Tektronix 7A24 User manual

PLEASE CHECK FOR
CHANGE INFORMATION
AT THE REAR OF
THIS MANUAL .
INSTRUCTION MANUAL .
Tektronix, Inc .
P .O . Box 500
Beaverton, Oregon

97077

Serial Number
070-2391-00

First Printing SEP 1977
Product Group 42

Revised
AUG
1986
COMMITTED TO EXCELLENCE
LIFI
103000-UP

Copyright (~' 1977 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 . TELEDUIPMENT
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 parcel 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 :
13000000

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

LIST OF ILLUSTRATIONS . ........ . ........ . ........ . ........................
ii
LIST OFTABLES ........... . ..... . . .
.
... . . . . .
. ................................. ii
SAFETY INFORMATION
. . . .............................. . ..... . . . . ..... . . . . .
SECTION 1
OPERATING INSTRUCTIONS
CONTROLS AND CONNECTORS ...... . ........ . ........
. ..... 1-1
FUNCTIONAL CHECK ............ . ........ . ........ . ........ . . . . .
.1-1
SETUP PROCEDURE . ........ . ..... . . . . ..... . . . . ..... . . . . . . . .
.1-1
CHECKOUT PROCEDURE
. . . ........ . . . . ..... . ........ . . . . . .1-3
DETAILED OPERATING
INFORMATION ................... .1-3
INTRODUCTION ....... . .......................................
. .1-3
SIGNAL CONNECTIONS ..... . . . . ........ . ..... . ........ . ...
.1-3
VERTICALGAIN
CHECK AND ADJUSTMENT ...... .1-3
INPUT COUPLING ..... . ..... . ....... .
. ........ . ........ . ....... 1-3
INPUT PROTECTION
FUSE ......................... . ... . . . .1-4
VERTICAL DEFLECTION FACTOR
. . . ........ . ........ . . . .1-4
POLARITY SWITCHING ....... . ........ . ........ . ........ . . .
.1-4
DISPLAY MODES
...... . ........ . ..... . . . . ..... . . . . ..... . . . . . . .1-4
TRIGGER MODES
... . . .
. ..... . . . . ..
. ..... . ..... . . . . ..... . . . . ... 1-4
TRACE
IDENTIFICATION . . . . . . . ........ . ........ . ........... .1-5
BASIC
APPLICATIONS . . . . . ....................................... 1-5
GENERAL ........ . ........ . ...................................... .1-5
PEAK-TO-PEAK VOLTAGE MEASUREMENTS ....... 1-5
INSTANTANEOUS VOLTAGE MEASUREMENTS
. . . . 1-6
COMPARISON MEASUREMENTS . ................. . . . . .
.1-6
DUAL TRACE PHASE
DIFFERENCE
MEASUREMENTS
. . . . . ....................................... . .1-7
HIGH RESOLUTION
PHASE MEASUREMENTS . . . . .1-8
COMMON
MODE REJECTION ..... . . . . ..... . . . . ..... . . . . .1-8
SECTION
2 SPECIFICATION
Electrical ... . ..... . ............ . ..... . . . . ..... . . . . . . . ..... . ....... .2-1
Environmental ...... . ..... . . . . ..... . . . . ........ . ........ . ....... .2-2
Physical ............... . ..... . . . . ........ . ........ . ........ . ....... .2-2
- ---------

------
-
THE REMAINING PORTION OF THIS TABLE OF CONTENTS
LISTS THE SERVICING INSTRUCTIONS . THESE
SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED
PERSONNEL ONLY . T O AVOID ELECTRICAL SHOCK, DO
NOT PERFORM ANY SERVICING OTHER THAN THAT
CALLED OUT IN THE OPERATING INSTRUCTIONS UNLESS
QUALIFIED TO DO SO .
SECTION 3
THEORY OF OPERATION
INTRODUCTION .......... . ..... . . . . ........ . ........
. .............. .3-1
BLOCK

DIAGRAM ....... . ........ . ........ . ........................ 3-1
CH 1

AND CH 2 ATTENUATORS
.............................
3-1
CH

1

AND CH

2 AMPLIFIERS ...........................
. . . . . . 3-2
DISPLAY SWITCHING AND OUTPUT ... . ..... . ..
. ..... .
..... 3-2
CH 1 AND CH 2 READOUT ... . ........ . ........ . ........ . . . . .
.3-3
PAGE
CHANGE
INFORMATION
SECTION 6 INSTRUMENT
OPTIONS
7A24 (SN B103000
& UP)
SECTION 7 REPLACEABLE
ELECTRICAL PARTS
SECTION 8
DIAGRAMS AND CIRCUIT BOARD
ILLUSTRATIONS
SECTION 9 REPLACEABLE
MECHANICAL PARTS
PAGE
SECTION
4 MAINTENANCE
PREVENTIVE MAINTENANCE . . .................................... .4-1
GENERAL ..... . ......... . ..... . . . . ........ . ........................... .4-1
CLEANING . ............ . ..... . . . . .................................... .4-1
LUBRICATION ......... . ........ . .................................... .4-1
TROUBLESHOOTING . . . . . ........ . .................................... .4-3
GENERAL ............... . ..... . . . . .................................... .4-3
TROUBLESHOOTING AIDS . .....................................
4-3
TROUBLESHOOTING EQUIPMENT .......................... .4-4
TROUBLESHOOTING PROCEDURE . . . ........ . ........ . . . . . . . 4-4
CORRECTIVE
MAINTENANCE . .................................... .4-6
GENERAL . . . ............ . ........ . .................................... .4-6
OBTAINING REPLACEMENT PARTS ......... . ............... 4-6
SOLDERING TECHNIQUES ...................... . ........ . ..... .4-6
COMPONENT REPLACEMENT . . . . . ..................... . ..... .4-7
FUSE AND ATTENUATOR REPLACEMENT .......... .4-7
SEMICONDUCTOR REPLACEMENT ...... . ............... 4-7
CIRCUIT BOARD REMOVAL ............... . ........ . ..... .4-7
INTERCONNECTING PINS ............................ . ..... .4-8
SWITCH REPLACEMENT .................... . ........ . ..... .4-8
READJUSTMENT AFTER REPAIR ............. . ............... 4-9
REPACKAGING FOR SHIPMENT .............................. 4-9
SECTION 6 PERFORMANCE CHECKAND
ADJUSTMENT
PRELIMINARY INFORMATION
................................
.5-1
ADJUSTMENT
INTERVAL .................................. .5-1
TEKTRONIX
FIELD SERVICE ................. . ........... . .5-1
USING THIS PROCEDURE
.............. . ........ . ........ . .5-1
TEST EQUIPMENT
REQUIRED ............. . ........ . ........ . .5-1
SPECIAL CALIBRATION FIXTURES . . . ........ . ........ . .5-1
TEST
EQUIPMENT ALTERNATIVES . . . ........ . ........ . . 5-1
PRELIMINARY PROCEDURE ......................... . ........ . .5-4
INDEX
TO
PERFORMANCE CHECK AND
ADJUSTMENT PROCEDURE
...................... . . . . ........ . . 5-4
LOW FREQUENCY PROCEDURE ............................. .5-5
HIGH FREQUENCYPROCEDURE ............... . ........... . .5-8

7A24 (SN
B103000
&
UP)
Figure
No .

PAGE
1-1

7A24
Dual-Trace Amplifier . . . .. ... . .. ... ...

iv
1-2

Release
Latch . . . ... ... .. ... ... ... ... ...
1-1
1-3

7A24 Front-Panel Controls
and Connectors .. ... 1-2
1-4

Measuring the peak-to-peak
voltage
of a waveform . . ... ... .. ... ... ... .. ...
. 1-5
1-5

Measuring
instantaneous voltage with
respect to some
reference .. ... ... .. . . . . . . .
1-6
1-6

Measuring phase difference between
two signals . 1-8
1-7

High resolution phase measurement
using
time-base magnifier . ... .. ... ... . .
. . . . . . . 1-8
1-8

Using the
ADD mode for common-mode
rejection
.. ... ... ... . .. ... ... .. . .. ... .1-9
2-1

7A24 dimensional drawing . . ... . .
. . . . . . . . . . 2-2
4-1

Lubrication procedure for a typical cam
switch . . . 4-1
4-2

Color code for resistors and capacitors . . . .. ..
. . 4-2
4-3

Semiconductor
electrode configurations . . . . . . . . 4-3
4-4

Orientation of multi-connector holders . . . . . . . . .
4-4
4-5

Coaxial end-lead connector assembly

.. .. ... . .
4-8
4-6

Exploded view of
circuit-board pin and ferrule

. . . 4-9
5-1

Test circuit
for Input Resistance Check/Adjust
step . ... .... .. .... ... .. ... ... ... .. ...
5-5
5-2

Approximately 2 .5 division pulse obtained
in step 11f . . . .. ... ... . .. ... .. . ..
. .. ... 5-9
5-3

Short pulse
before cancellation .. ... ... . .. ... 5-9
The
illustrations in Section 8 are located near their associated
diagrams on foldout pages .
8-1

Circuit board
locator .
8-2

Semiconductor lead
configurations .
8-3

A1
and
A3
Attenuator circuit board assembly .
8-4

A5 and A6 Amplifier circuit board assembly .
8-5

A5 and A6 Amplifier circuit board assembly .
8-6

A2 and A4 Readout circuit
board assembly .
8-7

7A24 Adjustment
locations .
8-8

7A24
Troubleshooting chart .
ILLU
ii

REVASEP 1980
Table
No .
PAGE
1-1 Trigger Signal Source ... .. ... ... ... ... ...
1-5
2-1 Electrical
Specifications
. . .
. ... ... .. . . . . . . . 2-1
2-2 Environmental
Specifications ... .. . . . . . . . . . .
2-2
2-3 Physical
Specifications . . . . . . . . .. ... ... ... .
2-2
5-1
Test Equipment . ... ... .. . .. ... ... ... . . . .
5-2
5-2 Attenuator Accuracy ... .. ... ... .. . .. . . .
. . 5-7

This manual contains safety
information which the user must follow to ensure safe operation of
this instrument .
WARNING information is
intended to protect the operator ; CAUTION information is intended to
protect the
instrument . The following are general safety
precautions that mustbe observed during all phases of
operation and
maintenance .
GROUND THE
INSTRUMENT
DO
NOT OPERATE IN EXPLOSIVE ATMOSPHERE
AVOID LIVE CIRCUITS
DO NOT SERVICE OR
ADJUST ALONE
WARNING
STATEMENTS
WARNING
To reduce electrical-shock
hazard, the mainframe (oscilloscope) chassis must be grounded . Refer to
the mainframe
manual for grounding
information .
Do
not operate this instrument in an area
where flammable gases
or
fumes are present . Such operation
could
cause
an explosion .
Electrical-shock hazards are present in
this instrument . The protective instrument covers must not be
removed by
operating personnel . Component
replacement and internal adjustments must be referred to qualified
service
personnel .
Do not service
or make internal adjustments to this instrument unless another person,
capable of giving first aid
and resuscitation, is
present .
7A24 (SN B103000 & UP)
Warning
statements accompany potentially dangerous procedures in this manual
. The following warnings appear
in
this
manual and are listed here for additional emphasis .
To avoid electric-shock hazard, disconnect
the instrument from the power source before soldering .
To avoid electric-shock
hazard, disconnect the instrument from the power source before replacing
components .

7A24 (SN 6103000 & UP)
iv
7A24 FEATURES
The 7A24 is a
dual-channel, wide-bandwidth amplifier plug-in unit designed for use with Tektronix
7000-series Oscillo-
scopes . Each channel
has
an
input impedance of 50 ohms and is internally fused . Internal
attenuators and gain circuits
are switched to
correspond
to
the settings of the VOLT/DIV switches . Channel 2 can be inverted
and added to channel 1
for differential
measurements
.
Figure 1-1 . 7A24 Dual-Trace Amplifier .

The 7A24 Vertical
Amplifier unit operates with any Tektronix 7000-series oscilloscope mainframe and any
78-
series
time-base unit to form a complete oscilloscope system . This section of the
manual describes the operation
of the
front-panel controls and connectors, provides a functional check procedure, detailed
operating information,
and basic applications
for this instrument .
INSTALLATION
The 7A24 is calibrated and
ready for use as received .
It can be
installed in any compartment of Tektronix
7000-series
oscilloscopes, but is principally used in
vertical plug-in
compartments . To install, align the
upper and lower
rails of the 7A24 with the
oscilloscope
tracks and fully insert it . The 7A24 is
fully inserted when
the front is flush with the front of
the oscilloscope
and the latch at the bottom-left corner
of the 7A24 is in
place against the front panel . See
Figure 1-2 for the latch location
.
To remove the 7A24, pull on the
latch (which is
inscribed with the unit
identification "7A24") and the
7A24 will unlatch .
Continue pulling on the latch to
slide the 7A24 out of the
oscilloscope .
Figure 1-2 . Release Latch .
CONTROLS
AND
CONNECTORS
All controls
and connectors required for operation of
the
Vertical Amplifier are located on the front panel .
Figure
1-3 provides a brief description of all front-
Section
1-7A24 (SN B103000 & UP)
panel controls and connectors .
See Detailed Operating
Instructions for more
information .
FUNCTIONAL
CHECK
The following
procedures are provided for checking
basic instrument functions .
Refer to the description of
the controls
and connectors while performing this
procedure . If performing the functional check
procedure reveals
a malfunction or possible incorrect
adjustment,
first check the operation of the associated
oscilloscope
and plug-in units, then refer to the
instruction manual
for maintenance and adjustment
procedures .
SETUP PROCEDURE
1 . Insert the 7A24 into the left vertical plug-in
compartment of a 7000-series oscilloscope mainframe .
2 . Insert a
7000-series time-base unit into the B hori-
zontal plug-in
compartment .
3 . Set the controls as follows
:
7A24 Vertical Amplifier
CH 1, CH 2 POSITION ...... .Midrange
CH 2 POLARITY ................. +UP
CH 1, CH 2VOLTS/DIV ..... 10
mV
CH 1, CH 2 INPUT
COUPLING .......................
.DC
CH 1, CH 2 VARIABLE ....... CAL IN
DISPLAY MODE ................. CH

1
TRIGGER
SOURCE ............. MODE
Time Base
Level/Slope ....................... Centered on
positive
slope
Triggering Mode ...............
.P-P Auto or Auto
Coupling ..........................
.AC
Source ............................. .Int
Time/Div ......................... .1 ms
Variable ........................... .Cal In
Magnifier ......................... .In
Position ...........................
.Midrange

Operating
Instructions--7A24 (SN B103000 & UP)
Cfi 1 POSITION ----~_-------
.-_ . .
Controls position of the CH 1 trace L
I
and ADD display mode trace
.
IDENTIFY
Deflects trace about 0 .3 division for
trace identification, in instruments
with readout also replaces readout
with the word IDENTIFY .
C :
F' 1~input connector
Provides siynai
connection to
CH
1 .
H 2 Pc7LARITY
Provides rneans of inverting the CH

-=
CH L POST T ION
Controls the pusition of the CH 2~r
trace only . Dis abled in Add .
FIT T input corm
Provides signal connection to CH 2 .1
VARIABLE - VOLTS/DIV - ~ -
Provides continuously
variable
uncalibrated settings between
cal-
VOLTS/DIV
Selects calibrated deflection factors
from 5 mV/div to 1 V/div ; eight
steps in a 1-2-b sequence .
Figure 1-3 . 7A24 Front-Panel controls and connectors .
GAIN adjustment
When
the VARIABL
F
control is
pushed in, it becomes n front-parcel
screwdriver adjustment for calibra
tion of deflection facto
Input Coupling
Selects signal input m od e .
TRIGGER SOURCE
Selects souce of the trigger signal
DISPLAY MODE
Selects the mode of operation .

Mainframe
Vertical

Mode .................... Left
Horizontal Mode ............... .B
Intensity ............................ CCW
Calibrator ......................... .1 kHz, 40 mV
under
load
Trigger Source ................... Left Vert
4 . Connect the mainframe to a power source
which
meets the voltage and frequency requirements of the
mainframe power supply .
5 . Turn the mainframe power on and allow about
five
minutes warmup .
6 . Advance the Intensity until a
free-running trace is
observed . Adjust the
position controls to center the
trace on the crt .
7 . Connect the
mainframe calibrator output to the
7A24 CH 1 Input connector
.
CHECKOUT PROCEDURE
8 . Check the crt display
for four divisions of vertical
deflection . If necessary, push in the CH 1 VARIABLE
control with a screwdriver and adjust the vertical
gain
for exactly four
divisions .
9 . Press the
IDENTIFY button and check that the
display moves upward about 0 .3
divisions
.
Also check
that the readout
information on the crt is replaced by
the word "IDENTIFY" .
10 . Press and release the CH 1 VARIABLE control to
its
outward position . Turn the VARIABLE control fully
counterclockwise and check for 1 .6 divisions or less
display amplitude . Press the VARIABLE control to the
CAL
IN position .
11 . Change the 7A24 Vertical Amplifier CH 1
VOLTS/DIV to 0 .1 V, the
mainframe calibrator volts to
0 .4 V (0 .2 V), and the time-base
Triggering
Source to
Ext . Connect the calibrator output
through a BNC T
connector
to the time-base Ext Trig In and the
7A24
CH
2 Input . Set the POLARITY switch to INVERT to
display
the opposite polarity of the square wave .
12 .
Return the POLARITY switch to +UP and set the
TRIGGER SOURCE to CH 1 . Change the time-base
Triggering Source to Int and observe that the trace is
no longer triggered .
13 . Return the TRIGGER SOURCE to
MODE and set
the DISPLAY
MODE to ADD . Observe that only the CH
1 POSITION
control moves the trace .
14 . Set the
DISPLAY MODE to CHOP . Observe that
the
channel one trace is controlled by the CH 1
POSITION control and the channel two signal is
controlled by the CH 2 POSITION control .
REVA MAR 1980
Operating Instructions--7A24 (SIN B103000 & UP)
This completes the basic
operating procedure for the
7A24 . Instrument
operation not explained here or
operation which needs further
explanation
is
discussed
under Detailed Operating
Information .
INTRODUCTION
DETAILED OPERATING
INFORMATION
For single-trace operation,
either of the two identical
amplifier channels can be
used independently by
setting the
DISPLAY MODE and TRIGGER SOURCE
switches
to CH 1 or CH 2 and connecting
the signal
to be observed
to the appropriate Input .
In the
discussions to
follow, single-trace
operations using CH
1 only
apply equally to CH 2 only
.
SIGNAL CONNECTIONS
The 50-ohm
input impedance of the 7A24 is ideally
suited for making
waveform measurements on 50-ohm
systems, in that
50-ohm coaxial cables can
be
connected
directly to the Input of
the 7A24 . The
7A24,
however, should not be connected
directly to a
power supply, power
line, or other voltage source that
would exceed the input
voltage limits of the 7A24 (see
Specification section, Table 2-1)
.
Probes
recommended
for use with the 7A24 are
the P6056 (10X) and
P605,7 (100X) . Both probes
are compatible with'50-
ohm systems, and will
allow optimum frequency
response . These probes also
contain trace IDENTIFY
and readout encoding
functions . A one-megohm input
impedance may be achieved by using the
P6201 FET
Probe .
VERTICAL GAIN
CHECK AND ADJUSTMENT
To check the gain of either channel, set the VOLTS/DIV
switch to 50 mV and connect a 0 .4 V (under load), one-
kilohertz signal from the oscilloscope calibrator to the
Input connector of the
channel
being checked . The
vertical
deflection should be exactly four divisions . If not, adjust
the front-panel GAIN for exactly fourdivisions of deflection
.
The GAIN adjustment is engaged by pressing in the GAIN
control knob and turning the knob with a narrow-blade
screwdriver (see Fig . 1-3, Front Panel Controls and Connect-
ors) . Turn the knob clockwise, then counterclockwise, until
the GAIN control is engaged . When the GAIN control is
engaged,
the vertical deflection will change as the knob is
turned . Turn the GAIN control knob
with the screwdriver
until the deflection is set to exactly
four divisions, then
remove the screwdriver .

- .
INPUT
COUPLING
The Channel 1 and
Channel 2 Input Coupling
(OFF-
DC)
switches select
the signal input coupling
mode .

Operating Instructions--7A24
(SN
B103000 & UP)
DC
The DC position couples both ac and do components
of the signal
into
the
input amplifier .
A 50-ohm
impedance is presented to the signal source .
OFF
The OFF position disconnects the signal source from
the amplifier and connects it to a resistive 50-ohm
termination .
INPUT PROTECTION FUSE
A fuse in the input of each channel protects
the 7A24
from damage due to excessive signal voltages . If
this
fuse is open, no display can be obtained .
If no waveform can be displayed, but the POSITION
control will move the trace on the crt, the condition of
the fuse should be checked by a qualified service
technician .
VERTICAL DEFLECTION
FACTOR
The
amount of
vertical
deflection produced by a signal
is
determined by the signal
amplitude, the attenuation
factor
of
the probe, the
setting of the VOLTS/DIV
switch, and the setting
of the VARIABLE control . Cali-
brated deflection factors indicated by the
settings of
the VOLTS/DIV switch apply only
when the VARIABLE
control is in the calibrated (CAL IN)
position
.
The VARIABLE control provides
variable, uncalibrated
settings between the calibrated steps of the
VOLTS/DIV switch . With
the VARIABLE control fully
counterclockwise and the
VOLTS/DIV switch set to 1
volt/division the uncalibrated vertical
deflection factor
is extended to at least 2
.5 volts/division . By applying
a
calibrated voltage source to the Input connector,
any
specific deflection factor can be set within the range
of the
VARIABLE control .
POLARITY SWITCHING
The CH
2 POLARITY switch may be used to invert the
displayed
waveform of the signal applied to the CH 2
Input . This is particularly useful in added-mode
operation of the 7A24when differential measurements
are to be made . The CH 2 POLARITY switch has two
positions, +UP and INVERT . In the +UP position, the
displayed waveform will have the same polarity as the
applied signal and a positive do voltage will move the
crt trace up . In the INVERT position, a waveform at
the CH 2 Input will be displayed on the crt in inverted
form and a positive do voltage will move the trace
down .
DISPLAY MODES
For single-trace operation, apply the signal either to
the CH 1 Input or the CH 2 Input and set the
DISPLAY MODE switch to the corresponding position :
CH 1 or CH 2 .
To display a signal in
one channel independently
when
a
signal
is also applied to the other channel,
simply select the desired channel
by setting the
DISPLAY MODE switch to the appropriate
CH 1 or CH
2 position .
Alternate Mode
The ALT position of the DISPLAY MODE switch
produces
a display which alternates between Channel
1 and Channel 2 with each sweep on the crt .
Although the
ALT mode can be used at all
sweep
rates, the CHOP mode provides a more satisfactory
display
at sweep rates below about 0 .5 millisecond/
division . At slow sweep rates, alternate mode
switching becomes visually perceptible .
Add Mode
The ADD position of the DISPLAY MODE switch can
be used to display the sum or difference of two
signals, for common-mode rejection to remove an
undesired signal, or for do offset (applying a do voltage
to one channel to
offset the do
component of a signal
on the other channel)
.
The overall deflection factor in
the ADD mode
with both VOLTS/DIV
switches set to
the same
position is the deflection factor
indicated by
either VOLTS/DIV switch
.
However, if the CH 1 and
CH 2VOLTS/DIV switches are set to different
deflection factors, the resultant amplitude is difficult to
determine from the crt display . In this case, the
voltage amplitude of the resultant display can be
determined accurately only if the amplitude of the
signal applied to one
channel
is
known . In
the ADD
mode, positioning of
the trace is controlled by
the
Channel 1 POSITION control only
.
Chop Mode
The CHOP position of the DISPLAY MODE switch
produces a display which is electronically switched
between channels at approximately a 500 kilohertz
rate (controlled by mainframe) . In general the CHOP
mode provides the best display at sweep rates slower
than about 0 .5 millisecond/division or whenever dual-
trace, non-repetitive phenomena is to be displayed .
TRIGGER MODES
CH 1
The CH 1 position of the TRIGGER SOURCE switch
provides a trigger signal obtained from the signal
applied to the CH 1 Input
connector . This provides a
stable display of the
signal applied to the CH 1 Input
connector .
CH 2
The CH
2 position of the TRIGGER SOURCE switch
provides a trigger signal obtained from the signal
applied to the
CH 2 Input
connector
. This provides
a
stable display
of the signal
applied to the CH
2 Input
connector .

MODE
In this position of
the TRIGGER SOURCE
switch, the
trigger
signal for the time-base
unit is dependent on
the
setting of the DISPLAY MODE
switch . The trigger
source
for each position of
the DISPLAY MODE switch
is shown
in Table 1-1 .
TABLE
1-1
Trigger
Mode Sources
Mode

Trigger Signal Source
TRACE IDENTIFICATION
GENERAL
BASIC
APPLICATIONS
PEAK-TO-PEAK
VOLTAGE
MEASUREMENTS
1 . Apply the
signal to either Input connector .
3 . Set the
Input Coupling switch
to DC .
CH
1, ^ Channel_ .1
CH
2 __ Channel
2
ADD ~_ -
Algebraic sum . of . Channel , 1_ . _and_Channel
2
CHOP

Algebraic
sum of Channel 1 and _ Channel l_2
ALT

Alternates between
Channel 1~and Channel 2
When
the IDENTIFY button
is pressed, the trace is
deflected about 0 .3
division to identify the 7A24 trace .
This feature is particularly
useful when multiple traces
are
displayed . In
instruments with readout, pressing
the
IDENTIFY button also
replaces the deflection factor
readout with the word "IDENTIFY"
.
The following information
describes the
procedures
and
techniques for making basic
measurements with a
7A24
and the associated Tektronix
oscilloscope and
time
base . 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 not
described
in this manual . Contact your local
Tektronix
Field
Office or representative for
assistance in making
specific
measurements with this instrument
.
To make
peak-to-peak voltage
measurements, use the
following procedure :
2 . Set the
DISPLAY MODE and TRIGGER
SOURCE
switches to
display the channel used .
4 . Set the
VOLTS/DIV switch
to display about five
vertical divisions of the waveform
.
5 . Set the time-base
Triggering controls for a stable
display . Set the time-base
unit to a sweep rate that
displays several
cycles of the waveform .
Operating Instructions-7A24
(SN B103000 & UP)
6 . Turn
the 7A24 POSITION control so
the lower
portion of the waveform
coincides with one of the
graticule lines below the center
horizontal line, and
the top
of the waveform is
within the viewing area .
With the time-base
Position control, move the display
so one of the upper peaks
lies near the center vertical
line (see Fig . 1-4) .
Figure 1-4 .
Measuring the peak-to-peak voltage
of a
waveform .
NOTE
This
technique can also be used to make
measurements between two points on the
waveform,
rather than peak-to-peak .
Substituting
the given values :
Volts Peak-to-Peak = 4 .5 X
1 X 10
The peak-to-peak
voltage is 45 volts .
2391-10
7 . Measure the
divisions of vertical deflection peak-to-
peak . Check
that the VARIABLE (VOLTS/DIV) control is
in the CAL
IN position .
8 .
Multiply the deflection measured
in step 7 by the
VOLTS/DIV switch setting .
Include the attenuation
factor of the probe, if used
.
EXAMPLE : Assume
that the peak-to-peak vertical
deflection is
4 .5 divisions (see Fig . 1-4) using a
10X
attenuator probe,
and the VOLTS/DIV switch is set to
1 V .
Volts
vertical

probe
Peak-to-

=
deflection X

VOLTS/

X attenuation
Peak

(divisions)

DIV setting

factor

Operating
Instructions-7A24 (SN B103000
&
UP)
INSTANTANEOUS VOLTAGE MEASUREMENTS
To measure the do level at a given point on a
waveform,
proceed as follows :
1 . Connect
the signal to either Input
connector .
2 . Set the DISPLAY MODE and TRIGGER
SOURCE
switches to display the channel used .
3 . Set the VOLTS/DIV switch to display
about five
divisions of the waveform .
4
.
Set the Input Coupling switch to OFF and
position
the
trace to the bottom graticule line or another
reference line . If
the voltage is negative with respect
to
ground,
position the trace to the top graticule line
.
Do not
move the POSITION control after this reference
line has been established .
NOTE
To measure a voltage level with respect to
a voltage other than ground, make the
following changes to step 4 : Set the Input
Coupling switch to DC and apply the
reference voltage to the Input connector,
then position the trace to the reference
line .
5 . Set the Input Coupling switch to DC . The
ground
reference
line
can be checked at any time by
switching to the OFF position .
6 . Set the time-base
Triggering
controls for a stable
display . Set the time-base sweep rate for an optimum
display of the waveform .
7 . Measure the distance in
divisions between the
reference
line
and the point on the waveform at
which the do level
is to be measured . For example, in
Figure 1-5 the measurement
is between the reference
line and point A .
8 . Establish the polarity of the waveform . With
the
CH 2 POLARITY switch in the +UP position,
any point
above the reference line is positive .
9 . Multiply the distance measured in
step
7by the
VOLTS/DIV setting . Include the
attenuation factor of
the probe, if used .
EXAMPLE : Assume the vertical
distance measured is
3 .6 divisions (see Fig . 1-5) and the waveform
is above
the reference line using a 1OX
probe with a
VOLTS/DIV setting of .5 V .
Using the formula :
Instan- vertical

VOLTS/
probe
taneous = distance X polarity X

DIV

X attenua-
Voltage (divi-

setting tion
sions)

factor
Substituting the given values
:
Instantaneous
Voltage

=3
.6
X +1
X 0 .5 VX 10
The instantaneous voltage is
18 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 . This
is particularly
useful when comparing unknown
signals to a
reference amplitude . One use for
the comparison-
measurement technique is to facilitate
calibration of
equipment where the desired amplitude
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
the correct adjustment is indicated
by an exact
number of divisions of deflection . The following
procedure
describes how to establish arbitrary
units of
measure for comparison measurements .
To establish an arbitrary vertical deflection factor
based
upon a specific reference amplitude, proceed as
follows :
1 . Connect the reference signal to the Input
connec-
tor
.
Set the time-base unit sweep rate to display
several cycles of the signal .
2 . Set the VOLTS/DIV switch and the VARIABLE
control to produce a display which is an exact number
of vertical divisions in amplitude . Do not change the
VARIABLE control after obtaining the desired
deflection .
Figure 1-5 .
Measuring
instantaneous voltage with respect
to some reference .
2391-11

3 . To establish an
arbitrary vertical deflection factor so
that 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 (divisions)
established
in
step
2 and the setting of the
VOLTS/DIV switch . This is the vertical conversion
factor .
reference signal
Vertical

amplitude (volts)
Conversion
Factor vertical VOLTS/DIV
deflection X switch
(divisions) setting
5 . To measure the amplitude of an unknown signal,
disconnect 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 make an accurate measurement
.
Do not readjust the VARIABLE
control .
6 . Measure the vertical deflection in divisions and
calculate
the amplitude
of the unknown signal using
the following . formula :
Signal
VOLTS/ vertical vertical
Amplitude = DIV setting X conversion X deflection
factor (divisions)
EXAMPLE : Assume a reference signal amplitude
of
3
volts, a VOLTS/DIV setting of .5 V, and the VARIABLE
control adjusted to provide a vertical deflection of four
divisions . Substituting these values in the vertical
conversion factor formula (step 4) :
Vertical

3 V
Conversion =

-
= 1 .5
Factor

4 X .5 V
Then with a
VOLTS/DIV setting of .2 V, 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)
:
Signal
Amplitude = .2 V X 1 .5 X 5 = 1 .5 volts
Operating
Instructions-7A24 (SN B103000 & UP)
DUAL-TRACE
PHASE DIFFERENCE
MEASUREMENTS
Phase comparison between two signals of the same
frequency can be made using the dual-trace feature of
the 7A24 . This method of phase-difference
measurement can be used up to the frequency limit of
the oscilloscope system . To make the comparison, use
the
following procedure :
1 . Set the CH 1 and CH 2 Input Coupling switches to
DC .
2 . Set the DISPLAY MODE to ALT or CHOP . In
general, CHOP is more suitable for low frequencies
and ALT is more suitable for high frequencies . Set the
TRIGGER SOURCE to CH
1 .
3 . Connect the reference signal to the CH 1 Input and the
comparison signal to the CH 2 Input . Use coaxial cables or
probes which have similar time-delay characteristics to
connect the signals to the input connectors .
4 . If the signals are of opposite polarity, set the CH 2
POLARITY switch to invert the Channel 2 display .
(Signals may be of opposite polarity due to 180°
phase
difference ; if so, take this into
account
in
the
final calculation
.)
5 . Set the VOLTS/DIV switches and the VARIABLE
controls of the two channels so the displays are equal
and
about five divisions in amplitude .
6 . Set the time-base unit to a sweep rate which
displays about one cycle of each waveform . Set the
Triggering controls for a stable display .
7 . Center the
waveforms
on the graticule
with
the
7A24
POSITION controls .
8 . Adjust the time-base Variable Time/Div control
until one cycle of the reference signal occupies exactly
eight horizontal divisions between the second and
tenth vertical lines of the graticule (see Fig . 1-6) . Each
division of the graticule represents 45 ° of the cycle
(360° ± 8 divisions = 45°/division) . The sweep rate
can now be stated
in
terms of degrees ; for example,
45°/division .
9 . Measure
the horizontal difference between
corresponding points on the waveform .
10 . Multiply the measured distance (in divisions) by
45°/division to obtain the exact amount of phase
difference .

Operating
Instructions--7A24 (SN
B103000 & UP)
Using the formula :
Substituting the given
values :
The phase difference
is 13 .5° .
Figure 1-6 . Measuring phase difference between two
signals .
2391-12
EXAMPLE : Assume a horizontal
difference of 0 .3
division
with a sweep rate of
45°/division as shown
in Figure 1-6 .
horizontal

sweep rate
Phase Difference =

difference

X

(degrees/
(divisions)
division)
Phase
Difference = 0
.3 X 45°
HIGH-RESOLUTION
PHASE MEASUREMENTS
More accurate dual-trace phase
measurements can be
made by increasing the
sweep rate (without changing
the Variable Time/Div control) .
One of the easiest
ways to increase the sweep
rate is with the time-base
Magnifier switch . Set the Magnifier
to X10 and
determine
the magnified sweep rate by dividing
the
sweep rate obtained previously by the
amount of
sweep magnification .
EXAMPLE
: If the sweep rate is increased
10 times by
the
Magnifier, the magnified sweep
rate is
45°/division
-
10 =4 .5°/division .
Figure 1-7 shows
the same signals as used in Figure
1-6 but with the
Magnifier
set to X10 . With a horizontal
difference of 3
divisions, the phase difference is :
horizontal
magnified
Phase Difference =

difference

X

sweep rate
(divisions)
(degrees/
division)
Substituting the given values :
Phase Difference =
3 X4 .5°
The phase
difference is 13 .5° .
COMMON-MODE REJECTION
2391-13
Figure 1-7 . High resolution phase measurement using time-
base magnifier .
The ADD feature
of the
7A24
can be used to display
signals which contain undesirable components
.
Undesirable common-mode signals of 8 divisions or
less can be eliminated by using the 7A24 as a
differential amplifier
in ADD mode . The procedure is
as follows :
1
.
Set the DISPLAY MODE switch to
ALT or CHOP
and the TRIGGER SOURCE switch
to MODE .
2 . Connect the signal containing both the desired and
undesired
information
to the CH 1 Input connector .
3 . Connect a signal similar
to the unwanted portion
of
the CH 1 signal to the CH 2 Input
connector . For
example,
in Figure 1-8 a line-frequency signal is con-
nected
to Channel 2 to cancel out the line-frequency
component of
the Channel 1 signal .
4
.
Set both Input Coupling switches to the DC
position
.
5 . Set the VOLTS/DIV switches so the signals
are
about
equal in amplitude .
6 .
Set the DISPLAY MODE switch to ADD .
Set the CH
2 POLARITY switch to INVERT so the common-mode
signals are of opposite polarity .

(A) CHANNEL 1 SIGNAL .(B) CHANNEL 2 SIGNAL .(C) RESULTANT DISPLAY . i-+-a-tr2391-14
Figure 1-8 . Using the ADD mode for common-mode
rejection . (A) Channel 1 signal
contains desired information
along with line-frequency component
. (B) Channel 2
contains line frequency only . (C) Resultant
CRT
display
using common-mode rejection
.
Operating
Instructions--7A24
(SN B103000 & UP)
7 . Adjust the
Channel 2VOLTS/DIV switch and
VARIABLE
control for maximum cancellation of the
common-mode
signal . The signal which remains
should be
only the desired portion of the Channel 1
signal .
EXAMPLE : An
example
of
this mode
of
operation is
shown in
Figure 1-8
.
The signal applied to Channel 1
contains
unwanted line-frequency components (Fig . 1-
8A) . A
corresponding line-frequency signal is
connected to
Channel 2 (Fig . 1-8B) . Figure 1-8C
shows the desired
portion of the signal as displayed
when common-mode
rejection is used .
The above
procedure can also be used
for examining a
signal superimposed on some do
level . A do voltage of
the
proper polarity applied to Channel 2 can be
used
to
cancel out the do portion of the
signal applied to
Channel 1 .

Deflection Factor
Calibrated
Range
Gain Ratio Accuracy
Uncalibrated (VARIABLE)
GAIN Range
Frequency Response Bandwidth
Maximum Input Voltage
Input Characteristics
DC Resistance
VSWR
Display Modes
Trigger Source Selection
REV APR 1986
Characteristic
Common-Mode Rejection Ratio
TABLE 2-1
Electrical
Section 2-7A24 (SN B103000 & UP)
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 twenty-minute warmup unless otherwise
noted .
Performance Requirement
5 mV/Div to 1 V/Div ; eight steps in a
1, 2, 5 sequence .
-±2% of indicated deflection factor with
GAIN adjusted at
10 mV/Div .
Continuously variable
between calibrated steps ; extends
deflection factor to at least
2
.5
volts per division .
Permits adjustment of
deflection factor for calibrated operation
with
all Tektronix 7000-series oscilloscopes .
Refer to 7000-series Oscilloscope
specification for system
bandwidths .
5 volts rms (0 .5 watts) .
50 .0 ohms, ± 1 .0
U
do coupled
.
5 mV to 20 mV : --1 .25 do to 350 MHz
_
--1 .40 350 MHz to 400
MHz
50 mV to 1 V :

--1 .25 do to 400
MHz
At least

10 :1, do to 50
MHz,

with

8 divisions or less
common-mode signal .
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 .

Specification--7A24 (SN B103000 N6 UP)
Temperature
Altitude
EMC
Transportation
Size
Weight
Characteristic
TABLE 2'3
Physical
Information
Fits all 7000-series plug-in compartments .
Figure o'1 . 7A24 dimensional drawing .
1
.2 Kilograms (2 Pounds 9 Ounces) .
Refer to 7000-series Oscilloscope System-EIS001B
Specification ; associated 7000-series Mainframe .
Qualified under NSTC Test Procedure 1A, Category II .
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INTRODUCTION
This section of the manual contains a description of
the
circuitry used in the 7A24 . The 7A24
description
begins
with a discussion of the instrument using the
block
diagram shown in the Diagrams section . The
circuit
diagrams are segmented with gray-tint blocks
named
according to circuit function . These circuit
block titles serve as indexes to the circuit discussion .
Detailed
diagrams of each circuit are located in the
diagram
foldout section at the rear of this manual
.
Refer to the appropriate diagram when reading this
discussion
.
BLOCK DIAGRAM
The Channel 1
Amplifier circuit provides gain setting,
variable gain
control, and trace positioning . The
Channel 2 Amplifier provides
signal-polarity inversion
in addition to gain
setting, variable gain control, and
trace positioning
. The signal to be displayed on the crt
is
applied to the CH 1 or CH 2 Input
connector . The
signal passes through the Input
Coupling switch,
where it is either
connected to the attenuators or to a
50-ohm dummy load
.
The
VOLTS/DIV switch selects
the correct amount
of attenuation, and the signal is
passed to
the Switched-Gain Amplifier .
When
the VOLTS/DIV switch is set to the 5 mV and
10 mV
positions, the signal connected to the Input
connector is
passed through the attenuators without
attenuation . When
the VOLTS/DIV switch is set in the
5 mV position, the
Switched-Gain Amplifier
operates
at full gain . In
all other positions of the VOLTS/DIV
switch, the gain
of the Switched-Gain Amplifier is
reduced by
two
.
Internal gain and balance adjustments
are included
in the Switched-Gain Amplifier .
Overall GAIN and VARIABLE gain are adjusted in the
Gain
Amplifier . Variable balance and high-frequency
adjustments are also controlled in the Gain Amplifier .
The output of the Gain Amplifier is connected to the
Positioning circuitry where the POSITION and
IDENTIFY functions are controlled . This circuitry also
shifts the signal level to provide zero volts at the plug-
in output . Channel 2 is identical to Channel 1, with
the
exception of the polarity-inversion function in
Channel 2 .
The Signal Splitter
Amplifier divides the signal for use
at the Display
and Trigger Channel Switching
amplifiers .
The Display and Trigger Channel Switching amplifiers
provide differential signal outputs for the
signal
and
trigger lines, from each channel, to a common display
and trigger output .
INPUT ATTENUATOR
Section 3--7A24 (SIN B103000 &
UP)
The
output of the Display
and Trigger Channel Switch-
ing
amplifiers are connected to
the oscilloscope
mainframe via the interface
connector .
Readout
encoding circuitry used in the
7A24 is
compatible with
all 7000-series
mainframes .
CH 1
AND
CH
2 ATTENUATORS O
NOTE
The CH 1 and CH 2 amplifier circuits are
identical with the exception of the CH 2
GAIN stage U2450, which includes a
POLARITY inverting circuit . Only CH 2 is
described in detail throughout this
discussion .
INPUT FUSE
AND SWITCH
Signals
connected to the Input connector pass through
a 0 .2 ampere
fuse (F100) before reaching the Input
Coupling switch
. The fuse protects the attenuators
and
amplifier by preventing excessive voltages
from reach-
ing these
components .
Input signals can be dc-coupled or internally
disconnected . S100A is a cam-type switch ; a contact-
closure chart showing the operation is given on the
schematic diagrams . When the Input Coupling switch
is in the DC position, the input signal is connected to
the attenuators . The
OFF
position opens
the signal
path to the attenuators
and connects the input signal
to an internal 50-ohm
dummy load . This provides a
ground reference
without the need to disconnect the
applied signal
from the Input connector, and presents
a constant
50-ohm load at the Input connector .
The effective overall deflection factor of the 7A24 is
determined by the setting of the
VOLTS/DIV switch,
S100B . The basic deflection factor is 10 millivolts per
division of crt deflection . To increase the deflection
factor to the values indicated on the front panel,
precision attenuators are switched into the circuit .
S100B is a cam-type switch . The dots on the contact-
closure chart (see Diagram 1) indicate when the asso-
ciated contacts are in the position shown (open or
closed) . In the 5 mV/Div and 10 mV/Div positions,
the attenuators are not used ; the input signal is
connected directly to the Switched-Gain Amplifier . The
10 mV/Div position decreases the gain of the
Switched-Gain Amplifier
. For
switch positions above
10 mV/Div, the attenuators are either switched into
the circuit
singly
or
are stacked, producing the

Theory of Operation-7A24 (SN B103000 & UP)
deflection factor indicated on the front panel
.
The
hybrid attenuators are
constant impedance, T-pad
dividers .
In addition to providing constant attenuation
at all frequencies within the
bandwidth
of the
instrument, the
input attenuators are designed
to
maintain
the same input impedance (50 ohms) for all
settings of the
VOLTS/DIV switch .
CH
1 AND
CH
2 AMPLIFIERS
SWITCHED-GAIN AMPLIFIER
The
coaxial coupler between the
Attenuator circuit
board and the Main Amplifier circuit board
acts as a
balun transformer to provide differential drive
to
U1350 at
high
frequencies . U1350 is a paraphase-type
amplifier with dual
differential outputs .
In the 5 mV position, full drive is provided from pins 5 and 9
ofU1350totheU1450load resistors, R1401 andR1403 .In
all other attenuator positions,
the signal-path drive current
through the load .resistors ,o divided in half
. The other half
is
diverted through pins 6 an . .
8 J
U1350 and is dissipated in
dummy-load resistors R1334 and R1336 . Resistor R1332
sets the basic gain by a factor of two for all positions of the
VOLTS/DIV switch except 5 mV .
Components CR1319 and R1319 maintain proper
collector voltage while switching between the 5 mV
and 10 mV positions . Components C1332 and R1332
compensate for thermal variations . Components R1336
and C1336 are high-frequency adjustments .
Fixed length inductors and capacitors are part of the
Amplifier etched circuit board and provide T-coil
peaking at the input of U1350 .
GAIN AND POLARITY INVERT AMPLIFIER
Integrated circuit U2450 is a variable-gain cascode
amplifier which sets the overall channel gain . The
GAIN (R24328) and VARIABLE (R2432A) controls
determine the ratio of base currents through pins 11
and 12 of U2450 . The base-current ratio determines
the shared collector output
levels between pins
5-6, 8-
9 .
Variable resistor
R2424
provides adjustable low-
frequency compensation
. Resistors R2422
and RT2420
compensate
for temperature variations
. Components
R2430 and C2430
provide
adjustable
high-frequency
compensation
. The U2450 input T-coil peaking
inductors
and capacitors are part of the circuit board .
Dc balance over the variable range is adjusted by
R2410 .
LEVEL
SHIFT AND
POSITION
CONTROL
This circuitry shifts the do
level
between U2450 and
U2550, and provides positioning current .
3-
2
Low frequency and do signals are
coupled through
R2450, L2450, 02450, R2455
and R2460, L2460,
02460, R2455
which shifts the quiescent level from
+8
volts to -8 volts . Capacitors
C2450 and C2460,
located in the transmission
line between U2450 and
U2550,
provide ac coupling for high-frequency signals .
Resistors R2452
and R2462 provide operating current
for 02450, 02460,
and U2450 while R2467 and
R2468 set the
operating point of these devices . The
level shifter
gain
is
unity .
Transistors 02470 and 02480 are current
sources
which add positioning current to the input of
U2550 .
When POSITION control R2487 is at center, 02470
and 02480 provide equal currents resulting in zero
offset current . As the control is rotated from center
the differential offset at 02470 and 02480 produces a
corresponding amount of positioning current .
Resistors
R2473, R2483, R2486, and R2487 form a base
voltage divider for
02470 and 02480 in all display
modes except ADD . In ADD,CR2474 and CR2484
conduct, which replaces R2487 with R2474 and
R2484 . Thus, the CH 2 POSITION control is disabled
in ADD mode which limits position control to Channel
1 only .
The IDENTIFY circuit, composed of R2488, CR2488,
and S2465, adds enough current to 02480 to produce
approximately 0 .3 division trace shift at the crt for
trace identification . When S2465 is closed, the
junction of CR2488, R2488, and R2489 becomes more
positive resulting in additional emitter current at
02480 (approximately 200 microamps) . When the
switch is
open, the junction shifts more negative and
less emitter current flows . In this condition,
when a
multiplier
probe is connected to the CH 2 Input, the
additional
resistance to ground produces just enough
current shift at the readout circuit (Diagram 4) to
indicate the appropriate
multiplier on the crt .
SIGNAL SPLITTER AMPLIFIER
Integrated circuit U2550
provides two separate signals
for use in the display and trigger channel
switches on
Diagram 3 . Components C2515 and R2515 provide
adjustable high frequency compensation . Output
transient response is adjustable at C2560, C2562,
R2560, and R2562 .
DISPLAY SWITCHING
AND
OUTPUT
DISPLAY AND TRIGGER SWITCHING
The display and trigger channel switches provide
selection of the channel one and/or channel two
signals from the Switching Amplifiers on Diagram 2
for use in the mainframe .
REV A, FEB 1979