Tektronix 7a15 Instruction Manual

1

Ν

E3-rFt

U

CT1C>

Μ

ΜΑΝ

V

A

L

Serial

Number

Tektronix,

Inc."Ρ.Ο.

Box

500

"

B

eaverton,

Oregon

97005

"

Phon

e ό

44-0161

"

Ca

b

les:Tektr

onix

070-1044-00



670

WARRANTY

All

Tekt

r

onix

ίη 5tr

ιι rηeηt5are

warrante

d

against-

defective

m

ateriais

and

workmanship

for

one

year,

Tektronix

'transfo

r

m

ers,

manufactured

in'

o

u

r

plant,

are

warrante

d

f

or

the life

of the

instrument,

Any

μιι

estions

withrespect

to

the

warranty,

mentioned

above

-s

h

ould-beta

ken

up''

with

your

TektronixFiel

d

CngineeιorRepre'sentativ?

.

All

r

equests

for

repairs

andreplacenι

entparts

should

b

e

di

r

ectedtothe

Tekt

roni

x

Fiel

d

Office

or

repr

esentative

in

your

area,'

Thisprocedurewill

assure

yo

u

the

fastest

possible

service

.Please

include

the

instrument

Type

(orPartRl τι

rriber3-αη

d Ser

i

al

o

r

Mod

el

Number

ινίΙhall

requests for

partsorservice

.

Specifications

an

d p

rice

change

privileges

reserved.

Copyrig

h

t

0

1970

by Tektronix,Inc.,B

eavertoη,-

Oregon

.

Printed

. intheUnitedStates of

America

.

All

rig

h

ts

rese

rve

d

.

Contentsofthis

publication

may n

ot

be

reprod

ucedin

any

form-without

permissionofthe

copyright

owner:,:. ", .

TABLE

OF

CONTENTS

Page



Page

SECTION

1SPECIFICATION



SECTION

5PERFORMANCE

CHECK/CALIBRATION

Introduction



1-1



Introduction



5-1

Electrical

Characteristics



1-1



Test

Equipment

Required



5-1

Environmental

Characteristics



1-2



Short-Form

Procedure

and

Index



5-2

Physical

Characteristics



1-2



Performance

Check/Calibration

Procedure



5-4

SECTION 2OPERATING

INSTRUCTIONS

General



2-1



SECTION

6ELECTRICAL

PARTS

LIST

Installation



2-1



Abbreviations

and

Symbols

Front-Panel

Controls



2-1



Parts

Ordering

Information

First

Time

Operation



2-1



IndexofElectrical

Parts

List

Control

Setup Chart



2-2

General

Operating

Information



2-4

Basic

Applications



2-5



SECTION 7



DIAGRAMS

AND

MECHANICAL

PARTS

ILLUSTRATIONS

SECTION 3CIRCUIT

DESCRIPTION

Introduction



3-1

Block

Diagram

Description



3-1

Detailed

Circuit

Description



3-1

SECTION 4MAINTENANCE

Introduction



4-1

Preventive

Maintenance



4-1

Troubleshooting



4-2

Corrective

Maintenance



4-5

Instrument

Repackaging



4-8

Mechanical

Parts

Illustrations

Instrument

Repackaging

SECTION

8MECHANICAL

PARTS

LIST

CHANGE

INFORMATION

Mechanical

Parts

List

Information

Index

of

Mechanical

Parts

Illustrations

Mechanical

Parts

List

Accessories

Abbreviations

and

symbols

used

in this

manual

are

based

onortaken

directly

from

IEEE

Standard

260

"Standard

Symbols

for

Units",

MIL-STD-12B

and

other

standardsofthe

electronics

industry.Change

information,ifany,islocatedatthe

rearofthis

manual

.

7

Α

15

Introduction



TABLE

1-1

(cost)

The

7

Α15vertical

amplifierplug-in

unit

isdesignedfor

u

se

with

Tektronix

7000-series

Oscilloscopes.The



7A15isα



Characteristic



Performance

wideband

general

purpose

amplifier,

withthe upper

fre-



Freq

uencyResponse



7500-series



7700-series

q

uency

limit

d

eterminedmainly

by

the

oscilloscope

in



System

De

pend

ent



Oscillosco

pe



Oscilloscope

which

it isused.

For

exam

p

le,

the7Α15usedwiththe

7504



Up

p

er

Ban

dwidth



60

MHz



75

MHz

oscilloscope

willhave

α System

Ban

dwidth

of60mega-

hertz

;

andwhen

usedwiththe

7704

oscilloscope,

the



(DC

Coupled)

system

bandwidth

will

be 75 megahertz.ΑPOLARITY



L

ower

Bandwidth

switch

providesαmeans

of

inverting

thedisplay.The7Α

15

canbeoperatedin

anyplug-in

com

partment

of

the

7000-



(AC Coupled)

series

oscilloscopes

.



W

ithoutProbe



2

h

ertzorless

This

instrument

will

meet

the

electrical

characteristics

listedinTable

1-1

following

complete

calibrationasgiven

in

Section5.

Theperformance

check

procedure

given

in

Section

5 p

rovidesαconvenient

method

of

checking

instru-

ment

p

erformance

without making

internal

ad

justments

.

SECTION

1

S

PE

CI

F

I

CA

ΤΙΟΝ

Ch

ange

information,ifany,

affectingthissection

will

be

foundatthe

rearofthemanual

.

The

following

electrical

characteristics

are

valid

over

the



Capacitance



20

picofarads

within1.5picofarad

statedenvironmental

range

for

instruments

calibrate

d

at

an

ambient

temperature

of

+2ρ°ς

to

+30°C,

and

after

α

five



R

andCProduct



W

ithin

1°/οover

alldeflection

factor

minute

warmup

unless

otherwise

noted

.



settings

Deflection

Factor

Calibrate

d R

ange

GAIN

C

h

aracteristic

GainRatio

Accuracy

Uncalibrate

d

(Variable)

TABLE

1-1

ELECTRICAL

C

HARACTERISTICS

P

erformance

5

mV/divto5 V/div;10stepsinα

1,2,5

sequence

.

W

ithin2%of

GAINadjustedat

10

mV/div

.

W

ithΡ6053ProbeΙ0

.2hertzorless

Maximum

Input



500V(DC

+

Peak

AC)

.

AC

com-

Voltage



I

p

onent1kHzorless

.

InputRandC

R

esistance



11megohm

within

2°/

ο

7Α15

Maximum

Input



0.5nanoampere

or

less,

0°C

to

Gate

Current



~

+35°C

.

2

nanoampere

or

less,

+35°C

to

+50°C

.

Displaye

d N

oise



0

.06divisionorlessat5

mV/

d

iv

(Tangentially



measuredin

7700-series

oscillo-

Measured)

scope

.

DC

Drift

Drift

W

ith

Time
(Ambient Tem-
perature

and

Line

Voltage

Constant)

Continuously

variablebetween

cali-

brated

steps;extendsdeflection

factor

to at least12.5

V/div

.

Short

Term



250microvolts/minute(P-P)or

P

ermits

a

d

justment

ofdeflection



0

.05division

(whicheverisgreater)

factor

for

all

7000-series

oscillo-



in

any

one

minute,

after

onehour

scopes

.



warmup.

Specification-7A15

Characteristic

Long

Term

Drift

With

Ambient

Tem-

perature

(Line

Voltage

Constant

TABLE

1-1

(cont)



TABLE

1-2

ENVIRONMENTAL

CHARACTERISTICS

Performance

250

microvolts/hour

(P-P)or0

.05

division

(whicheverisgreater)

in

any

one

hour,

after

one

hour

warmup

.

Refertothe

Specification

for

the

associated

oscilloscope

.

100

microvolt/degree

centigrade

or



TABLE

1-3

less

.



PHYSICAL

Fits

all

7000-series

plug-in

compartments

.

SECTION

2

OPERATING

I

NST

RU

CTIO

N

S

Ch

ange

information,ifany,

affecting

this

section

willbe

foundatthe

rear

of

this

manual

.

General



IDENTIFY



Wh

en p

ressed,deflects

trace

up-

The7Α15vertical plu

g-inunitsop

erates

with αTek

-



wardfor

i

d

entification

and changes

tronix

7000-series

oscillosco

peand

α 7Β__

series

time-base



CRT



readout

to

t

heword

u

nittoform

α complete

oscilloscopesystem

.Toeffectively



"IDENTIFY"

.

uset

he 7Α15,theop

eration

andca

pab

ilities

of

t

heinstru-

mentshou

l

d

bek

nown.This

sectiondescribes

the

operation



P

OLARITY

ofthe

front-panel controls,

gives

first-timeoperation

and

general

operating

information,

and

lists

some

measurement



+

UP



Αροp

itive-cesαsignal

atthe

IN-

PU

Trodus



p

ositive

d

eflection

techniques

usingthe

amplifier.



onthe

CRT

.

Installation



INVER

T



Invertsdisplay.Α

negative-going

The7Α15isdesignedto

operateinα

vertical

plug-in



signal attheINPUTprodu

ces

α

compartment

ofTek

tronix

7000-series

oscilloscopes.F

or



positive

d

eflectionontheCRT

.

Χ

-Υoperation,the7Α15

may

alsobeinstalledin

αhorizon-

talplug-in

compartment

(refertothe

Oscilloscope

Instruc-



CO

UPLIN

G

tion

Manual

forin

formationonΧ-Υoperation).To

install

AC

Capacitively

couplesthe

input

sig-

t

he 7

Α15intoαplug-in

compartment,pushitin u

ntil

it is



ηαΙtothevertical

amplifier

.

seated

flushagainstthe

frontpanelofthe

oscilloscope

.

To

remove,

pull

the

release

latchtodisengagethe 7Α15

from



GND



Disconnects

the

input

signalfro

m

t

heoscilloscope

.

Continue

to pullthe

release

latchto

re-



theamplifier

and groundst

h

e

am

move

t

h

e u

nit

fromthe

oscilloscope.



p

lifierinput

.Allowsthein

p

ut

coupling

capacitortobe ch

arged

to

theDC

voltage

app

liedtothe

IN-

FRONT

PANEL

CO

NTRO

LS



PUTconn

ector

.

Allcon

trolsrequ

iredfor operationoft

he 7Α15

are

lo-

DC

Thesignal

is

directly

coupledtothe

catedonthefront panelofthe

unit.Α

briefdescriptionof



amplifier

.

thefunction

oroperationofthefrontpanel

controls

follows.M

oredetailedinformationisgiven

und

er

General



GAIN



Screw

d

riveradj

ustmentpermits

OperatingIn

formation

.



A

dju

stment



calibration

ofdeflection

factor

.

VOLTS/DI

V

Selects

calibratedverticaldeflection

factor

from5mV/divto5V/div

in

α1,2,5se

q

uence

.

VA

RIA

BLE



P

rovides

uncalibratedvaria

b

lede

(VOL

TS/DIV)



flection

factors.E

xtends

t

h

e

h

ighestdeflection

factor

to

at least

12.5V/div.Pus

h k

nobinan

d

re-

leasetoactivate;theknob

moves

outwardfromthe

VOLTS/DI

V

controlwhenactivated.

VA

R BAL



Screwdriveradju

stmentpermits

Adj

ustment



b

alancing

of

theamp

lifier

for

minimum

tracesh

iftwh

ile

rotating

theVARIA

BLE

control

.

I

N

PU

T



BNCconnectorfor

applying

exter-

Connector



ηαΙ

signals

.

General

FIRST-TIME

O

PER

ATIO

N

7Α15

Wh

ensh

ippedfromthe

factory,the 7Α15

hasbeen

cali-

P

OSITIO

N

Controls

vertical p

ositionof

oscillo-br

ate

d

to

meet

thesp

ecifications

listed

in

Section1and

is

sco

pe

d

isplay

.



ready

to

beuse

d with anind

icator

oscilloscope

.

Operating

Instructions-7A15

T

h

e

following

stepsdemonstrate

th e

basicoperation of

t

he controlsoft

he

7

Α15.Itis

recommende

d

t

hatthispro-

cedure

be

followe

d

com

p

letely

for

familiarization

withthe

instrument.Operationoftheoscilloscope

andtime-base

unit

isdescri

bedintheinstructionmanualforth

ese

units

.

Setu

pIn

formation

1 . Insertthe 7Α15intoα

vertical

p

lug-in

compartment

ofα7000-series

oscilloscope

.

2

.

Insertα713--series

time-base

unitintoαhorizontal

p

lug-in

com

partment

.

2-2

3

.

Set

t

h

e

controls as

follows

:



Fig

.

2-1.Oscilloscope

displaywhen check

ing

amplifier

Gain

.

7

Α

15(L

eftVert

compartment)

P

OSITIO

N



Midrange

POLARITY

+UP

VOLTS/DI

V

10

m

V

CO

UPL

ING

DC

VARIA

BLE

CA

L

IN

713511(ΒHoriz

com

p

artment)

L

evel/Slope



Centere

d on p

ositive

slo

p

e

Triggeri

ng

Mo

de



Ρ-ΡAu

to

Coup

ling



AC

Source



Int

Time/Div



1

ms

Variable

(Time/Div)



Cal

In

M

agnifier



Χ

1

Β Delay

Mode



I

ndependent

P

osition



Mid

range

7504

(Indicator

Oscilloscope)

V

erticalMode



L

eft

Horizontal

Mode



Β

Β

Intensity



CCW

Calibrator



1kHz,

40

mV

Β

TriggerSou

rce



L

eft

Vert

4

.

Connectthe

oscilloscope

to

α p

ower

sourcewhich

meets

thevoltage

andfrequency

re

q

uiremen

ts oftheoscil-

loscope

power

supply

.

7.Connectthe

Calibratoroutputtothe 7Α15

INPU

T

conn

ector

.

8.Chec

ktheCR

Tdisplay

forfou

rdivisionsofvertical

deflection

(see

Fig.2-1).If

necessary,adj

ustthe

front

p

anel

GAINforfou

rdivisionsofverticaldeflection

.

9

.Press

theIDE

NTIFY

b

uttonand checkthatthe d

is-

play

moves

upward

about0.3

divisions

.

Alsocheckth

at

t

he

rea

d out

information

on

the

CRTis

replace

d by thewor

d

"IDENTIFY"

.

10

.Press

and

release

theVARIABLE

controltoits

out-

wardposition.

TurntheVARIA

BLE

control

fully

cou

nter-

clockwise,

and check

for1.6divisionsorlessdisplayamp

li-

tude

.PresstheVARIABLE

controltotheCAL

INposition

.

11.C

hangetheVOL

TS/DIVto0.1V,Calibrator

Volts

to0.4

V

an

d

t

heTriggering

Sou

rce

to

Ext

.

Connect

the

Calibrator

outputthrough α "Τ" connectortothe

timebase

Ext

Trig

In

an

d

t

he 7Α15INPUTcon

nector.Set the

P

OLARITY

switchtoINVER

T

todisplaytheopp

osite

polarityoft

he

s

q

uare

wave

.

This

completesthe

basicoperatingprocedure

forthe

7Α15

.

I

nstrument

operations

not

explai

nedhereorop

era-

tionswhich

nee

d

further

exp

lanation

arediscussedund

er

General

OperatingIn

formation.

5

.

Turn

theoscillosco

pe

p

ower

on

and

allow

about 5



CO

NTROLSE

T

UP

C

H

ART

minutes

warmup.

Figure

2-2sh

owsthefront panelofthe7Α15.Thischart

can bereproduced andusedasαfrontpanel

record

for

6.Advance

theΒIntensity

untilαfree-running

trace

issp

ecial

measurements,app

lications

or

p

roce

du

res,orit

may

observed.

Adj

ust thePositioncontrols to centerth

e t

r

ace



b

e

use

d

asαtraining

aidfor

familiarization

withthisinstru-

οηtheCRT

.



ment

.

7Α15

T

E

ST

SET-

UP

C

HAR

T

σ»οί~ορρν

POSITION

VAR

BAL

INPUT

imp

20

pF

ΤΕΚΤRΟΝΙ

%®

7

Α

75

P

OLARITY

Π

+

UP

-/I

NVER

T

V

ARIA

BLE

(CALIN)

V

OLTS/DI

V

Ί-

Ί

AC

GN

D

υ

DC

AMPL

IF

I

ER

F

ig.2-2.7

Α

15

control

setup

c

h

art

.

Operating

Instructions-7A15

2-

3

Oper

ati

ng Instructions-7A15

G

ENER

A

LOPER

ATI

NGINFO

RM

ATIO

N



T

heGNDpositionisalso

usedtopre-chargethecoup

ling

capacitortotheaverage

levelofthe

signal

app

liedtoth

e

Signal

Connection



I

NPUTconnector.T

hepre-charge

network

allowsthei

npu

t

In

general,

probesoffer

the

most

convenient

means

of



coupling

capacitortocharge totheDC

source

voltage

level

con

nectingαsignaltot

he

inputoft

he 7Α15.Tek

tronix



whe

ntheCO

UPLINGswitchis

settoGND.

p

robes

aresh

iel

ded

to

p

r

eventpickupofelectrostatic

inter-

ference.Α

10

Χ

attenuatorprobe

offers

αhighinput

im-



T

he

p

ed

ance

andallowsthecircuit

under test tooperate

very



procedure

for

usingthis

featureisas

follows

:

closetonormal

operatingconditions

.However,α10

Χ

p

robe

also

attenuatestheinput

signal

ten

times

.



1

.

Before

connecting

the

signal

con

tainingαDC

com-

p

onenttot

he 7Α15

INPUT,set

theCOUPLING

switchto

GND.Then

connectthesignaltotheINPUTconnector

.

Inhigh-frequency applications

requiring

maximum

over-

allbandwidth,useαcoaxialcableterminatedat

both end

s

inthech

aracteristic

imp

e

dance

of

thecable.Tomaintain

t

h

e

h

ig

h

-fre

q

uencych

aracteristics

of

t

h

e

a

pp

liedsignal,

use

h

igh-

q

uality

low-loss cable

.Resistive

coaxial

attenuators

can beusedto

min

imize

reflectionsiftheapp

liedsignalhas

s

u

itableamp

litu

de

.

Input

Coupling

T

h

e

AC-GND-DC

lever

switchallows

αch

oiceofinput

co

upling.Thety

pe

ofdisplaydesire

d

d

eterminesthemode

ofinputcouplingused.TheDC

p

osition

can be

usedfor

mostapp

lications.However,

ifthe

DC

com

ponentofthe

signalismuchlargerthanth

e

AC

component,theAC

p

osition

willprobablyprovide α

betterdis

p

lay.DC

coupling

shouldbeusedtodisplayACsignals b

elow about 2 h

ertz

an

d squ

are

waves

containing

low-frequency

com

ponen

ts,

as

t

hey

willbe

attenuatedinthe

ACposition

.

Ι

η

the

ACposition,theDCcomponentisbloc

ked by

α

capacitorintheinputcircuit.The

low-frequency

response

intheAC

positionisa

bou

t

2hertz

(-3dBpoint)

.

There-

fore,

some

low-frequency

attenuation

can

be

exp

ectednear

this

frequency

limit.Distortion

will

also

app

earinsquare

waveswhich h

ave

low-frequency

components

.

2-

4

2

.

Allow

abou

t

two

seconds

for

the

coup

lingcap

acitor

tocharge

.

3

.ResettheCO

UPL

ING

switchto

AC.Thetrace

(display)

will

remainonthe

scree

n

and

t

heACcompon

ent

ofthe

signal

canbe

measuredinthe

normal

manner

.

H

igh-level

low-frequency

signals

can

b

e

connecteddirec-

tly

to

the7Α

15INPUTconn

ector

with sh

ort

unsh

ielded



DeflectionFactor

leads usingαBNCto

BananaJackAdapter.This

method

wor

k

s

best

for

signals

below about

onekilohertzanddeflec-



Theamountof

vertical d

eflectionproduce

d byαsignal

is

tion

factors

above

one

volt/division.

Whenthis

met

hod

is



d

etermine

d bythe

signalamp

litude,theattenuation

factor

u

sed,

establis

h α

common

ground

betweenthe 7Α15

and

of

t

heprobe

(if

any),the

settingoft

heVOL

TS/DIVswitc

h

t

he

e

q

uipment

under test

(common

ground p

rovide

d by



andthe

settingoftheVARIABLE

control

(ifcon

trolisi

n

line

cordsis

usually

ina

deq

uate).Attempt

topositionth

e



t

he outwar

d p

osition).The

calibrate

d

d

eflection factors

in-

leads

away from

any

sourceofinterfere

n

ce to

avoiderrors



dicatedbytheVOLTS/DIVswitc

h

app

ly

onlywhent

he

inthe disp

lay.If

interferenceisexcessive

with

unshielded



VARIA

BLE

controlisinthe inward

(CA

L

IN)position

.

leads,

use α

coaxial

cableorαprobe

.

TheVARIA

BLE

controlprovides

uncali

b

rated

vertical

d

eflectionbetweenthe

calibrate

d

settingsoft

heVOLTS/

DIVswitch,

an

d exten

d

s

the

maximu

m

d

eflection

factor to

at

least12.5

volts/division

.

The

GAI

N

control,αfront-panel

screwd

riveradj

ustment,

sets

thegainof

the7Α15inthe 10mV/d

ivpositionoft

he

VO

L

TS/DIVswitch.The

gain

calibrationoftheunitshou

l

d

be c

h

ecked

for accuracypriortomaking

critical

measure-

ments,

using

eitherthe

oscilloscope

calibratoroutput or

α

standardamplit

ude

calibrator.If

adj

ustmentisnecessary,

theGAI

N

s

h

oul

d b

e adju

ste

d withtheVOL

TS/DIVswitc

h

setto10

m

V

.

V

ariable

B

alance

To

c

heck

an

d

/o

radjusttheVARBA

L,proceedasfol-

lows

:

1.Set theCOUPLINGto

GND

an

dad

just

the

time-base

TheGND

positionprovidesαground

referenceatt

he



controls

forαfree-running

trace

.

amplifier

input.The

signal

appliedtotheINPUTconnector

ispresentedwit

h α

one

megohm

load,wh

ile

theamp

lifier

in

putis

grounded.This

eliminates

the

needto

externally



2

.Press

and

releaseth

e

VARIA

BLE

controltoitsou

t-

gro

und

theINPUTto

establis

h αDCgroundreference

.



war

d p

osition

.

3

.While

rotati

ng the

V

ARIA

BLEcon

trol

throughout

its

range,

a

dju

st

the

VA

R BAL

(αfrontpanelscrewdriver

ad-

ju

stment)

for

minimum

trace

shift(0.5

div or

less

shift

as

VARIA

BLEcon

trolisturned

from

fully

clockwise

to

fully

counterclockwise)

.

Signal

P

olarity

The P

OLA

RITY

switch p

rovidesαmeans

of

inverting

thedisplay.W

it

h the

P

OLARITY

set

to

+

UP,

α

positive-

going

voltage at

theI

NPU

T

producesanupward

deflection

of

theCRTdisplay.W

it

h

P

OLARITY

settoI

NVER

T, α

p

ositive-going

voltageatt

h

e

I

NPU

T

will

p

roduce αdown-

ward

deflection of

theCRT

d

isplay.Ifαsymmetrical

wave-

form

suc

h

as

thecalibrator

square-waveistobeob

served,

the

time-base

must

be

triggeredexternally to

observe

t

he

p

olarity

i

nversion

.

This isdue

to the time-base

unit

trigger

ingonthe indicated

slo

pe ofthe disp

layedwaveform

w

hen



F

ig.2-3

.Oscilloscope

display

when

makingΡ-Ρvoltage

measu

re-

it is

triggeredinternally

.



m

ents

.

Display

Identification

2

.Reset

the

CO

UPLIN

G

to

AC,

adjust

the time-b

ase

Wh

en

the7Α15IDENTI FYbuttonisp

ressed,

the

C

RT



triggering

controls

for α

stabledisplay

andset

the

Time/Div

display

representing

theout

put of the 7

Α15is

deflected



todisplay

several

cycles of the

waveform

.

upward

about

0

.3

d

ivision

for

identification

.

This

feature

is

p

articularly

usefulinoscilloscopeshaving multi-tracedis-

p

lays

.



3.Set

t

he

VO

L

TS/DI

V

switc

h

todisplay

about

five

verticaldivisions

of the

waveform.C

heckth

at

theVAR-

IA

BLE

controlisin

the

CA

L

IN

(

push

ed

in)position

.

Wh

enusing

an oscilloscope

systemequipped

with

t

h

e

readout

feature,

information

suchasp

olarity,deflection

factor,

etc.,is

displayedontheCRT

.When

theIDENTI

F

Y

bu

ttonispressed,

the

readout

informationpertainingtothe

7

Α15is

replacedbythe

word

"IDENTI FY"to

aidin locat-

ing the 7Α15

readout

w

hen

more

than

one

verticalunit

is

used

.

Thefollowing informatio

n d

escribes theprocedure

an

d techniqu

es for

making

basic

measurements

wit

hthe

amplifier.T

hese app

lications

are

notdescribedin

d

etail

since

eachapplicationmustbeadaptedtotherequirements

of the

individual

meas

u

rement

.Familiarity

wit

hthe 7

Α

15

will

permit

t

hese

b

asic

tec

hn iques

tobeappliedtoαwide

varietyofuses

.

P

eak

-to-Pea

k

V

oltageMeasurement-AC



6.M

ultiply

the d

ista

nce

(indivisions)

measuredin

step

5

by

t

he

V

OLTS/DIVswitch

settings.Incl

udeth

e attenua-

Το make

α peak

-to-pea

k voltage

measurement,use

t

he



tion factor of

theprobe

being

used

.

followingprocedure

:

E

xample:Assumeαp

eak

-to-peakvertical

d

eflectionof4

.6

1 .Wit

htheCOUPLIN

G

settoGN

D,

connect

thesignal



d

ivisons

using α10Χ

attenuatorprobe

andαV

OLTS/DI

V

to

theI

NPU

T

con

nector

.



setting

of 0

.5

V

.

BASICAPPL

ICATIO

N

S

OperatingInstructions-7A15

4.W

it

hth

ePOSITIONcontrol,positionthedisplay

so

the

lower

portion of the

waveform

coincides

with

one

of

t

h

e

gratic

u le

linesbelow

t

h

e

center

h

orizontal

refere

nce

line,

and

the

topof

the

waveform

is in

the

viewing

area

.

M

ove

thedisplay

wit

h the

h

orizontalPositio

n control so

on

e of the

upperpeaksis

aligned

wit

hthe cen

ter

vertical

reference

line

(seeFig.2-3)

.

5.M

easure

the

verticaldeflection

from

pea

k to

pea

k

(divisions)

.

NO

ΤΕ

T

his

technique

may

also

be

usedtomake

measure-

ments

between

two

pointsonthe

waveform,

rather

than

peaktopeak

.

2-5

O

per

ating

Instructions-7A15

V

olts

(peak-to-peak)

_

vertical

V

OLTS/DIV

probe

d

eflection

Χ

switch

Χ

attenuation

(divisions)

setting

factor

Substituting

the

given

values

:

V

olts

(peak-to-peak)

=4.6Χ

0

.5Χ10

The

peak-to-

peak

voltageis23

volts

.

InstantaneousVoltageMeasurement-DC

To

measure

theDClevel atαgiven

pointonα

waveform,



F

ig

.

2-4

.



Oscilloscopedisplaywhen

measuringinstantaneous

DC

use

the following

proced

ure

:



level

.

1.Set

the

COUPLING

to

GND

an

d

p

osition

the

trace

to

thebottom

lineofthe

graticule

(or

other

selecte

d

reference

line).If

the

voltage

tobemeasuredis

negative

with

respect

to

ground,position

the

tracetothe

topline

of

the

grati-

cule

.Donot

move

the

verticalPOSITION

control

after

this

reference

h

as

been

established

.

ΝΟΤΕ

To

measureαvoltage

level

withrespecttoa

voltage

otherth

an ground,make

the

followingch

anges

to

step1:

SettheCO

UPLIN

G

to

DC

and

apply

the

r

eference

voltagetotheINPU

T

connector,th

en

positionthetracetothe

reference

line

.

2.Connect

the

signaltothe

INPUT

connector

.

3.Set the

COUPLING

toDC(the

ground

reference

can

b

e checkedat

any

time by

setting

the

COUPLI

NG

to

GND)

.

1ηsome

applications,itmaybenecessarytoestablish

α

setofdeflection

factors

other

than

those

indicate

d by the

4.Set

theVOLTS/DIV

switch

todisplay

about

five ver-



V

OLTS/DIV

switch.Thisisuseful

for

comparing

signals

to

tical

divisionsofthe

waveform.Checkthat

theVARIABLE



α

reference

signal

amplitude.Toestablishαnew

set

ofde-

controlisin

the

CAL

IN position.Adjust

the time-base



flection

factors

basedupon

α specific

reference

amplitude,

triggering

controls

forαstabledis

p

lay

.



proceedasfollows

:

5

.Measure the

vertical

distanceindivisions

between

the

reference

line

and

thepoint

on

the

waveformatwhichthe

DC

levelistobemeasured.Forexample,inFig.

2-4 the

measurementismade

betweenthe

reference

line

an

d

p

oint

Α

.

EMENEEMEME

M11111111M

ON

MEN

MENEM

6a

R

ι

R

EE

"

//

"

MENEM

_

MEMEMEMM

7.M

ultiply

thedistance

measured

in

step5by

the

V

OLTS/DIV

switch

setting.Includethe

attenuation

factor

of

theprobe,ifany

.Example:Assume

that

the

vertical

distance

measuredis4.8

divisions,

the

waveformisabove

the

reference

line,

u

sing

α 10Χattenuator

probe

and

α

V

OLTS/DIV

switch

setting

of0.5

V

.

U

sing

the

formula

:

Instantaneous

_

V

oltage

vertical

P

olarity

V

OLTS/DIV

probe

distance

ΧPolarity

Χ

Switch

Χ

attenuation

(divisions)



setting

factor

Substituting

the

given

values

:

InstantaneousVoltage=4.8Χ+1Χ

0

.5VΧ

10

The

instantaneous

voltageis+24

volts

.

V

oltage

ComparisonMeasurements

1.Applyαreference

signal

ofknown

amplitudetothe

INPUT

connector

.Using

theVOLTS/DIV

switch

and

the

V

ARIABLE

control,

adjust

thedisplay

foranexact

number

ofdivisions.Do

not

move

theVARIABLE

control

after

obtaining thedesireddeflection

.

2.Divide

the

amplitudeofthe

reference

signal

(volts)

6.E

stablishthe

polarity

of

the

signal.If

the

waveform

isby

theproductofthedeflection

(

d

ivisions)

from

step1an

d

a

bove

the

reference

line,

the

voltage

ispositive

;

below

the



theVOLTS/DIV

switch

setting.Thisisthe

Deflection

Con-

reference

line,

negative

.



versionFactor

.

2-6

Operating

Instructions-7A15

Deflection



6

.Measure

the

vertical

d

eflection

indivisionsand d

eter-

reference

signal

amplitude(vo

lts)

Conversion

=



mine

theamp

litudeby

the following

formula

:

F

actor



d

eflection

(divisions)ΧVOLTS/DIV

setting

3.Todetermine

the

amplitudeofαsignal

comparedto

α

reference,disconnect the

reference

signal

and apply

the

sig-

nal

tobe

comparedto

the 7Α15

INPUT

connector

.

4

.

Set

theVOLTS/DIV

switch toαsetting

thatprovides

sufficient

d

eflectiontomake

the

measurement

(do

not

readjust

theVARIABLE

control)

.

5.To

establishanAdjustedDeflectionFactoratany

setting

of

theVOLTS/DIV

switch, multiply

theVOLTS/

DIV

switch

settingby the

Deflection

ConversionFactor

establishedinstep2

.

Adjusted

SignalAmp

litude

=

DeflectionΧ



d

eflection

F

actor

(divisions)

E

xample:Assume

α

reference

signal

amplitudeof30

volts,αV

OLTS/DIV

switch

settingof5Van

d α

vertical

deflection of

four

divisions

.

Substituting

these

valuesinthe

Deflection

ConversionFactor

formula

(step

2)

:

Deflection



30volts

Conversion

=



=1.5

F

actor



4

(div)Χ5

V

T

hen

withαV

OLTS/DIV

switch

settingof2V,the

AdjustedDeflectionFactor

(step

5)is:

V

OLTS/DIV



Deflection



Adjuste

d

DeflectionFactor

= 2

V

Χ1.5

= 3

AdjustedDeflectionFactor

=switchΧConversion



volts/division

setting

F

actor

Todetermine

the

amplitude

of

an applied

signal

which

producesαvertical d

eflectionoffive

divisions,

use the

Sig-

This

AdjustedDeflectionFactoriscorrectiftheVAR-



ηαΙAmp

litude

formula

(step6):

IABLE

controlhas

not been

movedfrom

theposition

set

in

step1.



Signal

Amplitude=3VΧ5(div)=15

volts

NOTES

Introduction

This

sectionofthemanual

contains

αdescription of

the

circuitryused

i

nth

e7Α15amplifier.Thedescription

begins

withα d

iscussionoftheinstrument

using

the

blockdiagram

shown

in thediagrams

section.T

hen each

circuitisd

es-

cribedindetailusing

t

he b

loc

k d

iagramtoshow

intercon-

nectionsbetween

the

circuitsand

relationshi

p of

thefront

p

anel

controls

to

theind

ivi

d

u

al

stages

.

SECTION

3

CIRCUIT

DESCRIPTION

C

h

ange

information,ifany,

affectingthissection

willbefoundattherearofthis

manual

.

I

NPU

T

connector,

t

h

roughthe

input

coupling

circuittot

he

VO

L

TS/DIVswitch.

TheVOLTS/DIVswitc

h

p

rovides

t

h

e

appropriate

input

attenuationand

applies

thesignal

to

the



Input

Attenuator

7Α15

Inadd

itiontothe

fun

ctionsoftheamplifier

j

ust

ex-

p

lained,the7Α15

alsoprovides

readout

logic

for the

ind

i-

cator

oscilloscope.Logic

is supplie

dwhich

identifies

t

he

displayPolarity

and

the d

eflection

factor,

whether

calibra-

ted oruncali

b

rated

.Whe

nth

e

IDENTI F

Y

button

is

pressed,

thereadoutiserasedan

d

t

he

word

IDENTIFY

app

ears.At

the

same

time,

the

bottom

ofR274isgrounded

to d

eflect

the

traceupward

approximately0.25division

.

D

E

TAI

LE

D

CI

RCU

IT

DESCRIPTIO

N

Complete

schematics

of each

circuit

are given

in the

Diagrams

section.R

efer

to thesediagrams

throughout

t

he



Input

Coupling

following

circuit

description forelectrical

values and

rela-

tionsh

ip.



Input

signals

appliedto

the

I

NPU

T

connector

can

be

AC-coupled,

DC-coupled,orinternally

d

isconnected.Wit

h

t

he

coupli

ng switch

settoAC,

the

signalpat

h

is

throug

h

C1-R1-CO

UPLING

switch

-C3-R3 and

t

h

roug

hthe

VOL

TS/

BL

OCKDIAGRA

MDE

SCR

IPTION



DIVswitch to

the

inputamp

lifier.Ιη

thisposition,C1p

re-

vents

the

DC

componentofthesignal

from

passi

ng

to

t

h

e

Thefollowingdiscussionisp

rovided toaid

in

und

er-



amplifier.W

iththe

CO

UPLING

switch

settoDC,

thesignal

standing

the

overall

concept

of the 7Α15

before

theindi-



p

at

h

is

throughC3-R3 an

d theVOLTS/DIVswitchto

the

vid

u

al

circuits

arediscu

ssedindetail

.Eachblockon

t

he



amplifier

input.W

it

h theCOUPLIN

G

switch

settoGN

D,

B

lockDiagram,

(in

theDiagrams

section)

rep

resents

an

indi-



the

input

signalisAC-coupledthroughC1-

R

1-R2 to

ground

vidual

circuit

within

the

instrument.T

he numb

eroneach

to

p

rovideαconstant

load

for

the

signal

source.At

the

blockreferstothediagramonwhic

h the

complete circuit is



same

time,

theamplifier inputisgrounde

d to

provideα0

fo

und

.



volts

reference

level

.

R

esistor

R2

allows

C1

to bep

re-

chargedin

the

GND

position

so the

trace

will

remain

on

screen

when

the

ACbuttonisp

ressed

wit

h α

h

ighDC

level

Thesignaltobe

displayedonthe

CRTisapplie

d to

t

he



a

pp

lied.

I

npu

t

Amplifier

(Q103A-Q103B-Q110-Q210-Qll2-Q212)

.



Theeffective

overalldeflection

factorofthe7Α15is

Thegain

setting,

variable

gain,and

variable

balance

adjust-



d

etermi

ned by the

VO

L

TS/DIVswitch

attenuators.T

he

mentsare

containedin

this

stage

.

The

in

put

signalis



b

asicdeflection

factorofthe7Α15is5m

V

p

er

d

ivision

of

ch

anged

from

single-ended to

differential

by

this

stage

and



d

eflection.To

increase this

b

asicdeflection

factor

to the

applied

to thepolarity

selection

stage.TheP

olarity

Selec-



valuesind

icate

d on

the front p

anel,

p

recision

attenuators

tion

stage

(Q130-Q230-Q140-Q240)

p

rovides

signal

polarity



are

switch

ed

into the inputcircuit.Thei

npu

t

atte

nuators

inversion

when

the

frontpanel

POLARITY

switchisset

to



form

frequency-com

p

ensated voltagedividers.F

orDCand

I

NVER

T

.



low-frequency

signals,

they

areprimarily

resistance

d

ividers,

an

d

the

voltage

attenuationisd

etermine

d by

the

resistance

ratio

in

the

circuit.Thereactance

of

the

cap

acitors

i

nth

e

The

Out

put

Amplifier

stage

(Q160-Q260-Q170-Q270)



circuit

is

sohighat

low

frequencies

t

h

at theireffect

is

provides

vertical

p

ositioni

ng of theCR

T

display

and

im-



negligible.H

owever,

athigher

freque

n

cies,

thereactance

of

ped

ance

matching

betweenthe7Α15and

the

oscillosco

pe



the capacitors

d

ecreasesand

the attenu

ator

becomespri-

vertical



input

.T

he



Trigger



P

ickoffcircuit,



marilyαcapacitance

voltage

divider

.

0180-Q280-Q185-Q285,

ta

kes

the

signal

from

t

he

emitters

of

Q170-Q270

andamp

lifies ittop

rovide+and-trigger



Inad

dition to providing

constant

attenuationatall

fre-

signals

for

the

time

b

aseunit

.



q

uencies

within thebandwidth

of

the

system,

the

input

Circuit

Description-7A15

attenuators

are

designe

d to

maintain

the

sameinp

utRC



and

Q260

isprovided

by

R

161-C161andR261-C261



'

c

h

aracteristics

for

eac

h

settingoftheVOLTS/DIVswitch

.



respectively

.

R

171-C171

andR271-C271provide

thermal

The

attenuators

containad

ju

stablesh

untcap

acitorstop

ro-



compensation



for



Q170an

d

Q270



respectively

.

videinp

ut capacitance

.



C253-C175-R175

arehigh-fre

q

uencypeakingadjustments

for

calibrationoft

he 7Α15

.

In

put

Amplifier

The

signal

from

theinput

atte

n

uatorisconnecte

d tothe

Input

Amplifier throughR

109-R100-

R

101-C101.These

resistors

are p

artoftheattenuation

networ

katallVOL

TS/

DIVswitchpositions.R

esistorR101

limits

the

overd

rive

gate

currentofinputFET

Q103A

.

C101-CR

102-C102pro-

videaninputprotection

circ

u

ittop

rotect

Q103A

from

large

negative

voltage

swings.Protection

from

lar

ge p

ositive

voltage

swings

isprovided by

Q110,

w

hich

effectively

clamps

the

sourceofin

putFET

Q103A

to the

+15

volt

supply

.

Thei

nput

signaliscoupledth

roug

h

sou

rce

follower



R

eadoutBloc

k

Q103A

andemitter follower

Q110

to

the

baseofQ112,

one-halfofthe

inputparaphaseamp

lifier.Theot

herhalf

of



An

analog

coding

system

isusedin t

he 7Α15

to

convey

t

he paraphaseamp

lifier,

Q212,

is

α

grounded

-base

con-



information

from

theplug-intot

he oscilloscope

readou

t

figuration.The

reference

voltage

levelatthebaseofQ212



section

.Each

sym

bolusedbyt

he 7Α15req

uires

two

cur-

is

setbytheVAR BAL

control,αfront

paneladj

ust.T

h

e



rents

todefine

it.This

read

out

information

is

encoded

on

p

araphaseamp

lifier

convertsthesingle-endedinpu

t

into

α



~°

output

lines,

interface

connectorsΑ37 an

d Β

37,

by

the



,

d

ifferentialoutput.The

gainoftheamplifierisset

in

this



A30tοrsbetween

out

pu

t

and

B33

.

and

interface

connectors

stagebyfrontpanel

GAIN

controlR121 wit

hthe

variable



Α

30,Α32,Α33,

Β

29, Β32and33

.

control

settotheCA

LINp

osition.With theVAR

IA

BLE

controlintheo

u

tward(uncalibrated)positionandtu

rned



R

efer

toSch

ematic

Diagram3inth

e

Diagrams

section to



'

fullycounterclock

wise

to

minimum

resistance,th

e

gainof

fin

d

t

h

ititdithilif

h

t

heamplifierisreduce

d

byαfactor of at

least2.5

.

Thise

ressors

assocaewα

p

artcuar

settngote

extends the

maximum

uncalibrate

ddeflection

factor to at



Ti

ηα



resistors

switch

.

least

12.5volts/division.Damping

resistorsR114 and

R214

i

nthecollector

circuitsofQ112

and

Q212

respectively,



The

pro

b

e

connectedtotheINPU

T

connector

forms

α

serve

to

dampout

any

ringing

or

oscillations.C1 14-R

115



voltage

divi

der

wit

h 1175 to the

-15

volt

p

owersupplThye.

andC214-

R215

areth

ermal

compensation

networks,

amount

ofprobe

resistance

willdetermine

thebiasapp

lie

d

'

tothe

base

of

Q80.Forexample,

wit

hα10Χattenuator

P

olarity

Selection

Stage



p

robesuch

as the Ρ

6053 P

robe

connecte

d totheINPU

T

connector,the

biasapp

lie

d tothe

baseofQ80

will

allow

T

h eP

olarity

Selection

Stage

ma

d e

up

of



100

microamperes

of

collectorcurrent

to

flow.Whent

he

Q130-Q230-Q140-Q240

V

r

ονί

desαmeans

of

ίην.ιrtίηgt

h

e



tίme

slotpulse

from

the

oscilloscitt



itf

op

enerrogaes

n

erace

input

signal.Withth

e POLARITY

switch

set

to+UP,Q130



connectorΒ33,

t

his100

microamperes

of

currentisadde

d

an

d

Q230

are

biasedon

and

the

signalisp

assedstraight



tothe

current

correspondingtot

he

settingoft

heVOL

TS/

t

hrough

tothe

out

putamp

lifier.W

it

hthe POLAR

ITY



DI

V

switch to

increasethedeflection

factor

(in

the

d

is-

switch

settoI

NVER

T,

Q130and

Q230

are

biased

offand



p

laye

d

readout)

by

α

factor of10.

R

efertot

he appro

p

riate

Q140-10240

are

turned

on

to

p

rovide

signal

inversion

.



oscilloscope

Instruction

Manual

for

more

ίηf

οrm

α

+

ίοη

on

C131-R131

andC231-R231

are

thermal

compensation

net-



t

heReadout

System

.

System

.

works

.

Output

Amplifier

T

h e

Output

Amplifier

is

compose

d

of

Q160-Q260-Q170-Q270

an

dth

eir

associatedcircuitry.T

he

verticalPOSITIONcontrol

is

located

in theinputtothis

stage.ThermistorRT151

and

varactorsCR154-CR254

pro-

vide propercompensation

for transient

response

with

ch

anges

of

temperature.Thermal

compensation

for

Q160

3-2

TriggerPickoff

Stage

T

h e

Trigger

Pick

off

stage

consists

of

Q180-Q280-Q185-Q285

an

dth

eir

associatedcircuitry

.

E

mitter

followers

Q180

andQ280

provideisolationbe-

tween

the

trigger

output

circuitandthe

signal

output

cir-

cuit to p

revent

load

ing

ofthe

signal

out

putamp

lifier

.

R

186-C186

and

R

284-C284provide

thermal

compensation

for

Q185

and

Q285

res

p

ectively.Thetriggeroutput

ampli-

t

udeisapproximatelyth

e

sameasthesignal

output

ampli-

tude

.

The

oscilloscope displayed

readout

will

give

t

he correct

d

eflection

factor

from

theprobetip

(usingthe

recom-

men

ded attenuator p

robes),whereas theVOL

TS/DIVk

nob

on

theplug-in willdisplay

onlythe p

lug-indeflection

fac-

tor

.

ι

T

hetraceIDEN

TI F

Y

button,

w

henp

resse

d,d

oes

two

th

ings

:



I

ι

Circuit

Description-7A15

1.It

grounds t

he

j

unction

of

R

75-

R

274

(bottomend



h

ard,and

the displayed

rea

doutisreplacedby

the

word

ofR274)

to d

eflect

thetraceup

wardabout0.25divi-



IDENTI F

Y

.

sion

.

T

hese

two

actions

aidin

i

dentifyingthe 7

Α15trace

w

hen multip

le

traces

aredisplaye

d on

the

CRT

.Whe

nthe

2

.

T

he b

aseofQ80,

whichis

connected

to th

ejunc-



IDENTI FYb

uttonisreleased,

the

readoutis

restoredtoits

tion

ofR75-R274,

is

also

grounded.This

t

urns

Q80

on



p

revious

d

isplay

.

NOTES