Tektronix 7A22 User manual

Tektronix, Inc .
P
.O . Box 500
Beaverton, Oregon

97077
070-0931-00
Product Group 42
CHECK FOR CHANGE
INFORMATION
REAR O THIS MANUAL .
COMMITTED TO EXCELLENCE
N
MANUAL
Serial
Number
First
Printing JUL 1969
Revised SEP 1986

Copyright C
1969 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

T 4 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 :
B000000

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
REVSEP 1981
Section 2
Section 2

OPERATING INSTRUCTIONS
(cont)
7A22
Page
Voltage Measurement
. .............

2-4
Signal Input
Connectors ..... . ......

2-4
High Input Impedance . .............

2-5
Display Polarity .... . ........ . ......

2-5
Deflection Factor . . . . . ...... . ......

2-5
Bandwidth Selection ...... . ........

2-5
Voltage Comparison Measurements ...

2-10
Differential Operation ........ . ...... 2-10
DC Offset Operation ...... . . ...... .

2-11
Input Overdrive Indicator ... . ....... .

2-12
Readout . . . ...... . ...... . ........ 2-12
Trace Identify .......... . ........

2-13
The remaining portion
of this Table of Contents lists the
servicing instructions .
These
servicing instructions
are
for
use by qualified personnel only . To avoid electrical shock,
do notperform any servicing other than that called out in the
operating instructions unless qualified to doso .
Section 3
Page
SPECIFICATION
Introduction ................. . ..... 1-1
Electrical Characteristics
.... . . ...... 1-1
Deflection Factor . ....... . ....... 1-1
Gain . . . ...... . . ...... . . ....... 1-1
Differential Dynamic Range . ...... 1-1
DC Offset ..... . ....... . . ....... 1-1
Frequency Response ... . . ....... 1-1
Bandwidth Limit . ....... . . ....... 1-1
Recovery Time . . ........ . ....... 1-1
Common-Mode
Signal Range
.... . 1-1
Common-Mode Rejection Ratio ... . 1-1
Maximum Input Voltage . . . ...... . 1-3
Input R
and C ............... . . .
1-3
Maximum Input Gate Current
... . . .
1-3
Variable Balance
...... . ........
. 1-3
Step Attenuator DC Balance
... . . .
1-3
Displayed Noise (Tangentially
Measured) . . . ............... . . . 1-3
DC Drift .... . ....... . ....... . . . 1-3
Isolation Between
+
and ---
Inputs ..... . . ....... . ...... ... . 1-3
Environmental Characteristics .... . . . . 1-3
Altitude .... . . ....... . ...... . . . . 1-3
Transportation ...... . . ...... . . . . 1-3
Physical Characteristics . . . ...... . . . . 1-3
Finish ..... . . .............. . . . . 1-3
Dimensions . . ...... . ....... . . . . 1-3
Weight .... . . ...... . . ....... . . . 1-3
OPERATING INSTRUCTIONS
Introduction .. . .
. ...... . ........
. . . 2-1
Front Panel
Controls and Connectors . 2-1
Operating Instructions
........... . . .
2-2
First Time Operation
. . ........ . . .
2-2
General Operating Information . . . .... 2-4
Trace Drift ....... . ........ . .... 2-4
Input Gate Current ...
. . ............
2-4
CIRCUIT DESCRIPTION
Introduction ............ . ...... . . . . 3-1
Block Diagram Description ...... . . . . 3-1
Input Coupling ....... . ...... . . . . 3-1
Input Attenuators .... . ...... . . . . 3-1
Preamp ......
. ........ . .... . . . .
3-1
L
F ---3
dB
Point
............ . . . .
3-1
Output Amplifier ..... . ...... . . . . 3-2
HF --3 dB
Point
..... . ...... . . . . 3-2
General
Information
............ . . . . 3-2
Feedback Amplifiers
. . ....... . . . .
3-2
Differential Configuration
..... . . . .
3-3
Detailed
Circuit Description
...... . . . .
3-3
Input Coupling
. ...... . ...... . . . .
3-3
Input Attenuators ........... . . . . 3-4

7A22
SECTION 4
SECTION 3
REV C, MAR 197 9
CIRCUIT DESCRIPTION (cont)
Page SECTION 4
MAINTENANCE (cont) Page
Gate Current Compensation . 3-4
Special Parts
....... .... . 4-2
Input Amplifier ... .
....... 3-4 Soldering
Techniques ...... 4-2
X15 Preamp . .... . . .... 3-4
Component Replacement
Information ......... ....
4-3
DC Balance . .......... 3-4
Troubleshooting ............
4-5
Floating Power Supply ... 3-5
Introduction .............
4-5
Common-Mode Rejection .
3-5
Indicator Oscilloscope ..... 4-5
Cross Neutralization . ....
3-6
Operating Procedure and
Input
Overdrive Protection 3-7 Control
Settings . . .
. ...... 4-5
DC
Offset
............
3-7
Trouble Symptoms .
.... ... 4-5
Offset Generator ....... 3-7 Visual
Inspection .........
4-5
Input Overdrive Indicator .
3-8
Calibration Check ........
4-5
L F --3 dB Point Selector
. 3-9
Detailed Troubleshooting . . ...
4-5
Output Amplifier ......... 3-9
Test
Equipment Recommended 4-6
Gain Switching Amplifier
. 3-9
DC Balance Check ........ 4-6
Variable Output
stage . ... 3-11
Troubleshooting by Direct
Signal Output Amplifier . . 3-11
Replacement
............ 4-6
Trigger Output Amplifier . . 3-11
Components Checks ......
4-6
Indicator Oscilloscope Readout 3-11
Transistors ...........
4-6
Probe Sensing .........
3-11
Diodes . .... .........
4-8
Trace
Identify ......... 3-11
Resistors . . ... . ... .... 4-8
Capacitors .... ..... ..
. 4-9
MAINTENANCE
Repackaging
for Shipment . ... 4-9
Introduction ...............
4-1
Preventive Maintenance
...... 4-1
General
4-1
SECTION 5 PERFORMANCE
CHECK/
................
CALIBRATION
PROCEDURE
Cleaning
Front Panel ...... 4-1
Introduction ...... ......... 5-1
Cleaning Interior .........
4-1
Test Equipment
Required . . ... 5-1
Visual Inspection
. . ....... 4-1
General ................
5-1
Transistor Checks
..... . . . 4-1
Short Form Procedure ....... 5-2
Calibration ..............
4-1
Performance Check/Calibration
Corrective Maintenance ......
4-1
Procedure ............. ...
5-3
General . .... . . .........
4-1
General
................
5-3
Obtaining Replacement Parts 4-2
Preliminary Procedure
..... 5-3

SECTION 5
REV
B, MAR 197 9
Conpensation ... . . ....
5-9
-Input Atten
Compensation 5-9
---Input
Atten Shunt
Compensation ......... 5-10
H F -3dB Point ........

5-11
Abbreviations
and symbols used in this manual are based on or
taken
directly from IEEE Standard 260 "Standard
Symbols for
Units", MIL STD-12B and other standards of
the electronics
industry . Change information, if
any,
is
located atthe rear of this
manual .
PERFORMANCE
CHECK/
CALIBRATION
PROCEDURE
(cont)
Page
L F ---3 dB Point . . ......

5-11
CMRR ..............
. 5-12
Input Overdrive
Indicator . 5-12
Differential
Dynamic Range 5-13
Overall Noise Level
(Measured
Tangentially) . . 5-13
Overdrive
Recovery Time .

5-14
ELECTRICAL PARTS
LIST
Abbreviations and Symbols
Parts Ordering Information
Index of Electrical
Parts List
Electrical
Parts List
DIAGRAMS AND MECHANICAL
PARTS ILLUSTRATIONS
Diagrams
Mechanical
Parts Illustrations
MECHANICAL PARTS LIST
Mechanical Parts List
Information
Index of
Mechanical Parts
Illustrations
Mechanical Parts List
Accessories
7A22
PERFORMANCE CHECK/
SECTION 5
CALIBRATION PROCEDURE
(cont)
Page
Check or Adjust ..........
5-4
AC
Step Atten Balance . . .
5-4
Variable Balance .......
5-4
Coarse
DC Balance
.....
5-4
+ Gate Current Zero .....
5-5
---- Gate Current
Zero ..... 5-5
GAIN ...............
5-5
VARIABLE Control Ratio . .
5-5
VOLTS/DIV Gain Switching
5-5
SECTION 6
Isolation between
4- and --
Inputs
. ........... . . . 5-6
Total DC Offset Range ... 5-6
C241 +Cross Neutralization
5-7
C141 --Cross Neutralization
5-7
C115 X1 -I-Input
Atten Time
Constant
. . . . ......... 5-7
SECTION 7
C215 X1
-Input Atten Time
Constant . ............
5-7
Input Atten Accuracy ....
5-8
Input Atten
Differential
Balance ..............
5-8
SECTION 8
--l-Input Atteh Series

Type
7A22
Fig . 1-1 . Type
7A22 Differential Amplifier .

Introduction
The Type
7A22 Vertical Plug-in is a DC coupled differ-
ential
amplifier with excellent common-mode rejection char-
acteristics
and high gain for low level applications .
The
DC Offset capability of the Type 7A22 allows the
display
of the very small low-frequency signals
containing
a large
DC component, at deflection factors not possible
with
AC coupling
.
The vertical deflection factor range of the
Type
7A22 is from 10/W to 10 V .

The high and
low fre
quency --3 dB

points can

be selected at the front
panel,
to set the bandwidth of the instrument . Thus, for
low fre-
quency applications the signal-to-noise
ratio can be improved
by restricting the bandwidth of the Type
7A22 . The band-
width selection and excellent drift-with-time characteristics
provide measurement
capabilities in the biomedical, trans-
ducer, and other areas which
require stable, low deflection
factor, low noise measurements .
The Type7A22 is designed for
use in Tektronix 7000 Series
oscilloscopes .
The electrical
characteristics described in this section are
valid over the stated
environmental range for instruments
calibrated at
an ambient temperature of +20'C to +30 ° C
and after a5
minute warmup unless otherwise noted .
ELECTRICAL CHARACTERISTICS
Characteristic
Deflection Factor
(VOLTS/DIV)
Gain Ratio
Accuracy
VAR (CAL IN) Range
Differential Signal Range ^
(DC OFFSET' not used)
10 ~tV/Div to
10 mV/Div
20 mV/Div to
0 .1 V/Div
0 .2 V/Div to
1 V/Div
2 V/Div to
10 V/Div
Change
information, if any, affecting this section will
be found at the
rear of the manual .
Performance Requirements
Within 2% with GAIN adjusted at
1 mV/div
Continuously variable ; extends de-
flection factor to at least 25 V/div
Permits adjustment of deflection
factor at 1 mV/DIV for all main-
frames
At least _F_-1 V
At least J-10 V
At least
--1-100V
At least 4-1000V
DC OFFSET
COARSE Range from
Electrical Zero
10 [tV/Div to
10 mV/Div
20 mV to 0 .1
V/Div
2 V to 10 V/Div
Frequency Response (8
div Reference)
Overall Frequency
Response DC (Direct)
Coupled Input
AC (Capacitive) Cou-
pled Input Lower
Bandwidth Frequency
Bandwidth Limit
Accuracy
HF ---3 dB POINT
100 Hz to 1 MHz
Accuracy
LF
-3 dB POINT
0 .1 Hz to 10 kHz
20 mV/Div to
0 .1 V/Div
0 .2
V/Div to
10 V/Div
Common-Mode
Rejection Ratio
DC (Direct) Coupled
AC (Capacitive)
Coupled
Type 7A22
At least
+100V
to
-100V
At

least

+1000V

to

--1000 V
------ - --- -- -----------

- ------
Within 10% of selected frequency
6 steps in a 1-10 sequence
10 /us or less to recover to within
0 .5% of zero level after the re-
moval of a
+
or --- test input
ap-
plied for 1 s . Test signal not
to ex-
ceed Differential Signal Range .
Specified aberration
(0 .5%) based
on test signal amplitude
At
least +10V and -10V
At least +100V and -100V
At least +500V and ----500V

0 'o
CMRR
x m m a
10
3
n 0 3 3 0 3 0 a
10
Hz

100
Hz

1
kHz

10
kHz 100 kHz

1
MHz
m
Verification
Points
Q O 3
T
a N N
N n 3

ELECTRICAL CHARACTERISTICS (cont)
Characteristic v
Maximum Input Voltage
(each input)
DC (Direct) Coupled,
DC
-f-
Peak AC, AC
Component 1 MHz or
less
10 ttV/Div

to

10
mV/Div
20 mV/Div

to

0 .1
V/Div
.2 V/Div

to

10V/
Div
AC (Capacitive)
Coupled
Input DC Voltage
AC (Capacitive)
Coupled
Input DC Rejection
Input R and
R
C
__
Resistance
Capacitance
R
& C
Product
Maximum Input Gate
Current
10 [,V/Div to

10 mV/
Div
Displayed - Noise
(Tan-
getially Measured)
20
mV/Div to 10V
Div
Display Shift at 10 ttV
/Div
(AC
Coupled)
Variable Balance
_
Performance _ Requirements 'N `-
-j-_ 15 V
-1-200 V
-A-500 V
-+500V, each input
At least 4 X 10 5 :1
0 .2 T div ^ or less shift with VARIABLE
control turned from fully cw to
fully ccw position
16,utV or 0 .1 Div (whichever is
greater), 1 MHz HF ----3 dB POINT,
source resistance 250 or less
DC Drift
Drift with Time (Ambi-
ent Temperature and
Line Voltage Constant)
Short Term
Drift with Ambient
Temperature (Line
Voltage Constant)
Isolation between
-I-
and
-- Inputs
(+
INPUT to
an Open - INPUT, --
INPUT to an Open
INPUT)
Long Term
Finish
' Dimensions
Weight
ITEM
Specification-Type 7A22
5 tkV (P-P) or 0 .1

div (whichever
is greater) in any minute after 1
hour warmup
10 ~tV (P-P) or 0 .1 div (whichever
is greater) in any hour after 1
hour warmup
501AV/ ° C or less
At least 200
:1,
DC to
1 MHz
____ _CHARACTERISTIC
Front panel is anodized aluminum
___N_~4%
inch L
X
2% inch ^ W X
-z 2 5 / 8 Ibs
1 MQ ZL .
1
Approximately 47 .0 pF
Within between all de-
PLUG-INTESTED
ENVIRONMENTAL
OUTOF
INDICATOROSCILLOSCOPE
CHARACTERISTIC
flection factors
_
Altitude
x-25°C____
+50C __- .--
Non-operating To 50,000 feet
and --55°C
Transportation Qualified
under National Safe
-f-20 pA -t=100 pA each input
Transit Committee test procedure
-+-40 pA -±-=200 pA Differentially
1A,
Imo_ . . ... ._ .__ . .___ .___
Category I I
-+-_ 10 pA -t :-20 pA
___ . ._ . .__ . ._ ._ . . .
.±-4
div :+-20 div
PHYSICAL

Introduction
Change information, if any, affecting this section will
be
found at the
rear of the manual .
This section opens with a brief functional description of
the front-panel controls, input overdrive lamp, and input
connectors . Following the front-panel description is a familiar-
ization procedure and finally a general discussion of the
operation of the Type 7A22 .

-f-
INPUT
CONTROLS AND CONNECTORS
INPUT

Input overdrive indicator lamp turns on
OVERDRIVE

to
indicate
excessive differential drive
to the input amplifier
stage . Lights when
the differential dynamic range
between
input connectors is exceeded .
VOLTS/DIV

Volts per displayed division . Nineteen
position switch used to select the cali-
brated deflection factors .
VARIABLE

Two-position
switch activated by the
(CAL IN)

VARIABLE
knob to select calibrated or
uncalibrated deflection factors . At the
IN
position, the VARIABLE
control is in-
operative and the deflection factor
is
calibrated . When pressed and released,
the knob moves outward to activate the
VARIABLE control for
uncalibrated de-
flection factors
.
The uncalibrated posi-
tion provides continuously variable un-
calibrated attenuation between the cali-
brated deflection factors and extends
the deflection factor to at least 25
VOLTS/DIV .
GAIN

Screwdriver adjust control to set the CRT
display scale factor to agree with the
VOLTS/DIV switch indication . Adjusted
for proper deflection with the VOLTS/
DIV switch set to the 1 mV position .
POSITION

The control that vertically positions the
trace or display .
IDENTIFY

Momentary contact, push-button switch,
concentric with POSITION . Will cause
the trace, representing the output of the
Type 7A22, to move a small amount
when pressed . Aids in identifying the
Type 7A22 trace when multiple traces
are displayed .
HIGH

Nine position switch to select the ap-
FREQUENCY

proximate
high frequency
----3 dB
point .
----3 dB POINT - The switch positions are : 100 Hz, 300 Hz,
1 kHz, 3 kHz, 10 kHz, 30 kHz, 100 kHz,
300 kHz, and 1 MHz
.
LOW

Eight position switch to select DC coupl-
FREQUENCY

ing or the approximate low frequency
-3 dB POINT

----3 dB points . The switch positions are :
DC OFFSET, DC, .l Hz, 1 Hz,

10 Hz,
100 Hz, 1 kHz, and 10 kHz .
-- INPUT
J_
INPUT WAVEFORM
AC-GND-DC
Type 7A22
Signal input connector . Positive input
produces deflection upward (see Fig .
2-1) .
Signal input connector . Positive input
produces deflection downward (see
Fig .
2-1) .
Fig . 2-1 . Signals applied to the +INPUT
connector produces an
upright display,
while
signals
applied to the --INPUT are inverted .
A miniature illuminated push-button
type
switch . The buttons are
interlocked so
that only one button may be
depressed
at one time . When the 'AC' button is
depressed the signal is coupled through
0 .1'cF to the Input Amplifier and only
the varying component of the input sig-
nal is amplified .
When the 'DC' button is depressed the
signal is coupled directly to the Input
Amplifier and the entire input signal,
both
AC
and DC, is amplified . When
the 'GND' button (or none of the but-
tons) is depressed, the signal is coupled
through 0 .1 al` and through 1 M52 to
ground . The Amplifier Input is grounded
in this condition .