Tektronix 5A26 Manuel utilisateur

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ι

ι

ι

ι

ι

ι

ι

ι

ιι

ι

Ι

T

EK

T

R

O

N

IX

1

1

1

1

1

Te

k

tronix,

Inc

.

Ρ

.

Ο

.

Box500

Beaverton,

O

r

egon

97077

ι

ο7

α

-

ιο

47-

οο

I

N

ST

R

UCTIO

N

M

A

NU

A

L

Serial

Number

F

irst

P

ri

n ting

JUNE

1975

WARRANTY

All

TEKTRONIX

instruments

are

w

arrantedagainst

detectivematerials

and

wor

km

an

shi

p

for

one

y

ear

.

A

ny

q

u

estions

w

ith

r

espect

to'

the

w

arra

n

t

y

s

h

o

u

ld

betaken

up

with

your

TEKTRONIX

Field

En

gi

neer

-

or

representative

.

All re

qu

ests

for

repairs

and

replacement

parts

sh

o

u

ld

b

e

directed

to

the

TEKTRONIX

F

iel

d

Office

or

representative

in

your

area

.

This

ωίΗassu

re

you

t

h

e

fastest

possible

service

.

P

lease

include

instrument

Type

N

u

mber

o

r

P

art

Number

and

Ser

Number

w

ith all

re

qu

ests fo

r

parts

or

ser

u

ί

r

e

.

Specifications

and

price

change

privileges

reserved

.

Co

p

yrig

h

t ,

1975

by

Te

k

tro

n

ix,

Inc

.,

B

eaverto

n

,

Oregon

.

P

rinte

d

i

n

t

he

U

n

ited

States

of

A

m

erica

.

All

rig

h

ts

reserved

.

Contents

of

t

h

is

p

ublicatio

n

m

ay

not

be

re

p

roduce

d

i

n

any

fo

r

m

w

it

hou

t

p

er

m

ission

of

Te

k

troni

x

,

Inc

.

U

.S

.A

.

and

foreig

n

T

E

KTR

ON

IX

products

co

vered

by

U

.S

.

a

nd

foreig

n

paten

ts

and/or

pate

n

ts

pe

ndi

n

g

.

T

EK

TR

ON

IX

is

α

registere

d

trademar

k

of

Tektronix,

Inc

.

ι

10

ι

ι

TA

BLE O

F

CO

N

T

ENTS

P

AG

Ε



P

AG

Ε

LIST

O

F

ILLUSTRATIONS



i



S

E

CTIO

N

2

T

HE

O

R

YO

F

O

PER

ATIO

N

L

IST

O

F

TA

BLE

S



i



BL

OC

K

DIAG

R

A

M

DE

SC

R

I

P

TIO

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2-1

S

E

CTIO

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1

O

PER

ATI

NG

I

N

ST

RU

CTIO

N

S



CI

R

CU

IT

O

PER

ATIO

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PREP

A

R

ATIO

N

F

O

RU

SE



1-1



PRE

A

MPL

I

F

I

ER



2-2

CO

N

T

R

O

L

S,

CO

NNECTO

R

S,

A

ND



1-1



OU

T

PU

T

A

MPL

I

F

I

ER

S



2-3

I

N

DICATO

RS



RE

ADO

U

T



2-5

B

ASIC

O

PER

ATIO

N

1-3

P

re

p

aration



1-3



S

E

CTIO

N

3

REPL

AC

E

A

BLEELE

CT

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ICA

L P

A

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TS

Ste

p

Attenuator

B

alance

Ad

j

ustme

n

t



1-3

Gain

C

h

ec

k

1-4

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S

E

CTIO

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4 S

ERV

ICE

I

NF

O

RM

ATIO

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DE

TAI

LE

D

O

PER

ATI

N

G

I

NF

O

RM

ATIO

N

1-4



S

ERV

IC

ES

A

V

AI

L

A

BLE



4-1

Applying

Signals



1-4



M

AI

N

T

EN

A

NC

E

4-1

P

re-C

h

arging



1-4



Circ

u

it

B

oar

d

R

emoval



4-1

Sig

n

al

In

p

ut

Connectors



1-4



AD

JU

ST

MEN

TS

A

F

T

ER

REP

AI

R



4-1

H

ig

h Im ped

ance

In

p

u

t



1-5



DIAG

R

AM

S



4-2

Dis

p

lay

P

olarity



1-5



BL

OC

K

DIAG

R

A

M

Deflection

F

actor



1-5



AD

JUST

MEN

T

PR

OC

E

D

URE

V

oltage

Comparison

M

eas

urements



1-5



P

A

R

T

L

OCATIO

NS

A

N

D

DIAG

R

AM

S

Diffe

r

en

tial

O

p

eration



1-5

V

oltage

Pr

obes



1-6



S

E

CTIO

N

5

REPL

AC

E

A

BLE

ME

CH

AN

ICA

LP

AR

TS

Differential

M

easurements



1-6

S

PE

CI

F

ICATIO

N

S



1-7



C

H

A

N

G

E

I

NF

O

RM

ATIO

N

LIST

OF

ILLUSTRATIONS

FIG

URE



FIG

URE

NO

.



P

AG

E

NO

.

1-1



5

Α

26 Du

al

Differential

Am

p

lifier

.



ii



4-3



A

dju

stment

locations

.

1-2



Front-panel

cont

r

ols,

conn

ectors

an

d

1-2



4-4



Α

1,

A2-Channel

1

and 2

Pr

eam

p

lifier

circuit

i

nd

icators

.



b

oar

d

component

an

d

test

p

oint

locations

.

1-3



Dimensions

.



1-9



4-5



Α

2,

A2-Channel

1 a

nd2P

reamplifier

circuit

2-1



F

loating

P

ower

Su pp

ly

d

etaile

d

bloc

k

2-4



boar

d

locatio

n

s .

d

iagram

s

h

owing

sta

n

d

i

ng

cu

r

re

n

t

p

at

h

s



4-6



A3-Main

circuit

boa

r

d

com

po

n

e

n t a

n

d

test

t

hrough

t

he P

ream

p

lifie

r

.



p

oint

locatio

n

s

.

T

he

ill

u

strations

in

Section

4

are

locate

don

fol

dout

pages



4-7



A3-Main

ci

r c

u

it

b

oar

d

locatio

n

.

at

th

e

back

of

the

ma

n

ual

.



4-8



A3-Main

circ

u

it

b

oar

d

component

locations

.

4



4-9



A3-Main

circuit

board

location

.

-1



Circ

u

it

b

oar

d

locations

.

4-2



Common-mode

re

j

ectio

n

(cm

r )

display

.

L

IST

O

F

TA

BLES

TA

BLE

NO

.



P

AG

Ε

1-1



E

lectrical

Sp

ecifications



1-7

1-2



E

nvironmental

S

p

ecifications



1-8

1-3



Ph

ysical

Specifications



1-8

5

Α

26

Fig

.

1-1

.

5

Α

26

Dual

Differential

Amplifier

.

ι

ι

ι

ι

T

he

5

Α

26

Dual

Differe

n

tial

Am

p

lifier

is

α

d

ual-trace

h

ig

h

-gain

d

ifferential

amplifier

plug-in

for

u

se

wit

hTe

k

tronix

5000

Series

Oscilloscopes

.

T

h

e

unit

contains

two

i

d

entical

in

d

e

p

en

dent

am

p

lifier

chann

els

t

h

at

feature

h

ig

h

sensitivity

an

dα

h

ig

h

common-

mo

d

e re

j

ectio

n

ratio

.

E

achch

a

n

nel

h

as

α

ban

dwid

t

h

capability

of

do

to

1

mega

h

ertz,

an

dα

front-

p

anel

pu

s

h button switch

allows

the

re

d uction of

t

he

up

p

er

b

an

d

widt

h

limit,

t

hu

s

increasing

t

h

e

signal-to-

n

oise

ratio

for

low

freq

u

ency

applications

.

E

it

h

er

chann

el

may

be

used

for

single

c

h

annel

d

isplays,

or

electronically

switche

d

to p

ro

d uce

dual-trace

dis

p

lays

.

An

ill

u

minate

d k

no

bsk

irt

provi

d

es

α

d

eflectio

nfactor

rea

dout,

w

h

ic h

is

also

d

isplayed

on

t

h

e

crt

w

h

en used

i

nan

oscillosco

p

e

with

rea

dou

t

cap

abilities

.

PREP

A

R

ATIO

N

F

OR

US

E



4



V

O

L

TS/DI

V

Switc

h

es-

V

olts

per

ma

j

or

graticule

Ο

d

ivisio

n

.

Selects

calibrate

dd

eflection

factors

from

'



T

he

5

Α

26

is

cali

b

rate

d

an

d

ready

for

use

w

h

en

receive

d

.



50

microvolts/

d

ivision

to

5

volts/division

;

16

steps

in

T

he unit

may

be

installed

in

any

p

l

u

g-in

com

p

artment

.

R

e-



α

1-2-5

se

q

uence

.

Kn

ob

s

k

irt is

illuminate

dto

in

d

i-

fer

to

t

he oscilloscope

instruction

man

u

al

for

information



cate d

eflection

factor,

and

10

Χ

scaling

of

bot

h k

no

b

on

Χ

-

Υ

operation

.

To

install,

align

t

he u

pp

er

an

d

lower



s

k

irt

and

crt rea

d

out

is

provi

de

d

automatically

w

h

en

grooves

of

t

h

e

5

Α

26

with

t

he

plug-in

compartment

track

s,



α

10

Χ

co

d

e

dp

robe

is

used

.

an

d

fully

i

n

sert

t

he 5

Α

26

u

n

til

it

loc

k

s

i

nto place

.

To

re-

move,

pull

the

release

latc

hto

disengage

t

h

e

5

Α

26

from

t

he

'

~

oscillosco

p

e

.

CA

L

(

V

aria

b

le

V

O

L

TS/DI

V

)

Controls-

P

rovi

d

es

υη

-

calibrated

continuously

varia

b

le

d

eflection

factors

between

t

he

cali

b

rate

d

settings

of

t

he

VO

L

TS/DI

V

CO

N

T

R

O

L

S,

CO

NNE

CTO

R

S,

A

N

D

I

N

DICATO

R

S



switc

h

and

exten

d

st

h

e

d

eflection-factor

range

to

12

.5

volts/

d

ivision

.

T

he

following

descri

b

es

t

h

e

f

u

nction

of

t

h

e

front-

p

anel

controls,

con

n

ectors,

an

d

indicators

.

R

efer

to

F

ig

.

1-2

for

t

he

locatio

nof

t

h

e

co

n

trols,

con

necto

r

s

and

in

d

icators

.

M

ore

information

is

given

u

nder

Detaile

d

O

p

erating

Information

.

DIS

PL

AY

P

ush

B

utton-Applies

and

removes

logic

levels

to

t

he oscilloscope

system

to

enable

or d

isa

b

le

p

lug-in

operation

.

Switc

h

is

functional

on

ly

w

hen

p

l

u

g-in

is

op

erate

d

in

one

of

t

he

vertical

d

eflectio

n

p

l

u

g-in

compartments

.

Ο

2



P

OS

Co

n

trols-

P

ositions

d

is

p

lay

vertically

.

ι

BW

L

I

M

IT Pu

s

h

B

uttons-Allows

re

du

ction of

t

he

upper b

andwi

d

t

h

limit

to

increase

t

h

e

signal-to-noise

ratio

for

low-frequency

applications

.

Selects

upp

er

ban

dwi

d

t

h

limit

at

eit

h

er

1

mega

h

ertz

(

bu

tton

o

u

t)

or

10

k

ilo

h

ertz

(

bu

tton

in)

.

O

PER

ATI

N

G

I

N

ST

RU

CTIO

N

S

Section

1-5

Α

26

ST

EP

ΑΤΤΕΝ

B

A

L

Ad

j

ustments-

B

ala

n

ces

t

h

e

in

p

ut

am

p

lifier

for

minimum

trace

s

h

ift

t

hrou

g

h

o

u

t t

h

e

d

eflection

factor

gain-switc

h

ing

ra

n

ge

.

Input

Coup

li

n

g

P

ush B

uttons

AC-O

U

T:DC

.

B

utton

pus

h

e

d

in

selects

cap

acitive

coupling

of

signal

app

lie

d

to

associate

d+

or

-

inp

ut

connecto

r

;

button out

selects

d

irect

couplin

g

of inpu

t

sig

n

al

.

GND

.

Grou

n

d

s t

he preamplifier

in

put

an

d

connects

input

signal

to

groun

d

t

hroughα

1

mego

h

m

resistor

.

PRE

CH

G

.

B

ot

h

AC

and

GN

D

buttons

pus

hed

in

p

ermits

p

rec

h

arging of

t

h

e

cou

p

ling

cap

acitor

to

t

h

e

input

sig

n

al

d

o

level

.

R

elease

GN

D

button

fo

r

measurement

.

M

OD

EP

ush

B

utton

s-Select

c

h

annel to

b

e d

is

played

an

d

illumi

n

ate

t

h

e

p

ro

p

er

d

eflection

factor

setting

(1

Χ

or

10

Χ

)

on

t

he

VO

L

TS/DI

V

switc

h k

no

bsk

irt

.

B

oth buttons

pus

hed

i

n

provides

α

du

al-trace

d

isplay

.

Operating

Instructions-5A26

r

ο

Fig

.

1-

2

.

Front-panel

controls,

connectors,

and

indicators

.

Operating

Instructions-5A26

ι

ι

AC



O

UT

:

DC

(b

utton out)

+

an

d

-

In

p

u

t

Connectors-

BN

C

connectors

for

app

li-

cation of

external

voltage

signals

.

Connector

labele

d



GND



GND

(

bu

tton

in)

+

indicates

t

h

at

α

p

ositive-going

signal

will

cause

upwar

d

d

eflectio

n

;

connector

la

b

ele

d

-

indicates

t

h

at



M

OD

E



CH

1

an

d

CH

2

α

positive-going

sig

n

al

will

cause

downwar

d d

eflectio

n

.



(

b

uttons

in)

Con

nectors

inclu

de

co

d

e

d

-

prob

e

input

rings

for

activating

t

h

e

rea

dou

t

w

hen

using

readout-co

d

e

d

p

robes

.



d

.

A

d

j

ust

intensity

control for

normal

viewing

.

Traces

sh

oul

d

a

pp

ear

near

gratic

u

le

center

.

B

ASIC

O

PER

ATIO

N

e

.

Set

t

he

VO

L

TS/D

Ι

V

switc

h

es

to

.1

.

If

traces

s

h

ift,

Preparation



a

d

ju

st

t

he

ST

EP

ΑΤΤΕΝ

B

A

L

control

as

d

escri

bed

in

'



T

he

following

procedures

are

i

n

te

nded to

h

el

p p

lace

t

h

e

trace

on

t

hesc

r

ee

n

q

uic

kly

and

prepare

t

he

instrument

for

immediate

use

:

'



α

.

I

n

sert

5

Α

26

all t

he

way

into

oscillosco

p

e

plug-in

com

p

artment

.

ι

T

R

IGG

ER

Push

Bu

tton-Selects

time

base

triggeri

n

g

signal

from

eit

h

er

channel

.

b

.

Turn

oscilloscope Intensity

control to

mi

d

ra n

ge and

t

u

rn

oscilloscope

syste

m

p

ower

on

.

P

reset

time-b

ase

an

d

triggering

controls for 2

millisecon

d

/

d

ivision

sweep

rate

10



and

a

u

tomatic

triggeri

ng

.

c

.

Set 5

Α

26

front-

pan

el

controls

as

follows

:

ι

ι

ι

ι

ι

DIS

PL

AY



ON

(butto

n

in)

T

RIGG

ER



OU

T

:

CH

1

(b

u

tto

n

out)

P

OS



M

i

d

ra

nge

BW

L

I

M

IT



OU

T

: 1

MHz

(b

utton

o

u

t)

V

O

L

TS/D

1

V



5

ST

EP

ΑΤΤΕΝ

B

A

L



M

i

d

ra

nge

C

H

1

an

d CH2

+Input

Cou

p

li

n

g

CH

1

and

C

H

2

-

In

p

ut

Coupling

Step

Attenuator

B

alance

A

dju

stment

proce

dure

.

f

.

M

ove

CH

1

trace

2 d

ivisions

b

elow

graticule

h

orizontal

centerline,

and

C

H

2

trace

to b

ottom

of

graticule

with

P

OS

controls

.

g

.

Apply400

millivolt

pea

k

-to-

p

ea

k

signal

fro

m

oscillo-

scope

cali

b

rator

loop

wit

hα

test

lea

d or

1

Χ

probeto

CH

1

+

in

p

ut

connector

.

h

.

R

elease

CH

1

+

GND

b

utton

.

Disp

lay

will

be

α

s

qu

ar

e

wave

4

d

ivisions

in

amplitude

with

bottom

of d

is

p

lay

at

refere

n

ce esta

b

lis

hed

in

step

(f)

.

i

.

P

osition

b

ottom

of

s

q uare

wave

to

graticule

h

orizontal

centerline

.

j

.

Pu

s

h

in

C

H

1

+

AC

button an

d

note

that

display

s

h

ifts

d

ownwar

d 2

divisio

n

s .

k

.

Disconnect

test

lead

from

CH

1

+

in

put an d connect

to

CH

2

+

in

pu

t

.

Ι.

P

ush

in

T

RIGG

ER

butto

n

for

CH

2

triggering

an

d

repeat

ste

p

s

(f) t

h

ro

ug

h

(j)

for

CH2

operation

.

AC



OU

T

:

DC

(button



Ste

p

Attenuator

B

alance

A

d

j

ustment

Out)



Wh

en

t

h

e

ST

EP

ΑΤΤΕΝ

B

A

L

control

is

not

properly

a

dj

ust-

ed

,

t

h

e

d

is

p

lay

will

s

h

ift

vertically

(

d

ue

to

α

do

imbala

nce

i

n

GND



G

ND

(

button

in)



t

he

am

p

lifier)

as

t

h

e

VO

L

TS/DI

V

switc

h

is

rotate

d

t

h

ro

ugh

-

out

its

range

.

T

he

s

h

ift

is

more

noticeable

on

t

he

most

sensitive

positio

n

s

.

Op

erating

Instructions-5A26

α

.

Set

VO

L

TS/DI

V

switch to 5

.

Ground

both

+

an

d

-



b

.

Wait

about

1

second

for

coupling

ca

p

acitor

to ch

arge

.

inputs

(G

N

D

bu

ttons

pu

s

h

e

d

in)

and p

osition

trace to

graticule

h

orizontal centerline

.

c

.

R

elease

GND

bu

tton

a n

d ac

com

p

onent

can

b

e

meas

u

re

d

in

usual

manner

.

b

.

A

dj

ust

ST

EP

ΑΤΤΕΝ

B

A

L control

for

minim

u

m

trace

s

h

ift

as

VOL

TS/DI

V

switch

is

rotate

d

t

h

rou

g

ho u

t

its

range

.



Signal

In

p

ut

Connectors

Wh

en

connecting

signals

to

t

h

e

+

an

d

-

in

p

ut

connectors

on

t

he

5

Α

26,

consi

d

er

t

h

e

met

h

od

of co

up

ling

that

will

be



,

Gain

C

heck



u

se

d

.

Sometimes

un

s

h

iel

d

e

d

test

leads

can

b

e

u

se

d to

Wh

en

t

h

e

5

Α

26

is

first

inserte

d into

α

p

lug-in

com

p

artment,



connect

t

h

e

5

Α

26

to α

signal

sou

rce,

p

artic

u

larly

w

h

e

n

α

t

h

e

amplifier

gain

may

be

c

heck

e

d

an

d

ad

j

usted

if

necessary

.



h

ig

h

level,

low-frequency

signal

is

monitore

d

at

α

low

i

m

-

See

A

d

ju

stment

Proce

d

ure

in

Section

4

of

t

h

is

manual

for



p

ed

ance

p

oint

.

H

owever,

w

h

en

any

of

t h

ese

factors

are

com

p

lete

i

n

structions

.



missing,

it

becomes

i

n

creasingly

important

to use

s

h

iel

d

ed

signal

cab

les

.

In

all

cases,

t

he

signal-trans

p

orting

lea

d

s

s h

ou

l

d

be

k

e

p

t

as

s

hort

as

practical

.

D

E

TAI

LE

DO

PER

ATING

I

NFO

RM

ATIO

N

Applying

Signals



Wh

en

ma

k

ing

si

n

gle-e

nded

i

nput

measurements

(conve

n

tio

n

al

amplifier operation), b

e

sure

to establis

h

α

common

groun

d

con

nection

between

th e

d

evice

un

d

er test

an

d

t

he

5

Α

26

.

T

h e

s

h

iel

dofα

coaxial

cable

is

normally

u

se

d

for

t h

is

pur

pose

.

ι

ι

If

t

h

e

maxim

u

m

input

voltage

rating

at

t

he gates

of

t

h

e

input

FE

T's

is

exceeded,

t

he

gates

a

r

e



In

some

cases,

d

ifferential

meas

u

rements

re

q

uire

no

common

clampe

d

at

about

+

or

-

10

volts

.

If

t

h

e

signal



ground

connection,

a

nd

t

h

erefore

are

less s

u

sce

p

tible

to

sou

r

ce

can

supply

m

ore

t

ha

n

1/16

ampere,

t

he



interference

by

ground-loop

currents

.

Some

pro

b

lems

wit

h

input

protective

fuse(s)

will

o

p

e

n

.



stray

magnetic

co

u

pling

into

t

h

e

signal

transporting

leads

can

also

be

minimize

d

by

u

sing

α

d

ifferential

rat

h

er

t

h

an

α

single-en

d

e

d

measurement

.

T

h

ese

consi

d

eratio

n

s

are

d

is

Wh

en meas

u

ring

unk

now

n

voltages,

use

t

he h

ig

h

est

deflection



cu

sse

d

later

in this

sectio

n

under

Differential

O

p

eration

.

factor

first

.

If

t

he deflection

is

too

small

to

ma

ke

t

he

meas

u

rement,

switch to

α

lower

deflectio

n

factor

.

It is

always

im

portant to

consi

der

t h e

signal so

urce

loa

d

ing

(an

d

res

u

lting

ch

ange

in t

he

source

operating

c

h

aracteristics)



'

P

re-C

h

arging



d

u

e to

t

he

signal-trans

p

orting

lea

d

s

an

d

t

he inpu

t

circ

u

it

of

Wh

en

only

t

he ac

com

p

onent

of

α

signal

having

bot

hac and



t

h e

5

Α

26

.

T

h

e

circuit

at

t

he

in

pu

t

connectors

can

normally

d

o

components

is

to

b

e

measured,

t

he

p

re-c

h

arge

circ

u

it



b

e

re

p

rese

n

te

d

by

α

1

mego

h

m

resistance

to

ground

p

arallel-

permits

ch

arging

t

he

co

u

p

ling

ca

p

acitor

to

t

h

e

inpu

t

signal



ed

by

about

47

p

icofarads

.

Α

few

feet

of

s

h

iel

ded

ca

b

le



,

d

o

level

.



(20

to

40

p

icofara

d

s

p

er

foot)

may

increase

t

h

e

p

arallel

capacitance

to

100

picofarads

or

more

. I

n

ma

ny

cases,

t

he

effects

of

th

ese

resistive

and cap

acitive

loa

d

s

may

be

too

great

and

it

may

be

desira

b

le

to

minimize

t

h

em

t

h

roug

h

t

h

e



,

CAUTION



use

of

an

attenuator

pro

be

.

If

t

h

e

5

Α

26

input

is

connected

to

α

large

d

o

voltage

sour

ce

(10

volts

pea

k or

mo

r

e),

use

t

he

p

rech

arge

provision

.

Damage

to

t

h

e

signal



Attenuator

probes

not

only

decrease

t

he

resistive-ca

p

acitive

so

u

rce

could

r

esult since

t

he

pea

k

current



loa

d

ing

of

α

signal

source,

but

also

exten

d

t

he

measureme

n

t

t

hro

u

gh

t

h

e

ac

coupling

capacitor

and

t

he



range of

t

h

e

5

Α

26

to

inclu

d

e

substantially

h

ig

h

er

voltages

.

input

protection

circuitry

is

limited

only

by



Passive

atten

u

ator

p

rob

es

h

avi

n

g

attenuation

factors of

10

Χ

,



,

t

he

signal

source

internal

resistance

.



100

Χ

,

and

1000Χ

,

as

well

as

oth

er

s

p

ecial-

pu

r

pose

types,

are

available

t

h

roug

h

your

Te

ktronix

F

ield

E

ngineer

or

F

iel

d Office

.

α

.

B

efore

co

n

necting 5

Α

26

to

α

signal

contai

n

ing

α

d

o

com

p

one

n

t,

p

us

h

in

AC

and

G

N

D

b

uttons

.

T

h

en

connect



Some

measureme

n

t

situations

re

q

uire

an

extremely

h

ig

h

inpu

t

to

circ

u

it

u

nd

er test

.



resistance

in

pu

t

to

t

he 5

Α

26

with very

little

sou

rce

loadi

n

g

ι

ι

1

1

ι

or

signal

attenuation

.

In

s

uc

h

situatio

n

s,

α

passive

attenuator



Deflection

F

actor

p

robe

cannot

b

e

used

.

H

owever,

t

h

is

proble

m

may

be

solved



The

amount

of trace d

eflection

produced by

α

signal

is

'



by

using α

FE

T

Pr

obe

or

t

heh

ig

h-imp

e

d

ance

i

np

ut

p

rovision



determi

n

e

d

by

the

signal

am

p

litu

d

e, t

h

e

atten

uation

(if

any)

of

t

h

e

5

Α

26

as

described un

d

er

H

ig h

-Impe

d

ance

In

pu

t

.



of

t

h

e

pro

b

e,

th

e

setting

of

t

h

e

V

O

L

TS/DI

V

switch

,

an

d

t

he

setting

of

t

h

e

V

aria

b

le

control

.

T

h

e

d

eflection

factor

settings

are

calibrate

d

only

w

h

en

t

he

V

ariable

control

is

H

ig

h-Im

p

edance

In

put



rotate

d

f

u

lly

clockwise

i

n

to

t

he deten

t

p

osition

.

In

t

h

e

50

m

t

hro

u

gh

50

μ

p

ositions

of

t

he

V

O

L

TS/DI

V

switch

,

w

here

thein

p

ut

attenuator

is

not

used,

t

he

internal

gate

return

resistors

alone

esta

b

lis

h

t

he

1

mego

h

m

input



T

he

range

of

t

he

V

aria

b

le

control

is

at

least

2

.5

:1

.

It

provides

resistance

.

T

he

removal

of

t

he strap

from

t

he

P

ream

p

lifier



uncalibrated

d

eflection

factors

covering

t

h

e full

ra

nge

circuit

board

(see

F

ig

.

4-4,

C

hannel

1

and

2

P

reamplifier



between

t

he

calibrate

d

settings

of

t

h

e

VO

L

TS/DI

V

switch

.

circuit

board

com

p

onent

an

d

test

point

locations

in

t

he



T

he

V

ariable

control

can

be

set

to

exten

d

t

he

d

eflection

Diagramsan

d P

arts

L

ists

sectio

n

)

d

isconnects

t

hese

resis-



factor to

at

least

12

.5

volts/

d

ivision

.

tors

fro

m

groun

d

an

d

permits

t

he

in

pu

t

FE

T

gates

to

float,

p

rovi

d

i

n

gαvery

h

ig

hinput

impe

d

ance

.

To

re

d

uce

noise

and

obtain

α

more

u

sa

b

le

d

is

p

lay

w

he

n

t

he

V

O

L

TS/DI

V

switc

h

is

set

to

t

h

e

more

se

n

sitive

p

ositions,

T

h

e

in

pu

t

signal

m

u

st

be

k

ept

to

r

elatively

low

amplit

u

des,



p

u

s

h

in

t

he

BW

L

I

M

IT

button

to

re

d

uce

t

h

e

b

a

n

d

wid

t

hto

since

t

h

e

d

eflection

factor

is

restricte

d to

50

millivolts/



10

kH

z

if

t

h

is

limit

does

not

a

ppreciably d

istort

t

hed

esire

d

d

ivision

t

hr

oug

h

50

microvolts/

d

ivision,

an

d

d

o

cou

p

li

n

g



features

of

t

h

e

signal

u

nde

r

ob

servation

.

must

b

e

u

se

dto p

rovi

d

eα

d

o

p

at

h

for

t

he

FE

T

gate cu

rre

n

t

.

V

oltage

Com

p

arison

M

easurements

O

p

erating

Instructions-5A26

NOTE



Some

a

pp

lications

re

q

uire

d

eflection

factors

oth

er

t

han

the

In

t

h

e

0

.1 volt to

5

volt

r

ange

of

t

he

V

O

L

TS/



fixe

d

values provided by

t

he

V

O

L

TS/DI

V

switch

.

One

suc

h

DIV

switc

h

,

t

he

input

impedance

is

pa

r

alleled



app

lication

is

comparison

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