Tektronix 524ad series User manual

CATHODE-RAY

OSCILLOSCOPE

TYPE

S24AD

INSTRUCTION

MANUAL

TEKTRONIX, INC.

MANUFACTURERS

OF

CATHODE-RAY

AND

VIDEO

TEST

INSTRUMENTS

Sunset

Highway

and Barnes Road •

P.

0,

Box 831 • Portland

7,

Oregon,

U.S.

A.

Phone: CYpress

2-2611

• Cables:

Tektronix

TYPE

524AD

SERIAL

NUMBER

---

TYPE

S24AO

CATHOOE-tAY OSClllOSCOPf

•

B

GENERAL DESCRIPTION

General

The

'fektronix

Type

524AD is a

portable,

self-

contained

cathode-ray

oscilloscope specifically

designed

for

maintenance

and

adjustment

of

tele-

vision

transmitters

and

studio

equipment.

With

this

oscilloscope,

any

portion

of

the

tele-

vision

picture

can

be

observed,

from

complete

frames

to

small

portions

of

individual lines.

Any

one

of

the

525 lines in

the

picture

can

be

select-

ed

and

observed

in detail.

Internally-generated

time

markers

facilitate

sync-pulse

timing.

The

wide-band

vertical

amplifier

is

provided

with

a

network

that

can

be

switched

in

to

limit

the

high-frequency

response

to

that

recommended

by

the

IRE

Standards

Committee

for

stand-

ardized

pulse-level

measurements.

A second

switch

position

adds

high-frequency

compensa-

tion

to

make

flat

frequency

response

to

5 me,

within

one

per

cent,

but

at

the

sacrifice

of

best

transient

response.

The

vertical

amplifier

has

a

bandwidth

to

10

megacycles, a

de

sensitivity

to

0.15

volts

per

centimeter,

and

an

ac

sensitivity

increased

by

a

lOX ac-coupled

preamplifier

to

0.015

volts

per

centimeter.

A built-in

variable-duty-cycle

cali-

brator

aids

in pulse-level

measurements.

The

sweep

system

provides

calibrated

sweeps

as

fast

as

0.1

microsecond

per

centimeter,

in-

cludes a

3X

and

lOX magnifier, a television

composite-video-signal

sync

separator,

and

a

variable

delayed

sweep.

The

unblanking

pulse

is

de

coupled.

Characteristics

SWEEP

CIRCUIT

Hard-tube

type,

triggered

or

recurrent

opera-

tion

as

desired.

SWEEP-TIME

RANGE

Continuously

variable,

0.1

microsecond

per

centimeter

to

0.01

second

per

centimeter.

TRIGGER

REQUIREMENTS

TV

composite

video

signal

between

0.5

volt

and

15

volt

peak,

or

pulses 0.15

to

15

volts

peak

to

peak.

SWEEP

MAGNIFICATION

Magnifier

expands

the

trace

to

right

and

left

of

center,

either

3X

or

lOX. Magnified

sweep

speed limited

to

0.1

microsecond

per

centimeter.

EXTERNAL

SWEEP

INPUT

External

sweep

voltage

can

be

coupled

in via

100-k

potentiometer

through

de-coupled

sweep

amplifier,

with

magnification, if desired.

Hori-

zontal

positioning

included.

SINE-WAVE,

60-CYCLE

PHASED

SWEEP

This

sine-wave

sweep

is

adjustable

in ampli-

tude

and

the

phase

can

be varied

through

150

degrees. Applied via

the

sweep

amplifier.

In-

cludes

sweep-magnifier

and

horizontal-position-

ing

circuits.

TIME

MARKERS

Five

time

intervals

are

provided

of

1 µsec,

0.1

µsec, 0.05 µsec, 0.318 µsec

and

1.59 µsec. (200

markers

and

40

markers

per

television line.)

DC

UNBLANKING

The

de-coupled

unblanking

pulse

permits

the

slowest

sweeps

to

be used

with

uniform

spot

intensity

throughout

the

sweep.

VERTICAL

AMPLIFIER

Four

de-coupled

stages

provide

sensitivities

from

0.15

volts

per

centimeter.

Output

stage

is a

three-section

push-pull

distributed

amplifier.

An

ac-coupled lOX

preamplifier

can

be

switched

in for

highest

sensitivity,

giving

a sensitivity

of

0.015

volts

per

centimeter.

AC

VERTICAL-DEFLECTION

SENSITIVITY

Continuously

variable

from

0.015

volts

per

centimeter

to

50

volts

per

centimeter,

peak

to

peak.

DC

VERTICAL-DEFLECTION

SENSITIVITY

Continuously

variable

from

0.15

volts

per

centimeter

to

50

volts

per

centimeter,

peak

to

peak.

VERTICAL-AMPLIFIER

FREQUENCY

RESPONSE

DC

to

10

megacycles

at

a

maximum

sensitivity

of

0.15

volts

per

centimeter.

Two

cycles

to

10

megacycles

with

the

ac-coupled

preamplifier

for

sensitivity

increased

to

0.015

volts

per

centi-

meter.

@

GENERAL

DESCRIPTION

-

PAGE

1

TYPE

624AD

Over-compensation

of

high

frequencies

can

be

selected

with

a

switch

to

provide

flat

frequency

response,

within

I

per

cent,

to

5 me,

bnt

with

some

overshoot

on

transient

response.

VERTICAL-AMPLIFIER

TRANSIF.NT

RESPONSE

Rise

time

0.04

microseconds

between

response

points

10

per

cent

and

90

per

cent

of

the

final

value.

VERTICAL-AMPLIFIER

INPUT

IMPEDANCE

One

megohm

shunted

by

45

µµf

capacitance.

PROBE

INPUT

IMPEDANCE

Ten

megohms

shunted

by

15

µµf;

!OX

attenua-

tion.

SIGNAL-DELAY

NETWORK

A <lelay

network

supplies

an

additional

0.25

microsecond

of

delay

to

the

vertical-ampli-

fier

system

to

permit

the

triggering

waveform

to

he

displayed.

Total

signal

delay

is

0.34

micro-

seconds.

CALIBRATOR

A

variable-duty-cycle

square

wave

is

provided.

Seven

full-scale

ranges

between

0.05

volts

and

SO

volts,

continuously

variable,

can

be

read

di-

@

rcctly

from

the

dial

settings

with

an

accuracy

within

three

per

cent

of

full scale.

The

duty

cycle is

variable

between

I

per

cent

and

99

per

cent.

Frequency

varies

with

duty

cycle.

CATHODE-RAY

TUBE

A

type

5ABP1

cathode-ray

tube

is

supplied

with

the

Type

524AD

unless

a P7

or

a

Pll

is

specified

as

the

optional

choice.

CATJIODE-RAY

Tum;

ACCELERATING

VOLTAGE

Four

kilovolts.

(-+·2.5

and

-1.5

kv.)

CONSTRUCTION

Welded

aluminum

alloy, with

photo-etched

panel

and

blue

wrinkle

case.

DIMENSIONS

25"

long, 13" wide, 16¼" high.

\VEIGHT

61

pounds.

POWER

REQUIREMENTS

105

to

125

volts

or

210

to

250

volts

ac,

SO

to

60 cycles. 500

watts

at

117

or

234 volts.

TYPE

524AD

GENERAL

DESCRIPTION-

PAGE 2 ®

VOLTS/CM

INPUT

SELECTOR

INPUT

1,

INPUT

2

GND

VARIABLE

ATTEN.

CAL.

VOLT-

AGE RANGE

VARIABLE

ATTEN.

BAL.

CAL.DUTY

CYCLE

CAL.

VOLTAGE

CAL.OUTPUT

PROBE

POWER

SCALE

ILLUMINA-

TION

FOCUS

INTENSITY

ASTIGMATISM

VERTICAL

POSITION

®

Front-Panel

Controls

and

Connectors

VERTICAL

AMPLIFIER

Seven-position

gang

switch. Selects

attenuators

or

preamplifier

at

the

input

to

the

vertical

amplifier

to

select

vertical-deflection

sensitivity.

Six-position

switch

connects

INPUT

1,

INPUT

2,

or

the

calibrator

output

to

the

vertical

amplifier,

and

inserts

or

removes

a

capacitor

for ac

or

de coupling.

Coaxial

connectors

to

the

vertical-amplifier

system

via

the

INPUT

SELECTOR

switch.

Binding

post

connected

to

the

instrument

case.

Variable

resistor

between

cathodes

of

the

cathode-coupled

variable-gain

stage.

Varying

this

resistor

varies

the

coupling

between

stages

and

varies

the

overall

stage

gain.

Eight-position

switch

selects

attenuators

providing

seven

calibrator

voltage

ranges,

and

turns

the

calibrator

off.

Adjusts

grid

bias

of vertical

variable-gain

stage.

When

the

two

cathodes

of

this

cathode-coupled

stage

are

at

equal

voltage,

no

vertical

positioning

occurs

when

the

VARIABLE

ATTEN.

control

is

adjusted.

Variable

resistor

adjusting

time

constants

of

calibrator

multivibrator.

Time

con-

stant

of

one-half

of

multivibrator

is

lengthened

while time

constant

of

other

is

shortened.

Permits

duty

cycle

to

be

varied

between

one

per

cent

and

99

per

cent

limits.

Calibrated

potentiometer

across

the

CAL VOLTAGE RANGE

step-attenuator

output.

Gives

continuously

variable

voltage

within

the

step

range.

Coaxial

connector

from

arm

of

CAL VOLTAGE

potentiometer.

Provides

the

same

voltage

as

is applied

to

vertical amplifier input.

Connector

to

provide

plate

and

filament

power

for a

cathode-follower

probe.

CRT

CONTROLS

Potentiometer

in

the

graticule

light

circuit

to

vary

brightness

of

scale illumination.

Potentiometer

varying

the

voltage

of

the

focusing

anode

of

the

cathode-ray

tube.

Potentiometer

adjusting

the

control-grid

bias

on

cathode-ray

tube

to

adjust

spot

intensity.

Potentiometer

adjusting

the

grid

bias

of a

cathode-follower

voltage

regulator

supplying

astigmatism-grid

voltage

on

cathode-ray

tube.

Potentiometer

setting

the

grid

voltage

of

one-half

of

the

phase-inverter

amplifier

stage.

Since

the

amplifier is de coupled,

variation

of

the

de level

at

this

stage

varies

the

average

de

voltage

between

the

vertical-deflection

plates.

@

GENERAL

DESCRIPTION

-

PAGE

3

TYPE

524AD

HORIZONTAL

POSITION

EXT

MARKER

(CRT

CATH)

Time

Marker

Switch

PHASE

AMPLITUDE

+GATE

-GATE

MAG.

POS.

µSEC/CM

MULTIPLIER

SWEEP

DELAY

SWEEP

OUTPUT

FIELD

SHIFT

EXTERNAL

SWEEP

INPUT

@

TYPE

524AD

Pocentiometer

setting

bias

of

first sweep-amplifier V218A. Since

sweep

amplifier

is de coupled,

change

in de level

at

this

point

affects

average

voltage

between

horizontal-deflection plates.

TIME

MARKER

Front-panel

connector

connected

through

the

EXT

position of

the

time

marker

switch

and

through

a .015-µf

capacitor

to

the

cathode-ray

tube

cathode.

Six-position

gang

switch

selects circuit

constants

for

time-mark

time

intervals

and

connects

marker

to

cathode-ray

tube

cathode

circuit in five

of

the

six switch

positions.

In

sixth

position

switch

turns

off

time-marker

generator

and

connects

cathode-ray

tube

cathode

to

external

binding

post.

Control

to

delay

the

start

of

the

markers

up

to

1.5

µsec.

Variable

resistor

setting

bias

of

clipper amplifier

and

thereby

setting

amplitude

of

marker

pips.

SWEEP

GENERATOR

Front-panel

binding

post

to

cathode

of

gate-output

amplifier. Peak

voltage

about

30

volts

de coupled

to

binding

post.

Front-panel

binding

post

to

plate

of

gate-output

amplifier

through

0.047-µf capaci-

tor.

Peak

voltage

about

30 volts.

Screwdriver

front-panel

control

adjusts

bias

of

phase-inverter

sweep-amplifier

stage

to

permit

adjustment

fo magnified-sweep position

so

that

the

magnified

sweep

centers

at

the

center

of

the

screen.

Ganged

variable

resistors

in

timing-capacitor

charging

circuit

and

multivibrator-

timing

circuit.

Units

dial

controls

ten-position

gang

switch

increasing

resistance

by

equal

increments

in

both

timing-capacitor

circuit

and

multivibrator-timing

circuit.

Tenths

dial

controls

dual variable

resistors

in series

with

step

resistors.

Dial

is calibrated in

conjunction

with

variable resistors.

Sum

of

units-dial read-

ing

and

tenths-dial

reading

gives sweep-time

multiplying

factor.

Three-tum

potentiometer

setting

grid

bias

of

voltage-comparator

tube.

Deter-

mines

point

on

triggered

sawtooth

at

which delayed

trigger

voltage

is

generated.

Triggered

sawtooth

has

maximum

repetition

rate

of

30

per

second.

Permits

trig-

gering

sweep

on

any

line

of

television field.

Front-panel

connector

from

cathode-follower

amplifier provides a positive-going

sawtooth

voltage

simultaneously

with

the

sweep.

Fixed

peak

voltage

of

about

40 volts, de coupled

to

binding

post.

Extends

duration

of

one

delay-timing

sawtooth

so

that

an

extra

vertical sync

pulse is missed,

and

sawtooth

thereafter

synchronizes

with

alternate

field.

External

front-panel connection

to

the

sweep amplifier, de coupled

to

amplifier

through

EXT

SWEEP

ATTEN

potentiometer.

GENERAL

DESCRIPTION

-

PAGE

4

TIME

STABILITY

(EXT.

SWEEP

ATTEN.)

AMPLITUDE

(INT

60'v

SWEEP

PHASE)

SELECTOR

EXTERNAL

TRIGGER

INPUT

POWER

Seven-position

ganged

switch.

Selects

five sizes

of

timing

capacitors

in

sweep

circuit

and

corresponding

five sizes of

capacitors

in

multivibrator

timing

circuit.

In

remaining

two

positons,

connects

EXTERNAL

SWEEP

INPUT

connector

or

internally-developed

60-cycle

sine

wave

to

sweep

amplifier,

and

biases

gating

multivibrator

off

to

unblank

cathode-ray

tube.

Ganged

dual

potentiometer.

Adjusts

bias

on

gating

multivibrator

in

region

of

bias

for

recurrent

operation.

Second

potentiometer

provides

amplitude

adjustment

for

external

sweeps.

TRIGGER

Potentiometer

setting

bias

on

trigger-amplifier

tube

to

adjust

gain

and

operating

point.

Ganged

with

variable

resistor

in 60-cycle

phasing

circuit

which

varies

phase

of

sine-wave

sweep

when

SWEEP

TIME

switch

is

in

INTERNAL

60'v

SWEEP

position.

Ten-position

switch

selects

various

sources

of

trigger

voltage

and

arranges

trig-

ger-amplifier

output

circuit

to

maintain

positive

trigger

output

for

either

polarity

of

input

pulse.

In

the

UNDELA

YED

SWEEP

positions,

output

of

the

trigger-

phase

changer

is applied

to

sweep

circuit directly.

In

the

DELAYED

SWEEP

positions

marked

in

red

on

the

panel,

input

triggers

pass

through

a

sync

separator

and

are

arranged

to

trigger

a

sawtooth

generator

which

produces

a

second

trig-

ger

delayed

by

an

adjustable

time

after

the

first

trigger.

Coaxial

connector

to

EXT

position

of

trigger

SELECTOR

switch.

Toggle

switch

in

primary

circuit

of

power

transformer.

@

GENERAL

DESCRIPTION

-

PAGE

6

TYPE

524AU

OPERATING

INSTRUCTIONS

Preliminary

Instructions

COOLING

The

Type

524AD Oscilloscope is cooled

by

filtered,

forced-air

ventilation.

The

instrument

must

therefore

be

placed

so

the

air

intake

is

not

blocked,

and

the

filter

must

be

clean

enough

to

permit

adequate

air

circulation.

If

the

interior

temperature

does rise

too

high

for

some

reason,

a

thermal

cutout

switch

will

disconnect

the

pow-

er

and

keep

it

disconnected

until

the

temperature

drops

back

to

a safe value.

Keep

the

instrument

dry.

If

is it

exposed

to

excessive

dampness,

let it

dry

thoroughly

before

operating

it.

CATHODE-RAY

TUBE

CONTROLS

The

Type

SABP

cathode-ray

tube

used in

this

instrument

has

a

total

deflection

potential

of

about

4000 volts.

With

this

amount

of accel-

eration,

the

spot

can

be

bright

enough

to

dam-

age

the

screen

if it is left

long

in

one

place. Be

careful

to

turn

the

INTENSITY

control

to

the

left

so

that

the

spot

is dim

whenever

you

leave

the

instrument

unattended.

Individual

FOCUS, ASTIGMATISM,

and

INTENSITY

controls

are

available

on

the

front

panel.

These

controls

are

slightly

interdepen-

dent,

and

may

require

readjustment

for

different

INTENSITY

control

settings.

ILLUMINATED

GRATICULE

The

adjustable

graticule

lighting

control

la-

beled SCALE ILLUM.,

can

be

adjusted

to

suit

the

lighting

conditions

of

the

room.

The

colored

filter supplied is colored

to

provide

the

maxi-

mum

trace

contrast

for

the

Pl

phosphor

in

the

presence

of

room

light.

The

graticule

is

accurately

scribed

in

centi-

meters,

and

the

sweep

times

and

vertical-de-

flection

factors

are

given in

units

per

centimeter.

To

find

volts

from

the

amplitude

of deflection,

therefore,

multiply

centimeters

of

deflection

from

the

graticule

reading

by

the

volts

per

centi-

meter

indicated

by

the

vertical-amplifier dial

settings.

Similarly,

to

find time,

multiply

centi-

meters

along

the

time axis

of

the

graticule

by

the

sweep time

per

centimeter

indicated

by

the

sweep-dial

settings.

The

graticule

can

be

mounted

in

either

of

two

positions,

rotated

180

degrees

from

each

other.

In

one

position,

the

graticule

illumination

is

colored red,

and

in

the

other

position it is white.

The

red

contrasts

well

with

the

green

filter.

The

white is

more

satisfactory

photographically.

First Time Operation

To

place

the

Type

524AD in

operation

for

the

first time,

the

following

procedure

is

sug-

gested:

I.

Connect

to

a

source

of

50-60 cycle, 105-

125

v

power

(or

210-250 v if T401

primary

connections

have

been

changed

accord-

ing

to

the

directions

shown

in

the

Adjust-

ment

Section

of

this

manual).

2.

Set

controls

as

indicated below.

INPUT

SELECTOR CAL.,

AC

VOLTS/CM

15-50

VARIABLE

ATTEN.

Clockwise

CAL. VOLTAGE RANGE

50

CAL.

DUTY

CYCLE

Mid

range

CAL.VOLTAGE

0

SELECTOR

+SIG,

UNDELAYED

SWEEP

AMPLITUDE

Counterclockwise

STABILITY

Counterclockwise

TIME

100

µsec/cm

TIME

MULTIPLIER

5.0

MAGNIFIER

OFF

TIME

MARKER

EXT

3.

Turn

POWER

switch

to

ON

and

wait

about

60 seconds.

4.

Set

INTENSITY

control

at

about

¼

clockwise rotation.

5.

Adjust

VERTICAL

POSITION,

HORI-

ZONTAL

POSITION,

ASTIGMA-

TISM,

and

FOCUS

until

a

sharply

fo-

cussed

spot

is

obtained

at

the

left

center

of

the

screen.

CAUTION

-

DO

NOT

ALLOW

THIS

SPOT

TO

BE

EXCES-

SIVELY

BRIGHT

OR

REMAIN

FOR

LONG

IN

ONE

POSI-

TION.

@

OPERATING

INSTRUCTIONS-

PAGE

1

'l'YPE

524AlJ

6.

Advance

the

sweep

ST

ABILITY

con-

trol

until a

sweep

appears,

then

turn

it

back

until

the

sweep

just

disappears.

7.

Set

the

CAL.

VOLTAGE

control

to

5

(50

v).

8.

Advance

the

trigger

AMPLITUDE

con-

trol

to

obtain

a

stable

trace

of

a

square

wave

(about

3½

cm

vertical

deflection).

The

oscilloscope is

now

displaying

the

square-

wave

calibrating

voltage.

To

observe

other

waveforms,

connect

to

either

INPUT

1

or

IN-

PUT

2

and

set

the

INPUT

SELECTOR ac-

cordingly.

Adjust

the

VOL

TS/CM

and

VARI-

ABLE

ATTEN

for

the

desired

amount

of

verti-

cal deflection,

and

then

select

the

appropriate

sweep

time

by

means

of

the

sweep

TIME

and

µSEC/CM

MULTIPLIER

controls.

Sweep Operation

GENERAL

The

sweep

circuit

of

the

Type

524AD

is

very

flexible

and

is

capable

of

synchronizing

at

high

frequencies.

Fundamental

frequencies

as

high

as

10

me

can

be

observed

easily.

By

adjusting

the

sweep

STABILITY

control,

the

sweep

can

be

made

to

run

recurrently

or

triggered

as

de•

sired.

ADJUSTMENT

OF

SWEEP

STABILITY

The

sweep

STABILITY

control

varies

the

multivibrator

bias

and

therefore

determines

whether

the

sweep

will

operate

recurrently

or

wait

for

a

trigger

impulse.

Correct

functioning

for

triggered

operation

is

therefore

obtained

when

the

STABILITY

control

is

set

just

under

the

point

where

oscillation

takes

place.

The

pro-

cedure

is

to

remove

the

trigger

source

by

turn-

ing

the

trigger

AMPLITUDE

control

counter-

clockwise,

advance

the

STABILITY

knob

until

a

sweep

appears,

and

then

decrease

it until it

just

disappears.

NOTE-

When

using

the

internal

(

+SIG.

or

-SIG.)

trigger

impulses

to

view

signals

at

fundamental

fre-

quencies

of

about

2

me

or

higher,

it

will

be

necessary

to

advance

the

STABILITY

control

somewhat

above

the

normal

operating

point

to

secure

a

stable

pattern.

The

µSEC/CM

MULTIPLIER

dials

also

may

have

some

effect up-

on

the

critical bias

for

triggered

op-

eration

of

the

multivibrator.

The

STABILITY

control

may

need

to

be

readjusted

when

the

MULTI-

PLIER

dials

are

changed.

FUNCTION

OF TRIGGER SELECTOR

This

control

selects

the

trigger

impulses

to

be

used

from

three

sources:

the

line

frequency

(601\/),

the

vertical

amplifier

(+SIG.

or

-SIG.)

and

the

EXTERNAL

TRIGGER

INPUT

coax

connector.

The

trigger

SELECTOR

switch

is

divided

into

two

sectors

of

rotation.

One

sector,

marked

in black,

provides

positions

for all

types

of

trigger

signals

without

the

delayed-trigger

cir-

cuit.

The

other

sector

provides

the

same

posi-

tions

as

the

first sector,

but

includes

the

delayed

trigger

circuits.

When

using

those

marked

(+

),

the

sweep

starts

during

the

rising

portion

of

the

trigger

impluse.

When

using

the

positions

marked

(-),

the

sweeps

start

during

the

falling

protion.

For

satisfactory

operation

in

the

EXT

positions,

trigger

amplitudes

between

.5

volts

and

15

volts

peak

should

be

provided.

Larger

trigger

voltages

should

be

attenuated

externally.

ADJUSTMENT

OF TRIGGER

AMPLITUDE

The

trigger

AMPLITUDE

control

sets

the

bias in

the

trigger

amplifier

and

thereby

adjusts

the

amplitude

of

the

impulse

which

reaches

the

multivibrator.

After

the

sweep

STABILITY

is

set as

described

previously,

and

the

trigger

SE-

LECTOR

switch

is

set

to

the

correct

position,

advance

the

trigger

AMPLITUDE

control

until

a

stable

trace

is

obtained.

When

the

trigger

source

is a

slowly

changing

wave

such

as a sine

wave

or

sawtooth,

adjustment

of

the

AMPLI-

TUDE

setting

will

change

the

phase

of

the

sig-

nal relative

to

the

start

of

the

sweep.

In

general, it is

desirable

to

use

the

minimum

AMPLITUDE

setting

required

to

insure

a

stable

trace.

If

poor

synchronizing

is

experienced

when

the

Type

524AD is

used

to

observe

repetitive

signals

containing

erratic

peak

voltages,

such

as

are

produced

by

vibrating

contacts,

it

may

be possible

to

form

a

stabilized

trigger

signal

by

the

use of

auxiliary

limiting

and

differentiat-

ing

circuits.

The

trigger

SELECTOR

switch

should

then

be

set

to

the

proper

EXT

polarity,

and

connection

should

be

made

to

the

EXTER-

NAL TRIGGER

INPUT

connector.

ADJUSTMENT

OF

SWEEP

TIME

The

combination

of

sweep

TIME

and

µSEC/CM

MULTIPLIER

controls

allows

the

operator

to

vary

the

sweep

time

so

that

the

marked

portion

of

the

graticule

(

10

cm)

is cov-

ered

in

any

time

from

.1

sec

to

1 microsec.

The

approximate

number

of

microseconds

for

a

horizontal

deflection of 1

cm

can

be

determined

easily

by

multiplying

the

TIME

setting

by

the

sum

of

the

MULTIPLIER

dial

readings.

Mul-

tiply

this

figure

by

ten

to

determine

the

time

required

to

sweep

the

entire

10-cm

portion

of

the

graticule

which

is

calibrated

in

centimeters.

TYPE

524AD

OPERATING

INSTRUCTIONS-PAGE

2

®1

The

MULTIPLIER

consists

of

a 10-step

con-

trol

and

a

continuously

variable

control,

with

the

step-control

dial

numbers

serving

as

indices

for

the

hand-calibrated

variable

dial.

These

dial

readings

are

added

to

determine

the

multi-

plying

number.

Since

100 dial

divisions

are

pro-

vided

for

each

10-to-1

TIME

range,

accurate

indication

and

precise

resetting

are

made

pos-

sible.

The

overall

accuracy

of

the

sweep-time

cali-

bration

is

dependent

on

several

factors,

includ-

ing

linearity

of

the

sweep

amplifier

and

the

cathode-ray

tube,

but

the

actual

time

for

a

10-cm

sweep

will

be

within

five

per

cent

of

the

indicated

time

at

any

setting

of

the

controls.

Compensation

for

variations

caused

by

different

tubes, etc.,

can

be

made

by

means

of

screwdriver

adjustments

inside

the

case.

Procedure

for

these

adjustments

will be

found

in

the

Main-

tenance

section.

RECURRENT

SWEEP

Jn

case

it is

desirable

to

have

a

sweep

without

using

any

sort

of

trigger,

retard

the

trigger

AMPLITUDE

control

and

advance

the

sweep

STABILITY

control

until

a

stable

repetitive

sweep

is

obtained.

SINGLE

SWEEP

The

triggered

sweep

circuit

used

in

the

Type

524AD

inherently

provides

for

single-

sweep

operation.

The

beam

is

blanked

out

until

the

trigger

simultaneously

turns

it

on

and

starts

the

sweep.

For

single-sweep

operation,

a

me-

chanical

contact

or

hand

key

can

be

connected

between

the

EXTERNAL

TRIGGER

INPUT

connector

and

ground,

with

the

trigger

SELEC-

TOR

switch

at

-EXT.

If

multiple

sweeps

occur

because

of

intermittent

or

bouncing

contact,

a

capacitor

of

.1

µf

to

1 µf

should

be

connected

across

the

contact.

This

capacitor

will

charge

to-

ward

about

10

volts

through

1

megohm

and

the

long

time

constant

will

prevent

an

immediate

re-

currence

of

the

sweep.

Use

minimum

dependable

trigger

AMPLITUDE

setting.

SWEEP

DELAY

The

SWEEP

DELAY

control

will

produce

triggers

no

faster

than

30

times

per

second.

This

control

adjusts

the

amount

of

delay

between

receipt

of

the

trigger

and

the

start

of

the

sweep.

The

delay

circuit

operates

only

when

the

trigger

SELECTOR

switch

is in

the

DELAYED

SWEEP

sector.

The

panel

markings

give

an

approximate

indication

of

the

delay.

When

a

composite

television

signal

enters

the

sweep-delay

circuitry

a

sync

separator

ex-

tracts

the

60-cycle

field-sync

pulse.

The

sweep

delay,

operating

30

times

per

second,

accepts

every

other

vertical-sync

pulse

and

starts

the

sweep

from

zero

milliseconds

to

25

milliseconds

after

the

accepted

sync

pulse.

This

amount

of

delay

allows

the

sweep

to

display

any

of

the

lines in

one

field.

FIELD

SHIFT

When

the

FIELD

SHIFT

button

is

depress-

ed,

the

other

60-cycle

vertical-sync

pulse

is ac-

cepted

by

the

sweep

delay

circuitry,

allowing

display

of

the

other

interlaced

field.

SWEEP

MAGNIFIER

Frequenty

it is

desirable

to

examine

a

portion

of

the

waveshape

under

observation

in

greater

detail,

for

instance

the

rate

of

fall

of

a fairly

long

pulse.

In

the

524AD,

the

sweep

magnifier

makes

it

possible

to

expand

any

desired

33.3

per

cent

or

IO

per

cent

of

the

sweep

to

cover

the

entire

tube

face.

The

operating

procedure

is

as follows:

Turn

the

sweep

MAGNIFIER

to

OFF.

Adjust

the

sweep-time

and

horizontal-

positioning

controls

so

that

the

portion

of

the

wave

to

be

magnified

is

at

the

center

of

the

tube.

Then

move

the

MAGNIFIER

control

to

either

3X

or

lOX

and

the

portion

of

the

wave

in

the

center

of

the

tube

will be

magnified

linearly

in

both

directions.

The

accuracy

of

sweep

magni-

fication will be

within

five

per

cent

for

sweep

speeds

to

1.0 µSEC/CM.

The

accuracy

will de-

crease

for

sweep

speeds

in

excess

of

this

amount.

If

the

portion

of

the

wave

to

be

magnified

moves

from

the

center

of

the

screen

when

the

MAGNIFIER is

turned

to

one

of

the

two

po-

sitions

for

magnification,

the

MAG. POS.

ad-

justment

should

be

reset.

(See

Maintenance

section.)

NOTE:

A

sweep

of

10

cm

per

mi-

crosecond

is

about

the

limit

of

the

sweep

amplifier.

Some

non-linear-

ity

will

result

if

the

sweep

exceeds

this

value.

EXTERNAL

SWEEP

INPUT

In

the

full-counterclockwise

position

of

the

sweep

TIME

switch

a

binding

post

labeled

EXT

SWEEP

INPUT

is

connected

to

the

sweep-

amplifier

input.

This

connection

can

be

used,

for

example,

for a

sine-wave

oscillator

for fre-

quency-comparison

measurements,

for

an

aux-

iliary

slow-sweep

generator,

etc.

The

connection

to

the

sweep

amplifier

is

made

through

a po-

tentimeter

ganged

with

the

sweep

STABILITY

control,

for

adjustment

of

the

amplitude

of

the

external

sweep.

The

magnifier

circuits

and

the

horizontal-positioning

control

operate

on

sweep

voltages

applied

at

this

connector.

At

maximum

sensitivity

with

the

MAGNIFIER

at

lOX

and

the

SWEEP

ATTEN.

control

full clockwise,

the

deflection

factor

is

about

.25

volts

per

centi-

meter,

peak

to

peak.

@

®J

OPERATING

INSTRUCTIONS-PAGE

3

TYPE

524AD

INT

601'\,

SWEEP

This

circuit is

provided

in

the

second

most

counterclockwise

position

of

the

sweep

TIME

switch.

The

principal use

of

this circuit is

to

facilitate

the

determination

of

bandpass

charac-

teristics

of

filters, amplifiers, etc., in

conjunc-

tion

with

swept-frequency

signal

generators

which

can

be

swept

at

a 60-cycle

rate.

A 60-cycle

sine-wave

sweep

is

provided

whose

phase

can

be

varied

over

a ISO-degree

range

by

means

of

a

ganged

control

on

the

trigger

AMPLITUDE

control

knob,

and

whose

amplitude

can

be

varied

by

means

of

the

ganged

control

on

the

sweep

STABILITY

control

knob.

The

signal is ap-

plied

to

the

sweep

amplifier

so

that

the

magni-

fier

and

positioning

circuits function in

the

con-

ventional

manner.

Vertical Amplifier

The

risetime

of

the

Type

524AD is

designed

so

that

at

the

fastest

sweep

time

of

one-tenth

microsecond

per

centimeter

at

the

fastest

rise-

time

that

the

vertical

amplifier

is

capable

of,

the

rise will

take

place in a little less

than

half

a

centimeter

of

horizontal

distance,

and

the

trace

of

a sine

wave

near

the

upper-frequency

limit

at

10

megacycles

will

appear

as

one

cycle

per

centimeter

of

horizontal

distance.

The

use

of

de

coupling

in

the

vertical

ampli-

fier

makes

it possible

to

display

both

the

de

and

ac

components

of

a signal

simultaneously.

The

ability

to

include

the

de

component

makes

it possible

to

observe,

for

example,

when

zero

bias

or

grid

cutoff

occurs,

or

how

close

to

the

cathode

voltage

the

plate

voltage

of

a

tube

can

drop,

and

such

similar

characteristics.

VARIABLE

ATTEN

BAL,

FRONT-PANEL

CONTROL

After

a

warm-up

period

of

several

minutes,

it

should

be

possible

to

rotate

the

VARIABLE

ATTEN.

control

back

and

forth

to

different

positions

without

a

change

in

the

vertical

posi-

tion

of

the

no-signal trace.

If

such

a

change

should

occur,

the

VARIABLE ATTEN. BAL.

control

should

be

readjusted

while

the

VARI-

ABLE ATTEN.

control

is

being

rotated

back

and

forth

until

no

such

change

in vertical posi-

tion occurs.

SIGNAL

DELAY

The

sweep

circuit

requires

approximately

a

tenth

microsecond

of

time

to

get

underway

and

to

get

the

crt

beam

unblanked

after

receipt

of

a

trigger

signal. A

total

signal

delay

of

0.34

mi-

crosecond

occurs

in

the

vertical

amplifier, includ-

ing

a

quarter-microsecond

delay

in a signal de-

@

lay line.

When

the

triggering

waveform

has

a

very

sharp

rise,

therefore,

approximately

a

quart-

er-microsecond

of

sweep

shows

on

the

screen

before

the

waveform

appears.

However,

when

the

triggering

waveform

begins

with

a

slower

rise,

an

appreciable

portion

of

the

wave

may

pass

before

an

adequate

trigger

voltage

can

develop.

In

practice

it

has

been

found

that

the

additional

quarter-microsecond

of

delay

provided

is

about

the

optimum

to

permit

the

display

of

the

start

of

a

slower-rising

waveform.

CONNECTION

TO

DEFLECTION

PLATES

Banana

jacks

are

provided

to

permit

cvnnec-

tions

to

be

made

directly

to

the

deflection

plates

with

low

stray

capacitances.

These

jacks

are

located

at

the

left

rear,

accessible

through

an

opening

in

the

back

of

the

case.

The

terminal

marked

Y2

is

the

top

plate

and

the

terminal

marked

X2

is

the

right-hand

plate. Deflection

factors

are

approximately

25

volts

per

cm

de

at

the

horizontal-plate

jacks,

and

15

volts

per

cm

at

the

vertical-plate

jacks.

A switch

on

the

access panel

makes

connec-

tions

to

the

vertical-deflection

plates

in

four

ways

labeled IRE, NORMAL,

FLAT

and

EXT. : IRE for

bandwidth

reduced

to

comply

with IRE

minimum

standards,

NORMAL for a

normal

10-mc

response

with

optimum

transient

response, FLAT for

high-frequency

compensa-

tion

to

5 me, flat

within

one

per

cent,

but

with

some

overshoot,

and

EXT. for

external

con-

nection

to

the

deflection plates

by

means

of con-

nectors

on

the

access panel.

In

the

EXT. posi-

tion,

the

external

signal is applied

to

the

deflec-

tion

plates

through

blocking

capacitors

with

one-megohm

resistors

to

the

vertical amplifier.

The

one-megohm

resistors

retain

the

function

of

the

vertical position

control.

If

direct

connection

to

the

horizontal

plates

is

desired,

it

is

important

to

maintain

the

correct

average

potential

to

prevent

defocusing

of

the

beam.

The

average

potential

of

the

vertical-de-

flection plates

(measured

from

the

chassis)

is

approximately

160

volts

and

this

same

value

should

be

maintained

on

the

horizontal

plates

when

they

are

de

coupled.

When

de

coupling

to

the

horizontal

plates

is

not

necessary,

exter-

nal

connection

may

be

accomplished

by

replac-

ing

the

jumper

plugs

with

I-megohm

resistors

and

inserting

blocking

capacitors

in series

with

the

horizontal-signal

source.

The

HORIZON-

TAL

POSITION

control

will

then

function for

positioning

the

external

signal.

The

TIME

switch

should

be

turned

to

EXT

SWEEP,

to

prevent

internal-sweep

signals

from

coupling

through

the

I-megohm

resistors.

When

bal-

anced

input is

not

desired,

the

unused

deflection

plate

should

be

bypassed

to

ground.

TYPE

524AD

OPERATING

INSTRUCTIONS

-

PAGE

4

Miscellaneous

SWEEP

OUTPUT

The

SWEEP

OUTPUT

binding

post

makes

available

the

sawtooth

waveshape

appearing

at

the

plate

of

the

sweep-generator

tube.

A

cath-

ode

follower

isolates

the

sweep

generator

from

the

effects

of

the

external

loads

connected

to

the

binding

post.

The

sawtooth

amplitude

is

approximately

30 volts,

peak

to

peak.

GATE

OUTPUT

A

thirty-volt

peak-to-peak

squarewave

of

either

polarity

is available

at

the

binding

posts

marked

+GATE

and

-GATE.

The

-GATE

signal

is

taken

from

the

plate

of

the

gate-output

amplifier

through

a 0.05-µf

capacitor

to

remove

the

de

component.

The

+GATE

signal

is de

coupled

from

the

cathode

of

the

gate-output

am-

plifier

and

provides

a

good

flat-topped

square-

wave.

at

the

slowest

sweep

speeds.

TIME

MARKERS

Time

markers

are

inserted

as

beam

intensi-

fication pips

on

the

cathode-ray

tube

at

intervals

of

1 µsec,

0.1

µsec,

and

0.05 µsec,

or

pips

spaced

40

or

200

per

television line.

The

marker

PHASE

control

delays

the

start

of

the

markers

up

to

1.5

microseconds,

allowing

the

markers

to

be

phased

along

the

sweep.

The

AMPLITUDE

control

varies

the

brightness

of

the

marker

pip.

This

should

be

kept

as

low

as

possible

for

mini-

mum

sweep

distortion

and

trace

defocusing.

In

the

EXT.

position

of

the

marker

switch,

the

crt

cathode

is

capacitively

coupled

to

the

front-panel

binding

post

labeled

EXT.

MARKER.

The

first

marker

pip

may

be

slightly

out

of

position,

but

all

subsequent

pips will

be

well

within

the

2-per-cent

timing

accuracy.

Special Television

Instructions

IRE

RESPONSE

The

full

bandwidth

of

the

Type

524AD

will

generally

be

desired

for all

engineering

measure-

ments

or

maintenance

of

television

circuits

or

equipment.

However,

for

monitoring

the

signal

level

of

an

existing

facility

it

has

been

found

that

restricted

high-frequency

response

is de-

sirable,

with

bandwidth

as

low

as

is

consistent

with

satisfactory

readings

of

signal

levels.

The

IRE-response

position

of

the

VERTI-

CAL

AMPLIFIER

switch

on

the

crt

access

panel

has

been

provided

to

limit

the

high-fre-

quency

response

for signal-level

measurements,

as

recommended

by

the

IRE

Standards

Com-

mittee.

The

FLAT-response

position

of

the

switch

provides

flat-frequency

response

to

5 me,

within

1

per

cent,

but

with

attendant

overshoot

for

fast

pulses.

SWEEP

DELAY

The

524AD

sweep-delay

system

contains

a

sync-separator

circuit

which

adapts

the

system

particularly

to

television

signals

but

limits

its

usefulness

for

other

applications.

Jitter-free

sweep

delay

is

obtained

with

television

signals

by

establishing

a

coarse

time

delay

from

a

verti-

cal-sync

pulse

and

then

actually

triggering

the

sweep

from

a

selected

horizontal-sync

pulse.

Thus,

by

operating

the

FIELD

SHIFT

button

in

conjunction

with

the

SWEEP

DELAY con-

trol

and

selecting

the

appropriate

sweep

speed,

any

particular

horizontal-sync

pulse, line,

or

lines

can

be

observed.

Hooo

When

using

sweep

delay

the

sweep

is

trig-

gered

30

times

per

second.

With

a

sweep

speed

of

0.1

microsecond

per

centimeter

(1

microsec-

ond

for

10

cm)

the

beam

is

on

the

screen

only

30

microseconds

of

each

second

or

0.00003 of

the

time.

The

resulting

display

is

correspond-

ingly

dim

and

should

be

viewed

through

the

viewing

hood

when

the

ambient

light

is

objec-

tionably

bright.

TIME

MARKER

Time

markers

are

useful

for

accurately

meas-

uring

and

adjusting

the

timing

of

the

horizontal

sync

and

blanking

pulses

generated

in

the

sync

generator.

They

are

normally

not

required

for

adjusting

the

vertical

pulse

group.

Individual

horizontal-sync

pulses

may

be

ob-

served

with

sweep

delay

and

with

the

viewing

hood,

the

best

technique

being

to

start

the

sweep

on

a

selected

sync

pulse

and

to

choose

a

sweep

length

which

allows

the

to

be

in-

spected

with

time

markers

and

sweep

magnifi-

cation.

A

much

brighter

picture

will

be

obtained

if

the

sweep

is

triggered

directly

by

the

horizontal

sync

pulses

without

sweep

delay.

Trigger

from

+SIG

or

-SIG

and

advance

the

trigger

AM-

PLITUDE

control

until a

stable,

clear

display

is

obtained.

Sweep

speed

should

be

about

6

to

10

microsec/cm.

This

display

requires

much

lower

marker

amplitude

than

for

the

first

meth-

od,

giving

better

marker

accuracy.

A

high

marker

amplitude

may

change

the

crt

cathode

potential

sufficiently

to

affect

the

horizontal-

and

vertical-deflection

sensitivities

during

the

time

of

each

marker

pip,

thus

displacing

the

pips

from

their

proper

positions

on

the

screen.

@

OPERATING

INSTRUCTIONS-

PAGE

6

TYPE

624AD

The

.005H

time

marker

will

be

found

very

useful in

adjusting

and

measuring

horizontal-

sync

pulse

timing, since

the

F.C.C.

standards

give

time

measurements

in

terms

of

H.

H is

the

time

between

horizontal

sync

pulses, ap-

proximately

63.5

microseconds.

The

.005 H

marker

is

set

to

3.15

megacycles,

200

times

15.75 kc,

thus

producing

markers

each

.5

per

cent

of

H.

Similarly

the

0.025 H

marker

is set

to

630 kilocycles.

RADIO-FREQUENCY

INTERFERENCE

In

some

transmitter

locations

rf

interference

to

the

video

trace

may

be

experienced

from

rf

pickup

into

the

station

video

equipment

itself

or

direct} f

into

the

oscilloscope

input.

This

type

of difficulty

can

be

reduced

by

use

of

completely

shielded

connections,

short

signal

leads,

and

husky,

short

ground

straps.

wh·en

using

the

probe,

be

sure

at

all

times

to

maintain

the

short-

est

possible

ground

connection

directly

to

the

probe body.

PROBE

ADJUSTMENT

Proper

operation

of

the

sweep

delay

depends

somewhat

upon

correct

adjustment

of

the

probe

and

vertical-amplifier

attenuators

..

Adjustment

of

the

probe

can

be

checked

by

observing

the

calibrator

VOLTS/CM

waveform

through

the

@

probe

with

the

switch

at

0.15

volts/cm

to

0.5

volts/cm.

Further

instructions

for

tuning

the

attenuators

are

contained

in

the

Mainten-

ance

section.

LINE

INDICATING

VIDEO

In

the

event

it is found

necessary

to

observe

a

particular

horizontal

line

or

other

detail

with

the

524AD Oscilloscope, a

spare

picture

monitor

may

be

connected

to

the

LINE-INDICATING

VIDEO

output

jack

at

the

rear

of

the

cabinet

to

determine

that

the

oscilloscope is

displaying

the

desired

portion

of

the

picture.

The

picture

appearing

on

the

monitor

will be

brightened

during

the

time

of

the

524AD

sweep

gate.

The

bandwidth

of

the

line-indicating

video

circuit

is

somewhat

restricted

but

is

adequate

for

this

purpose.

The

line-indicating

video

technique

can

be

used

to

determine

the

range

and

resolution

of a

television

system

which

is

transmitting

a

mono-

scope

test-chart

signal.

Grey-scale

information

from

the

test

chart

will

be

displayed

by

the

524AD

as

signal-voltage

level,

while

the

line-

indicating

video

system

depicts

the

portion

of

the

test

chart

being

scanned.

Test-chart

band-

width

wedges

provide

squarewave

test

signals

whose

frequency

is

determined

by

the

portion

of

the

wedges

being

scanned.

TYPE

624AD

OPERATING

INSTRUCTIONS

-

PAGE

6 ®

CIRCUIT

DESCRIPTION

.5WEEP BLOCK DIAGRAM DESCRIPTION

The

trigger

SELECTOR

switch

selects

the

source

and

polarity

of

input

trigger

voltage

and

determines

whether

delayed

triggering

is

pro-

vided.

The

trigger

phase

inverter

provides

the

re-

quired

positive

input

to

the

trigger

amplifier

or

the

sync

separator

for

either

polarity

of

input

trigger

voltage.

The

sync

separator

extracts

the

synchroniz-

ing

pulses

from

the

television

composite

signal.

The

sweep-delay

circuit

provides

a

means

of

delaying

the

initiation

of

a

sweep

by

an

adjust-

able

amount

of

time

after

receipt

of

the

vertical

sync

pulse.

The

FIELD

SHIFT

switch

changes

synchro-

nization

of

the

sweep

to

either

field

of

a tele-

vision frame.

The

trigger

amplifier raises

the

level

of

the

trigger

signal

for

triggering

the

multivibrator.

The

multivibrator

provides

a basic

square-

wave

signal

used

in

several

circuits:

The

clamp-

tube

sweep

generator,

unblanking,

external

gate,

time-marker

circuit,

and

the

video

monitor

line

indicator.

The

clamp

and

de

restorer

provide

a linear

sawtooth

voltage

of

constant

de

starting

level

which is applied

through

a

cathode

follower

to

the

sweep

amplifier.

The

sweep

sawtooth

volt-

age

is

also

available

at

a

front-panel

connector

through

a

cathode-follower

impedance

converter.

The

unblanking

circuit applies a positive

square

wave

to

the

cathode-ray

tube

to

turn

on

the

beam

during

the

period

of

the

sweep.

The

floating

power

supply

is

added

in

series

with

the

output

of

the

unblanking

amplifier

to

provide

the

unblanking

pulse

at

high-voltage

negative

bias

to

the

cathode-ray

tube

control

grid.

The

external-gate

circuit

provides

both

posi-

tive

and

negative

square-wave

pulses

at

front-

panel

connectors

which

are

synchronized

with

the

sweep.

The

magnifier

circuit

includes

the

horizontal-

positioning

control.

A

switch

selects

a multipli-

cation

of

the

sweep

speed

by

a

factor

of

ten,

three,

or

one.

The

trace

is

magnified

both

to

right

and

to

left

of

screen

center.

The

sweep

output

amplifier

provides

phase

inversion

and

amplified

push-pull

sawtooth

sweep

voltage

at

the

horizontal-deflection

plates,

DI

and

D2,

of

the

cathode-ray

tube.

VERTICAL

AMPLIFIER

BLOCK DIAGRAM

The

INPUT

SELECTOR

switch

connects

the

vertical-amplifier

system

to

either

of

two

front-panel

connectors

or

to

an

internal

cali-

brator

circuit.

A vertical-deflection-sensitivity

switch

selects

a

preamplifier

for

the

two

most

sensitive posi-

tions

and

selects

various

attenuators

for

the

posi-

tions

of

less sensitivity.

The

preamplifier

provides

a

gain

of

ten

times

for

the

two

most

sensitive

positions

of

the

VOLTS/CM

switch.

In

the

second

position

the

overall

gain

is

reduced

by

means

of

an

in-

put

attenuator.

A

cathode

follower

reduces

the

effects of

changing

input

capacitance

with

gain

in

the

variable-gain

cathode-coupled

amplifier.

Gain

of

this amplifier is

adjusted

by

switch-

ing

cathode-coupling

resistors.

Plate

output

from

the

grounded-grid

half feeds vertical sig-

nal

through

the

delay

network.

Plate

output

from

the

input

half supplies

vertical

signal

to

the

triggering

circuit

through

the

trigger-selec-

tor

switch.

The

VARIABLE

ATTEN.

BAL.

control

ad-

justs

the

cathode-follower

grid

voltage

which

sets

the

de level

of

the

cathode-coupled

stages

so

that

adjustment

of

the

VARIABLE

ATTEN.

control

will

not

affect

the

vertical position of

the

trace.

The

delay

network

provides

a signal

delay

of

¼

microsecond

which

is

long

enough

to

permit

the

sweep

to

be

triggered

by

the

observed

signal

and

well

under

way

before

the

signal itself is

applied

to

the

deflection plates.

Single-ended

output

from

the

delay

network

is

converted

to

balanced

push-pull

output

by

a

cathode-coupled

phase-inverter

stage,

which

also

includes

the

vertical-positioning

control.

The

current

regulator

provides

an

adjustment

for

the

operating

point

of

the

push-pull

ampli-

fier.

Cathode-follower

drivers

drive

the

push-pull

distributed-amplifier

output

stage

which

in

turn

drives

the

vertical

deflection plates.

The

IRE-NORMAL-FLAT-EXT

switch

lo-

cated

on

the

access

panel

on

the

left

rear

panel

provides

four

circuit

connections

for

the

vertical

deflection

plates

of

the

cathode-ray

tube:

I -

for

normal,

10-mc

bandwidth,

2 - for

band-

width

reduced

to

comply

with

the

IRE

mini-

mum

standards,

3 - for

high-frequency

compen-

sation

to

5 me,

but

with

slight

overshoot,

and

4 - for

external

connection

to

the

deflection

plates

by

means

of

connectors

located

on

the

access panel.

@

CIRCUIT

DESCRIPTION

-

PAGE

l

TYPE

624AD

AUXILIARY

CIRCUIT

BLOCK

DIAGRAM

The

time-mark

generator

provides

accurately

spaced

time

markers

by

intensity

modulating

the

cathode-ray

beam

with

shaped

pulses

from

in-

ductance-capacitance

oscillators.

The

calibrator

oscillator

produces

square

waves

of

adjustable

duty

cycle

with

peak-to-peak

amplitude

set

by

calibrated

controls.

The

line-indicating video circuit

provides

a

video signal

output

on

which

is

superimposed

a positive

gate

synchronized

with

the

oscillo-

scope sweep,

to

apply

to

the

television video

monitor

for

the

purpose

of

indicating,

by

a

bright

line , n

the

monitor

raster,

the

line

of

the

com-

posit

.!

video signal

being

displayed

on

the

Type

524AD Oscilloscope.

The

internal

60-cycle

phased-sweep

circuit

provides

a 6.3-volt 60-cycle

ac

voltage

adjustable

approximately

150

degrees

in

phase.

Detailed Circuit Description,

TRIGGER SELECTOR

The

trigger-selector

switch, SW201 is a

three-

section, ten-position

front-panel

control.

This

control

selects

the

source

of

trigger

signal, ar-

ranges

the

circuits

to

accommodate

either

nega-

tive

or

positive

trigger

signals,

and

includes

or

removes

a

delayed-trigger

circuit.

The

switch

is divided

into

two

sectors

of

rotation.

One

sec-

tor

provides

positions

for

all

the

types

of

trigger

signals

without

the

delay-trigger

circuit.

The

other

sector

provides

the

same

positions as

the

first

sector

but

includes

the

delayed-trigger

cir-

cuits.

In

the

undelayed-trigger

sector

positions,

marked

in

black

on

the

front

panel,

either

the

in-phase

or

inverted

output

of

the

trigger-in-

verter

stage

feeds

directly

to

the

trigger

ampli-

fier.

In

the

DELAYED

SWEEP

sector

positions,

marked

in

red

on

the

front

panel,

either

the

in-

phase

or

inverted

output

of

the

trigger-inverter

stage

is applied

through

the

trigger-delay

cir-

cuits

to

the

trigger

amplifier.

TRIGGER

CIRCUITS

V201A is

the

trigger-inverter

amplifier. A

positive

trigger

signal is

obtained

regardless

of

trigger

input

polarity

by

selecting

either

invert-

ed

signal

from

the

plate

or

in-phase

signal

from

the

cathode

of

V201A.

Internal

60-cycle

triggering

is

provided

in

both

delayed

and

undelayed·positions

of

the

SELEC-

TOR

switch. In

the

undelayed

position, 6.3-volt,

60-cycle

ac

is applied

to

the

grid

of

the

trigger-

inverter

tube

V201A,

and

cathode

output

is

ap-

plied

directly

to

trigger

amplifier V207

on

the

sweep

chassis.

In

the

delayed position

the

60-cycle

voltage

taken

from

the

cathode

of

V201A is applied

to

the

television

sync-separator

circuits

to

trigger

the

phantastron,

V204.

The

sync-separator

circuits

will

also

accept

a 60-cycle

signal. V202 is

over-driven

so

that

a,

flat-top-

ped

waveform

is applied

through

V203B, V203A,

and

C210

to

the

grid

of

V204.

The

negative

square

wave

at

the

grid

of

V204

triggers

the

phantastron

rundown

action.

In

the

quiescent

state

the

grid

of V20SB is held above

the

grid

of V205A, so

that

the

B

section

conducts

while

the

A

section

is

cut

off.

When

the

plate

of

V204

starts

its

phantastron

rundown

action,

it

carries

the

grid

of

V205B

with

it.

When

the

grid

of

the

B section

of

V205

has

dropped

down

near

the

grid

voltage

of

the

A section,

current

transfers

from

the

B to

the

A section

and

a positive

step

is

generated

at

the

B-section

plate.

The

voltage

of

the

A-section

grid

is

determined

by

R230,

labeled

SWEEP

DELAY

on

the

front

panel,

which

can

be

adjusted

to

cause

current

transfer

at

any

point

on

the

sawtooth.

Internal

60-cycle

triggering

is

not

sufficiently

stable

to

use for

observing

a line of a television

composite

video

signal.

For

observing

a single line

of

a television

signal,

triggering

should

be

accomplished

by

means

of

the

sync

pulses

of

the

composite

video

signal.

SYNC

SEPARATOR

The

sync-separator

circuits

separate

the

sync

portion

of

the

composite

video signal for

the

purpose

of

triggering

the

sweep

delay. Diode-

connected

V201B establishes a bias level

at

the

grid

of V202B

through

R212

such

that

the

sync

pulses of

the

composite

video

signal

are

kept

well

within

the

amplify,ing region

of

V202 re-

gardless

of

the

signal

amplitude.

V202 is a pulse

amplifier

whose

in-phase

output

is applied

to

the

grid

of

the

sync-separator

tube

V203B.

The

grid

of V203B is

returned

to

+120

volts

through

R215

and

limited

by

grid

cmrent

to

a

voltage

near

cathode,

which

is

at

ground

potential.

The

positive

peaks

of

the

pulses

are

effectively

clamped

to

ground

potential.

The

video

portion

of

the

composite

sign;,! is

therefore

below

cut-

off

of

V203B because

the

sync

pulses

have

an

amplitude

,of several

volts

at.

this

point.

Between

pulses

the

plate

of

V.203B

rests

at

+120

volts.

During

the

period

that

a

sync

pulse

is

present

at

V203.B

grid,

the

plate

drops

several

volts.

The

vertical

sync

pulses

are

transmitted

through

R217, V203A

and

C210

to

the

grid

of

V204,

the

phantastron,

while

the

horizontal

pulses

are

not

transmitted

through

R217

to

the

cathode

of

V203A

because

of C208,

but

are

dif-

ferentiated

by

C209

and

R218,

and

applied

to

the

grid

of

V205B.

The

vertical

pulses

arriving

at

the

phantastron

grid.

are

formed

into

a

nega-

tive-going

waveform

of

several

volts

to

trigger

the

rundown

action.

TYPE

624AD

CIRCUIT

DESCRIPTION

-PAGE

2 @

PHANTASTRON

SAWTOOTH GENERATOR

In

the

quiescent

state

just

before

the

operation

of

the

phantastron,

the

control

grid

of

the

phan-

tastron

is held

at

approximately

ground

poten-

tial

by

grid

current

flowing

in R220

and

R221

which

connect

to

+120

volts,

and

the

suppressor

is

held

below

plate-current

cutoff

by

screen

cur-

rent

flowing in

voltage

divider, R223, R222,

R224,

which

is

connected

between

+225

and

-150

volts.

When

the

negative

pulse

through

V203A

arrives

at

the

grid

of

V204,

the

grid

is

driven

toward

screen-current

cutoff.

As

the

grid

approaches

screen-current

cutoff,

screen

current

is

rapidly

reduced

and

the

screen

rises,

carrying

the

suppressor

with

it

through

C211

to

a

voltage

high

enough

to

allow

plate

current

to

flow.

When

plate

current

begins

to

flow,

the

plate

begins

to

drop

from

its

zero-

plate-current

voltage

of

+120

volts

and

the

phantastron

rundown

action

commences.

The

grid

of V204 is

connected

to

a positive

voltage

source

through

R220

and

R221

which

total

several

megohms,

so

that

in

the

quiescent

state

before

the

phantastron

is

tripped,

current

flowing

in

these

resistors

prevents

the

grid

volt-

age

from

rising

more

than

a

fraction

of

a

volt

positive.

One

end

of

timing

capacitor

C210 is

connected

to

the

plate

of

V204

which

with

no

plate

current

flowing,

rests

at

approximately

+115

volts.

The

timing

capacitor

C210, is

there-

fore initially

charged

to

about

115 volts.

When

the

rundown

is

initiated

and

plate

cur-

rent

begins

to

flow,

the

plate

voltage

drops

momentarily,

a few volts,

carrying

the

grid

down

with

it

the

same

amount

through

C210,

which

is still

charged

to

115

volts. C210

begins

to

discharge

into

+120

volts

through

R220

and

R22L

The

discharge

current

through

R220

and

R221

determines

the

voltage

of

the

grid

of V204,

which

in

turn

determines

the

plate

voltage,

be-

cause

during

the

rundown

phase

of

operation

the

phantastron

tube

acts

as

a

class

A

linear

amplifier

in

which

the

plate

voltage

varies

in-

versely

but

linearily

with

grid

voltage.

A

given

grid

voltage

therefore

exactly

determines

a

cor-

responding

plate

voltage.

The

charge

voltage

remaining

on

C210

must

always

be

slightly

larger

than

the

plate

voltage

because

the

grid

end

must

be

slightly

below

ground

but

above

plate-current

cutoff,

to

re-

main

within

the

linear

region.

If,

for

example,

the

voltage

across

C210

were

momentarily

to

become

too

small,

the

grid

voltage

would

rise

and

the

plate

voltage

would

therefore

drop,

thus

restoring

the

grid

end

to

its

proper

potential

so

as

to

maintain

the

discharge

current

constant.

Since

the

voltage

drop

from

the

discharge

current

from

C210,

flowing

through

R220

and

R221,

determines

the

grid

voltage

of

the

phan-

tastron,

a

change

in

voltage

drop

across

these

resistors,

resulting

from

a

change

in

discharge

current

from

C210, will

therefore

cause

a

change

in

grid

voltage

in

the

correct

direction

to

op-

pose

the

change

in

voltage

drop.

For

example,

if C210

were

simply

to

discharge

through

a re-

sistor,

the

discharge

current

would

fall

off

ex-

ponentially

with

time.

The

falling

off

of

dis-

charge

current

would

result

in a

decreasing

drop

in R220

and

R221

and

cause

the

grid

of V204

to

rise. V204

plate

would

then

fall,

dropping

the

control-grid

end

of

C210

the

requisite

amount

to

increase

the

discharge

current

and

thus

tend

to

maintain

it

at

a

constant

value.

With

a con-

stant

discharge

current

flowing

from

C210

the

voltage

across

this

capacitor

will fall

off

linearly,

and

since

the

righthand

end

of

this

capacitor

remains

near

ground

voltage,

the

plate

of

V204

also falls linearly.

When

C210 is

nearly

discharged

and

the

plate

V204

nears

cathode

potential,

the

cathode

cur-

rent,

which

has

been

flowing

largely

through

the plate,

suddenly

transfers

to

the

screen,

the

screen

voltage

drops,

carrying

the

suppressor

with

it,

and

thereby

completely

cuts

off

plate

current

from

V204.

When

plate

current

is

cut

off

the

plate

im-

mediately

returns

toward

+120

volts

as

fast as

C210

can

charge,

carrying

the

grid

with

it

through

C210,

until

grid

current

through

R220

and

R221

prevents

it

from

going

farther

positive,

and

the

original

quiescent

state

is

resumed

with

the

phantastron

ready

to

accept

another

nega-

tive

triggering

voltage.

V205 is

the

comparator

tube

which

generates

a

trigger

pulse

when

the

sawtooth

reaches

a

prescribed

percentage

of

its

final value.

During

the

quiescent

state

of

phantastron

V204,

the

grid

of

comparator

tube

V20SB is held

at

approxi-

mately

115

volts

through

resistor

R218,

and

the

cathode

of

the

comparator

tube

rests

at

a

point

just

above

the

grid.

The

grid

of

the

second

half

of

the

comparator,

V20SA, is

set

at

a

bias

de-

te1·mined

by

the

setting

of

R230,

labeled

SWEEP

DELAY

on

the

front

panel,

at

any

point

be-

tween

ground

and

+120

volts.

When

the

phantastron

rundown

action

begins,

the

sawtooth

voltage

of

the

phantastron

plate

carries

the

grid

of V20SB

down.

V20SB

cathode

closely follows

the

grid

as

it

drops

until

it ap-

proaches

the

grid

voltage

of

the

A section,

at

which

time

cathode

current

transfers

from

the

B

section

to

the

A section.

The

differentiated

horizontal

sync

pulses

ar-

riving

at

the

B-section

grid

of

V205

through

C209

are

of

greater

amplitude

than

the

drop

in

sawtooth

voltage

resulting

from

the

phantastron

rundown

action

during

the

time

between

horizon-

tal

sync

pulses.

The

time

of

transfer

of

cathode

current

from

the

B

section

to

the

A

section

of

@

CIRCUIT

DESCRIPTION

-

PAGE

3

TYPE

524AD

the

comparator

tube

is

therefore

always

coinci-

dent

with

a

horizontal

sync

pulse,

and

a single

line

of

the

video

picture

can

thus

be displayed

without

jitter.

FIELD

SHIFT

The

rundown

time

of

the

phantastron

trig-

ger-delay

circuit is

made

approximately

half

again

as

long

as

the

time

between

vertical sync

pulses

so

that

the

maximum

frequency

of

opera-

tion

is

somewhat

less

than

the

60-cycle repeti-

tion

rate

of

the

pulses.

This

arrangement

assures

that

the

sweep

will be

triggered

only

by

alter-

nate

vertical sync pulses,

and

one

of

the

inter-

laced fields

can

therefore

be

observed

repeti-

tively

to

the

exclusion

of

the

other

interlaced

field.

When

the

composite

video signal is first

applied

to

the

trigger

circuit

the

delayed

trigger

will

synchronize

with

one

of

the

fields

and

stay

synchronized

with

this

same

field unless

the

rundown

time

is

momentarily

changed.

The

FIELD

SHIFT

circuit

performs

this

change

by

extending

the

time

of

one

rundown

by

ap-

proximately

the

interval

between

vertical sync

pulses. A

momentary

pushbutton

switch,

norm-

ally closed, is labeled

FIELD

SHIFT

on

the

front

panel. In

the

closed position

of

this

switch,

the

junction

between

R225

and

C212 is

grounded

and

C212 is

therefore

charged

to

about

110 volts.

When

the

switch

is opened,

the

negative

end

of

C212 is

connected

to

+225

volts

through

R225,

which

reverses

the

direction

of

charge

and

leaves

it

charged

to

about

100

volts

in

the

opposite

direction.

Then,

when

the

button

is released,

the

junction

of

R225

and

C212 is

grounded

again

and

the

current

through

R220 is

reversed

so

that

the

grid

of

the

phantastron

is

momentarily

depressed

to

the

extent

that

the

plate

voltage

actually

rises for a

short

period

before

continu-

ing its

rundown.

As

the

reverse

voltage

of

C212

decreases,

the

phantastron

grid

rises

and

when

equilibrium is

reestablished

with

C212 again

charged

to

110

volts

as before,

the

rundown

ac-

tion

of

the

phantastron

resumes.

The

time

of

delay caused

by

the

temporary

runup

is approxi-

mately

equal

to

the

time

between

vertical sync

pulses,

so

that

two

pulses

are

skipped

instead

of

one,

and

the

rundown

is

thereafter

synchronized

with

the

alternate

interlaced fields.

SWEEP

CIRCUIT

Trigger

output

from

the

trigger

delay circuits

or

from

the

undelayed circuits is applied

to

trig-

ger

amplifier V207

by

means

of

the

C section

of

the

trigger

SELECTOR

switch

SW201.

The

bias

of

V207 is

adjustable

by

means

of

the

front-

panel control, R242, labeled

trigger

AMPLI-

TUDE, a

part

of

a

voltage

divider

with

R243,

connected

between

-150

volts

and

ground.

Neg-

ative

plate

output

of

V207 is coupled

through

disconnect diode V208

and

multivibrator

coup!-

@

ing

capacitor

C221

through

C225

to

the

grid

of

positive-going

multivibrator

V210.

In

the

qui-

escent

state,

V210 is

conducting

and

its pljlte

is down.

When

the

negative pulse

from

V208

arrives

at

V210 grid,

plate

current

is

cut

off

and

V210

plate

rises

toward

+225

volts

carrying

the

grid

of

negative-going

mu)tivibrator

V209 up.

V209 plate

then

drops,

carrying

the

grid

of

V210

down

still

farther.

Diode

V208 disconnects

the

trigger

circuit

from

the

plate

of V209 as soon

as

this

plate

drops

below

the

plate

of

trigger

amplifier V207.

The

grid

of

V210 is

returned

to

+225

volts

through

R251

and

through

µSEC/CM MULTIPLIER

resistor

R290

and

R291,

and

starts

immediately

to

go

positive

but

is

controlled in its rise

by

the

charging

rate

of

the

sweep TIME capacitor. (C225 in

the

dia-

gram

as

drawn.)

When

this

capacitor

has

charged

so

that

the

grid

of V210

just

gets

into

the

region

of

plate-current

conduction, V210

plate

drops

and

the

resulting

negative

step

is

coupled

to

the

grid

of V209

through

C226 which

causes the plate

to

rise, and,

through

C225,

further

raises V210 grid,

and

the

original stable

quiescent

state

is

rapidly

resumed

with

V210

conducting.

The

length

of

the

period

of

cutoff

depends

on

the

size of the

capacitor

selected

by

SW202A

and

B,

and

the

size

of

R290

and

R291.

During

the

period of

conduction

of

V209, the

negative-going

multivibrator,

the

grid

voltage

of

V213 is held below

plate-current

cutoff. V213

is

the

sweep-clamp

tube

whose

grid

is

normally

held

at

about

ground

potential

by

voltage

divid-

er

R264, R263, R240

and

R241

connected

be-

tween

-150

volts

and

+225

volts.

With

this

grid

near

ground,

the

tube

conducts

heavily

so

that

the

plate

is held

near

ground.

When

the

negative

gate

from V209 depresses

the

grid

of

V213 below

plate-current

cutoff,

the

plate

is

free

to

rise

toward

+450

volts

at

a

rate

determined

by

the

charging

rate

of

the

timing

capacitor,

C231

to

C235,

charging

toward

+450

volts

through

R292

and

R293

and

R294.

The

nega-

tive

gate

to

the

grid

of

V213

is

chosen

to

be

appreciably

longer

than

the

time

required

for

the

beam

to

sweep across

the

cathode-ray

tube

screen,

but

short

compared

to

the

time

constant

of

the

timing

capacitor

and

resistor,

so

that

the

final

voltage

to

which

the

timing

capacitor

charges

is

only

about

ten

per

cent

of

the

+450

volts,

and

the

portion

of

the

charge

curve

during

which

the

beam

is

on

the

screen

is

only

five

per

cent

of

this

voltage.

The

first six

to

ten

per

cent

of

the

charge

curve

of

a capacitor

is

very

nearly

linear.

At

the

termination

of

the

negative

gate

at

the

grid

of

clamp

tube

V213,

the

grid

returns

posi-

tive,

clamp-tube

plate

current

again flows

and

brings

the

plate

down

near

ground

potential,

at

the

same

time

charging

the

timing

capacitor,

and

the

sweep circuit is

restored

to

its

original

quiescent

state

ready

for

another

trigger

voltage

to

arrive

at

the

multivibrator.

TYPE

524AD

CIRCUIT

DESCRIPTION

-

PAGE

4 @

The

sweep

STABILITY

control

adjusts

the

bias

of

the

normally-cutoff

negative-going

multi-

vibrator,

V209.

If

the

bias

is

set

near

enough

to

ground

potential,

plate

current

will

commence

to

flow,

tripping

the

multivibrator

and

initiating

a sweep.

When

the

multivibrator

resets

at

the

termination

of

one

sweep

it will

immediately

retrip

and

the

circuit

will free

run.

A bias level

just

below

the

free-run

level is

normally

used

when

it is

desired

to

trigger

the

sweep

from

the

trigger-amplifier

signal.

The

sawtooth

voltage

from

the

clamp-tube

sweep

generator

is

capacitively

coupled

to

the

grid

of

cathode

follower V215B,

whose

cathode

is

returned

to

-150

volts. V214 is a

clamp

which

sets

the

grid

of

V215B

at

ground

potential

be-

fore

each

sweep.

Output

from

the

cathode

of

cathode

follower

V215B

supplies

sawtooth

volt-

age

to

the

sweep

output

and

magnifier

section,

and

to

V215A, a

second

cathode

follower

which

provides

a

sawtooth

voltage

to

a

front-panel

connector

labeled

SWEEP

OUTPUT.

The

unblanking

waveform

is

gated

by

the

multivibrator.

The

grid

of

V212A is

connected

to

the

grid

of

positive-going

multivibrator

V210

so

that

it is

driven

negative

below

plate-cur-

rent

cutoff

during

the

same

period

that

V210 is

cut

off.

The

rise

time

of

the

plate

of V212A is

speeded

by

L202.

Cathode

follower V212B re-

moves

the

loading

effects

on

V212A of

the

re-

mainder

of

the

unblanking

circuit.

External

gate

signals

of

both

polarities

are

available

at

the

front

panel

through

connectors

labeled

+GATE

and

-GATE.

Both

are

de-

rived

from

V211B

whose

grid

is

coupled

to

the

plate

of

positive-going

multivibrator

V210. Be-

tween

sweeps

the

grid

of

V211B is

held

below

cutoff

by

means

of

voltage

divider

R254, R255

connected

between

the

plate

of

V210

and

-150

volts. C229

speeds

the

rise

time

of

the

grid

of

V211B.

The

+GATE

pulse

output

has

a

peak

value

in

the

vicinity

of

30

volts

and

a

rise

time

of

about

0.2

microseconds.

The

output

impedance

is

approximately

300

ohms

coupled

from

the

cathode.

The

negative

pulse

from

the

plate

of

V211B is

capacitively

coupled

to

the

-GATE

at

an

impedance

level

of

about

10,000

ohms.

The

wave

shape

of

this

output

is

there-

fore

more

susceptible

to

external

circuit

effects.

V211A is a

cathode-follower

voltage

regulator

whose

grid

voltage

is

set

by

means

of

R268, a

voltage

divider

labeled

ASTIGMATISM

on

the

front

panel,

connected

between

+450

volts

and

-150

volts,

used

to

set

the

voltage

of

9,

the

second

anode

of

the

cathode-ray

tube,

for

astig-

matism

control.

MAGNIFIER AND

SWEEP

OUTPUT

AMPLIFIER

V218A is

an

amplifier.

Its

output

is applied

to

the

grid

of V221

through

cathode

follower

V219B.

Feedback

between

the

grid

circuit

of

V221

and

the

grid

of

V218A is

provided

through

V217

by

way

of

frequency-compensated

resistor

networks,

R310 A

to

C.

The

amount

of feed-

back

is

determined

by

the

voltage

division

of

the

feedback-loop

voltage

divider, R301, R310.

SW301,

labeled

MAGNIFIER,

selects

the

series

arm

of

the

voltage

divider, R310,

so

that

volt-

age

division in

the

ratio

1,

3,

or

10

is

accom-

plished

to

produce

net

gain

at

the

grid

of V221

in

these

ratios.

With

the

switch

in

either

the

3X

or

lOX

magnified

positions,

the

grid

of

V218A

is

driven

to

grid

current

in

the

positive direction.

V217

eliminates

the

effects

of

this

grid

current

from

the

feedback

system.

V217B is a

cathode

follower

whose

cathode

is

connected

to

the

cathode

of

diode-connected

V217A.

The

anode

of

this

diode is

connected

to

the

grid

of

V218A

and

to

+225

volts

through

R305.

By

this

ar-

rangement,

the

plate

of

the

diode closely follows

the

cathode,

which

follows

the

grid

of

V217B,

until

grid

current

starts

to

flow in V218A.

When

this

occurs,

grid

current

through

R305

holds

the

diode

plate

at

this

voltage

level while

the

cathode

is free

to

rise past.

Horizontal

positioning

is

provided

by

adjust-

able R303, a

three-turn

helical

potentiometer,

which

determines

the

negative

voltage

return

point

of

the

grid

circuit

of

V217

and

V221. C304

on

the

lower

end

of

R303

bypasses

voltages

in-

duced

in

the

long

lead

from

the

front-panel

con-

trol

to

the

sweep

chassis.

V218B is a

cathode-follower

voltage

regulator

supplying

the

screen

of

V218A.

Push-pull

output

is

obtained

by

means

of

common-cathode

coupling

between

V221

and

V220.

Plate

output

is applied

to

the

cathode-

ray-tube

deflection

plates

through

cathode

fol-

lowers

V222A

and

V222B,

and

through

two

NEZ

neon

tubes

in series.

The

neon

tubes

provide

a de

drop

of

about

150

volts

below

the

de

level

of

the

cathode-follower

cathodes

to

place

the

quiescent-state

deflection-plate

potential

near

+160

v. R352

and

R357

limit

current

which

might

otherwise

be excessive in

the

case

of

ac-

cidental

grounding

of

the

deflection plates. C307

and

C308

provide

high-requency

bypassing

for

these

resistors.

Screwdriver

adjustable

R325,

labeled

SWEEP

AMP

CURRENT

ADJ

on

the

chassis

adjusts

the

size of

the

common-cathode

resistor

to

set

the

quiescent-state

current

level.

Screwdriver

adjustable

R328,

labeled

MAG.

POS.

on

the

front

panel,

adjusts

the

grid

of

V220

about

the

level

of

the

grid

of

V221

to

pro-

vide

horizontal

positioning

of

the

magnified

sweep

so

that

the

magnified

sweep

will

center

at

the

same

point

as

the

unmagnified

sweep.

A feedback

loop

between

the

plate

and

grid

of

V220, R335, R330,

stabilizes

the

gain

of

the

@

CIRCUIT

DESCRIPTION

-

PAGE

5

TYPE

524AlJ

amplifier. R330 is a

screwdriver

adjustable

re-

sistor

labeled

L.F.

SWEEP

TIME

ADJ.

on

the

chassis,

by

means

of

which

the

amount

of

feed-

back

can

be

adjusted

to

accommodate

the

hori-

zontal

sentitivity

of

the

cathode-ray

tube

to

the

front-panel

sweep-time

calibrations. A

screw-

driver

adjustable

capacitor, C305A, labeled H.F.

SWEEP

TIME

on

the

chassis,

and

paralleled

by

C305B,

provides

compensation

for

the

grid-to-

plate

capacitance

of

V220.

R353

and

R356,

which

present

high

imped-

ance

to

the

sweep-signal

voltage

while supply-

ing

operating

current

for

the

NE2

neon

tubes,

form

the

positive

end

of

a

voltage

divider

which

provides

adjustable

focusing

potential

for

the

cathode-ray

tube.

The

voltage

at

this

junction

is

about

-400

volts.

TIME-MARKER

GENERATOR

The

time

marks

are

generated

by

means

of

V602

in

a

Colpitts

oscillator

circuit

with

the

screen

used for

the

anode

at

+120

volts,

and

the

plate

used

for

electron-coupled

output.

Switched

inductors

and

capacitors

provide

the

five timing

intervals. V625 is a de-coupled

multivibrator

with

the

triode

section

conducting

in

the

quies-

cent

state.

The

positive-gate

waveform

causes

the

pentode

grid

to

rise

at

a

rate

determined

by

the

time

constants

in

the

grid

circuit until

the

pentode

section

begins

to

conduct

and

the

triode

section

is

cut

off.

The

PHASE

control

determines

the

voltage

level

at

which

this

occurs

and

thus

the

time

at

which

the

markers

begin.

D630 is

cut

off in

the

quiescent

state

and

does

not

begin

to

conduct

until

the

plate

of

V625A

has

begun

its fall.

This

helps

to

improve

the

gating

waveform.

During

the

quiescent period, V601A

remains

conducting

and

the

resulting

low

cathode

im-

pedance

loads

the

grid

circuit

of

V602,

prevent-

ing

oscillation.

The

negative

gate

drives V601A

well below

cutoff

and

cathode

current

ceases:

Magnetic

energy

in

the

oscillator

coil

changes

to

oscillating

energy,

maintained

by

V602

and

limited in

amplitude

by

grid

current

in

this

tube.

Only

short-duration

current

pulses

reach

the

plate.

These

pulses

are

peaked

in L605

and

ap-

plied

to

V601B

as

negative

pips

through

C609.

The

grid

of

V601B is held positive

between

pulses limited

by

grid

current

through

R607, so

that

positive pulses

appear

at

V601B plate.

These

in

turn

are

shaped

by

L606

and

applied

to

the

grid

of

V603

where

they

are

again

amplified

and

shaped.

The

gain

of

V603 is

adjustable

by

means

of

variable

resistor

R610, labeled AM-

PLITUDE

on

the

front

panel.

Marker

pips

are

applied

to

the

cathode-ray

tube

cathode

to

cause

brightening

of

the

trace.

External

marker

sig-

nals

can

be

applied

to

the

cathode-ray

tube

through

a

front

panel

connector

labeled

EXT

MARKER

with

the

time-marker

control

set

to

EXT.

The

grounding

link

must

be

opened

when

external

connections

are

made

to

the

cathode,

but

must

be

replaced

and

left

connected

at

other

times.

CALIBRATOR

The

CAL. VOLTAGE RANGE

switch

ap-

plies de

power

to

the

multivibrator

and

selects

the

desired

tap

on

the

calibrator

voltage

divider.

The

plates

of

multivibrator

sections V41A

and

V41B

are

grounded

through

their

plate-load

re-

sistors

and

the

cathodes

are

connected

to

-150

volts.

The

grids

are

returned

to

ground

(posi-

tive

with

respect

to

cathode)

through

R125

and

variable

potentiometer

R127, labeled CAL.

DUTY

CYCLE

on

the

front

panel.

The

time

constant

of

the

grid-to-plate

coupling-capacitor

charging

circuits

can

be

varied

by

adjusting

the

position

of

the

potentiometer

arm

to

add

resis-

tance

to

one

grid

while

subtracting

resistance

from

the

other.

The

length

of

the

time

constant

determines

the

time

the

grid

is

kept

below

grid-

current

conduction

during

its

cutoff

period.

V42A is an amplifier

whose

grid

is held below

plate-current

cutoff

during

the

same

period

as

V41B.

During

this

period

V42A

plate

rests

at

the

voltage

determined

by

voltage

divider

Rl28,

Rl29,

R131

and

adjustable

R130

connected

be-

tween

ground

and

+225

volts.

During

the

conduction

period

of

V41 B

the

plate of V42A

drops

below

cutoff

of V42B.

The

cathode

of

V42B

therefore

operates

between

ground

and

approximately

the

divider voltage.

The

cathode

resistor

in

cathode

follower V42B

is

tapped

to

provide

various

voltage

ranges,

se-

lectable

by

means

of

the

D

section

of

the

CAL.

VOLTAGE RANGE

switch,

SW40.

An

ad-

justable

potentiometer,

R136, labeled CAL.

VOLTAGE

on

the

front

panel,

provides

a cali-

brated,

continuously-adjustable

squarewave

out-

put

to

the

CAL.

OUTPUT

front-panel

connec-

tor.

VERTICAL

AMPLIFIER

The

INPUT

SELECTOR switch, SW2, con-

nects

either

INPUT

1,

INPUT

2

or

the

cali-

brator

to

the

vertical

amplifier,

and

inserts

or

removes

a

capacitor

from

the

input

circuit

to

provide

either

ac

or

de coupling.

The

VOLTS/CM

switch,

SW3,

connects

the

signal selected

by

the

INPUT

SELECTOR

switch

to

the

vertical-amplifier

system

through

a

preamplifier

for

the

two

most

sensitive posi-

tions,

and

through

resistor-capacitor

attenuators

for

the

positions

giving

less sensitivity.

In

the

first, full-clockwise position, a

sensitivity

of

.015 to .05

volts

per

centimeter

is

obtained

with

a

preamplifier

which

has

a

gain

of

ten.

In

the

second position, a

sensitivity

of

.OS

to

.15

volts

per

centimeter

is

obtained

by

i11serting a 10/3

resistance-capacitance

attenuator

in

the

input

TYPE

524AD

CIRCUIT

DESCRIPTION-

PAGE

6 @ii

circuit

of

the

preamplifier.

The

third

position

of

the

switch

connects

the

input

directly

to

the

vertical

amplifier,

and

subsequent

positions

in-

s~rt

attenuators

with

increasingly

large

attenua-

t10n.

An

ac-dc

switch

permits

a

capacitor

to

be

inserted

in

the

input

circuit in

the

event

a de

component

is

undesirable.

PREAMPLIFIER

The

preamplifier

consists

of

two

pentode

am-

plifiers

with

a

cathode

follower

between

stages

and

a

second

cathode-follower

output

stage

feeding

the

B

section

of

the

VOL

TS/CM

switch

SW3.

The

use

of

the

cathode

follower

betwee~

stages

and

into

the

switch

circuit

minimizes

the

effect

on

the

preamplifier

of

the

change

of

capacitance

with

switch

position.

VERTICAL

AMPLIFIER

ATTENUATOR

The

vertical-amplifier

input

stage

is

also

a

cathode

follower

which

supplies

the

variable

attenuator

stage

through

series-peaking

coil L4.

The

variable-attenuator

stage

is a

cathode-

coupled

long-tail

pair

of

pentodes,

with

a sep-

3:rate

cathode

resistor

for each,

and

with

coup-

lmg

between

cathodes

provided

by

means

of

a

variable resistor, R35, labeled

VARIABLE

AT-

TEN.

R34 in

the

plate

circuit

of

the

input

tube

V12,

of

this

pair

provides

the

internal

trigge;

source.

VllB,

a

cathode-follower

voltage

regu-

lator

supplying

grid

bias

voltage

for

the

ground-

ed

grid

is

for

the

purpose

of

adjusting

the

no-

signal

cathode

voltage

of

V13

to

the

no-signal

voltage

of

the

cathode

of

Vl2,

so

that

adjust-

ment

of

the

VARIABLE

ATTEN.

control

will

not

affect

the

de

level

and

position

of

the

trace.

A

screwdriver

front-panel

control

labeled

VARI-

ABLE

ATTEN.

BAL.

permits

this

adjustment

to

be

made.

Plate

and

screen

voltage

supply

is

provided

by

means

of

Vl4,

a

cathode-follower

voltage

regulator.

Plate

voltage

to

V13 is fed

through

the

delay-network

termination

resistor,

and

the

delay

network.

DELAY

NETWORK

The

delay

network

provides

¼

microseconds

of

delay

to

the

vertical-deflection

signal

which

is

time

enough

to

permit

the

sweep-sawtooth

voltage

to

be

well

under

way

before

the

vertical-

deflection signal is displayed

on

the

cathode-ray

tube

when

the

sweep

is

triggered

by

the

signal

being

displayed.

The

delay

network

consists

of

24

M-derived

low-pass

sections.

The

M

of

these

sections

is

1.27

which

produces

the

minimum

phase

dis-

persion

with

frequency

for

the

best

transmis-

sion

of

pulses

without

phase

distortion.

Regu-

lated

+10s

volts

from

cathode-follower

voltage

regulator

V14 is supplied

to

the

plate

of

V13

through

the

delay

network

and

its

terminating

resistor,

RS0I.

The

shunt

capacitors

of

the

net-

work

sections

are

adjustable

to

compensate

for

slight

variations

in

the

manufactured

compo-

nents.

Cutoff

frequency

of

the

sections

is

about

3.5

times

the

upper

frequency

limit of

the

bal-

ance

of

the

amplifier

to

minimize

any

distortion

of

the

pulse

response

caused

by

the

network.

PHASE

INVERTER,

VERTICAL

POSITIONING

Output

from

the

delay

network

is applied

to

V21,

the

input

stage

of a

cathode-coupled

phase

inverter.

The

VERTICAL

POSITION

adjust-

ment

is

provided

by

means

of

RS9

which

adjusts

the

grid

bias

on

V22.

Positioning

results

from

the

difference in de level

between

the

two

halves

of

the

phase

inverter. Since

the

amplifier is

de

coupled, a de

change

at

this

level

appears

also

at

the

deflection plates.

Push-pull

output

from

the

phase

inverter

drives

the

push-pull

distributed

amplifier

through

cathode

followers,

V23B

and

V24B.

CURRENT

ADJUST

CIRCUIT

Bias level

of

the

cathode

followers is

set

to

control

the

de

operating

level of

the

distributed

amplifier,

by

V23A

and

V24A

which, in

turn,

receive bias

from

screwdriver-adjustable

voltage

divider R66, labeled

CURRENT

ADJ.

The

ac

impedance

of V23A

and

V24A

is

kept

very

high

by

use

of

large

unbypassed

cathode-resistors

R68

and

R74, while

the

plate

current

can

be

varied easily

through

a sufficient

range

to

effect

the

required

bias range.

DISTRIBUTED

OUTPUT

AMPLIFIER

The

push-pull

distributed

amplifier

has

three

tubes

in each half.

L9

and

Lil

are

the

grid

and

plate

delay

lines.

The

signal

from

the

cathode

follower V23B is fed

down

the

grid

line

termin-

ated

in

RSS.

As

the

signal

passes

each grid,

it

is

amplified

and

appears

at

the

plate

of

each

tube.

At

each

plate

the

amplified grid-line signal is ap-

plied

to

the

plate

line

whereupon

it

travels

down

the

plate

line

at

the

same

speed

as

the

signal

in

the

grid

line,

and

is

therefore

reinforced

each

time

it

passes

a plate.

For

example, a positive

pulse

traveling

down

grid

line

L9

from

the

cathode

of

V23B

passes

the

grid

of

V31

and

passes

on

toward

V33.

The

negative

pulse

volt-

age

at

the

grid

of

V31 is amplified

and

appears

at

the

plate

of

V31

as

a

negative

pulse.

The

negative pulse

on

the

plate

line

Lll

starts

to

travel

to

right

and

to

left

along

the

line,

and

the

portion

going

to

the

right

approaches

the

plate

tap

of V33.

The

lines

are

constructed

so

that

the

time

of

propagation

of

the

pulse

along

the

grid

line

between

V31

and

V33 is

the

same

as

the

time of

propagation

of

the

amplified

pulse

along

the

plate

line

between

V31

and

V33

so

that

at

the

moment

the

grid

pulse, amplified

in

@

CIRCUIT

DESCRIPTION-

PAGE

7

TYPE

524AD

Tektronix 524AD series User manual

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