Tektronix 475 User manual

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TEKTRONIX.
INSTRUCTION MANUAL

WARRANTY
All TEKTRONIX instruments are warranted against
defective materials and workmanship for one year. Any
questions with respect to the warranty should be taken up
with your TEKTRONIX Field Engineer or representative.
All requests for repairs and replacement parts should be
directed to the TEKTRONIX Field Office or representative
in your area. This will assure you the fastest possible
service. Please include the instrument Type Number or Part
Number and Serial Number with all requests for parts or
service.
Specifications and price change privileges reserved.
Copyright © 1972 by Tektronix, Inc., Beaverton, Oregon.
Printed in the United States of America. All rights reserved.
Contents of this publication may not be reproduced in any
form without permission of Tektronix, Inc.
U.S.A. and foreign TEKTRONIX products covered by U.S.
and foreign patents and/or patents pending.
TEKTRONIX is a registered trademark of Tektronix, Inc.
Tektronix, Inc. -® P.O.Box 500 -® Beaverton, Oregon 97005 -® Phone: [phone] -® Cables: Tektronix
070-1333-00
872

TABLE
Introduction
Operating Voltage
Controls And Connectors
Applications
General
Peak-To-Peak Voltage Measurements—AC
Instantaneous Voltage Measurements—DC
Comparison Measurements
Time-Duration Measurements
Frequency Measurement
Risetime Measurements
Time-Difference Measurements
Delayed or Mixed Sweep Time Measurement
Delayed or Mixed Sweep Magnification
Pulse Jitter Measurements
Delayed Trigger Generator
Normal Trigger Generator
Multi-Trace Phase Difference Measurements
High Resolution Phase Measurements
X-Y Phase Measurement
Common-Mode Rejection
Operational Features
General
Intensity Control
Graticule
Vertical Mode of Operation
Deflection Factor
Ground Considerations
OF CONTENTS
Page
1 Input Coupling
1 Trigger Source
3 Trigger Coupling
Trigger Slope
Trigger Level
12 A Sweep Triggered Light
12 A Trigger Mode
14 A Trigger Holdoff
15 Horizontal Mode of Operation
18
Horizontal Sweep Rates
20 Sweep Magnification
20 External Horizontal (X-Y) Operation
21 Output Signals
23 Intensity Modulation
25 Calibrator
28 Obtaining Basic Displays
29 Introduction
30 Normal Sweep Display
30 Magnified Sweep Display
32 Delayed Sweep Displays
33 Mixed Sweep Display
34 X-Y Display
User’s Calibration
35 General
36 TRACE ROTATION Adjustment
36 Vertical GAIN
36 Probe Compensation
38 Basic Timing Accuracy
38 External Horizontal Gain Accuracy
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475 OSCILLOSCOPE
Introduction
This Operators 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 also provides a few methods
of making several different measurements of electrical
phenomena. Also included is a rudimentary procedure for
checking basic instrument calibration.
Operating Voltage
This instrument is designed for operation from a
power source with its neutral at or near earth
(ground) potential with a separate safety-earth
conductor. It is not intended for operation from two
phases of a multi-phase system, or across the legs of a
single-phase three-wire system.
This instrument can be operated from either a 115-volt
or a 230-volt nominal line voltage source, 48 to 440 hertz.
The line voltage selector switch in the instrument converts
®
475
the instrument from one nominal operating voltage to the
other. The regulating range selector assembly on the
instrument rear panel selects one of three regulating ranges
for each nominal line voltage, and also contains the line
fuses for overload protection for both nominal line
voltages. To select the correct nominal line voltage and
regulating range, proceed as follows:
1. Disconnect the instrument from the power source.
2. To.convert from 115-volts nominal to 230-volts
nominal line voltage, set the selector switch to the 230 volts
position (toward the rear of the instrument). Change the
line-cord plug to match the power source or use a
115-to-230 volt adapter.
NOTE
Color-coding of the cord conductors is as follows (in
accordance with National Electrical Code):
Line Black
Neutral White
Safety earth (ground) Green

3. To change regulating ranges, loosen the two captive
screws which hold the cover onto the regulating range
selector assembly; then pull to remove the cover.
4. Pull out the range selector switch bar (see Fig. 1).
Slide the bar to the desired position and plug it back in.
Select a range which is centered about the average line
voltage to which the instrument is to be connected (see
Table 1).
115/230V SWITCH INSIDE
Selector switch bar
_ (shown in medium position)
-
IGHT SIDE, REAR)
TABLE 1
Regulating Ranges
Range Selector 15 Se es
Switch Position ce folts 30- folts
Nominal Nominal
LO (switch bar in 99 to 198 to
left holes) 121 volts 242 volts
M (switch bar in 103.5 to 207 to
middle holes) 126.5 volts 253 volts
HI (switch bar in 108 to 216 to
right holes) 132 volts 264 volts
Fig. 1. Power supply regulating range selector.
5. Re-install the cover and tighten the two captive
screws.
®

6. Before applying power to the instrument, check that
the line voltage selector switch and the indicating tabs on
the regulating range selector assembly are in the correct
positions for the line voltage the instrument will be
operated on.
This instrument may be damaged if operated with the
line voltage selector switch or the regulating range
selector assembly set to incorrect positions for the
line voltage applied.
The 475 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
475
(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.
The feet on the rear panel provide a convenient cord
wrap to store the power cord when not in use.
Controls And Connectors
The major controls and connectors for operation of the
475 are located on the front panel of the instrument.
Several auxiliary functions are provided on the rear panel.
To make full use of the capabilities of this instrument, the
operator should be familiar with the function and use of
each of these controls and connectors. A brief description
of each is given here. Some of the more important
instrument specifications are included here also.
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OSCILLOSCOPE
9)
. CH 1 and CH 2 VOLTS/DIV-—selects the vertical deflection
. VARiable—provides continuously variable uncalibrated deflec-
. UNCALibrated—indicates when the VARiable VOLTS/DIV
. POSITION—positions the display vertically.
. CH 1 OR X and CH 2 OR Y-—input connectors for application
. AC-GND-DC-selects the method used to couple a signal to the
factor in a 1-2-5 sequence (VARiable control must be in the
calibrated detent for the indicated deflection factor). Calibrated
position accuracy is within 3%.
tion factors between the calibrated settings of the VOLTS/DIV
switch.
control is out of the calibrated detent position and the vertical
deflection factor is uncalibrated.
of external signals to the inputs of the vertical amplifier. In the
X-Y mode of operation, the signal connected to the CH 1 OR X
connector provides horizontal deflection and the signal
connected to the CH 2 OR Y connector provides the vertical
deflection. Input impedance is 1 megohm paralleled by approxi-
mately 20 picofarads. Minimum bandwidth in the normal mode
of operation is DC to at least 200 MHz. X-axis has a bandwidth
in X-Y operation of DC to 1 megahertz and is compensated to
have 1° or less phase difference with relation to the Y axis from
DC to 1 MHz.
input of the vertical amplifier. In the AC position, signals are
capacitively coupled to the vertical amplifier. The DC
component of the input signal is blocked. Low frequency
—3 dB point is about 10 Hz. In the GND position, the input of
the vertical amplifier is disconnected from the input connector
and grounded. Allows precharging of the input coupling
capacitor. In the DC position, all components of the input
signal are passed to the input amplifier.
475
®

{ POSITION
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7.
11,
VERTical MODE-selects mode of operation for vertical
amplifier system.
CH 1: Channel 1 only is displayed.
ALTernate: Dual-trace display of the signals of both
channels. Display is switched between channels at the end of
each sweep.
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;
CHOP: Dual-trace display of the signals of both channels.
Display is switched between channels at a repetition rate of
approximately 1 MHz.
CH 2: Channel 2 only is displayed. Must be selected in X-Y
operation.
. 100 MHz or 20 MHz BW/TRIG VIEW—Multi-position switch
that limits the bandwidth of the vertical amplifier system to ap-
proximately 100 MHz or 20 MHz when pulled (100 MHz posi-
tion not provided for SN below B100000) or causes signal con-
nected to A External Input connector to be displayed on the
CRT when pressed. When not pressed, full bandwidth is pro-
vided.
. INVERT —Channel 2 display is inverted in the INVERT (button
in) position.
. BEAM FINDer—comoresses the display to within the graticule
area independently of display position or applied signals and
provides a visible viewing level.
INTENSITY—controls brightness of the CRT display.
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475

12.
13.
14,
15.
16.
de
18.
FOCUS —adjusts for optimum display definition.
SCALE ILLUMination—controls graticule illumination.
ASTIGmatism—screwdriver adjustment used in conjunction
with the FOCUS control to obtain a well-defined display. Does
not require readjustment in normal use.
TRACE ROTATION -—adjusts trace to align with the horizontal
graticule lines.
X10 MAGnifier—increases displayed sweep rate by a factor of
10. Extends fastest sweep rate to 1 nanosecond/division.
Calibrated magnified sweep accuracy is typically within 3%.
POSITION-—positions the display horizontally.
CALIBRATOR—a combination current loop/squarewave
voltage output device. Provides a 30 mA (within 2%) square-
wave current, 300 mV (within 1%) squarewave voltage signal
with a repetition rate of approximately 1 kHz.
19. TRIGger MODE-—determines the mode of operation for A
Trigger circuit.
AUTOmatic: 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.
NORMal: The sweep is initiated by the applied trigger
signal. In the absence of an adequate trigger signal, there is
no trace.
SING SWP: when this pushbutton is pushed, A Sweep
operates in the single sweep mode. After a sweep is
displayed, further sweeps cannot be presented until the
SING SWP button is pushed.
475

7 ese BooLroyAIGGER SY 20. A TRIGger HOLDOFF-—provides continuous control of time
EVEL between sweeps. Allows triggering on aperiodic signals (such as
complex digital words). In the fully clockwise position (B
ENDS A), A sweep is reset at the end of B sweep to provide the
fastest possible sweep repetition rate for delayed sweep
presentations.
21. COUPLING—determines method used to couple signals to
trigger generator circuit.
AC: Signals are capacitively coupled to the input of the
trigger generator circuit. DC is rejected and signals bDelow
about 60 Hz are attenuated.
LF REJ: Signals are capacitively coupled to the input of the
trigger circuit. DC is rejected and signals below about 5 kHz
are attenuated.
HF REJ: Signals are capacitively coupled to the input of
the trigger circuit. DC is rejected and signals below about
60 Hz and above about 50 kHz are attenuated.
DC: All components of a trigger signal are coupled to the
input of the trigger circuit.
22. SLOPE -selects the slope of the trigger signal which starts the
sweep.
+: Sweep can be triggered from the positive-going portion
of a trigger signal.
—: Sweep can be triggered from the negative-going portion
of a trigger signal.
Pose
POSITION
9
300mv 30mA
“— Goi J 23. LEVEL-—selects the amplitude point on the trigger signal at
which the sweep is triggered.
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