accurately at
any setting of the TIME / DIV switch , the repetition rate of
the reference signal must be known . If it is not known , it
can be measured before the Variable TIME / DIV switch is
set in
step
2 .
4. Divide the repetition rate of the reference signal
( seconds ) by the product of the horizontal deflection estab

lished in step 2 ( divisions ) and the setting of the TIME / DIV
switch . This is the horizontal conversion factor :
Horizontal
Conversion
Factor
=
5. To measure the repetition rate of an unknown signal ,
disconnect the reference signal and connect the unknown
signal
to the
input
connector . Set
the TIME
/ DIV
switch to
a setting that provides sufficient horizontal deflection to
make
an
accurate measurement
. Do not
readjust the Vari
able TIME / DIV control .
Repetition
Rate
reference
signal
repetition
rate (
seconds )
horizontal TIME / DIV
deflection X
switch
( divisions )
setting
6.
Measure the
horizontal
deflection in
divisions and
calculate the repetition rate of the unknown signal using
the
following
formula :
=
TIME / DIV
horizontal
horizontal
switch
X conversion X deflection
setting
factor
(
divisions )
Example . Assume a reference signal frequency of 455
hertz
( repetition
rate 2.19
milliseconds ) , and a
TIME / DIV
switch
setting of
.2 ms ,
with the
Variable
TIME / DIV
432
control
adjusted to
provide
a horizontal
deflection
of
eight
divisions . Substituting these values in the horizontal conver
sion factor formula ( step 4 ) :
Horizontal
Conversion
Factor
2.19
ms =
0.2 ms X 8
=
1.37
Then , with a TIME / DIV switch setting of 50 µs , the
repetition rate of an unknown signal which completes one
cycle in seven horizontal divisions can be determined by
using the
repetition
rate
formula (
step 6 ) :
Repetition
Rate
=
50 μs
X
1.37 X
7 =
480
μs
This answer can be converted to frequency by taking the
reciprocal of the repetition rate ( see applications on Deter
mining Frequency ) .
Time - Duration Measurements
To
measure time
between two points
on a
waveform , use
the following procedure :
1. Connect the signal to either input connector .
17

2. Set
the
vertical
mode of
operation to
display the
channel
used .
3. Set the
VOLTS / DIV
switch
to
display
about
five
divisions of the
waveform .
4. Set the
Triggering
controls to
obtain a
stable
display
.
5.
Set
the
TIME /
DIV
switch to
the
fastest
sweep
rate
that displays less than eight divisions between the time
measurement points ( see Fig . 3 ) .
6. Adjust
the
vertical
POSITION
control
to move
the
points between which the time measurement is made to the
center horizontal line .
7. Adjust the horizontal POSITION control to center
the
display
within
the
center eight
divisions
of
the
graticule
.
8.
Measure the
horizontal
distance
between
the
time
measurement points . Be sure the Variable TIME / DIV
control is set
to CAL .
18
432
Horizontal
distance
Fig . 3. Measuring the time duration between points on a waveform .
9. Multiply the distance measured in step 8 by the
setting of the
TIME / DIV
switch
.
Example . Assume that the distance between the time
measurement points is five divisions ( see Fig . 3 ) and the
TIME
/
DIV
switch
is
set to .1
ms .