Tektronix 1A2 User manual

Table of contents

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INSTRUCTION

MAN

OUAL

Tektronix,

Inc.

S.W.

Millikan

Way

@

P.

O.

Box

500

@

Beaverton,

Oregon

97005

@

Phone

644-0161

@

Cables:

Tektronix

070-0430-01

tyPE

[A2

PLUG-IN

466

http://manoman.sghill.com

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a

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TYPE

1A2

DUAL-TRACE

PLUG-IN

UNIT

CALIBRATED

“~~

7

PREAMP

.

POSITION

POSITION

CH1421N

ADD

ONLY

VAR

VAR

ATTEN

BAL

ATTEN

BAL

} .

TRIGGER

SELECTOR

QD)

|

“move

\@)

cn

A©°

cue

ALT

cHoP

“a

VARIABLE

VARIABLE

VOLTS/CM

CH!

votts/

cM

)

5

2

5

:

8

TRIG

OUT

|

(05

/Puito

/

INVERT

puto

20

invert

BRATEO

a

SERIAL

©

CHANNEL

1

CHANNEL

2

AC pc

GND

AC

pc

GND

INPUT

2

PORTLAND,

OREGON,

U.S.A.

y,

TEKTRONIX,

Fig.

1-1.

Type

1A2

Dual

Trace

Plug-In

Unit.

SECTION

I

CHARACTERISTICS

Introduction

The

Type

1A2

Dual-Trace

Plug-In

Unit

contains

two

identi-

cal

fast-rise

calibrated

preamplifier

channels.

Either

chan-

nel

can

be

used

independently,

or

electronically

switched

to

produce

dual-trace

displays.

In

addition,

both

channels

can

be

combined

at

the

output,

adding

or

subtracting

according

to

the

settings

of

the

polarity

switches.

Each

channel

has

its

own

input

coupling,

attenuator,

gain,

polarity

and

position controls

which

allows

each

display

to

be

adjusted

independently

for

optimum

viewing.

There

are

two

modes

of

dual-trace

operation:

Chopped

or

Alternate.

In

the

chopped

mode,

an

internal

multivibra-

tor

switches

the

channels

at

a

free-running

rate

of

about

220

kHz.

In

the

alternate

mode,

the

oscilloscope

time-base

generator

internally

switches

the

channels

at

the

end

of

each

sweep

during

the

retrace

interval.

The

Type

1A2

can

be

used

with

any

of

the

Tektronix

530-,

540-,

or

550-series

Oscilloscopes.

It

can

also

be

used

with

the

580-series

Oscilloscopes

in

conjunction

with

the

Type

81

or

81A

Plug-In

Adapter.

The

Type

1A2

can

also

be

used

with

other

oscilloscopes

and

devices

through

the use

of

the

Type

127,

132,

or

133

Plug-In

Power

Supplies.

CALIBRATED

PREAMPLIFIER

Characteristic

Performance

Requirement

Supplemental

Information

Deflection

Factor

.05

volts/cm

to

20

volts/em

in

9

calibrated

steps

for

each

channel

Steps

in

1-2-5

sequence

Deflection

Accuracy

Within

=&3%

of

indicated

deflection

with

VARIABLE

control

fully

clockwise

With

gain

correct

at

.05

V/cm

Variable

Deflection

Factor

Uncalibrated

deflection

factor

at

least

2.5

times

the

VOLTS/CM

switch

indication.

This

permits

continuous

(uncalibrated)

adjustment

from

0.05

volts/em

to

at

least

50

volts/cm.

Frequency

Response

(not

more

than

3dB

down):

Type

1A2

with

Tektronix

oscilloscope;

544,

546,

or

547

DC

to

50

MHz

581,

581A,

585,

585A

DC

to

50

MHz

with

Type

81A

Plug-In

Adapter

DC

to

33

MHz

with

Type

81

Plug-in

Adapt-

er

541,

541A,

543,

543A,

545,

|

DC

to

33

MHz

545A,

545B,

or

555

551

DC

to

27

MHz

531,

531A,

533,

533A,

535,

|

DC

to

15

MHz

or

535A

536

DC

to

11

MHz

Risetime:

Type

1A2

with Tek-

tronix

oscilloscopes;

544,

546,

or

547

7

ns

‘581,

581A,

585,

585A

7

ns

with

Type

81A

Plug-In

Adapter

11

ns

with

Type

81

Plug-in

Adapter

541,

541A,

543,

543A,

545.

|

11

ns

545A,

545B,

or

555

551

13

ns

531,

531A,

533,

533A,

535,

|

24

ns

or

535A

536

32

ns

Input

RC

Characteristics

Typically

1

MQ

parallel

with

approximately

15

pF

Maximum

Input

Voltage

600

volts

combined

DC

and

peak

AC;

600

volts

peak-to-peak

AC

Input

Coupling

Modes

AC

or

DC,

selected

by

front-panel

switch

GND,

disconnects

amplifier

input

signal

and

grounds

@i

1-1

Characteristics—Type

1A2

Characteristic

Performance

Requirement

Supplemental

Information

AC

Low-Frequency

Response

Typically

3

dB

down

at

2

Hz

direct;

0.2

Hz

with

10

probe

Display

Modes

Channel

1

only

Channel

2

only

Dual-trace,

alternate

between

channels.

Dual-

trace,

chopped

between

channels.

Added

algebraically

Chopped

Repetition

Rate

220

kHz

20%

rate

to

show

successive

2

us

segments

of

each

trace

Common

Mode

Rejection

Ratio

20:1

for

common-mode

signals

up

to

10cm

in

amplitude

With

optimum

GAIN

adjustment

for

both

channels

Polarity

Inversion

Signal

on

either

Channel

1

or

2

can

be

inverted

Output

Trigger?

Measured

at

TRIG

OUT

connector

Output

Trigger

Voltage

Approximately

0.5

V/cm

or

gain

of

10

VOLTS/CM

at

.05

Bandwidth

Low-Frequency

3

dB

down

is

about

10

Hz

when

output

of

the

amplifier

is

working

into

1

MQ;

High-Frequency

3dB down

is

amplitude

dependent

and

shown

in

the

graph

of

Fig.

1-2

Output

Coupling

AC

1Applies

only

to

instruments

with

a

serial

number

of

716

or

higher.

MECHANICAL

CHARACTERISTICS

ACCESSORIES

Characteristic

Information

.

;

.

.

.

CG

i

Alumi

i

hassi

Standard

accessories

supplied

with

this

instrument

will

be

onstruction

Uminumeal’oy

Chassis

found

in

the

Mechanical

Parts

List.

For

optional

accessories,

Finish

Anodized

front

panel

see

the

current

Tektronix,

Inc.

catalog.

10

9

4

;

x

7

\

6 \

5

\

4

=

\

6

N

3

Qo

a

2

\

2

N

=

3

>

2

|

6

9

=

o

8

AN

&

47

z

AN

F

6

\

\

5

4

\

\

3

\

2

1

2

3

4

5 6

7

Frequency

in

MHz

at

3

dB

down

Fig.

1-2.

Type

1A2

Trigger

output

amplitude

and

High-Frequency

Response

(3

dB

down).

SECTION

2

OPERATING

INSTRUCTIONS

FUNCTIONS

OF

FRONT-PANEL

CONTROLS

The

functions

of

all

controls,

adjustments

and

connectors

except

the

MODE

and

TRIGGER

SELECTOR

switches

are

identical

for

both

channels.

POSITION

PULL

TO

INVERT

GAIN

VAR

ATTEN

BAL

MODE

VOLTS/CM

VARIABLE

AC-DC-GND

TRIGGER

SELECTOR?

TRIG

OUT*

Positions

the

trace

vertically

on

the

CRT.

Only

the

Channel

1

POSITION

controls

position

in

the

ADD

mode.

A

two-position

switch

that

presents

the

display

in

a

normal

or

inverted

polarity

with

respect

to

the

applied

signal.

A

screwdriver

adjustment

that

calibrates

the

basic

deflection

factor

of

the

channel.

A

screwdriver

adjustment

for

setting

the

amplifier

DC

levels

so

the

trace

does

not

shift

position

under

no-signal

conditions

as

the

VARIABLE

VOLTS/CM

control

is

turned.

A

five-position

switch

that

sets

the

mode

of

operation

as

follows:

ALT—Dual-trace

alternate

mode

of

opera-

tion

(triggered

electronic

switching

between

channels

during

the

beam

retrace

interval).

CH

1—Selects

the use

of

Channel

1

only.

ADD—Permits

adding

the

outputs

of

the

two

channels

algebraically.

CH

2—Selects

the

use

of

Channel

2

only.

CHOP—Dual-trace

chopped

mode

of

oper-

ation

(free-running

electronic

switching

of

channels

at

about

a

220-kHz

rate).

Nine-position

switch

to

select

the

calibrated

vertical-deflection

factors.

Provides

overlapping

variable

uncalibrated

attenuation

between

the

calibrated

deflec-

tion

factors

and

extends

the

attenuation

range

to

about

50V/CM.

Three-position

switch

to

provide

either

AC-

or

DC-coupled

input

into

the

amplifier.

A

third

position

(GND)

connects

the

ampli-

fier

input

to

ground

without

grounding

the

input

signal.

Determines

whether

the

Channel

1

or

Chan-

nel

2

signal

is

applied

to

the

Trigger

Amplifier.

Output

signal

of

the

Trigger

Amplifier.

Permits

the

use

of

Channel

1

or

2

as

an

external

trigger

source.

FIRST

TIME

OPERATION

The

following

procedure

will

help

you

become

familiar

with

the

Type

1A2

operation.

1.

Insert

the

Type

1A2

into

the

oscilloscope,

tighten

the

securing

rod

and

turn

on

the

oscilloscope

power.

2.

Allow

about

2

to

3

minutes

warm-up

time

and

free

run

the

oscilloscope

sweep

at

0.5

sec/cm.

3.

Set the

applicable

Type

1A2

front-panel

controls

for

both

channels

as

follows:

AC-DC-GND

DC

VOLTS/CM

.05

VARIABLE

CALIBRATED

PULL

TO

INVERT

Pushed

in

POSITION

Centered

MODE

CH

1

TRIGGER

SELECTOR?

CH

1

4.

Position

the

trace

about

one

centimeter

above

the

grati-

cule

centerline

with

the

Channel

1

POSITION

control.

5.

Place

the

MODE

switch

to

CH

2

and

position

the

trace

one

centimeter

below

the

graticule

center

line

with

the

Channel!

2

POSITION

control.

6.

Place

the

MODE

switch

to

ALT.

Both

Channel

1

and

2

traces

should

be

displayed.

7.

Set the

oscilloscope

Time/Cm

switch

to

50

msec.

Note

that

for

each

sweep

cycle

one

channel

is

displayed

and

the

other

is

shut

off.

Electronic

switching

from one

channel

to

the

other

occurs

during

the

retrace

interval.

8.

Set

the

MODE

switch

to

CHOP.

Notice

that

both

traces

seem

to

start

simultaneously

and

continue

across

the

CRT.

9.

Set the

oscilloscope

Time/Cm

switch

to

5ysec

and

adjust

the

oscilloscope

trigger

controls

to

obtain

a

stable

display.

Notice

that

each

trace

is

composed

of

many

short-

duration

bits

or

segments

with

visible

switching

transients

existing

between

channels

(see

Fig.

2-1A).

10.

To

see

the

chopped-mode

switching

action

clearly,

increase

the

sweep

rate

to

1

wsec/cm.

Notice

that

Channels

1

and

2

are

alternately

on

and

off

at

about

2

us

intervals.

(See

Fig.

2-1B.)

Chopping

rate

is

determined

by

the

free-

running

multivibrator

switching

rate

and

is

about

220

kHz.

11.

Blank

out

the

switching

transients

between

channels

by

setting

the

CRT

Cathode

Selector

switch

(located

on

the

rear

panel

of

most

Tektronix

oscilloscopes)

to

the

Dual-Trace

Chopped

Blanking

position

(see

Fig.

2-1C).

12.

Set

the

oscilloscope

Time/Cm

switch

to

0.5

msec.

Using

coaxial

cables,

a T

connector

connected

to

Channel

1

and

a

connector

adapter

{if

needed),

apply

0.1

volt

from

the

oscilloscope

Amplitude

Calibrator

to

the

Channel

1

and

2

input

connectors.

13.

Set

the

trigger

controls

for

+internal

(plug-in)

trigger-

ing

or

connect

a

jumper

coaxial

cable

from

the

TRIG

OUT

connector!

to

the

oscilloscope

Trigger

Input

connector

and

1Applies

only

to

instruments

with

a

serial

number

of

716

or

higher.

2-1

Operating

Instructions—Type

1A2

ae

fit

trace

Jt tf ft

J

4

HEqenaqaqneqeduauananaqaauakaaquqneugaququahaguane

(A)

naa

Re

Chan.

2

trace

+

a

i

ll

tittedt

if

td

+

Sweep

Rate

20

yusec/div

Chopping

R

<

L-

4

+

Chopping

Rate+

J]

+ +

4 4

|

Chan.

Y

_o

ok

1

es

ee

eee

ee

ON

4

Switching

tC

transients

ad

between

qt

channels

(B)

Tt

HAE

EH

¢

i!

r"Chan.

2

“ON"

|

+

|

| |

||

=

4

4

+

+

+

4

T

T

Sweep

Rate

1

usec/div

L

ee

ee

ee

ee

|

Chan.

In]

|

|

_,

Switching

transients

|

|

|

y

(

blanked

out

SE

|

AY

(CC)

FREER

EER

EEE

EEE

HEE

EEE

HEH

|

sen

>

$f]

[

[

Jd

L

TSweep

Rate

1

ysec/div

Fig.

2-1.

Chopped-mode

waveforms:

(A)

trace

broken

up

into

segments,

(B)

chopped-mode

switching

action

from

channel

to

channel,

and

(C)

switching

transients

blanked

out.

set

the

trigger

controls

for

+

external

triggering.

Both

Chan-

nel

1

and

2

should

display

the

calibrator

waveform.

Each

waveform

should

be

2

cm

in

amplitude.

NOTE

If

the

waveforms

are

not

exactly

2

cm

in

amplitude,

overlook

the

inaccuracy

until

completing

this

oper-

ating

procedure.

Subsequent

paragraphs

describe

how

to

properly

set

the

gain

of

the

unit.

14.

Set

the

MODE

switch

to

ADD.

There

should

be

one

waveform

display

4¢cm

in

amplitude.

This

is

the

addition

of

the

Channel

1

and

2

signals

(2cm

each),

Notice

that

only

the

Channel

1

POSITION

control

will

move

the

display

vertically.

15.

Pull

out

the

Channel

1

PULL

TO

INVERT

switch

and

free

run

the

time

base.

The

display

should

be

a

straight

2-2

line,

indicating

the

algebraic

difference

between

the

two

signals.

Since

both

signals

have

equal

amplitudes

and

wave-

shape,

the

difference

is

zero.

NOTE

If

the

display

is

not

a

straight

line,

this

indicates

that

the

gains

of

the

channels

are

not

matched.

This

may

be

overlooked

until

this

operating

pro-

cedure

is

completed.

Subsequent

paragraphs

describe

how

to

properly

set

the

gain

of

each

channel.

Before

the

Type

1A2

is

used

for

accurate

measurements,

the

GAIN

and

VAR

ATTEN

BAL

for

each

channel

should

be

adjusted.

These

adjustments

are

described

in

the

following

paragraphs.

Gain

Adjustments

The

gain

adjustments

should

be

checked

periodically

to

assure

correct

vertical

deflection

factors,

particularly

when

the

Type

1A2

is

used

for

the

first

time

or

is

moved

from

one

oscilloscope

to

another.

Use

the

following

procedure

to

check

the

gain

of

each

channel:

1.

Set

the

applicable

Type

1A2

front-panel

controls

for

both

channels

as

follows:

AC-DC-GND

DC

VOLTS/CM

.05

PULL

TO

INVERT

Pushed

in

POSITION

Centered

VARIABLE

CALIBRATED

MODE

CH

1

TRIGGER

SELECTOR

CH

1

2.

Set the

oscilloscope

sweep

rate

and

triggering

controls

for

a

0.1

msec/cm

free-running

sweep.

3.

Apply

a

0.2-volt

peak-to-peak

signal

from

the

oscillo-

scope

calibrator

through

a

coaxial

cable

to

the

Channel

1

Input

connector.

NOTE

For

maximum

accuracy

use

a

calibrator

signal

source

which

has

an

amplitude

accuracy

of

better

than

3%.

4.

The

resulting

display

should

be

exactly

4m

in

ampli-

tude.

If

not,

set

the

Channel

1

GAIN

for

the

correct

wave-

form

amplitude.

(Use

the

Channel

1

POSITION

control

to

align

the

display

with

the

graticule

markings.}

5.

Set

the

MODE

switch

to

CH

2

and

apply

the

calibrator

signal

to

the

Channel

2

input

connector.

6.

The

display

should

be

exactly

4cm

in

amplitude.

If

not,

adjust

the

Channel

2

GAIN

contro!

for

the

proper

display

amplitude.

Use

the

Channel

2

POSITION

control

to

align

the

display

with

the

graticule

markings.

7.

Disconnect

the

calibrator

signal.

Operating

Instructions—Type

1A2

502

coaxial

cable

with

GR

connectors

P6034

or

P6035,

Probe

Y

ye

_-Y

ge

X

=

GR

Type

874

Connectors

Optional

Items

‘Select

length

which

will

move

small

reflection

(due

to

input

Z

of

Type

1A2)

out

of

area

of

interest.

*Used

to

reduce

reflection

by

a

factor

of

4.

Doubles

probe

attenuation

factor.

Used

to

reduce

bulk

on

front

of

the

Type

1A2.

GR

Type

874-K

Coupling

Capacitor

017-0028-00

‘50.9

GR

2X

GR-to-BNC

I

type

1A2

Attenuator

Adapter

|

Input

017-0046-00

017-0064-00

Let

yet:

|

‘Short

50

{2

coaxial

50

{2

BNC

I

cable

with

GR

Termination

|

connectors

011-0049-00

I

017-0505-00

|

Fig.

2-2.

Using

the

P6034

or

P6035

Probe

with

the

Type

1A2.,

Variable

Attenuator

Balance

Adjustments

If

the

VAR

ATTEN

BAL

control

of

a

channel

is

not

properly

set,

the

position

of

a

no-signal

free-running

trace

will

shift

vertically

as

the

VARIABLE

control

is

turned.

If

there

is

a

trace

shift,

set

the

VAR

ATTEN

BAL

adjustment

for

each

channel

as

follows:

1.

Set

the

Type

1A2

front-panel

controls

to

the

same

positions

as

in

the

Gain

Adjustments

procedure

except

the

AC-DC-GND

switch

must

be

set

to

GND

and

the

MODE

switch

to

ALT.

2.

Carefully

adjust

the

Channel

1

VAR

ATTEN

BAL

control

to

a

point

where

there

is

no

trace

shift

as

the

Channel

1

VARIABLE

control

is

turned

back

and

forth

through

its

full

range.

3.

Carefully

adjust

the

Channel

2

VAR

ATTEN

BAL

control

to

a

point

where

there

is

no

trace

shift

as

the

Channel

2

VARIABLE

control

is

turned

back

and

forth

through

its

full

range.

4.

Due

to

interaction

between

channels,

repeat

steps

2

and

3

until

there

is

no

further

interaction.

GENERAL

OPERATION

Either

of

the

two

channels

of

the

Type

1A2

can

be

used

independently

by

setting

the

MODE

switch

to

CH

1

or

CH

2

and

connecting

the

signal

to

be

observed

to

the

appropriate

input.

Table

2-1

lists

several

input

systems

compatible

with

the

Type

1A2

input.

Fig.

2-2

shows

a

block

diagram

of

the

input

when

using

the

system

outlined

in

Method

7

of

Table

2-1.

Figure

2-3

shows

the

X,

and

R

curves

for

the

Type

1A2.

Use

of

Probes

A

conventional

passive

attenuator

probe

with

a

standard

42-inch

cable

lessens

both

capacitive

and

resistive

loading,

but

at

the

same

time

reduces

sensitivity.

The

attenuation

introduced

by

the

probe

permits

measurement

of

signal

volt-

ages

that

would

overscan

the

CRT

if

applied

directly

to

the

Type

1A2.

However,

in

applying

high-amplitude

signal

volt-

ages

to

either

the

probe

or

Type

1A2,

do

not

exceed

their

maximum

voltage

ratings.

When

making

amplitude

meas-

urements

with

an

attenuator

probe,

be

sure

to

multiply

the

observed

amplitude

by

the

probe

attenuation

factor.

To

assure

the

accuracy

of

pulse

or

high-frequency

measure-

ments,

check

the

probe

compensation.

To

make

the

adjust-

ment,

proceed

as

follows:

1.

Set

the

oscilloscope

Amplitude

Calibrator

for

a

calibra-

tor

output

signal

of

suitable

amplitude

(at

least

2

cm).

2.

Place

the

MODE

switch

to

the

appropriate

channel

set-

ing

(CH

1

or

CH

2)

to

be

used

with

the

probe.

3.

Touch

the

probe

tip

to

the

calibrator

output

connector

and

adjust

the

oscilloscope

controls

to

display

several

cycles

of

the

waveform.

4,

Adjust

the

probe

compensation

for

best

square-wave

response

as

shown

in

the

right-hand

picture

of

Fig.

2-4.

NOTE

If

a

square-wave

source

other

than

the

oscilloscope

calibrator

is

used

for

compensating

the

probe,

do

not

use

a

repetition

rate

higher

than

5

kHz.

At

higher

repetition

rates, the

waveform

amplitude

appears

to

change

as

the

probe

is

compensated.

Thus,

proper

compensation

is

difficult.

If

the

probe

remains

improperly

compensated,

measurements

will

be

inaccurate.

2-3

Operating

Instructions—Type

1A2

1M

T

=S

N

100

k

x

~

AN

~

N

N

N

X

\

\,

N

Xe

Ohms

10k

x

x

aN

»

aN

.

\

\

1000

—

eH

ww

N

N

N

100

:

1

MHz

10

MHz

Frequency

in

Megacycles

Per

Second

Fig.

2-3.

Type

1A2

nominal

input

resistance

and

capacitive

reactance

vs

frequency

at

any

position

of

the

VOLTS/CM

switch.

AC-DC-GND

Switch

To

display

both

the

DC

and

AC

components

of

an

applied

signal,

set

the

AC-DC-GND

switch

to

DC;

to

display

only

the

AC

component

of

a

signal,

set

the

AC-DC-GND

switch

to

AC.

In

the

AC

position

of

the

switch,

the

DC

component

of

the

signal

is

blocked

by

a

capacitor

in

the

input

circuit.

The

input

time

constant

of

the

input

circuit

is

about

0.1

second

and

the

low-frequency

response

of

the

unit

is

down

3

dB

at

about

2Hz.

If

a

10X

attenuator

probe

is

used

with

the

Type

1A2,

the

low-frequency

response

will

be

extended

to

about

0.2

Hz

with

a

100X

probe,

low-frequency

response

ts

about

2

Hz.

Placing

the

AC-DC-GND

switch

to

the

GND

position

grounds

the

input

circuit

of

the

Type

1A2

to

provide

a

DC

2-4

zero

reference.

When

the

AC-DC-GND

switch

is

set

to

GND,

the

switch

internally

disconnects

but

does

not

ground

the

applied

signal

at

the

input

connector.

The

GND

position

of

the

switch

eliminates

the

need

for

externally

grounding

the

input

of

the

unit

or

probe

tip

to

establish

the

ground

reference.

VOLTS/CM

Switch

and

VARIABLE

Control

The

amount

of

vertical

deflection

produced

by

a

signal

is

determined

by

the

signal

amplitude,

the

attenuation

factor

{if

any)

of

the

probe,

the

setting

of

the

VOLTS/CM

switch

and

the

setting

of

the

VARIABLE

control.

Calibrated

deflec-

tion

factors

indicated

by

the

settings

of

the

VOLTS/CM

switch

apply

only

when

the

VARIABLE

control

is

set

to

the

CALI-

BRATED

position.

Errors

in

display

measurements

may

result