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PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.




7A18A
DUAL TRACE
AMPLIFIER

INSTRUCTION MANUAL
Tektronix, Inc .
P.O. Box 500
Beaverto$, Oregon 97077 Serial Number
070-4329-00 First Printing OCT 1982
Product Group 42 Revised FEB 1983
Copyright ~ 1971 , 1982 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 U 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 number on 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 :
8000000 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
7A18A




TABLE OF CONTENTS
Page Page

Section 1 SPECIFICATION Section 5 MAINTENANCE
Introduction . . . . . . . . . . . . . . . . . . . . 1-1 Preventive Maintenance . . . . . . . . . . 5-1
Electrical Characteristics . . . . . . . . . . 1-1 Troubleshooting . . . . . . . . . . . . . . . . . 5-1
7A1 8A and Mainframe Frequency Replacement Parts . , . . . . . . . . . . . . 5-3
Response . . . . . . . . . . . . . . . . . . . . . 1-1 Component Replacement . . . . . . . . . 5-4
Environmental Characteristics . . . . . . 1-2
Physical Characteristics . . . . . . . . . . 1-2 Section 6 OPTION INFORMATION

Section 2 OPERATING INSTRUCTIONS Section 7 ELECTRICAL PARTS LIST
Installation . . . . . . . . . . . . . . . . . . . . . 2-1 Abbreviations and Symbols
Front Panel Controls and Connectors 2-1 Parts Ordering Information
General Operating Information . . . . . 2-2
Basic Applications . . . . . . . . . . . . . . . 2-4 Section 8 DIAGRAMS AND CIRCUIT BOARD
ILLUSTRATIONS
Symbols
Symbols and Reference Designators
Voltage and Waveform Conditions
THE FOLLOWING SERVICING INSTRUC-
TIONS ARE FOR USE BY QUALIFIED PER- Section 9 MECHANICAL PARTS LIST
SONNEL ONLY. TO AVOID PERSONAL INJU- Mechanical Parts List Information
RY, DO NOT, PERFORM ANY SERVICING Index of Mechanical Parts Illustrations
OTHER THAN "HAT CONTAINED IN OPER- Mechanical Parts List
ATING INSTRUCTIONS UNLESS YOU ARE Accessories
QUALIFIED TO DO SO.



Section 3 CIRCUIT DESCRIPTION
Introduction . . . . . . . . . . . . . . . . . . . . 3-1
Block Diagram Description . . . . . . . . 3-1
Detailed Circuit Description . . . . . . . . 3-1
CHANGE INFORMATION
Section 4 PERFORMANCE CHECK &
ADJUSTMENT Abbreviations and symbols used in this manual are based
Recalibration Interval . . . . . . . . . . . . . 4-1 on or taken directly from IEEE Standards 260 "Standard
Test Equipment Required . . . . . . . . . 4-1 Symbols for Units", MIL-STD-12B and other standards of
Part I-Performance Check . . . . . . . 4-4 the electronics industry . Change information, if any, is locat-
Part II-Adjustment . . . . . . . . . . . . . 4-8 ed at the rear of this manual .
LIST OF ILLUSTRATIONS
Fig.
No . Page

2-1 Front-panel controls and connectors . . . . . 2-1
2-2 Measuring the peak-to-peak voltage of a .
waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2-3 Measuring instantaneous voltage with
respect to some reference . . . . . . . . . . . . . 2-5
2-4 Measuring phase difference betwen two
signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2-5 High resolution phase measurment using
time-base magnifier . . . . . . . . . . . . . . . . . . . 2-7
2-6 Using the ADD mode for common-mode
rejection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
3-1 Channel 1 Input Amplifier detailed block
diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3-2 Channel 2 Input Amplifier detailed block
diagram . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 3-4
3-3 U270 input combinations for DISPLAY
MODE selection . . . ....... . . . . . 3-5
3-4 Input/Output combinations for DISPLAY . . .
. . .
MODE and TRIGGER SOURCE switch
selections . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
4-1 Locations of adjustments used in this
procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
5-1 Electrode configuration for semiconductors
used in this instrument . . . . . . . . . . . . . . . . 5-2
6-1 7A1 8A Option 06 . . . . . . . . . . . . . . . . . . . . . 6-1
6-2 Side view of 7A1 8A-Option 06 . . . . . . . . . 6-3
6-3 Rear view of A2-Amplifier board for either
Option 06 or standard 7A1 8A . . . . . . . . . . . 6-3

8-1 and 8-2 are of circuit board assemblies and are in the
diagrams section
7A18A




OPERATORS SAFETY SUMMARY
The general safety information in this part of the summa- supply conductors or between either supply conductor and
ry is for both operating and servicing personnel. Specific ground . A protective ground connection by way of the
warnings and cautions will be found throughout the manual grounding conductor in the power cord is essential for safe
where they apply, but may not appear in the summary. operation.



Terms in This Manual
Grounding the Product
CAUTION statements identify conditions or practices
that could result in damage to the equipment or other This product is grounded through the grounding conduc-
property . tor of the power cord . To avoid electrical shock, plug the
power cord into a properly wired receptacle before connect-
ing to the product input or output terminals. A protective
WARNING statements identify conditions or practices ground connection by way of the grounding conductor in the
that could result in personal injury or loss of life . power cord is essential for safe operation.



Terms as Marked on Equipment Danger Arising From Loss Of Ground

CAUTION indicates a personal injury hazard not immedi- Upon loss of the protective-ground connection, all acces-
ately accessible as one reads the marking, or a hazard to sible conductive parts (including knobs and controls that
property including the equipment itself . may appear to be insulating) can render an electric shock.



DANGER indicates a personal injury hazard immediately Use The Proper Power Cord
accessible as one reads the marking. Use only the power cord and connector specified for your
product.

Symbols In This Manual
Use only a power cord that is in good condition.
This symbol indicates where applicable
cautionary or other information is to be found.
Refer cord and connector changes to qualified service
personnel.
Symbols As Marked On Equipment

rUse The Proper Fuse

DANGER - High voltage. To avoid fire hazard, use only the fuse of correct type,
voltage rating and current rating as specified in the parts list
for your product.
Protective ground (earth) terminal .

Refer fuse replacement to qualified service personnel .
ATTENTION - refer to manual .

Do Not Operate In Explosive Atmospheres
Power Source
To avoid explosion, do not operate this product in an
This product is intended to operate from a power source explosive atmosphere unless it has been specifically certi-
that will not apply more than 250 volts rms between the fied for such operation .
7A18A




SERVICE SAFETY SUMMARY
FOR QUALIFIED SERVICE PERSONNEL ONLY
Refer also to the preceding Operators Safety Summary


Do Not Service Alone Disconnect power before removing protective panels,
soldering, or replacing components .
Do not perform intenal service or adjustment of this prod-
uct unless another person capable of rendering first aid and
resuscitation is present.
Power Source
This product is intended to operate from a power source
that will not apply more than 250 volts rms between the
Use Care When Servicing With Power On
supply conductors or between either supply conductor and
Dangerous voltages exist at several points in this prod- ground . A protective ground connection by way of the
uct. To avoid personal injury, do not touch exposed connec- grounding coductor in the power cord is essential for safe
tions and components while power is on . operation.
7A18A Dual Trace Amplifier
Section 1-7A18A




SPECIFICATION
Introduction switch . Channel 2 can be inverted for differential measure-
ments. The 7A1 8A can be operated in any plug-in compart-
The 7A1 8A Dual Trace Amplifier plug-in unit is designed
ment of the 7000-Series Oscilloscopes.
for use with TEKTRONIX 7000-Series Oscilloscopes.


The following electrical characteristics are valid over the
The 7A1 8A is a dual-channel, medium-bandwidth amplifi-
stated environmental range for instruments calibrated at an
er . Internal gain and compensation circuits are automatically
ambient temperature of +20