Tektronix 7a13 User manual

INSTRUCTION

Serial

Number

Tektronix,

Inc.

S.W. Millikan Way P.

0.

Box 500 Beaverton, Oregon 97005 Phone 644-0161 Cables: Tektronix

INSTRUCTION

MANUAL

Tektronix, Inc.

Seriol

Number

___

__

_

7A13

AMPLIFIER

S.W. Millikan

Way

.

P.

O.

Box

500

• Beoverron,

Oregon

97005

•

Phone

644

-

0161

•

Cables:

Tektronix

070-0978-00 1069

Scans

BY

Artek

Nedia

Artek

Media

1042

PlurnrnerCir.

SW

Rochester.

MN

55902

"High resolutionscans of obsoletetechnical manuals"

If your looking for a quality scanned technical manual in PDF format pleasevisit

our WEB site at www.artekmedia.com or drop us an email at

[email protected] and we will be happyto email you a current list of the

manualswe have available.

If you don't see the manual you need on the list drop us a line anyway we may

still be able to point you to other sources. If you have an existing manual you

would like scanned please write for details, This can often be done very

reasonably inconsiderationfor adding your manualto our library.

Typically the scans in our manuals are done as follows;

1) Typed text pagesare typicallyscanned in black and white at 300 dpi.

2)

Photopages are typicallyscanned ingray scale modeat 600 dpi

3)

Schematicdiagram pages are typically scanned in black and white at 600

dpi unlessthe original manual had colored high lighting (as is the case for

some70's vintageTektronixmanuals).

If you purchased this manual from us (typically through our Ebay name of

ArtekMedia) thank you very much. If you received this from a well-meaning

"friend" for free we would appreciate your treating this much like you would

"share ware". By that we mean a donation of at least $5-10 per manual is

appreciated in recognitionof the time (a manualcan take as muchas 40 hoursto

reproduce, book, link etc.), energy and quality of effort that went into preserving

this manual. Donations via PayPal go to: [email protected] or can be

mailedto us the address above.

Dave

&

LynnHenderson

Artek Media

Scans

By

Artel

Media

Artek Media

1042 Plummer Gir.

SW

Rochester, MN 55902

www.artekmedia.com

"High resolution scans of obsolete technical manuals"

If your looking for a quality scanned technical manual

in

PDF format please visit

our WEB site at www.artekmedia.com or drop us

an

email at

[email protected] and

we

will be happy to email you a current list ofthe

manuals we have available.

If you don't see the manual you need

on

the list drop us a line anyway we may

still be able to point you to other sources. If you have

an

existing manual you

would like scanned please write for details, This can often be done very

reasonably

in

consideration for adding your manual to our library.

Typically the scans

in

our manuals are done as follows;

1)

Typed text pages are typically scanned

in

black and

wh

ite at 300 dpi.

2) Photo pages are typically scanned

in

gray scale mode at 600 dpi

3)

Schematic diagram pages are typically scanned

in

black and white at 600

dpi unless the original manual had colored high lighting (as

is

the case for

some 70's vintage Tektronix manuals).

If you purchased this manual from us (typically through our Ebay name of

ArtekMedia) thank you very much. If you received this from a well-meaning

"friend" for free

we

would appreciate your treating this much like you would

"share ware". By that we mean a donation of at least $5-10 per manual

is

appreciated

in

recognition ofthe time

(a

manual can take

as

much

as

40 hours to

reproduce, book, link etc.), energy and quality of effort that went into preserving

this manual. Donations via PayPal go to: manuals@artekmedia.com or can be

mailed to us the address above.

Dave &Lynn Henderson

Artek Media

WARRANTY

All

Tektronix

instruments

are

warranted

against

defective

materials

and

workman·

ship

for

one

year.

T.

ktronix

transformers.

manufactured

in

our

plant,

are

warranted

for

the

life

of

the

instrument.

Any

questions

with

respect

to

the

war-

ranty

mentioned

obove

should

be

taken

up with your Tektronix Field Engineer.

Tektronix

repair

and

replacement-port

service

is

geared

directly to

the

field,

therefore

all

requests

for

repairs

and

re~

placement ports should

be

directed to the

Tektronix Field

Office

or

reph!tSentative

in

your

area.

This

procedure

will

assure

you

the

fostest

possible

service.

Please

include

the

instrument Type

and

Serial

or

Model

Number

with all requests

for

ports

or

service.

Specifications

and

price

change

privi.

leges reserved.

Copyright

®

1969

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 permis4

sion

of

the

copyright

owner.

Type

7A13

TABLE

OF

SECTION

1

SPECIFICATION

lntroduction

Electrical Characteristics

Deflection Factor

Common Mode Signal Range

Differential Signal Range

Frequency Response

Overdrive Recovery

Common Mode Rejection Ratio

Maximum lnput Voltage

lnput

R

and C

Page

1-1

1-2

Maximum Gate Current

DC Drift

Displayed Noise

Comparison Voltage

System Characteristics

Environmental Characteristics

Altitude

Transportation

SECTION

2

OPERATING INSTRUCTIONS

lntroduction

Front-Panel Description

Test Setup Chart

Familiarization Procedure

First-Time Operation

Front Panel Adiustments

Examples of Voltage/Signal Measurements

Single-ended operation DC Measurement

Differential Comparator Operation, DC

Measurement

Single-Ended Operation, Waveform

Measurement

Differential Amplifier Operation

Use of Vc OUT

0-10

V Tip Jack

General Discussion

Common Mode Rejection

Amplitude and Common Mode Rejection

Factors Which Affect CMRR

Differential Amplifier Applications

X-Y

Applications

Passive Signal Coupling Methods

SECTION

3

CIRCUIT DESCRIPTION Page

Introduction

3-1

Block Diagram Description

3-1

Input Mode Switches

3-1

Input Attenuators

3-1

Input Source and Emitter Followers

3-1

Differential and Common ModeSignal Clamps

3-1

Differential Comparator

3-1

X 1

and

X 10

Gain-Switching Amplifier

3-1

X 1, X2

and

X5

Gain-Switching Amplifier

3-1

Driver Am~lifier

3-1

Output Amplifier

3-1

Trigger Amplifier

3-1

Feedback Limiter

3-3

Readout Logic

3-3

Vc Decimal Lamp Driver

3-3

Detailed Circuit Description

3-3

Input Mode Switch

3-3

Input Attenuators

3-3

Input Source and Emitter Followers

3-3

Differential Signal and Common Mode Signal

3-4

Clamps

Differential Comparator

3-4

X

1

and

X 10

Gain-Switching Amplifier

3-4

X 1, X2

and

X5

Gain-Switching Amplifier

3-5

Driver Amplifier

3-5

Output Amplifier

3-5

Trigger Amplifier

3-5

Feedback Limiter

3-5

Readout Logic and Vc Decimal Lamp Driver

3-5

Low Voltage Power Supplies

3-5

Comparison Voltage Generators

3-5

SECTION

4

MAINTENANCE

Preventive Maintenance

General

Cleaning the Front Panel

Cleaning the Interior

Visual Inspection

Transistor Checks

Type

7A13

TABLE

OF CONTENTS

SECTION 1 SPECIFICATION Page

1-1

Introduction

Electrical Characteristics

Deflection

Factor

Common

Mode

Signal

Range

Differential

Signal

Range

Frequency Response

Overdrive

Recovery

Common

Mode

Rejection Ratio

Maximum

Input

Voltage

Input

Rand

C

Maximum

Gate

Current

DC

Drift

Displayed

Noise

Comparison

Voltage

System

Characteristics

Environmental

Characteristics

Altitude

Transportation

1-1

1-2

SECTION 2 OPERATING INSTRUCTIONS

®

Introduction

2-1

Front-Panel

Description

2-

1

Test Setup

Chart

2-1

Familiarization

Procedure

2-2

First-Time

Operation

2-2

Front Panel

Adjustments

2-3

Examples

of

Voltage/Signal

Measurements

2-3

Single-ended

operation

DC

Measurement

2-3

Differential

Comparator

Operation,

DC

2-4

Measurement

Single-Ended

Operation,

Waveform

2-4

Measurement

Differential

Amplifier

Operation

2-4

Use

of

Vc

OUT

0-

10 V Tip Jack

2-4

General

Discussion

2-5

Common

Mode

Rejection

2-6

Amplitude

and

Common

Mode

Rejection

2-9

Factors

Which

Affect

CMRR

2-9

Differential

Amplifier

Applications

X-

Y

Applications

Passive

Signal

Coupling

Methods

2-11

SECTION 3 CIRCUIT DESCRIPTION

Introduction

Block

Diagram

Description

Input

Mode

Switches

Input

Attenuators

Input

Source

and

Emitter

Followers

Page

3-1

Differential

and

Common

Mode

Signal

Clamps

3-1

Differential

Comparator

3-1

X 1

and

Xl

0

Gain-Switching

Amplifier

3-1

Xl,

X 2

and

X 5

Gain-Switching

Amplifier

3-1

Driver

Amplifier

3-1

Output

Amplifier

3-1

Trigger

Amplifier

Feedback Limiter

Readout

Logic

Vc

Decimal

Lamp

Driver

Detailed

Circuit Description

Input

Mode

Switch

Input

Attenuators

Input

Source

and

Emitter

Followers

3-1

3-3

Differential

Signal

and

Common

Mode

Signal

3-4

Clamps

Differential

Comparator

3-4

X 1

and

Xl

0

Gain-Switching

Amplifier

3-4

Xl,

X2

and

X5

Gain-Switching

Amplifier

3-5

Driver

Amplifier

3-5

Output

Amplifier

3-5

Trigger

Amplifier

Feedback Limiter

Readout Logic

and

Vc Decimal Lamp

Driver

Low

Voltage

Power

Supplies

Comparison

Voltage

Generators

SECTION 4 MAINTENANCE

Preventive

Maintenance

General

Cleaning

the

Front Panel

Cleaning

the

Interior

Visual Inspection

Transistor Checks

3-5

4-1

Type

7A13

CONTENTS

Page

4-

1

4-1

4-2

4-4

Page

Check/Adjust Step Attenuator DC Balance

5-8

Check/Adjust Position Center

5-8

Check/Adjust Trigger DC Balance

5-9

Check/Adjust Signal Output DC Level

5-9

Check/Adjust Trigger Output DC Level

5-9

Check/Adjust Gain

5-9

Check Gate Current

5-9

Calibration

Corrective Maintenance

General

Obtaining Replacement Parts

Special Parts

Soldering Techniques

Switch Replacement

Lamp Replacement

Troubleshootins

4-5

Preliminary Comparison Voltage Check

&

5-10

Thermal Compensation Adjustment

4-5

-

Introduction

General

Indicator Oscilloscope

Operating Procedures and Control Settings

Trouble Symptoms

Visual Inspection

Calibration Check

Detailed Troubleshooting

General

Check Comparison Voltage

5-10

Check/Adjust Common Mode Thermal

5-10

Compensation

lnput Resistance

&

DC Attenuation Ratio

5-1

1

Adjustments

Check/Adjust +Input

10X

DC

5-1

1

Attenuation Ratio

Check/Adjust +Input

1

X

DC Input

5-12

Resistance

Check/Adjust +Input

1OOX

DC

5-13

Attenuation Ratio

Test Equipment Recommended Check/Adjust -Input

10X

DC

Attenuation Ratio

Troubleshooting by Direct Replacement

4-6

Troubleshooting Aids

4-6

Check/Adjust -Input

1X

DC Input

5-14

Resistance

Troubleshooting Techniques

4-7

High-Frequency Compensation Adjustments

5-15

Component Checks

Instrument Repackaging

4-8

Check/Adjust High-Frequency

5-15

Compensation

4-9

Attenuator Compensation Adjustments

5-20

SECTION

5

PERFORMANCE CHECK/

CALIBRATION

Check/Adjust

+

Input Attenuator

Compensation

Check/Adjust -Input Attenuator

Compensation

Introduction

Test Equipment Required Common Mode Rejection Adjustments

General

5-

1

Check/Adjust Amplifier High-Frequency

Common Mode Rejection

Test Equipment

5-

1

Check/Adjust Attenuator Common Mode

Rejection at

100

Hz

Short-Form Performance Check/Calibration

5-3

Procedure

Check/Adjust Attenuator Common Mode

Rejection at

10

kHz

Performance Check/Calibration Procedure

5-5

General

5-5

Trigger

&

Signal Amplifier Response Checks

Preliminary Procedure

DC and Gain Adjustments Check Trigger Amplifier Gain and Step

Response

Check/Adjust Position Center

&

DC Balance

5-7

Check Trigger Amplifier High-Frequency

Sine Wave Response

Check/Adjust

X 10

DC Balance

5-8

Type

7A13

TABLE

OF CONTENTS (ContJ

Calibration

Page

4-1

Corrective

Maintenance

4-1

General

4-1

Obtaining

Replacement Parts 4-1

Special Parts

4-2

Soldering

Techniques

4-2

Switch Replacement

4-4

Lamp Replacement

4-5

Troubleshooting

4-5

Introduction

4-5

General

4-5

Indicator

Oscilloscope

4-5

Operating

Procedures

and

Control

Settings

4-5

Trouble

Symptoms

4-5

Visual Inspection

4-6

Calibration

Check

4-6

Detailed

Troubleshooting

4-6

General

4-6

Test Equipment Recommended

4-6

Troubleshooting

by

Direct Replacement

4-6

Troubleshooting

Aids

4-6

Troubleshooting

Techniques

4-7

Component

Checks

4-8

Instrument Repackaging

4-9

SECTION 5 PERFORMANCE CHECK/

CALIBRATION

ii

Introduction

Test Equipment Required

General

Test Equipment

Short-Form Performance

Check!Calibration

Procedure

Performance

Check!Calibration

Procedure

General

Preliminary Procedure

DC

and

Gain

Adjustments

5-1

5-3

5-5

5-6

5-7

Check!

Adjust

Position Center &

DC

Balance

5-7

Check!

Adjust

X

10

DC Balance

5-8

Page

Check/

Adjust

Step

Attenuator

DC

Balance

5-8

Check!

Adjust

Position Center

5-8

Check!

Adjust

Trigger

DC

Balance

5-9

Check!

Adjust

Signal

Output

DC

Level

5-9

Check!

Adjust

Trigger

Output

DC

Level

5-9

Check!

Adjust

Gain

5-9

Check

Gate

Current

5-9

Preliminary Comparison

Voltage

Check &

5-

10

Thermal Compensation

Adjustment

Check Comparison

Voltage

5-

10

Check!

Adjust

Common

Mode

Thermal

5-

10

Compensation

Input

Resistance &

DC

Attenuation

Ratio 5-11

Adjustments

Check!

Adjust

+

Input

10X

DC

5-11

Atten

uation

Ratio

Check!

Adjust

+

Input

1X

DC

Input

5-12

Resistance

Check!

Adjust

+

Input

100

X

DC

5-13

Atten

uation

Ratio

Check!

Adjust

-Input

10

X

DC

5-13

Attenuation

Ratio

Check!

Adjust

-

Input

1X DC

Input

5-14

Resistance

High-Frequency Compensation Adjustments

5-15

Check!

Adjust

High-Frequency

5-15

Compensation

Attenuator

Compensation Adjustments

5-20

Check!

Adjust

+

Input

Attenuator

Compensation

5-20

Check!

Adjust

-

Input

Attenuator

5-23

Compensation

Common

Mode

Rejection Adjustments

5-25

Check!

Adjust

Amplifier

High-Frequency

5-25

Common

Mode

Rejection

Check!

Adjust

Attenuator

Common

Mode

5-27

Rejection

at

100

Hz

Check!

Adjust

Attenuator

Common

Mode

5-28

Rejection

at

10kHz

Trigger

& Signal

Amplifier

Response Checks

5-28

Check

Trigger

Amplifier

Gain

and

Step

5-28

Response

Check

Trigger

Amplifier

High-Frequency

Sine

Wave

Response

5-30

Type

7A13

TABLE OF CONTENTS

(Confl

Page Page

Check Signal Amplifier High-Frequency 5-31

SECTION

6

ELECTRICAL PARTS

LIST

Response Abbreviations

.&

Symbols

Check Signal Amplifier 5-MHz Bandwidth 5-31

Sine Wave Response Parts Ordering Information

Comparison Voltage Adjustments 5-31

Check/Adjust 10-Volt Calibration 5-32

SECTION

7

DIAGRAMS AND MECHANICAL

Check/Adjust 1-Volt Calibration 5-33

PARTS ILLUSTRATlONS

Check Comparison Voltage Linearity 5-33 Diagrams

Mechanical Parts Illustrations

Check Volts Counter Mechanical Backlash 5-33

Check Electrical Zero 5-34

SECTION

8

MECHANICAL PARTS LIST

Noise

&

Overdrive Recovery Checks 5-34 Mechanical Parts List Information

5-35 Index of Mechanical Parts Illustrations

Check Noise Mechanical Parts List

Check Overdrive Recovery Time 5-36 Accessories

iii

®

Type

7A13

TABLE

OF CONTENTS (ConfJ

Page

Check

Signal

Amplifier

High-Frequency 5-31

Response

Check

Signal

Amplifier

5-MHz

Bandwidth

5-31

Sine

Wave

Response

Comparison

Voltage

Adjustments

Check/Adjust

10-Volt

Calibration

Check/Adjust

1-Volt

Calibration

Check Comparison

Voltage

Linearity

5-31

5-32

5-33

Check

Volts

Counter

Mechanical

Backlash

5-33

Check Electrical

Zero

Noise

&

Overdrive

Recovery Checks

Check

Noise

Check

Overdrive

Recovery Time

5-34

5-35

5-36

Page

SECTION 6

ELECTRICAL

PARTS

LIST

Abbreviations

.&

Symbols

Parts

Ordering

Information

SECTION 7 DIAGRAMS

AND

MECHANICAL

PARTS

ILLUSTRATIONS

Diagrams

Mechanical

Parts

Illustrations

SECTION 8 MECHANICAL

PARTS

LIST

Mechanical

Parts List

Information

Index

of

Mechanical

Parts

Illustrations

Mechanical

Parts List

Accessories

iii

Fig.

1-1.

Type

7A13

Diffe~entialComparator.

Type

7A13

FIg. 1_1.

Type

7A13

~

--

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II

7001'

VAR

SAL

7A13

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KI

••

.w

-Ii

-II

'.

fI

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COMP"RISOH

VOLTAGE (Vel

•

(;l

'.-

:>IFFERENTIAL

COMPARATOR

Typ.

7A13

Oiff

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lial

Camparatar.

@

ArtekMedia

Digitally signed by ArtekMedia

DN: cn=ArtekMedia, o=ArtekMedia.com,

ou, [email protected],

c=US

Date: 2008.11.16 13:58:26 -06'00'

Type 7A13

SECTION

I

Change information,

if

any, affecting this section

will

be found at the

rear ofthe manual.

INTRODUCTION

The Type 7A13 Vertical Plug-In

is

a DC coupled differential

comparator with excellent common-mode rejection and medi-

um gain characteristics for medium level applications. The

Type 71413 is designed for use inTektronix 7000 series oscillo-

scopes. It may be used as a differential input preamplifier

or conventional preamplifier in addition to its use as a com-

parator.

In the differential input mode, the dynamic range allows

the application of common-mode signals up to +10 or -10

volts to be applied to the unit without attenuation. Common-

mode reiection ratio of at least 20,000:1 at DC to 100kHz

permits measurements of differential signals less than 1 mV

in amplitudeon 10volt common-mode signals.

When used as a differential comparator, the Type 7A13

has an effective offset range of 10,000 divisions.

ELECTRICAL CHARACTERISTICS

The electrical characteristics described in Table 1-1 are

valid over the stated environmental range for instruments

calibrated at an ambient temperature of +20° C to +30°

C

and after a 20-minute warmup period unless otherwise noted.

TABLE

1-1

ELECTRICAL CHARACTERISTICS

Characteristic

Deflection Factor

(VOLTS/DIV)

Calibrated Range

Gain Ratio Accuracy

Uncalibrated (Vari-

able)

Common Mode Signal

Range

1mV/Div to

50 mV/Div;

XI0

Vc In

10mV/Div to

50 mV/Div;

XI0

Vc Out

0.1 V/Div to

0.5 V/Div;

XI0

Vc In

0.1 V/Div to

0.5 V/Div;

XI0

Vc Out

Characteristic

1V/Div to 5 V/Div;

XI0Vc In

DifferentialSignal Range

1mV/Div to

50 mV/Div;

XI0

Vc In

10mV/Div to

50 mV/Div;

XI0 Vc Out

0.1 V/Div to

0.5 V/Div;

XI0

Vc In

0.1 V/Div to

0.5 V/Div;

XI0

Vc Out

1V/Div to 5 V/Div;

XI0

Vc In

Frequency Response

(8 Div Reference)

FULL Bandwidth

Upper Limit

AC (Capacitive)

Coupled Input

Lower Bandwidth

,

Frequency

5MHz Bandwidth

Overdrive Recovery

(1

X

Attenuator at

1 mV/Div)

Common Mode Rejec-

tion Ratio

1mV/Div to

50 mV/Div

XlOVc In

'

DC to 100kHz

100kHz to 1MHz

1MHz to 10MHz

20MHz

10mV/Div to

50

mV/Div;

X

10Vc

Out;

0.1 V/Div to 5 V/Div;

XlOVc In or Out

DC to 10kHz

AC Coupled at 60 Hz

Performance Requirement

1mV/Div to 5V/Div, 12 steps in

a 1,2,5 sequence

Within 1.5% of GAIN adjusted

at 1 mV/Div

Continuously variable: extends

deflection factor to at least 12.5

V/Div

At least +10V and -lOV

At least +100V and -100V

At least +500 V and -500 V

Performance Requirement

At least +500 V and -500 V

At least 0.8 V

At least 8V

At least 80V

See Table 1-2, System Characteris-

tics

10Hz or less

DC to 5MHz within 500 kHz

1

pS to recover within 1.5 mV,

0.1 ms to recover within 0.5 mV,

following removal of a +10 V or

-10 V overdrive signal.

See Fig. 1-2.

At least 20,000:1, 20 V P-P or less

test signal

At least 10,000:1, 10V P-P or less

test signal

CMRR

=

10,000/frequency (MHz)

At least 250:1, 1V P-P or less test

signal

At least 2,000:l

At least 500:l

SECTION'

SPECIfICATION

Type 7A13

Change

information,

if

any,

affecting

this section will

be

found

at

the

rear

of

the

manual.

INTRODUCTION

The Type 7A13 Vertical Plug-In

is

a

DC

coupled differential

comparator

with excellent common-mode rejection

and

medi-

um

gain characteristics for medium level applications. The

Type 7A13

is

designed for use

in

Tektronix 7000 series oscillo-

scopes.

It

may

be

used

as

a differential input preamplifier

or

conventional preamplifier

in

addition to

its

use

as

a com-

parator.

In

the differential input mode, the dynamic

range

allows

the application of common-mode signals up to + 1°

or

-1

°

volts to

be

applied

to the unit without attenuation. Common-

mode rejection ratio of

at

least 20,000:1

at

DC

to 100

kHz

permits measurements of differential signals less than 1

mV

in

amplitude on 10 volt common-mode signals.

When

used

as

a differential

comparator,

the Type 7A13

has

an

effective offset

range

of 10,000 divisions.

ELECTRICAL

CHARACTERISTICS

The electrical characteristics described

in

Table

1-1

are

valid

over

the stated environmental

range

for instruments

calibrated

at

an

ambient

temperature of

+20

0 C to

+30

0 C

and

after

a 20-minute warmup period unless otherwise noted.

TABLE

1-1

ELECTRICAL

CHARACTERISTICS

Ch

aracteristic

Performance

Requirement

Deflection Factor

(VOL

TS/DIV)

Calibrated Range 1

mV

/Div to 5 V/Div, 12 steps

in

a 1, 2, 5 sequence

Gain

Ratio Accuracy Within 1.5%

of

GAIN adjusted

at

1 mVjDiv

Uncalibrated (Vari- Continuously variable: extends

able) deflection factor to

at

least 12.5

V/Div

Common

Mode

Signal

Range

1

mV

/Div to At least

+10V

and

-10V

50 mY/Diy;

X10

Vc

In

10mV/Divto

At least

+looV

and

-100V

50 mY/Diy;

X10

Vc

Out

0.1

V/Div to

0.5 V/Div;

X10

Vc

In

0.1

V/Div to At least

+500

V

and

-500

V

0.5 V/Div;

X10

Vc

Out

®

Characteristic

Performance

Requirement

1 V/Div to 5 V/Div; At least

+500

V

and

-500

V

X10

Vc

In

Differential Signal Range

1 mY/Diy to

At

least 0.8 V

50 mY/Diy;

X10

Vc

In

10mV/Divto

At least 8 V

50 mY/Diy;

X10

Vc

Out

0.1

V/Div to

0.5 V/Div;

X10

Vc

In

0.1

V/Div to At least 80 V

0.5 V/Div;

X10

Vc

Out

1 V/Div to 5 V/Div;

X10

Vc

In

Frequency Response

(8

Div

Reference)

FUll

Bandwidth See Table 1-2, System Characteris-

Upper limit tics

AC

(Capacitive) 10

Hz

or

less

Coupled Input

lower

Bandwidth ,

Frequency

5 MHz Bandwidth

DC

to 5 MHz within 500

kHz

Overdrive Recovery 1

fLS

to recover within 1.5mV,

(1

X Attenuator

at

0.1

ms

to recover within 0.5

mY,

1 mY/Diy) following removal of a

+10

V

or

-10

V overdrive signal.

Common Mode Rejec- See

Fig.

1-2.

tion Ratio

1 mY/Diy to

50

mV

/Div

X10Vc

In

DC

to 100

kHz

At least 20,000:1, 20 V

P-P

or

less

test signal

100

kHz

to 1 MHz At least 10,000:1, 10 V

P-P

or

less

test signal

1 MHz to

10MHz

CMRR

= 10,000/frequency

(MHz)

20MHz

At least 250:1, 1 V

P-P

or

less test

signal

10mV/Divto

50mV/Div;

X10Vc

Out;

0.1

V/Div to

5V/Div;

X10Vc

In

or

Out

DC

to 10

kHz

At least 2,000:1

AC

Coupled

at

60

Hz

At least 500:1

1-1

........

TABLE 1-1

ELECTRICAL CHARACTERISTICS (contl

Characteristic

Maximum lnput Voltage

DC (Direct) Coupled

DC

+

Peak AC

1mV/Div to

50 mV/Div;

XI0

Vc In

10mV/Div to

50 mV/Div;

XI0

Vc Out

0.1 V/Div to

0.5 V/Div;

XI0

Vc In

0.1 V/Div to

0.5 V/Div;

XI0

Vc Out

1V/Div to 5 V/Div;

XI0

Vc In

AC (Capacitive)Coup-

led lnput

lnput

R

and

C

Resistance

Capacitance

R

and

C

Product

Maximum Gate Current

0" C to +35O C

Both Inputs

+35" C to +50° C

Both Inputs

DC Drift

Drift With Time (Am-

bient Temperature

and Line Voltage Con-

stant)

Short Term

Long Term

Drift With Ambient

Temperature (LineVol-

tage Constant)

Amplifier Crosstalk

SYSTEM CHARACTERISTICS

Characteristic

Displayed Noise (Tan-

gentially Measured)

Comparison Voltage

Range

Accuracy

Electrical Zero

Vc OUT Resistance

Performance Requirement

40 VDC. 40V Peak AC,

1

kHz or

less

400 VDC. 400 V Peak AC, 1kHz

or less

500 VDC. 500V Peak AC, 1kHz

or less

500 VDC

1Mawithin 0.15%

20 pF within 0.4 pF at 1MHz

Within 1

%

for all deflection fac-

tor settings.

0.2 nA or less (0.2 Div at 1mV/Div)

2 nA or less (2 Div at 1mV/Divr

1 mV P-P or less or 0.1 Div or less

(whichever is greater) any 1 minute

interval within 1 hour after 20 min-

utes from turn-on.

-

1 mV P-P or less or 0.1 Div (which-

ever is greater) during any hour

after the first hour and 20 min-

utes from turn-on.

2 mV/lOoC or less, 0.2 Div/lOoC

(whichever

is

greater)

1

%

or less shift within 20 ns of

step of fast rise squarewave when

switching undriven input from

GND to AC or DC

The system characteristics listed in Table 1-2 are to specify

the performance of the plug-in with various combinations of

probes and in various indicator oscilloscopes.

Performance Requirement

40OPV or less at 1mV/Div in

Type 7700-Series or 7500-Series

indicator oscilloscope

OV to &10V

&

(0.1

%

of setting +5 mV)

0.5 mV or less

15 kf2 within 5 ki2

TABLE 1-2

SYSTEM CHARACTERISTICS

'Accuracy percentages apply to all deflection factors. Plug-in GAlN

must be set at the deflection factor designated at the applicable

position of the VOLTS/DIV switch. When a probe is used, the GAlN

must be set with the calibration signal applied to the probe tip.

2EXTernal CALibrator, O°C to 50°C: The plug-in GAlN is set (within

10°C of the operating temperature) using an external calibrator

signal whose accuracy is within 0.25%.

4NTernal CALibrotor, lS°C to 35OC: The plug-in GAlN

is

set using

the oscilloscope's own calibrator and the instrument is operating

within the

+

15OC to

+

35'~range.

41N~ernalCALibrator, O°C to 50°C: The plug-in GAlN is set (within

10°C of the operating temperature) using the oscilloscope's own

calibrator, and the instrument is operating within the O°C to +50°C

range.

ENVIRONMENTAL CHARACTERISTICS

TABLE 1-3

Type 7A13 tested alone (separate from indicator oscil-

loscope)

Characteristic

Altitude

Non-Operating

Transportation

Information

To 50,000 feet and

-55"

C

Qualified under National Safe

Transit Committee test procedure

1

A, Category I1

Specification-Type

7A13

TABLE

1-1

ELECTRICAL

CHARACTERISTICS

(contl

Ch

aracteristic

Performance

Requirement

Maximum Input Voltage

DC

(Direct) Coupled

DC

+ Peak AC

1 mY/Diy to 40

VDC.

40 V Peak AC, 1

kHz

or

50 mY/Diy; less

X10

Vc

In

10mV/Divto

400

VDC.

400 V Peak AC, 1

kHz

50 mV/Div;

or

less

Xl0

Vc

Out

0.1

V/Div

to

0.5 V/Div;

X10

Vc

In

0.1

V/Div

to

500

VDC.

500 V Peak AC, 1 kHz

0.5 V/Div;

or

less

Xl0

Vc

Out

1 V

IDiv

to

5 V

IDiv;

X10

Vc

In

AC

(Capacitive) Coup- 500

VDC

led Input

Input

Rand

C

Resistance 1

Mn

within 0.15%

Capacitance

20

pF

within 0.4

pF

at

1 MHz

Rand

C Product Within 1% for all deflection fac-

tor settings.

Maximum

Gate

Current

0°

C to

+35°

C 0.2

nA

or

less (0.2

Div

at

1

mV

IDiv)

Both Inputs

+35°

C

to

+50°

C 2

nA

or

less

(2

Div

at

1

mV

IDi¥T

Both Inputs

DC

Drift

Drift With Time

(Am-

bient Temperature

and

line

Voltage Con-

stant)

Short Term 1

mV

pop

or

less

or

0.1

Div

or

less

(whichever

is

greater)

any

1 minute

interval within 1 hour

after

20 min-

utes from turn-on.

long

Term 1

mV

pop

or

less

or

0.1

Div

(which-

ever

is

greater) during

any

hour

after the first hour

and

20 min,

utes from turn-on.

Drift With Ambient 2

mV

/l0°

C

or

less, 0.2 Div/lO° C

Temperature (line Vol- (whichever

is

greater)

tage

Constant)

Amplifier Crosstalk 1%

or

less shift within 20

ns

of

step

of fast rise

squarewave

when

switching undriven input from

GND

to AC

or

DC

1-2

Ch

aracteristic

Displayed Noise (Tan-

gentially Measured)

Comparison Voltage

Range

Accuracy

Electrical Zero

Vc

OUT Resistance

Performance

Requirement

400

{tV

or

less

at

1

mV

IDiv

in

Type 7700-Series

or

7500-Series

indicator oscilloscope

OV

to

-+-10V

-+-

(0.1

%

Of

setting

+5

mY)

0.5

mV

or

less

15

kn

within 5

kn

SYSTEM

CHARACTERISTICS

The system characteristics listed

in

Table 1-2

are

to specify

the performance of the plug-in with various combinations of

probes

and

in

various indicator oscilloscopes.

TABLE

1-2

SYSTEM

CHARACTERISTICS

Indicatar Prabe

BW

Tr

'Accuracy

("!o)

Sig

Out

..

Oscillascape (MHz)

(ns)

2EXT

'INT

BW

Tr

CAL CAL CAL

(MHz)

(ns)

7500 Series

Nane

75 4.7 1.5 2.5 3.5 55 6.4

P6053

75 4.7 1.5 2.5 3.5 55

6.4

P6048

7700 Series

Nane

100 3.5 1.5 2.5 3.5 55

6.4

P6053

100

3.5

1.5 2.5 3.5 55 6.4

P6048

'Accuracy

percentages

apply

to

all

deflection factors. Plug-in GAIN

must

be

set

at

the

deflection

factor

designated

at

the

applicable

position of

the

VOLTS/DIV switch.

When

a

probe

is used,

the

GAIN

must

be

set

with

the

calibration

signal

applied

to

the

probe

tip.

2EXTernai

CAlibrator,

O°C to SOoC: The plug-In GAIN is

set

(within

10°C

of

the

operating

temperature)

using

an

external

calibrator

signal

whose

accuracy is within

0.2S

%.

'INTernal CALibrotor,

ISoC

to

3SoC:

The

plug-in

GAIN is

set

using

the

oscilloscope's own

calibrator

and

the

instrument is

operating

within

the

+ISoC

to

+3SoC

range.

'INTernal

CAlibrator,

OOC

to

SOoC: The

plug-in

GAIN is

set

(within

10°C

of

the

operating

temperature)

using

the

oscilloscope's own

calibrator,

and

the

instrument is

operating

within

the

OOC

to +

SOOC

range.

ENVIRONMENTAL

CHARACTERISTICS

TABLE

1-3

Type

7A

13

tested

alone

(separate

from

indicator

oscil-

loscope)

Characteristic

Altitude

Non-Operating

Transportation

Information

To 50,000 feet

and

_55°

C

Qualified under National Safe

Transit Committee test procedure

1A,

Category

II

®

CMRR VOLTS

P-P

100K:l

10K:l

1,000:1 10

-

CMRR Performance Requirement

P-P Amplitude of Sinuroidal Test Signal

DC

10kHz 100kHz 1 MHz 10MHz 20MHz

Frequency

@)

."

Iii'

I

!->

....

'<

."

..

"I

>

Co>

...

0

3

0

:l

3

0

0.

..

~

ii'

!l

o·

:l

2-

o·

III

C

."

?"

:;

."

~

C

~.

0

3

<

.....

c

:c.

;.

0

c:

III

::r

...

0

3

<

.....

c

:c.

0.

~

;p

!l

o·

:l

C'

...

0

?

....

I

Co)

CMRR

100K:1

10K:1

1,000:1

DC 10

kHz

100

kHz

1

MHz

Frequency

10MHz

20

MHz

VOLTS

p.p

10

VI

"D

CD

n

3i

n

Q

::t.

o

1

"D

CD

......

l>

....

Co)

NOTES

J

---.

i

I

Type

7A13

SECTION

2

OPERATING INSTRUCTIONS

Change information, if any, affecting this section

will

be

found at the

rear of the manual.

INTRODUCTION

This section opens with a brief functional description of

the front panel controls and connectors (see Fig. 2-1). Fol-

lowing the front-panel description is a familarization pro-

cedure and finally a general discussion of the operation of

the Type 7A13.

FRONT-PANEL DESCRIPTION

Ri,

N

00

1-50mV Illuminates when switch S10, lo-

VAR

IN

ONLY cated on left side of plug-in, is

Lamp turned cw. This indicates a

+

IN-

PUT and -INPUT impedance of

approximately infinity whenever

the VOLTS/DIV switch

is

set be-

tween 1 and 50 mV, VARIABLE

knob is pushed in and 1

X

probe

is

used.

NOTE

With VOLTS/DIV switch set from .1 V to

5

V, lamp

remains on but input impedance is

==:I

Mn

and the

input attenuator is uncompensated.

COMPARISON VOLT- Selects polarity of comparison

AGE (Vc)

+

and

-

voltage.

Pushbuttons

COMPARISON VOLT- Reads out the voltage selected by

AGE (Vc) Counter the COMPARISON VOLTAGE (Vc)

selector switch in conjunction with

FINE, VOLTS/DIV and PULL VAR

for

X

10 Vc RANGE controls.

COMPARISON VOLT- Selects one of ten voltage ranges

AGE (Vc)Selector Switch from zero to ten volts.

COMPARISON VOLT- Selects a comparison voltage

AGE (Vc) FINE Control somewhere between the lower and

upper limits of the selected band

above.

+

INPUT Connector Provides

a

means of connection for

signal measurement. It also con-

tains a third contact for probe at-

tenuation information. This ena-

bles proper readout of deflection

factor on CRT screen.

+

INPUT Mode Switch Selects AC, DC, GND or Vc Mode

of coupling for the +INPUT chan-

nel.

VOLTS/DIV Switch Selects one of twelve volts per

division calibrated deflection fac-

tors.

VOLTS/DIV VARIABLE Selects an uncalibrated deflection

Control factor somewhere between the

PULL VAR FOR XI0Vc

RANGE Switch

-INPUT Connector

-INPUT Mode Switch

STEP ATTEN BAL

Adjustment

GAIN

Adjustment

XI0 BAL

Adjustment

twelve settings above. A minimum

of 2.5 times the VOLTS/DIV switch

setting is provided. The UNCAL

lamp lights when the VARIABLE

control

is

out of the CAL detent.

Selects a Vc Range 10X that

which is indicated on the VOLTS/

DIV Switch. This only occurs for

10, 20, and 50 mV/DIV and

.l,

.2

and .5 VIDIV settings of the

VOLTS/DIV switch.

Same as for + INPUT connector

above.

Selects AC, DC, GNDor Vc Mode

of coupling for the -INPUT chan-

nel.

Adjusts for no vertical trace move-

ment as the VOLTS/DIV switch

setting is varied from 10 to 50

mV/DIV.

Adjusts the amplifier gain for dis-

play of four divisions upon receipt

of a 4-mV signal when the VOLTS/

DIV switch

is

set to 1mV and the

VARIABLE control is set to CAL.

Adjusts for no vertical trace move-

ment as VARIABLE (VOLTS/DIV)

knob

is

pulled out

VAR BAL CONTROL Adjusts for no vertical trace move-

ment as VARIABLE (VOLTS/DIV)

knob is varied throughout its

range.

Release Latch Pull to withdraw plug-in from indi-

cator oscilloscope.

BW Switch Selects either the FULL bandwidth

or 5 MHz.

Vc OUT 0-10V Jack Provides a convenience outlet for

the comparison voltage.

POSITION Control Positions display vertically on the

CRT face.

Vc REF-IDENT Pushbut- Internally disconnects both signals

ton and applies Vc to both inputs.

TEST

SETUP CHART

Fig. 2-70 shows a drawing of the front panel controls and

connectors. This chart can be reproduced and used as a test

setup record for special measurements and applications, or

it may be used as a training aid for operation of the Type

7A13.

.-

._------

-

--.----

Type 7A13

SECTION 2

OPERATING

INSTRUCTIONS

Change

information,

if

any,

affecting

this section will

be

found

at

the

rear

of

the

manual.

INTRODUCTION

This

section opens

with

a brief functional description

of

the front panel controls and connectors

(see

Fig.

2·1).

Fol-

lowing the front-panel description

is

a familarization pro-

cedure and finally a general discussion of the operation of

the Type

7A13.

FRONT-PANEL

DESCRIPTION

R

in

c::::o

00

1-50

mV

VAR

IN

ONLY

Lamp

Illuminates when switch

510,

lo-

cated on left side of plug-in,

is

turned

cwo

This

indicates a +

IN-

PUT

and

-INPUT

impedance of

approximately infinity whenever

the

VOLTS/DIV

switch

is

set be-

tween 1 and

50

mY,

VARIABLE

knob

is

pushed

in

and 1X probe

is

used.

NOTE

With VOLTS/DIV switch set from

.1

V to 5

V,

lamp

remains on but input

impedance

is

;:::::

1

Mn

and

the

input

attenuator

is

uncompensated.

COMPARISON

VOLT-

AGE

(Vc)

+ and -

Pushbuttons

COMPARISON

VOLT-

AGE

(Vc)

Counter

Selects polarity of comparison

voltage.

Reads

out the voltage selected

by

the

COMPARISON

VOLTAGE

(V

c)

selector switch

in

conjunction

with

FINE,

VOLTS/DIV

and

PULL

VAR

for X

10

Vc

RANGE

controls.

COMPARISON

VOLT-

Selects one

of

ten voltage ranges

AGE

(Vc)

Selector

Switch

from

zero to ten

volt-s.

COMPARISON

VOLT-

AGE

(Vc)

FINE

Control

+

INPUT

Connector

+

INPUT

Mode

Switch

VOLTS/DIV

Switch

VOLTS/DIV

VARIABLE

Control

®

Selects a comparison voltage

somewhere between the lower and

upper

limits

of the selected band

above.

Provides a means of connection for

signal measurement.

It

also con-

tains a third contact for probe at-

tenuation information.

This

ena-

bles proper readout of deflection

factor on

CRT

screen.

Selects

AC,

DC,

GND or

Vc

Mode

of coupling for the +INPUT chan-

nel.

Selects one

of

twelve volts per

division calibrated deflection fac-

tors.

Selects an uncalibrated deflection

factor somewhere between the

PULL

VAR

FOR

X10

Vc

RANGE

Switch

-INPUT

Connector

-INPUT

Mode Switch

STEP

A

TTEN

BAL

Adjustment

GAIN

Adjustment

X10

BAL

Adjustment

VAR

BAL

CONTROL

twelve settings above. A

minimum

of

2.5

times

the

VOLTS/DIV

switch

setting

is

provided.

The

UNCAL

lamp

lights

when the

VARIABLE

control

is

out

of

the

CAL

detent.

Selects a

Vc

Range lOX that

which

is

indicated on the

VOLTS/

DIV

Switch.

This

only occurs

for

10,

20,

and

50

mV/DIV

and

.1,

.2

and

.5

V

/DIV

settings of the

VOLTS/DIV

switch.

Same as for +

INPUT

connector

above.

Selects

AC,

DC,

GND or

Vc

Mode

of coupling for the

-INPUT

chan-

nel.

Adjusts for

no

vertical trace

move-

ment as the

VOLTS/DIV

switch

setting

is

varied

from

10

to

50

mV/DIV.

Adjusts the amplifier

gain

for dis-

play of four divisions upon receipt

of a

4-mV

signal when the

VOLTS/

DIV

switch

is

set to 1

mV

and the

VARIABLE

control

is

set to

CAL.

Adjusts for

no

vertical trace

move-

ment as

VARIABLE

(VOLTS/DIV)

knob

is

pulled out.

Adjusts for

no

vertical trace

move-

ment as

VARIABLE

(VOLTS/DIV)

knob

is

varied throughout

its

range.

Release

Latch

Pull

to withdraw plug-in

from

indi-

cator oscilloscope.

BW

Switch

Selects either the

FULL

bandwidth

or 5

MHz.

Vc

OUT

0-10

V Jack

Provides

a convenience outlet for

the comparison voltage.

POSITION

Control

Positions

display vertically on the

CRT

face.

Vc

REF-IDENT

Pushbut- Internally disconnects both signals

ton and applies

Vc

to both inputs.

TEST

SETUP

CHART

Fig.

2-10 shows a drawing of the front panel controls and

connectors.

This

chart can be reproduced and

used

as a test

setup record for special measurements and applications, or

it

may be

used

as a training aid for operation

of

the Type

7A13.

2-1

Operating Instructions--Type

7A13

Fig.

2-1.

Front panel

of

Type

7A13

and location of

Ri,

e

switch

S10.

FAMILIARIZATION PROCEDURE

3. Turn the Intensity control fully counterclockwise and

turn the oscilloscope Power ON. Preset the time-base plug-in

First-Time Operation

triggering controls for a

.5

ms/div sweep rate and automatic

triggering.

The following steps are intended to help get the trace on

the CRT screen quickly and to prepare the unit for immedi-

ate use. These steps are intended to acquaint you with some

of the basic functions of the Type 7A13.

1. Insert the unit into the oscilloscope vertical plug-in com-

partment.

2.

Set the Type 7A13 front panel controls as follows:

COMPARISON VOLTAGE Pushbuttons canceled

(Vc) Polarity

COMPARISON VOLTAGE As

is

(Vc) Counter

+

INPUT Mode GND

4.

Wait about five minutes for the Type 7A13 and the

oscilloscope to warm up.

NOTE

About five minutes is sufficient warmup time when

using the Type 7A13 for short-term DC measure-

ments. For long-term DC measurements using the

lower deflection factors, allow at least one hour.

5.

Adjust the Intensity control for normal viewing of the

trace. The trace should appear near the graticule center.

6.

Using the POSITION control, position the trace two

divisions below graticule center. Set VOLTS/DIV to

1

mV

position.

-

INPUT Mode GND NOTE

VOLTS/DIV

1

V If trace is off screen, perform Front Panel Adjust-

VARIABLE In (CAL) ments outlined below.

STEP ATTEN BAL As

is

GAIN As is

XI0

BAL As is

VAR BAL As

is

BW

5

MHz

POSITION Midrange

7. Apply a

4

mV peak-to-peak calibrator signal through a

coaxial cable to the

+

INPUT connector on the Type 7A13.

8.

For DC coupled, single-ended operation, set the

+

INPUT Mode Switch to DC. The display should be

4

divi-

sions of square wave amplitude with the bottom of the dis-

play at the reference established in step

6.

Op

erating

Inslrudions.-Type

7AI3

.

1A13

,."III"

.llAL

COMI'AfiATOII

fig

.

l-1.

front

pon

~'

of Typo

7AI3

ond

loeollon of . ,. "'" 00 ,witch

510

.

FAMILIARIZATION

PROCEDURE

First-Time

Operation

The

following steps

are

intended

10

help get Ihe trace on

the

CR

T screen quickly

and

to prepare the unit lor immedi·

ate

use. These steps

are

in

tended to acquaint you with some

of the basic functions of

th

e Type 7

A13

.

1.

Insert the unil inlo the oscilloscope vertical plug.in com-

portment.

2.

Set the Type

7Al3

front ponel conlrols as follows:

COMPARISON

VOLTAGE

(Vc)

Polarity

COMPA

RI

SON

VOLTAGE

(Vc)

Counter

+

INPUT

Mode

-

INPUT

Mode

VOLTS/DIV

VARIAB

LE

STEP

AITEN

BAL

GAIN

X

10

BAL

V

AR

BAL

BW

POSITION

2-2

Pu

shbuttons canceled

As

is

GND

1V

In

(CA

L)

As

is

As

is

As

is

As

is

SM

Hz

Midrange

3. Turn the Intensily control

fully

counterclockwise

and

turn the oscilloscope Power

ON.

Preset the time·bose plug.

in

triggering controls for a

.5

ms

/div sweep rate

and

automatic

triggering.

4.

Wait

about five

mi

nutes for the Type 7A13

and

the

oscilloscope to worm

up.

NOTE

About

five minutes

is

sufficient

wo

rm

up time

when

using

the

T

ype

7Al3

for

shor

t-term

DC

mea

s

ure

-

ments. F

or

long

.term

DC

measurements

u

si

ng

the

lower

de

flection

factors

,

allow

at

leas!

one

hour.

5.

Adiust the

In

tensity control lor normal viewing of the

trace.

Th

e trace should

appear

near

the graticule center.

6.

Using

Ihe POSITION control, position the trace two

divisions below grolicule center. Set

VOLTS/DIV

10

1

mV

position.

NOTE

If

trace

is

off

sc

re

en,

perform

Front

Pan

el Adjust-

ments

outlined

below

.

7. Apply a 4

mV

peak.to.peok calibrator signal through a

coaxial coble to Ihe +

INPUT

connector on thc Type

7A13

.

B.

For

DC

coupled, single-ended operation, set the +

INPUT

Mode Switch to

DC.

The display should

be

" divi-

sions of square wove amplitude with the bollom

01

the

di

s-

play

01

the reference established

in

step

6.

®

Operating Instruction-Type 7A13

NOTE

If the display amplitude is not

4

divisions, adjust

GAlNcontrol until it is.

9. For AC coupled, single-ended operation, re-position the

display to place the bottom of the display at the graticule

center line.

10. Set the + INPUT Mode switch to AC and note that the

display shifts downward about two divisions to its average

level.

11. Disconnect the calibrator signal from the

+

INPUT

connector. Set both the

+

and

-

INPUT Mode switches to

GND.

12. Set the VOLTS/DIV switch to 1m\kry the VARI-

ABLE control throughout its range while observing the CRT

trace.

13. Adjust VAR BAL so that there

is

no trace movement

while varying the VARIABLE control.

14. Set the VOLTS/DIV switch to 10mV. Pull out the

PULL VAR FOR XI0 Vc RANGE knob while observing the

CRT trace.

15. Adjust XI0 BAL so that there is no trace movement

while moving the PULL VAR FOR XI0 Vc RANGE knob

in and out.

16. Vary the VOLTS/DIV switch from 20 mV to 1mV while

observing the CRT trace.

17. Adjust STEP ATTEN BAL so that the trace does not

move while varying the VOLTS/DIV switch.

18. Repeat steps 12 through 17 until optimum settings are

achieved.

19. Push in the PULL VAR FOR

X

10 Vc RANGE knob.

Front Panel Adjustments

These adjustments must be accomplished each time the

Type 7A13 is placed in a different oscilloscope, and should

be checked prior to any critical measurement of waveforms.

Preset Type 7A13 controls as follows:

COMPARISON VOLTAGE

(Vc) Polarity Pushbuttons canceled

Counter

+

INPUT Mode

-

INPUT Mode

VOLTS/DIV

VARIABLE

STEP ATTEN BAL

GAlN

XI0 BAL

VAR BAL

BW

POSITION

As is

GND

1

v

In (CAL)

Midrange or as

is

As

is

Midrange or as is

5MHz

Midrange

Allow 20 minutes Warmup time.

VAR BAL Adjustment

1. Set the VOLTS/DIV switch to 1mV.

2.

Vary the VARIABLE control throughout its range while

observing the CRT trace.

3. Adjust VAR BAL so that there is no trace movement

while varying the VARIABLE control.

X

10 BAL Adjustment

1.

Set the VOLTS/DIV switch to 10mV. Pull out the PULL

VAR FOR X10 Vc RANGE knob while observing the CRT

trace.

2. Adjust XI0 BAL so that there is no trace movement

while moving the knob in and out.

STEP ATTEN BAL Adjustment

1.

Vary the VOLTS/DIV switch from 20 mV to 1mV while

observing the CRT trace.

2. Adjust STEP ATTEN BAL so that the trace does not move

while varying the VOLTS/DIV switch.

3. Repeat all balance adjustments until optimum settings

are achieved.

GAlN Adjustment

1. Using the POSITION control, position the CRT trace two

divisions below graticule center.

2. Set VOLTS/DIV to 1mV position.

3. Apply a

4

mV peak-to-peak calibrator signal through a

coaxial cable to the

+

INPUT connector on the Type 7A13.

4. Set the + INPUT Mode switch to DC.

5. Adjust GAlN control so that the display is four divisions

of square wave amplitude with the bottom of the display at

the reference established in step 1.

Examples of Voltage/Signal Measurements

The following examples are provided to illustrate some of

the various ways to use the Type 7A13. All examples pre-

sume that the Type 7A13 front panel adjustments have been

made satisfactorily. These examples can be duplicated by

an operator to serve as familiarization exercises.

NOTE

In all the following examples the COMPARISON

VOLTAGE (Vc) selector switch setting and the

VOLTS/DIV switch setting have been set on the

basis of a voltage input whose approximate value

is known (and is within the maximum input signal

range of the Type 7A13). The switch settings can

bedetermined by single ended or differential com-

parator methods, starting with the least sensitive

VOLTS/DIV setting of

5

V.

Example 1

Single-ended operation,

DC

measurement. Measure the

voltage output of 1.5 volt battery. (Any convenient DC

source can be substituted by setting the deflection factor

of the Type 7A13 accordingly.)

NOTE

If

the

display

amplitude

is

not 4 divisions,

adjust

GAIN control until it

is.

9.

For

AC

coupled, single-ended operation, re-position the

display to place the bottom of the display

at

the graticule

center line.

10.

Set the +

INPUT

Mode switch to

AC

and note that the

display shifts downward about two divisions to

its

average

level.

11.

Disconnect the calibrator signal

from

the +

INPUT

connector. Set both the + and -

INPUT

Mode switches to

GND.

12.

Set the

VOLTS/DIV

switch to 1

m'v.---Vory

the

VARI-

ABLE

control throughout

its

range while observing the

CRT

trace.

13.

Adjust

VAR

BAL

so

that there

is

no

trace movement

while varying the

VARIABLE

control.

14.

Set the

VOLTS/DIV

switch to

10

mY.

Pull

out the

PULL

VAR

FOR

Xl

0

Vc

RANGE

knob while observing the

CRT

trace.

15.

Adjust

Xl

0

BAL

so that there

is

no

trace movement

while moving the

PULL

VAR

FOR

Xl

0

Vc

RANGE

knob

in

and out.

16.

Vary the

VOLTS/DIV

switch

from

20

mV

to 1

mV

while

observing the

CRT

trace.

17.

Adjust

STEP

A

TTEN

BAL

so

that the trace does not

move while varying the

VOLTS/DIV

switch.

18.

Repeat steps

12

through 17

until

optimum settings are

achieved.

19.

Push

in

the

PULL

V

AR

FOR

Xl

0 Vc

RANGE

knob.

Front Panel Adjustments

These adjustments

must

be accomplished each time the

Type

7A13

is

placed

in

a different oscilloscope, and should

be checked prior to any critical measurement of waveforms.

Preset Type 7A

13

controls as follows:

COMPARISON

VOLTAGE

(Vc)

Polarity

Counter

+

INPUT

Mode

-

INPUT

Mode

VOLTS/DIV

VARIABLE

STEP

A

TTEN

BAL

GAIN

X10

BAL

VAR

BAL

BW

POSITION

Pushbuttons canceled

As

is

GND

1V

In

(CAL)

Midrange or as

is

As

is

Midrange or as

is

Midrange or as

is

5MHz

Midrange

Allow

20

minutes Warmup time.

VAR

BAL

Adjustment

1.

Set the

VOL

TS/DIV

switch to 1

mY.

®

Operating

Instructions--Type

7A

13

2.

Vary the

VARIABLE

control throughout

its

range while

observing the

CRT

trace.

3.

Adjust

VAR

BAL

so

that there

is

no

trace movement

while varying the

VARIABLE

control.

X 10

BAL

Adjustment

1.

Set the

VOLTS/DIV

switch to

10

mY.

Pull

out the

PULL

VAR

FOR

X10

Vc

RANGE

knob while observing the

CRT

trace.

2.

Adjust

Xl

0

BAL

so

that there

is

no

trace movement

while moving the knob

in

and out.

STEP

A

TTEN

BAL

Adjustment

1.

Vary the

VOLTS/DIV

switch

from

20

mV

to 1

mV

while

observing the

CRT

trace.

2.

Adjust

STEP

A

TTEN

BAL

so

that the trace does not move

while varying the

VOLTS/DIV

switch.

3.

Repeat all balance adjustments

until

optimum settings

are achieved.

GAIN Adjustment

1.

Using

the

POSITION

control, position the

CRT

trace two

divisions below graticule center.

2.

Set

VOLTS/DIV

to 1

mV

position.

3.

Apply a 4

mV

peak-to-peak calibrator signal through a

coaxial cable to the +

INPUT

connector on the Type

7A13.

4.

Set the +

INPUT

Mode switch to

DC.

5.

Adjust

GAIN

control

so

that the display

is

four divisions

of

square wave amplitude

with

the bottom

of

the display

at

the reference established

in

step

1.

Examples of Voltage/Signal Measurements

The

following examples are provided to illustrate some of

the various ways to

use

the Type 7A

13.

All

examples pre-

sume that the Type 7A

13

front panel adjustments have been

made satisfactorily. These examples can be duplicated

by

an operator to serve as familiarization exercises.

NOTE

In

all

the

following

examples

the

COMPARISON

VOLTAGE

(Vc) selector switch setting

and

the

VOLTS/DIV switch setting

have

been

set

on

the

basis

of

a

voltage

input

whose

approximate

value

is

known

(and

is

within

the

maximum input signal

range

of

the

Type 7A

13).

The switch settings

can

be

determined by single

ended

or

differential com-

parator

methods, starting with

the

least sensitive

VOLTS/DIV setting

of

5

V.

Example 1

Single-ended

operation,

DC

measurement. Measure the

voltage output

of

1.5

volt battery.

(Any

convenient

DC

source can be substituted by setting the deflection factor

of

the Type

7A13

accordingly.)

2-3

Operating Instructions--Type 7A13

Set the Type 7A13 front panel controls as follows:

COMPARISON VOLTAGE

(Vc) Polarity Either

+

or

-

Counter As

is

+

INPUT Mode GND

+

INPUT Connector Connected to battery posi-

tive terminal. Negative ter-

minal connected to ground

lug on front panel.

-

INPUT Mode GND

VARIABLE In (CAL)

STEP ATTEN BAL As

is

GAIN As

is

X10 BAL As

is

VAR BAL As

is

BW

5MHz

POSITION Midrange

1. Use the POSITION control to set the trace to DC-0 ref-

erence.

2. Place the

+

INPUT Mode switch to DC.

3. Multiply the number of divisions displayed by the

deflection factor (3 div

X

.5 V

=

1.5 V). The input voltage

amplitude

is

1.5 volts k0.3 Volts.

Note that if the input voltage were applied to the

-

IN-

PUT connector, with

+

INPUT Mode switch set to GND and

-

INPUT Mode switch set to DC, the 3 divisions deflection

would be downward, since the

-

INPUT causes an inverted

presentation.

Example

2

Differential Comparator Operation, DC measurement.

Measure the voltage output of a 1.5 volt battery.

Type 7A13 control settings are the same as for Example 1

above.

1. Set the COMPARISON VOLTAGE (Vc) Polarity switch to

+

and set the counter to 0150.

2. Set the VOLTS/DIV switch to 20 mV and pull the VARI-

ABLE knob out.

3. Using the POSITION control, set the trace to DC zero

reference (graticule center).

4. Simultaneously place the

+

INPUT Mode switch to DC

and the

-

INPUT Mode switch to Vc.

5. Using COMPARISON VOLTAGE (Vc) controls, reset the

trace to DC zero reference.

6.

Read the value of the input voltage on the COMPARI-

SON VOLTAGE (Vc) counter. It should be 1.5 volts

f

0.3

volts.

7.

Disconnect the battery from the Type 7A13.

Example

3

Single-Ended Operation-waveform measurement.

Measure the oscilloscope Calibrator

+

Volts waveform and

DC level.

Type 7A13 control settings are same as for examples 1 and

2 except for the

+

INPUT connector, which should be con-

nected to the Calibrator

+

VOLTS BNC connector on the

oscilloscope via coaxial cable.

1. Set the oscilloscope Calibrator control to 40 mV.

2. Set VOLTS/DIV Switch to 10mV position.

3. Set

+

INPUT Mode switch to AC and set the time base

plug-in controls for a stable display.

4. Compute AC waveform amplitude using the POSITION

control to establish a reference line. (4 divisions deflection

times 10mV/DIV yields 40 mV.)

5. Determine the DC level on which the waveform

is

rid-

ing, using the method shown in either example 1 or 2. Note

the DC level of the top or bottom of the waveform as de-

sired.

NOTE

For signals with a high

AC

to DC ratio, the AC and

DC signal components can be evaluated simultan-

eously by using DC coupling and single-ended

operation methods.

6.

Disconnect the calibrator signal.

Example

4

Differential Amplifier Operation. Measure the difference

between the oscilloscope Calibrator

+

Volts output and a

modified Calibrator

+

Volts output.

Type 7A13 control settings are the same as example 3

above with the following exception: The

-

INPUT Mode

switch should be set to DC.

1.

Set the VOLTS/DIV Switch to 20 mV position.

2. Connect a BNC T adapter to the Calibrator

+

Volts

output of the oscilloscope.

3. Build and connect a voltage divider to the BNC T as

illustrated in Fig. 2-2.

4. Connect the junction of the two resistors to the

-

IN-

PUT connector via coaxial cable.

5. Set the oscilloscope Calibrator

+

Volts output to 4 V.

6.

Simultaneously place the

+

INPUT and

-

INPUT Mode

switches to GND. Using the POSITION control, set the trace

to DC zero reference two divisions below the graticule hori-

zontal centerline.

7. Simultaneously set both the

+

and

-

INPUT Mode

switches to DC. Adjust the time-base plug-in triggering con-

trols if necessary to obtain a stable waveform.

8.

Measure the waveform amplitude. It will be equal to

the difference between the two input waveforms. (Approxi-

mately 40 mV; this

is

the voltage drop across the 1

k0

resis-

tor.)

Operating Instructions-Type 7A13

Set the Type 7A

13

front panel controls as follows:

COMPARISON

VOLTAGE

(V

c)

Polarity

Counter

+

INPUT

Mode

+

INPUT

Connector

-

INPUT

Mode

VOLTS/DIV

VARIABLE

STEP

A

HEN

BAL

GAIN

XlO

BAL

VAR

BAL

BW

POSITION

Either + or -

As

is

GND

Connected to battery posi-

tive terminal. Negative ter-

minal connected to ground

lug

on front panel.

GND

.5V

In

(CAL)

As

is

As

IS

As

is

As

is

5MHz

Midrange

1.

Use

the POSITION control to set the trace to

DC-O

ref-

erence.

2.

Place the +

INPUT

Mode switch to

DC.

3.

Multiply the number of divisions displayed by the

deflection factor

(3

div X

.5

V =

1.5

V).

The

input voltage

amplitude

is

1.5

volts

+0.3

Volts.

Note that

if

the input voltage were applied to the -

IN-

PUT

connector, with +

INPUT

Mode switch set to GND and

-

INPUT

Mode switch set to

DC,

the 3 divisions deflection

would be downward, since the -

INPUT

causes an inverted

presentation.

Example 2

Differential Comparator Operation,

DC

measurement.

Measure the voltage output of a

1.5

volt battery.

Type 7A

13

control settings are the same as for Example 1

above.

l.

Set the

COMPARISON

VOLTAGE

(Vc)

Polarity switch to

+and set the counter to 0150.

2.

Set the

VOLTS/DIV

switch to

20

mV

and

pull

the

VARI-

ABLE

knob out.

3.

Using

the POSITION control, set the trace to

DC

zero

reference (graticule center).

4.

Simultaneously place the +

INPUT

Mode switch to

DC

and the -

INPUT

Mode switch to

Vc.

5.

Using

COMPARISON

VOLTAGE

(Vc)

controls, reset the

trace to

DC

zero reference.

6.

Read the value of the input voltage on the

COMPARI-

SON

VOLTAGE

(Vc)

counter.

It

should be l.5 volts

+0.3

volts.

7.

Disconnect the battery

from

the Type 7A

13.

2-4

Example 3

Single-Ended

Operation-waveform

measurement.

Measure the oscilloscope Calibrator +

Volts

waveform and

DC

level.

Type

7A13

control settings are same as for examples 1 and

2 except for the +

INPUT

connector, which should be con-

nected to the Calibrator +

VOLTS

BNC

connector

on

the

oscilloscope via coaxial cable.

1.

Set the oscilloscope Calibrator control to

40

mV.

2.

Set

VOLTS/DIV

Switch to

10

mV

position.

3.

Set +

INPUT

Mode switch to

AC

and set the time base

plug-in controls for a stable display.

4.

Compute

AC

waveform amplitude using the

POSITION

control to establish a reference line.

(4

divisions deflection

times

10

mV

/DIV yields

40

mV.)

5.

Determine the

DC

level

on

which the waveform

is

rid-

ing, using the method shown

in

either example 1 or

2.

Note

the

DC

level of the top or bottom of the waveform as de-

sired.

NOTE

For signals with a high

AC

to

DC

ratio,

the

AC

and

DC

signal

components

can

be

evaluated

simultan-

eously

by

using

DC

coupling

and

single-ended

operation

methods.

6.

Disconnect the calibrator signal.

Example 4

Differential Amplifier Operation. Measure the difference

between the oscilloscope Calibrator +

Volts

output and a

modified Calibrator + Volts output.

Type

7A13

control settings are the same as example 3

above with the following exception:

The

-

INPUT

Mode

switch should be set to

DC.

1.

Set the

VOLTS/DIV

Switch to

20

mV

position.

2.

Connect a

BNC

T

adapter

to the Calibrator +

Volts

output of the oscilloscope.

3.

Build

and connect a voltage divider to the

BNC

T as

illustrated

in

Fig.

2-2.

4.

Connect the junction of the two resistors to the -

IN-

PUT

connector via coaxial cable.

5.

Set the oscilloscope Calibrator +

Volts

output to 4

V.

6.

Simultaneously place the +

INPUT

and -

INPUT

Mode

switches to GND. Using the POSITION control, set the trace

to

DC

zero reference two divisions below the graticule hori-

zontal centerline.

7.

Simultaneously set both the + and -

INPUT

Mode

switches to

DC.

Adjust the time-base plug-in triggering con-

trols

if

necessary to obtain a stable waveform.

8.

Measure the waveform amplitude.

It

will

be equal to

the difference between the two input waveforms. (Approxi-

mately

40

mV;

this

is

the voltage drop across the 1 kn

resis-

tor.)

®

Operating Instructions--Type

7A13

Fig.

2-2.

Voltage divider for Example

4.

Connectto

+INPUT

Connector

Use

of

Vc OUT

0-10

V Tip Jack

r--J

I

COMPARISON VOLTAGE (Vc) can be read on a voltmeter

or oscilloscope connected to the Vc OUT 0-10V tip jack. The

reading (or waveform) must be equal to the COMPARISON

VOLTAGE Vc switch and FINE control settings. If a high im-

pedance voltmeter (one which draws little or no current from

the measured voltage) is used, the measured value will be

within +0.5% or -+5 mV (whichever is greater) of the Vc

counter.

)I

r--1

L-

--

I

kc2

If an accurate, low impedance measuring device

is

used,

the value read will be the value applied to the selected input

channel, but it will disagree with the COMPARISON VOLT-

AGE Vc control setting. The amount of difference will be

determined by the degree of loading caused by the measur-

ing device. When the load is removed by disconnecting the

measuring device, the voltage will return to that indicated by

the COMPARISON VOLTAGE Vc control.

The Vc OUT 0-10 output can be used as a voltage source,

but the accuracy and value of Vc will vary inversely with the

loading effect, just as it does with a measuring device con-

nected to it. This

is

illustrated in Fig.

2-3.

b

NOTE

Use shielded leads whenever connecting to the Vc

OUT 0-10 tip jack while waveform observations

are being made. Stray voltages of 10

mV or more

can be picked up by unshielded cables connected

to the tip jacks. This induced noise will affect the

CRT presentation whenever one of the INPUT Mode

switches is in the Vc position.

Connect to Connect to

Calibrator -INPUT

+Volts Connector

I

-

BNC T CONNECTOR

I

L--,------

J

-

!

-

GENERAL

DISCUSSION

f

An oscilloscope with a differential amplifier

is

a device

that amplifies and displays a voltage difference that exists

at every instant between signals applied to its two input chan-

nels. The following~conclusionscan be drawn from this def-

inition when two signals are applied to the input of a dif-

ferential amplifier.

(COMPARISON VOLTAGE)

10

9

8

7

6

V)

5

0

'5

4

3

2

1

0

00

500K 50K

5

K

LOAD RESISTANCE

Fig.

2-3.

Effect of external load connected to Comparison Voltage

Vc

OUT

0-10

V jack.

Connect

to

+INPUT

Connector

I BNC T CONNECTOR I

L

_________

..J

Connect

to

Calibrator

.+Volts

Fig.

2-2.

Voltage

divider

for

Example

4.

Use

of

Vc

OUT

0-10

V Tip Jack

COMPARISON VOLTAGE

(Vc)

can

be

read

on

a voltmeter

or

oscilloscope

connected

to the

Vc

OUT 0-10 V tip jack. The

reading

(or waveform) must

be

equal

to the COMPARISON

VOLTAGE

Vc

switch

and

FINE

control settings.

If

a high

im-

pedance

voltmeter (one which

draws

little

or

no current from

the

measured

voltage)

is

used, the

measured

value

will

be

within

-+-0.5"10

or

-+-5

mV

(whichever

is

greater)

of

the

Vc

counter.

If

an

accurate,

low

impedance

measuring

device

is

used,

the

value

read

will

be

the

value

applied

to the selected input

channel,

but

it will

disagree

with

the

COMPARISON

VOLT-

AGE

Vc

control setting. The

amount

of

difference will

be

determined

by the

degree

of

loading

caused

by

the

measur-

ing device.

When

the

load

is

removed

by

disconnecting

the

measuring device,

the

voltage

will return to

that

indicated

by

the COMPARISON VOLTAGE

Vc

control.

The Vc OUT 0-10

output

can

be

used

as

a

voltage

source,

but the

accuracy

and

value

of

Vc

will vary inversely with

the

loading

effect, just

as

it

does

with a measuring

device

con-

nected to

it.

This

is

illustrated

in

Fig. 2-3.

NOTE

Use

shielded

leads

whenever

connecting

to

the

Vc

OUT

0-10

tip

jack

while

waveform

observations

are

being

made.

Stray

voltages

of

10

mV

or

more

can

be

picked

up

by

unshielded

cables

connected

to

the

tip

jacks.

This

induced

noise

will

affect

the

CRT

presentation

whenever

one

of

the

INPUT

Mode

switches

is

in

the

Vc

position.

GENERAL

DISCUSSION

10

9

8

7

6

en

~

..J

0

>5

4

3

2

1

0

00

Operating Instructions-Type 7A

13

100kn

~

--L-

(COMPARISON

VOLTAGE)

Vc=

10.0

Vc

=

9.0

Vc

=

8.0

Vc

=

7.0

Vc=6.0

Vc=

5.0

Vc

=

4.0

Vc

=

3.0

Vc

=2.0

Vc

= 1.0

500K

50K

LOAD

RESISTANCE

Connect

to

-INPUT

Connector

5K

An oscilloscope with a differential amplifier

is

a

device

that

amplifies

and

displays a

voltage

difference

that

exists

at

every

instant

between

signals

applied

to

its

two

input chan-

nels. The following' conclusions

can

be

drawn

from this def-

inition

when

two

signals

are

applied

to

the

input of a dif-

ferential amplifier. Fig.

2-3.

Effect

of

external

load

connected

to

Comparison

Voltage

Vc

OUT

0-10

V jack.

2-5

Operating

Instructions--Type

7A13

Source lmpedance

10

kn

-

stray and lead

capacitance

-L

-

2

-

9.95

v

5

kn

-INPUT

Source Impedance

I/

Apparent

DCCMRR

=

200:

1

FREQUENCY

(81

I

Fig.

2-4.

The effect of difference in source impedance upon apparent

CMRR.

(High impedance sources.)

1.

If two signals are in phase and of equal amplitude (here- plitude the output signal is a complex quantity derived from

after called common-mode), the output will be zero. both amplitude and phase differences.

2.

If the two signals are in phase but of different ampli-

tudes, the output will equal the amplitude difference.

Common Mode Rejection

3.

If the two signals are out of phase and of equal ampli-

tude the output will be the phasor difference between the The definition of the term "differential amplifier" implies

two signals. (Sinusoidal signals.) a rejection of equal amplitude, coincident signals. This impli-

cation is correct. However, the degree of reiection depends

4.

If the two signals are out of phase and of different am- primarily on the symmetry of the amplifier inputs. The

Operating Instructions--Type 7A

13

IAI

181

1000:1

100:1

10:1

1

:1

100

Hz

10.00

V

Generators

Source

Impedance

10

kQ

,..--+-

stray

and

lead

h

capacitance

~

-=

5 kQ

Source

Impedance

1

kHz

10

kHz

9.90

V

9.9S V

-INPUT

100

kHz

FREQUENCY

(+INPUT) -

(-INPUT)

'"

-0.05

V

Apparent

DC

CMRR

200:

1

(See

graph

for

effect

on

AC

CMRR)

1

MHz

IOMHz

Fig.

2-4.

The effect of difference in source

impedance

upon

apparent

CMRR.

IHigh

impedance

sources. I

1.

If

two signals

are

in

phase

and

of

equal

amplitude (here-

after called common-mode), the

output

will

be

zero.

2.

If the two signals

are

in

phase

but of different ampli-

tudes, the

output

will

equal

the amplitude difference.

3. If the two signals

are

out

of phase

and

of

equal

ampli-

tude the

output

will

be

the

phasor

difference between the

two signals. (Sinusoidal signals.)

4.

If the two signals

are

out

of

phase

and

of different am-

2-6

plitude the

output

signal

is

a complex quantity derived from

both amplitude

and

phase

differences.

Common Mode Rejection

The definition of the term "differential amplifier" implies

a rejection of

equal

amplitude, coincident signals.

This

impli-

cation

is

correct. However, the

degree

of rejection

depends

primarily on the symmetry of the amplifier inputs. The

@

Operating Instructions--Type

7A13

Source Impedance

FREQUENCY

Fig.

2-5.

The effect of difference in source impedance upon apparent

CMRR.

(Low impedance sources.)

amount of difference signal contributed by a particular am-

plifier at a specific frequency

is

documented with a math-

ematical relationship that

is

called the common-mode re-

jection ratio (CMRR). This ratio and associated terms are

defined as follows:

Common-Mode: Refers to signals that are identical in both

amplitude and time. It

is

also used to identify the respective

parts of two signals that are identical in amplitude and time.

Common-Mode Rejection: The ability of a differential am-

plifier to reject common-mode signals.

Common-Mode Rejection Ratio (CMRR):Ratio of the deflec-

tion factor for a common-mode signal to the deflection factor

for a differential signal.

NOTE

Since the differential amplifier

is

part of an oscillo-

scope, the output signal used to calculate the CMRR

is measured from the CRT screen and VOLTS/DIV

switch setting. Thus, a differential amplifier that

produces a

.001

volt output when driven

by

a

10

volt peak to peak common-mode signal has a

CMRR of

10

-

.001

or

10,000:l.

(A)

'"

:e

u

(8)

1000:1

100:1

100

H.

10.0000

V

Generators

Source

Impedance

lOOn

~

stray

and

lead

h

capacitance

-----

-=-

50

n

Source

Impedance

1

kH.

10

kH.

100

kH.

FREQUENCY

Operating Instructions-Type 7A13

(+INPUT)

-

(-INPUT)

=

-0.0005

V

Apparent

DC

CMRR

0:

20,000:

1

(See

graph

for

effect

on

AC

CMRR)

1

MH.

10

MH.

Fig.

2-5.

The

effect

of

difference

in source

impedance

upon

apparent

CMRR.

(Low

impedance

sources.)

amount

of

difference

signal

contributed

by

a

particular

am-

plifier

at

a specific

frequency

is

documented

with a math-

ematical

relationship

that

is

called

the

common-mode

re-

jection ratio

(CMRR).

This ratio

and

associated

terms

are

defined

as

follows:

Common-Mode:

Refers to

signals

that

are

identical

in

both

amplitude

and

time.

It

is

also

used to identify

the

respective

parts

of

two

signals

that

are

identical

in

amplitude

and

time.

Common-Mode

Rejection: The ability

of

a differential

am-

plifier

to

reject

common-mode

signals.

®

Common-Mode

Rejection Ratio

(CMRR):

Ratio

of

the

deflec-

tion

factor

for a

common-mode

signal to

the

deflection

factor

for a differential signal.

NOTE

Since

the

differential

amplifier

is

part

of

an

oscillo-

scope,

the

output

signal

used

to

calculate

the

CMRR

is

measured

from

the

CRT

screen

and

VOLTS/DIV

switch

setting.

Thus,

a

differential

amplifier

that

produces

a

.001

volt

output

when

driven

by

a

10

volt

peak

to

peak

common-mode

signal

has

a

CMRR

of

10

-:-

.001

or

10,000:

1.

2-7

Operating Instructions-Type

7A13

Fig.

2-6.

Capacitive and inductive reactance versus frequency.

Operating Instructions-Type

7A13

1

Mn

100

kn

10

kg

1

kn

100

n

10

n

1 n

0.1 n

.01 n

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:/

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Fig.

2-6.

Capacitive and inductive reactance versus frequency.

2-8

~

IX

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/

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IV

....

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1"-

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®

Operating Instructions--Type

7A13

Amplitude and Common-Mode Rejection

In the text which follows, the term "Input Signal Range"

means the common-mode operating range of voltage through

which the amplifier will produce a usable output. This should

not be confused with the maximum (non-destructive) input

voltage, which

is

related to the breakdown limits of the am-

plifier components.

Factors Which Affect CMRR

Frequency.

Since the common-mode output voltage

is

a factor of phase differences as well as gain between chan-

nels, the frequency of the input common-mode signal has a

direct bearing on the CMRR. Generally, as the frequency

of the input signal increases, the CMRR decreases. (Exception:

with AC-coupled input, the CMRR will become higher as fre-

quency

is

increased from DC to over 100

Hz.)

Source Impedance.

The specified CMRR assumes that

the points being measured have identical source impedance.

The source impedance and the amplifier input impedance

form an RC divider which determines the portion of the signal

that appears across the amplifier. input, and the apparent

effect on CMRR. See Fig. 2-4 and

2-5.

The user may desire to construct a similar graph of CMRR

versus frequency for specific applications where the source

or signal.transporting lead impedances are unbalanced. Fig.

2-6

is

included for this purpose.

Signal Transporting Leads.

A principal requirement for

maximum CMRR

is

that the signals arrive at the amplifier's

two inputs with no change in phase or amplitude. Slight

differences in attenuation factors, or phase shift between two

input attenuators may reduce the CMRR 20% or more.

Attenuator probes extend the usable voltage range of a

differential amplifier by reducing the input signal level below

(A1

Right

IBI

Wrong

circuit

under test

ICI

Wrong

equipment under test

XI0

Probe

A

XI0

Probe

B

Fig.2-8. Connecting a differential amplifier across

a

circuit.

the maximum common-mode input voltage. However, a re-

duction in the apparent CMRR will usually occur because of

com~onentvalue differences within the probes. For example,

Differential

amplifierWorst case

difference

between

Probe

A

and

Probe

B

1% (0.5% resistors)

2%(1%resistors)

10% (5%resistors)

Fig.

2-7.

Simplified circuit showing the limitation in CMRR that a

Fig.

'2-7

illustrates the change in

CMRR

(apparent) due to

difference between attenuator probes can introduce. Differences be-

X,10

prpbes

that

are within

'1

21

and

3%

of

their

atten'-

.

CMRR

limitation

introduced

by probes

11

1:l

55:l

11:l

tween probe capacitances add to the effect on

AC

signals.

atlon value.

Amplitude

and

Common-Mode Rejection

In

the

text

which follows, the term

"Input

Signal Range"

means

the

common-mode

operating

range

of

voltage

through

which

the

amplifier will

produce

a

usable

output.

This should

not

be

confused with the maximum (non-destructive) input

voltage,

which

is

the

breakdown

limits of

the

am-

plifier

components.

Factors Which Affect

CMRR

Frequency. Since

the

common-mode

output

voltage

is

a

factor

of

phase

differences

as

well

as

gain

between

chan-

nels,

the

frequency

of

the

input

common-mode

signal

has

a

direct

bearing

on

the

CMRR,

Generally,

as

the

frequency

of the input signal increases, the

CMRR

decreases.

(Exception:

with AC-coupled input, the

CMRR

will

become

higher

as

fre-

quency

is

increased

from

DC

to

over

100 Hz.)

Source

Impedance.

The specified

CMRR

assumes

that

the

points

being

measured

have

identical source

impedance.

The source

impedance

and

the

amplifier input

impedance

form

an

RC

divider

which

determines

the portion

of

the signal

that

appears

across

the amplifier input,

and

the

apparent

effect

on

CMRR.

See

Fig. 2-4

and

2-5.

The user

may

desire

to

construct a similar

graph

of

CMRR

versus frequency for specific

applications

where

the

source

or

signal.

transporting

lead

impedances

are

unbalanced.

Fig.

2-6

is

included for this

purpose.

Signal

Transporting

Leads. A principal

requirement

for

maximum

CMRR

is

that

the

signals

arrive

at

the

amplifier's

two

inputs with no

change

in

phase

or

amplitude.

Slight

differences

in

attenuation

factors,

or

phase

shift

between

two

input

attenuators

may

reduce

the

CMRR

20%

or

more.

Attenuator

probes

extend

the

usable

voltage

range

of a

differential amplifier

by

reducing the input signal level

below

Worst

case

difference

between

Probe

A

and

Probe

B

--------

Xl0

Probe

A I ,

-=€)

~

»>,

+

INPUT

+ :

9M!2

I

MatCheK!

U,

:

1

M!2

roll

I

resistors. I

Xl0

Probe

B:

I

==E)

~

M'-INPUT

- :

9M!2

_______

J

CMRR

limitation

introduced

by

probes

Differential

amplifier

1%

(0.5%

resistorsI

111

:1

2%

(1%

resistorsI 55:1

10%

(5% resistorsI 11:1

Fig.

2-7.

Simplified circuit

showing

the

limitation in

CMRR

that

a

difference

between

attenuator

probes

can

introduce. Differences

be-

tween

probe

capacitances

add

to

the

effect

on

AC

signals.

®

Operating

Instructions---

Type

7A

13

IAI Right

----,

I~

____

",""",\

I't-------{

1

probe

shields

I tied

together

1/

I

III'T--~,--f-I

circuit "

under

test

common

ground

IB)

Wrong

----,

I~----""

I

___

...J

circuit

under

test

ICI

Wrong

----,

I

___

...J

circuit

under

test

probe

shields

should

not

be

grounded

to

equipment

under

test

Fig.2-8.

Connecting a

differential

amplifier

across a circuit.

the

maximum

common-mode

input

voltage.

However, a re-

duction

in

the

apparent

CMRR

will usually

occur

because

of

component

value

differences within the probes. For

example,

Fig. 2-7 illustrates the

change

in

CMRR

(apparent)

due

to

Xl0

probes

that

are

within 1, 2,

and

3%

of

their

attenu-

ation

value.

2-9

Tektronix 7A13 User manual

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