Tektronix 7A18A User manual

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COMMITTED TO EXCELLENCE
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

Section 1
Section 2
THE FOLLOWING SERVICING INSTRUC-
TIONS AREFORUSE BY QUALIFIED
PER-
SONNEL ONLY . T O AVOID PERSONAL
INJU-
RY, DO NOT, PERFORM
ANY SERVICING
OTHER THAN "HAT
CONTAINED IN OPER-
ATING INSTRUCTIONS UNLESS
YOU ARE
QUALIFIED TO DO SO .
Section 3
Section 4
TABLE OF
CONTENTS
CHANGE INFORMATION
7A18A
Abbreviations and symbols
used in this manual are based
on or
taken directly from IEEE Standards 260 "Standard
Symbols
for Units", MIL-STD-12B and other standards of
the electronics industry . Change information, if any, is locat-
ed at the rear of this manual .
Page
SPECIFICATION
Introduction
....... . . ...... ..... 1-1
Electrical
Characteristics
... .
...... 1-1
7A1 8A
and Mainframe Frequency
Response
....... ....... .......
1-1
Environmental Characteristics ......
1-2
Physical Characteristics
. ........ .
1-2
OPERATING
INSTRUCTIONS
Installation
....... ..... ........ .
2-1
Front Panel Controls and Connectors
2-1
General Operating Information .... .
2-2
Basic Applications ... ........... .
2-4
CIRCUIT DESCRIPTION
Introduction ....... ..... ........
3-1
Block Diagram
Description
. . ......
3-1
Detailed Circuit
Description
........
3-1
PERFORMANCE
CHECK &
ADJUSTMENT
Recalibration Interval
..... ........ 4-1
Test Equipment Required . ........
4-1
Part
I-Performance Check ....... 4-4
Part
II-Adjustment ..... ........
4-8
Page
Section 5
MAINTENANCE
Preventive
Maintenance ....... ... 5-1
Troubleshooting .... .......... ... 5-1
Replacement
Parts . ......... ... , 5-3
Component
Replacement .... . . ... 5-4
Section
6 OPTION INFORMATION
Section
7 ELECTRICAL PARTS
LIST
Abbreviations and Symbols
Parts Ordering
Information
Section 8
DIAGRAMS AND CIRCUIT BOARD
ILLUSTRATIONS
Symbols
Symbols
and Reference Designators
Voltage
and Waveform Conditions
Section 9
MECHANICAL PARTS LIST
Mechanical Parts List Information
Index of Mechanical Parts Illustrations
Mechanical Parts List
Accessories

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

Terms
in This Manual
OPERATORS
SAFETY
SUMMARY
The
general safety information in this part
of the summa-
ry is for both
operating and servicing
personnel . Specific
warnings
and cautions will be found
throughout the manual
where they apply, but may not appear
in the summary .
CAUTION statements identify
conditions or practices
that
could result in damage to
the equipment or other
property .
WARNING statements
identify conditions or practices
that could result in personal
injury or loss of life .
Terms as Marked on
Equipment
CAUTION indicates a personal
injury hazard not immedi-
ately accessible as one reads
the marking, or a hazard to
property including the
equipment itself .
DANGER indicates a
personal injury hazard immediately
accessible as one reads the
marking .
Symbols In This Manual
This
symbol indicates where applicable
cautionary or other information is to be
found .
Symbols As Marked
On Equipment
DANGER - High voltage .
Protective ground (earth) terminal
.
Power Source
ATTENTION - refer to manual
.
This product is intended to operate from
a power source
that
will not apply more than 250
volts rms between the
7A18A
supply
conductors or between either supply
conductor and
ground . A protective ground connection by
way of the
grounding conductor in the power cord is
essential for safe
operation .
Grounding the Product
This
product is grounded through the
grounding conduc-
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
ground connection by way of
the grounding conductor in the
power cord is essential for safe
operation .
Danger Arising From Loss Of
Ground
Upon loss of the protective-ground connection,
all acces-
sible conductive parts (including
knobs and controls that
may appear to be
insulating) can render an electric shock .
UseThe Proper Power
Cord
Use only the power cord and
connector specified for your
product .
Use only a power cord
that is in good condition .
Refer cord and
connector changes to qualified service
personnel .
r Use The Proper Fuse
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
.
Refer fuse replacement
to qualified service personnel
.
Do Not
Operate In Explosive Atmospheres
To
avoid explosion, do not operate
this product in an
explosive atmosphere unless it has been
specifically certi-
fied
for such operation .

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

7A18A Dual Trace Amplifier

Introduction
The7A1 8A Dual Trace Amplifier plug-in unit is designed
for use with TEKTRONIX 7000-Series
Oscilloscopes .
The 7A1 8A is a dual-channel, medium-bandwidth amplifi-
er . Internal gain and compensation circuits are automatically
switched to correspond to the setting of the VOLTS/DIV
SPECIFICATION
Table 1-1
ELECTRICAL
Section 1-7A18A
switch . Channel 2 can be inverted for differential measure-
ments .
The7A1
8A can be operated
in any plug-in compart-
ment of the 7000-Series Oscilloscopes .
The following electrical characteristics are valid over the
stated
environmental range for instruments calibrated at an
ambient temperature of +20°C to +30°C, and after a five
minute warmup unless otherwise noted .
Characteristic PerformanceRequirement Supplemental Information
Deflection Factor
Calibrated Range 5 mV/Div to 5 V/Div ; ten steps in a
1,2,5 sequence .
Deflection Factor Accuracy Within 2% with GAIN adjusted at
10 mV/Div .
Uncalibrated (VARIABLE) Continuously variable between
calibrated steps ; extends deflection
factor to at least 12 .5 V/Div .
GAIN
Permits adjustment of deflection factor
for
calibrated
operation with all 7000-series
oscilloscopes .
Frequency ResponseSystem
Dependent (8 div reference signal)
Upper Bandwidth DC (Direct) 75 MHz
Coupled
Lower Bandwidth AC
(Capacitive) 10
Hertz
or less
Coupled
With 10X
Probe
1 Hertz
or less
Maximum Input
Voltage
DC Coupled 250 volts, (DC + Peak AC) ; AC
component
500 volts peak-to-peak
maximum, one kilohertz or less .
AC Coupled 500 volts, (DC
+ Peak AC) ; AC
component
500
volts
peak-to-peak
maximum,
one
kilohertz
or less .
,hannel Isolation
50 :1 display ratio up to 50 megahertz .

Specification-7A18A
Performance
Requirements
Approximately
20
.0 pF
0 .06 div or less
at all deflection
factors
0 .1 ms or less
to recover to within
one
division
after the removal of an
overdrive
signal of up to
+75
divisions
or -75
divisions regardless of
overdrive
signal duration .
At least
10 :1 up to 50
megahertz .
0 .02 division
or less in any one
minute,
after one
hour warmup .
Nor
more than 0 .01 division
perdegree
C
.
700
picoseconds or less .
Channel
1 only .
Dual-trace, alternate between
channels .
Added algebraically .
Dual-trace chopped
between channels .
Channel 2 only .
Channel 1 only .
Follows DISPLAY MODE
selection .
Channel 2 only .
Characteristics
Input R and
C
Resistance
Capacitance
AC
Product
Displayed
Noise
(Tangentially Measured)
Overdrive
Recovery Time
Common Mode Rejection
Ratio
DC
Drift
Drift with Time (Ambient
temperature and line
voltage
constant)
Size
Drift with Temperature
(line voltage
constant)
Time Delay between
Channels
Display Modes
Trigger source
Selection
Refer to the
Specification for the associated
oscilloscope .
Weight
Table
1-1 (cont)
Table 1-2
ENVIRONMENTAL
CHARACTERISTIC
Table 1-3
PHYSICAL
Fits all 7000-series
plug-in compartments
.
, : :e2 Pounds
10 Ounces ( 1 .4 kilograms)
Supplemental
Information
Within ± 1 % between
all deflection
factors .

General
Installation
OPERATIN
To effectively use the 7A1 BA, the operation
and capabili-
ties of the instrument must be
known . This section de-
scribes front-panel control functions, general
information on
signal input connections, and other subjects
that pertain to
various measurement applications .
The 7A1 8A is calibrated
and ready for use as received . It
can be installed in any compartment
of Tektronix 7000-Se-
ries oscilloscopes, but is
intended for principal use in vertical
plug-in compartments . To
install, align the upper and lower
rails of the 7A18A with the oscilloscope
tracks and fully in-
sert it . The front
will
be
flush with the front of the oscillo-
scope when the 7A1 8A is
fully inserted, and the latch at the
bottom-left corner of the 7A1 8A will be
in
place
against the
front panel .
To remove
the 7A1 8A, pull on the latch (which is in-
scribed
with the unit identification "7A18A") and the 7A18A
will unlatch
.
Continue
pulling
on
the latch to slide the 7A1 8A
out of the oscillscope .
FRONT PANEL CONTROLS AND
CONNECTORS
The
following descriptions apply to the controls and con-
nectors of both Input
Amplifier
channels
when applicable .
See Fig . 2-1
.
Input Connector

Provides signal connection to the
channel .
AC-GND-AC

Selects signal input coupling mode .
INSTRUCTIONS
AC-The AC component of the sig-
nal is coupled to the amplifier in-
put while the DC component is
blocked .

POSITION
GND-Grounds the amplifier input
while maintaining the same load
for the input signal . Provides a
charge path for the AC coupling

IDENTIFY
capacitor to precharge the input
circuit before switching the input
to AC .
Section
2-7A18A
4329-07
Fig . 2-1 . Front-panel controls and connectors . (7A18A shown .)
DC-Both AC and DC components
of the
signal
are coupled to the
amplifier input .
Controls position
of the trace . Posi-
tioning of the trace in the "ADD"
Display Mode is controlled by CH 1
POSITION control only .
Deflects trace about 0 .3 division for
trace
identification . In instruments
with readout, also replaces readout
with the word "IDENTIFY" .