HP 333A Manuale di servizio

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3

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OPERATING

AND

SERVICE

MANUAL

MODEL

333A/334A

DISTORTION

ANALYZER

Serial

Numbers:

333A:

1137А03146

and

greater

334A:

1140А05641

and

greater

Appendix

С,

Manual

Backdating

Changes,

adapts

this

manual

to

lower

serial

numbers.

WARNING

To

help

minimize

the

possibility

of

electrical

fire

or

shock

hazards,

do

not

expose

this

instrument

to

rain

or

excess

moisture.

Manual

Part

No.

00333-90008

Microfiche

Part

No.

00333-90058

Copyright

Hewlett-Packard

Company

19

66

P.O.

Box

301,

Loveland,

Colorado,

80537

U.S.A.

Printed:

October

1975

HEWLETT

ш

PACKARD

CERTIFICATION

Hewlett-Packard

Company

certifies

that

this

instrument

met

its

published

specifications

at

the

time

of

shipment

from

the

factory.

Hewlett-Packard

Company

further

certifies

that

its

calibration

measurements

are

traceable

to

the

United

States

National

Bureau

of

Standards,

to

the

extent

allowed

by

the

Bureau’s

calibration

facility,

and

to

the

calibration

facilities

of

other

International

Standards

Organization

members.

WARRANTY

AND

ASSISTANCE

This

Hewlett-Packard

product

is

warranted

against

defects

in

materials

and

workmanship

for

a

period

of

one

year

from

the

date

of

shipment,

except

that

in

the

case

of

certain

components,

if

any,

listed

in

Section

I

of

this

operating

manual,

the

warranty

shall

be

for

the

specified

period.

Hewlett-Packard

will,

at

its

option,

repair

or

replace

products

which

prove

to

be

defective

during

the

warranty

period

provided

they

are

returned

to

Hewlett-Packard,

and

provided

the

proper

preventive

maintenance

procedures

as

listed

in

this

manual

are

followed.

Repairs

necessitated

by

misuse

of

the

product

are

not

covered

by

this

warranty.

NO

OTHER

WARRANTIES

ARE

EXPRESSED

OR

IMPLIED,

INCLUDING

BUT

NOT

LIMITED

TO

THE

IMPLIED

WARRANTIES

OF

MERCHANTABILITY

AND

FITNESS

FOR

A

PARTICULAR

PURPOSE.

HEWLETT-PACKARD

IS

NOT

LIABLE

FOR

CONSEQUENTIAL

DAMAGES.

If

this

product

is

sold

as

part

of

a

Hewlett-Packard

integrated

instrument

system,

the

above

warranty

shall

not

be

applicable,

and

this

product

shall

be

covered

only

by

the

system

warranty.

Service

contracts

or

customer

assistance

agreements

are

available

for

Hewlett-Packard

products.

For

any

assistance,

contact

your

nearest

Hewlett-Packard

Sales

and

Service

Office.

Addresses

are

provided

at

the

back

of

this

manual.

Model

333A/334A

Section

I

SECTION

|

GENERAL

INFORMATION

1-1.

DESCRIPTION.

1-2.

The

Hewlett-Packard

Models

333A

and

334A

Distortion

Analyzers

are

solid

state

instruments

for

measuring

distortion

on

ac

voltages.

The

Models

333A

and

334A

include

two

control

loops

that

auto-

matically

tune

both

legs

of

a

bridge

circuit

which

re-

jects

the

fundamental

when

the

rejection

circuit

is

initially

set

within

the

range

of

the

loops.

The

334A

has

a

high

impedance

detector

which

operates

from

550

kHz

to

greater

than

65

MHz

and

provides

the

ca-

pability

of

monitoring

the

distortion

of

the

amplitude

modulation

on

an

rf

carrier.

1-3.

Distortion

levels

of

0.

1%

to

100%

full

scale

are

measured

in

seven

ranges

for

any

fundamental

frequen-

cy

of

5

Hz

to

600

KHz.

Harmonics

are

indicated

upto

3

MHz.

The

high

sensitivity

of

these

instruments

re-

quires

only

0.

3V

rms

for

the

100%

set

level

reference.

The

distortion

characteristics

can

be

monitored

atthe

OUTPUT

connectors

with

an

oscilloscope,

a

true

rms

voltmeter,

ог

a

wave

analyzer.

The

instruments

are

capable

of

an

isolation

voltage

of

400

volts

above

chassis

ground.

1-4.

The

voltmeter

can

be

used

separately

for

general

purpose

voltage

and

gain

measurements.

It

has

a

frequency

range

of

b

Hz

to

3

MHz

(20

Hz

to

500

kHz

for

300

uV

range)

and

а

voltage

range

of

300uV

to

300

V

rms

full

scale,

1-5.

The

AM

detector

included

in

the

Model

334A

is

a

broadband

дс

restoring

peak

detector

consisting

of

@

semiconductor

diode

and

filter

circuit.

AM

distor-

.

tion

levels

as

low

as

0.

3%

can

be

measured

on

a

3

V

to8

V

rms

carrier

modulated

30%

in

the

standard

broadcast

band.

Distortion

less

than

1%

can

be

measured

at

the

same

level

of

the

carrier

up

to

65

Mc.

Table

1-1.

MODEL

333A

DISTORTION

MEASUREMENT

RANGE

Any

fundamental

frequency,

5

Hz

to

600

kHz.

Distortion

levels

of

0.

1964-1009

are

measured

full

scale

in

7

ranges.

DISTORTION

MEASUREMENT

ACCURACY

Harmonic

measurement

accuracy

(full

scale)

Fundamental

Input

Less

Than

30

V

100%-0.

3%

0.1%

1-6.

ACCESSORY

FEATURES.

1-7.

The

accessory

available

with

the

333A

and334A

Distortion

Analyzers

is

a

voltage

divider

probe,

-hp-

Model

Ко.

10001A.

The

features

of

the

probe

are:

a.

10

megohms

shunted

by

10

pF,

giving

10:1

attenuation.

b,

DC

to

30

MHz

bandwidth.

2%

division

accuracy.

d.

600

V

peak

input.

e.

5

ns

rise-time.

1-8.

OPTION.

1-9,

Option

01іѕа

standard

-hp-

Model

333A

or

334A

with

a

special

meter

and

meter

amplifier,

compen-

sated

to

permit

response

to

VU

(volume

units)

characteristics.

1-10

INSTRUMENT

IDENTICATION.

1-11.

Hewlett-Packard

uses

a

two-section

serial

number.

The

first

section

(prefix)

identifies

a

series

of

instruments.

The

last

section

(suffix)

identifies

a

particular

instrument

within

the

series.

На

letter

is

included

with

the

serial

number,

it

identifies

the

coun-

try

in

which

the

instrument

was

manufactured.

Н

the

Serial

prefix

of

your

instrument

differs

from

the

one

on

the

title

page

of

this

manual,

a

change

sheet

will

be

supplied

to

make

this

manual

compatable

with

new

-

er

instruments

or

the

backdating

information

in

Арреп-

dix

C

will

adapt

this

manual

to

earlier

instruments.

All

correspondence

with

Hewlett-Packard

should

in-

clude

the

complete

serial

number.

Specifications

Fundamental

Input

Greater

Than

30

V

100%-0.

3%

10

На

300

ЕН?

30

Hz

300

ЕН?

10

Hz

3

MHz

10

Hz

1.2

MHz

0.1%

Elimination

Characteristics:

Fundamental

Rejection

>

80

dB

Second

Harmonic

Accuracy

for

a

fundamental

of:

5

Hz

to

20

Hz:

better

than

+1

dB

20

Hz

to

20

kHz:

better

than

«0.

6

dB

20

kHz

to

100

kHz:

better

than

-1

dB

100

kHz

to

300

kHz:

better

than

-2

dB

300

kHz

to

600

kHz:

better

than

-3

dB

1-1

Section

I

Model

333A/334A

Table

1-1.

Specifications

(Cont'd)

Distortion

Introduced

by

Instrument:

>

-70

АВ

from

5

Hz

to

200

kHz

>

-64

dB

from

200

kHz

to

600

kHz

Meter

indication

is

proportional

to

the

aver-

age

value

of

a

waveform.

FREQUENCY

CALIBRATION

ACCURACY

Better

than

+5%

from

5

Hz

to

300

kHz

Better

than:

1096

from

300

kHz

to

600

kHz

INPUT

IMPEDANCE

Distortion

Mode:

1

МО

+5%

shunted

by

«70

pF.

Voltmeter

Mode:

1

МО

+5%

shunted

by

«30

pF

(333A

only),

1

MQ

+5%

shunted

by

«35

pF

(334A

only),

1

to

300

V

ranges;

1

МО

+5%

shunted

by

«70

pF,

300

u

V

to

0.3

V

ranges.

INPUT

LEVEL

FOR

DISTORTION

MEASUREMENTS

0.3

V

rms

for

100%

set

level

(up

to

300

V

may

be

attenuated

to

set

level

reference).

The

minimum

measurable

distortion

for

floating

operation

on

the

X1

frequency

range

is

50dB

below

the

fundamental.

DC

ISOLATION

Signal

ground

may

be

+400

Vdc

from

external

chassis,

VOLTMETER

RANGE

300

рУ

to

300

V

rms

full

scale

(13

ranges),

10

dB

per

range.

VOLTMETER

FREQUENCY

RANGE

5

Hz

to

3

MHz

(300

uV

range:

20

Hz-500

kHz).

VOLTMETER

ACCURACY:

20

Hz-500

kHz

5

Hz-3

MHz

5

Hz-500

kHz

30

Hz-300

kHz

lmV-30V

1

10

Hz-i

MHz

100

V-300

V

|

10

Hz-300

kHz

300

ру

MODEL

334A

Same

as

Model

333A

except

as

indicated

below:

AM

DETECTOR

High

impedance

dc

restoring

peak

detector

with

semi-conductor

diode

operates

from

550kHz

to

greater

than

65

MHz.

Broadband

input.

Maximum

input;

40

V

p-p

ac

or

40

V

peak

transient.

.

CARRIER

FREQUENCY

550kHzto

1.6

MHz:

Distortion

introduced

by

detector

is

«

0.

3%

for

3

to

8

volt

carriers

modulated

30%.

i-2

NOISE

MEASUREMENTS

Voltmeter

residual

noise

on

the

300

pV

range:

«

25

u

V

rms

terminated

in

shielded

6000;

«30

u

V

rms

terminated

in

shielded

100

КО.

OUTPUT

For

input

frequencies

from

20

Hz

to

600

kHz,

0.1

V

rms

+

0.01

V

open

circuit

for

full

scale

meter

deflection;

0,05

V

rms

+

0.005

V

into

2

КО

for

full

scale

meter

deflection.

AUTOMATIC

NULLING

MODE

Set

Level:

At

least

0,2

V

rms.

Frequency

Ranges:

X1,

manual

null

tuned

to

less

than

3%

of

set

level;

total

frequency

hold-in

+0.

5%

about

true

manual

null.

X10

through

ХОК,

manual

null

tuned

to

less

than

1090

of

set

level;totalfrequency

hold-in

+1%

about

true

manual

null,

AUTOMATIC

NULL

ACCURACY

5

Hz

to

100

Hz:

Meter

reading

within

0

to

+3

dB

of

manual

null.

100

Hz

to

600

kHz:

Meter

reading

within

0

to

+1.5

dB

of

manual

null.

HIGH-PASS

FILTER

3

dB

point

at

400

Hz

with

18

dB

per

octave

roli

off.

60

Hz

rejection

>

40

dB.

Normally

used

only

with

fundamental

frequencies

greater

than

1

kHz.

POWER

SUPPLY

100

v/120

V/220

V/240

V

+

5%

=

10%,

48

-

66

Hz,

approximately

4

watts.

1.6

MHz

to

65

MHz:

Distortion

introduced

by

detector

is

<

1%

for

3

to

8

volts

rms

carriers

modulated

30%.

NOTE

Distortion

measurement

at

carrier

levels

as

low

as

i

volt

may

be

made

with

reduced

accuracy.

OPTION:

01

Indicating

meter

has

VU

characteristics

con-

forming

to

FCC

Requirements

for

AM,

FM,

and

TV

broadcasting.

Model

333А

/334А

Section

П

SECTION

И

INSTALLATION

2-1.

INTRODUCTION.

2-2.

This

section

contains

information

and

instruc-

tions

necessary

forthe

installation

and

shipping

of

the

Models

333A/334A

Distortion

Analyzers.

Included

are

initial

inspection

procedures,

power

and

grounding

requirements,

installation

information,

and

instruc-

tions

for

repackaging

for

shipment.

2-3.

INSPECTION.

2-4,

This

instrument

was

carefully

inspected

both

mechanically

and

electrically

before

shipment.

It

shouldbe

physically

free

of

mars

or

scratches

and

in

perfect

electrical

order

upon

receipt.

To

confirm

this,

the

instrument

should

be

inspected

for

physical

damage

intransit.

Also

checkfor

supplied

accessories,

and

test

the

electrical

performance

of

the

instrument

using

the

procedure

outlined

in

Paragraph

5-5.

If

there

is

damage

or

deficiency,

see

the

warranty

on

the

inside

front

cover

of

this

manual.

2-5.

POWER

REQUIREMENTS.

2-6.

The

Model

333A/334A

can

be

operated

from

any

ac

source

of

100

V/120

V/220 V/240

V

+

5%

-

10%,

48

-

66

Hz.

With

the

instrument

disconnected

from

the

ac

power

source,

move

the

slide

(located

on

the

rear

panel)

until

the

desired

line

voltage

appears.

Power

dissipation

is

approximately

4

watts.

2-7.

THREE-CONDUCTOR

POWER

CABLE.

2-8.

То

protect

operating

personnel,

the

National

Electrical

Manufacturers’

Association

(NEMA)

recom-

тепа

that

the

instrument

panel

and

cabinet

be

grounded.

АП

Hewlett-Packard

instruments

are

equipped

with

a

three-conductor

power

cable,

which,

when

plugged

in-

toanappropriate

receptacle,

grounds

the

instrument.

The

offset

pin

on

the

power

cable

three-prong

connec

=

tor

is

the

ground

wire.

2-9

INSTALLATION.

2-10.

The

Model

333A/334A

is

fully

transistorized;

therefore,

no

special

cooling

is

required.

However,

the

instrument

should

not

be

gperated

where

the

am-

bient

temperature

exceeds

55°

C

(131

Е).

2-11.

BENCH

INSTALLATION,

2-12.

The

Model

333A/334A

is

shipped

with

plastic

feet

and

tilt

stand

in

place,

ready

for

use

as

a

bench

instrument.

2-13.

RACK

INSTALLATION,

2-14.

The

Model

333A/334A

may

be

rack

mounted

by

using

the

5"

RackMount

Kit

(-hp-

Part

No.

5060-0775).

Instructions

for

the

conversion

are

included

with

the

kit.

The

rack

mount

for

the

Model

333A/334A

is

an

EIA

standard

width

of

19

inches.

When

mounted

in

à

rack

using

the

rack

mount

kit,

additional

support

at

the

rear

of

the

instrument

should

be

provided

if

vibra-

tion

or

similar

stress

is

likely.

2-15.

REPACKAGING

FOR

SHIPMENT.

2-16.

The

following

paragraphs

contain

a

general

guide

for

repackaging

of

the

instrument

for

shipment,

Refer

to

Paragraph

2-17

if

the

original

container

is

to

be

used;

2-18

if

it

is

not.

If

you

have

any

questions,

con-

tact

your

local

-

hp

-

Sales

and

Service

Office.

(See

Appendix

B

for

office

locations.)

NOTE

Ц

the

instrument

is

to

be

shipped

to

Hewlett-Packardfor

service

or

repair,

attachatag

to

the

instrument

identify

-

ing

the

owner

and

indicate

the

service

orrepairto

be

accomplished.

Include

the

model

number

and

full

serial

num-

ber

of

the

instrument.

In

any

corres-

pondence,

identify

the

instrument

by

model

number,

serial

number,

and

serial

number

prefix.

2-17.

If

original

container

is

to

be

used,

proceed

as

follows:

а,

Place

instrument

in

original

container

if

avail-

able.

Н

original

container

is

not

available,

a

suitable

one

can

be

purchased

from

your

nearest

-hp-

Sales

and

Service

Office.

b.

Ensurethat

container

is

well

sealed

with

strong

{аре

or

metal

bands.

2-18.

If

original

container

is

not

to

be

used,

proceed

as

follows:

a.

Wrap

instrument

in

heavy

paper

or

plastic

be-

fore

placing

in

an

inner

container.

b.

Place

packing

material

around

all

sides

of

in-

strument

and

protect

panelface

with

cardboard

strips.

c.

Place

instrument

and

inner

container

in

a

heavy

carton

or

wooden

box

and

seal

with

strong

tape

or

metal

bands.

d.

Mark

shipping

container

with

"DELICATE

INSTRUMENT,

"

"FRAGILE,

"

etc.

2-1

Section

Ш

пеене

RE

DETECTOR

MAX

INPUT

VOLTAGE

40

VOLT

P-P

AC

OR

40

VOLT

PEAK

TRARSENT

333A/2544-C-Q3854

j

334A

ONLY

LINE

switch

turns

instrument

ac

power

on.

Pilot

lamp

glows

when

instrument

is

turned

ON.

(2)Meter

indicates

distortion

or

voltage

level

of

input.

(3)

море

switch

selects

MANUAL

or

AUTOMATIC

bridge

tuning

operation.

(4)

FREQUENCY

RANGE

switch

selects

frequency

range

which

corresponds

to

fundamental

of

input

signal.

(5)COARSE

BALANCE

control

provides

coarse

ad-

justment

for

balancing

the

Wien

bridge

circuit.

(6)

FINE

BALANCE

control

provides

a

vernier

ad-

justment

for

balancing

the

Wien

bridge

circuit.

(1)

Frequency

dial

tunes

the

Wien

bridge

circuit

to

fundamental

of

input

signal.

(8)

HIGH

PASS

FILTER

switch

inserts

or

bypasses

HIGH PASS

FILTER

in

SET

LEVEL

and

DIS-

TORTION

function.

When

inserted,

filter

pro-

vides

>

40

dB

attenuation

to

50

-

60

Hz

hum

components

but

no

attenuation

to

frequencies

over

1

kHz.

OUTPUT

connectors

provide

means

of

monitor-

ing

output

of

meter

circuit.

(10)

Frequency

vernier

provides

fine

adjustment

of

frequency

dial.

METER

RANGE

switch

selects

full

scale

range

of

meter

in

percent,

dB

and

rms

volts.

Model

333A/334A

METERS

JANGE

547

LEVES

CAUTION!

(12)sENSITIVITY

selector

provides

0

-

50

dB

attenu-

ation

of

input

signal

in

10

dB

steps

in

SET

LEVEL

and

DISTORTION

functions.

(IS)SENSITIVITY

VERNIER

control

provides

fine

adjustment

of

sensitivity

setting.

Mechanical

zero

adjust

provides

mechanical

zero

adjustment

of

meter.

FUNCTION

switch

selects

type

of

operation

of

instrument.

(16)

shorting

bar

connects

circuit

ground

to

chassis

ground.

INPUT

terminals

provide

connections

for

input

signal.

(18)

NORM

RF

DET

(Model

334A

only)

selects

front

panel

INPUT

or

rear

panel

RF

INPUT

connector.

(9)

RF

INPUT

connector

(Model

334A

only)

provides

input

connection

for

AM

RF

carrier

input

signal.

FUSE

provides

current

overload

protection

for

instrument

circuits.

(21)

Line

voltage

switch

sets

instrument

to

operate

from

100

V/120

V/220

V/240

V.

(22)

Ac

power

connector

provides

input

connection

for

ac

power.

Figure

3-1.

Front

and

Rear

Panel

Description

3-0

Model

333A/334A

Section

ПІ

SECTION

ІП

OPERATING

3-1.

INTRODUCTION.

3-2.

The

Models

333A

and

334A

Distortion

Analyzers

measure

total

harmonic

distortion

of

fundamental

fre-

quencies

from

5

Hz

to

600

kHz;

harmonics

upto

3

MHz

are

included.

The

sharp

elimination

characteristics

(>80

dB),

the

low

level

of

instrument

induced

distor-

tion,

and

the

meter

accuracy

of

these

instruments

re-

sult

in

highly

accurate

measurement

of

low

level

har-

monic

distortion,

3-3.

Anrms

calibrated

voltmeter

is

inherent

in

the

333A

and

334A.

The

voltmeter

provides

a

full

scale

sensitivity

of

300

и

volts

rms

(residual

noise

«254

volts).

The

voltmeter

frequency

range

is

from

5

Hz

to

3

MHz

except

on

the

0,

0003

volt

range,

which

is

from

20

Hz

to

500

kHz.

3-4.

CONTROLS

AND

INDICATORS.

.

8-5.

Figure

3-1

illustrates

and

describes

the

function

'

of

all

front

and

rear

panel

controls,

connectors,

and

indicators,

The

description

of

each

component

is

keyed

to

the

drawing

included

within

the

figure.

3-6.GENERAL

OPERATING

INFORMATION.

3-7,

INPUT

CONNECTIONS.

3-8.

The

input

signal

can

be

connected

to

the

333A

and

334A

through

twisted

pair

leads

or

a

shielded

cable

with

banana

plug

connectors.

Keep

all

test

leads

as

short

as

possible

to

avoid

extraneous

pickup

from

stray

ac

fields.

When

measuring

Low-level

signals,

ground

loops

may

occur

causing

erroneous

readings.

Ground

loops

may

be

avoided

by

connecting

the

333A/

334A

Distortion

Analyzer

to

an

appropriate

isolation

transformer

to

break

the

chassis

ground

from

power

supply

ground.

Connect

all

other

instruments

to

one

power

strip

with

the

three-prong

connectors

as

close

as

possible.

3-9,

VOLTMETER

CHARACTERISTICS,

3-10.

The

RMS

VOLTS

markings

on

the

meter

face

are

basedonthe

ratio

betweenthe

average

and

effective

(rms)

values

of

a

pure

sine

wave.

The

ratio

of

average

to

effective

values

in

a

true

sine

wave

is

approximately

0.9to

1.

Whenthe

meter

is

used

to

measure

complex

waves,

the

voltage

indicated

may

not

be

the

rms

value

of

the

signal

applied.

This

deviation

of

meter

indica-

tion

exists

because

the

ratios

of

average

to

effective

values

are

usually

not

the

same

in

a

complex

wave

as

іп

а.віпе

wave.

The

amount

of

deviation

depends

on

the

magnitude

and

phase

relation

betweenthe

harmonics

and

fundamental

frequency

of

the

signal

applied.

Table

3-1

lists

the

deviation

of

the

meter

indication

of

a

sine

wave

partly

distorted

by

harmonics.

Ав

in-

dicated

in

the

table,

harmonic

content

of

less

than

10%

results

in

very

small

errors.

INSTRUCTIONS

Table

3-1

Effect

of

Harmonics

on

Voltage

Measurements

True

Meter

RMS

Value

Indication

Fundamental

=

100 100

Fundamental

+

10%

100

2nd

harmonic

Fundamental

+

20%

2nd

harmonic

Fundamental

+

50%

2nd

harmonic

Fundamental

+

10%

8rd

harmonic

Input

Voltage

Characteristics

100

-

102

100

-

110

96

-

104

Fundamental

+

20%

3rd

harmonic

94

-

108

Fundamental

+

50%

3rd

harmonic

90

-

116

l

NOTE

This

chart

is

universal

in

application

since

these

errors

are

inherent

in

all

average-responding

voltage-measuring

instruments.

3-11.

When

making

distortion

measurements

where

the

fundamental

frequency

is

suppressed

and

the

re-

mainder

of

the

signal

is

measured,

the

reading

ob-

tained

on

an

average

responding

meter

may

deviate

irom

the

true

total

rms

value.

When

the

residual

wave

contains

many

inharmonically

related

sinusoids,

the

maximum

error

in

the

distortion

reading

is

about

11

%

(11

%

of

the

measured

distortion)

low

for

dis-

tortion

levels

below

10

%.

EXAMPLE:

Measured

Maximum

Error

Total

Distortion

In

Meter

Indication

Distortion

2.5%

+0.

11x0.

025=

0.025+0,

0027=

0.00027

0.

0277

or

2.

8%

This

example

representsthe

maximum

possible

error,

and

in

most

cases

the

error

is

less.

In

distortion

measurements,

the

reading

of

an

average-responding

meter

is

sufficiently

close

to

the

rms

value

to

be

satisfactory

for

most

applications.

3-12.

OUTPUT

TERMINALS.

3-13,

The

OUTPUT

terminals

provide

a

0.1

V

rms

open

circuit

output

for

full

scale

meter

deflection.

These

terminals

can

be

used

to

monitor

the

output

signal

with

an

oscilloscope,

a

true

rms

voltmeter,

or

a

wave

analyzer.

The

combination

of

the

distortion

meter

and

oscilloscope

provides

more

significant

in-

3-1

Section

Ш

formation

about

the

device

under

test

than

the

expression

of

distortion

magnitude

alone.

Information

obtained

from

the

oscilloscope

pattern

is

specific

and

reveals

the

nature

of

distortion

which

sometimes

occurs

at

such

low

levels

that

it

is

difficult

to

detect

in

the

presence

of

hum

and

noise.

The

impedance

at

the

OUTPUT

terminals

is

2000

ohms,

therefore,

ca-

pacitive

loads

greater

than

50

pF

should

be

avoided

to

maintain

the

accuracy

of

meter

readings.

3-14.

OPERATING

PROCEDURES.

3-15.

INSTRUMENT

TURN-ON.

a.

Setthe

115-230

VAC

switch

to

coincide

with

the

line

voltage

in

use.

Turn

switch

to

ON

position.

Pilot

lamp

willglow,

indicating

application

of

primary

power.

3-16.

ADJUSTMENT

OF

METER

MECHANICAL

ZERO.

3-17.

The

meter

is

properly

zero-set

when

the

pointer

rests

over

the

zero

calibration

mark

and

the

instrument

is

in

its

normal

operating

enivronment

and

is

turned

off.

Zero-set

the

meter

as

follows

to

obtain

maximum

accuracy

and

mechanical

stability:

a,

Turn

instrument

on

and

allow

it

to

operate

for

at

least

20

minutes,

to

let

meter

move-

ment

reach

normal

operating

temperature.

b.

Turn

instrument

off

and

allow

30

seconds

for

all

capacitors

to

discharge.

c.

Rotate

zero

adjustment

screw

clockwise

un-

ti!

pointer

isleft

of

Zero

and

moving

upscale.

d.

Continue

rotating

screw

clockwise;

stop

when

pointer

is

exactly

at

zero.

e,

When

pointer

is

exactly

over

zero,

rotate

adjustment

screw

slightly

counterclockwise

to

relieve

tension

on

pointer

suspension.

1f

pointer

moves

offzero,

repeat

steps

c

through

е,

but

make

counterclockwise

rotation

less.

3-18.

DISTORTION

MEASUREMENT.

CAUTION?

DO

NOT

EXCEED

THE

INPUT

VOLT-

AGES

LISTED

BELOW

TO

PREVENT

DAMAGING

COMPONENTS

ON

À2

BOARD.

VOLTMETER

FUNCTION

-1V

RANGE

AND

BELOW,

AND

-DISTORTION

ANALYZER

575

FUNCTION

-

MAXIMUM

SENSITIVITY.

1.

800

V

ABOVE

100

Hz

2.

50

V

ABOVE

1

kHz

3-19.

MANUAL

MODE.

a.

Turn

instrument

on

and

mechanically

zero

meter

according

to

procedure

in

Paragraphs

3-15

and

3-16,

3-2

Model

333A/334A

Set

NORM-R.

F.

DET.

switch

to

NORM.

Set

FUNCTION

switch

to

ЗЕТ

LEVEL.

Set

MODE

switch

to

MANUAL,

If

fundamental

frequency

is

1kHz

or

greater,

set

HIGH

PASS

FILTER

switch

to

IN,

Set

SENSITIVITY

selector

to

MIN.

position,

and

rotate

VERNIER

control

maximum

counterclockwise.

NOTE

The

bandwidth

of

the

SENSI-

TIVITY

selector

is

reduced

in

the

two

extreme

CCW

positions

(positions

used

with

an

input

signal

greater

than

30

V).

Set

METER

RANGE

switch

tó

SET

LEVEL,

and

set

BALANCE

COARSE

and

FINE

con-

trols

to

center

position.

Connect

signal

to

be

measuredto

333A/334A

INPUT

terminals.

WARNING

В

REMOVE

SHORTING

STRAP

BETWEEN

FRAME

GROUND

(4)

AND

CHASSIS

GROUND

(

у

)

TERMINALS

ON

FRONT

PANEL

INPUT

TERMINALS

WHEN

MEASURING

DISTORTION

BETWEEN

TWO

POINTS

WHICH

ARE

DC

OF

FSET

FROM

GROUND

POTENTIAL.

Set

SENSITIVITY

selector

to

obtain

meter

indication

greater

than

1/3

full

scale.

Adjust

SENSITIVITY

VERNIER

for

full

scale

meter

indication

if

making

distortion

measure-

ment

in

percent;

if

making

distortion

measure-

ment

in

dB

adjust

SENSITIVITY

VERNIER

for

0

dB

meter

indication.

NOTE

If

unable

to

adjust

for

full

scale

or

0dB

indication,

(which

indicates

input

signal

is

below

0.3

volts),

set

METER

RANGE

selector

down-

scale.

Use

this

new

setting

as

the

1000

ог

0dB

SET

LEVEL

position,

thus

making

the

next

range

3090

or

-10

dB,

etc.

Set

FREQUENCY

RANGE

switch

and

frequency

dial

to

fundamental

frequency

of

input

signal.

Set

FUNCTION

switch

to

DISTORTION,

Adjust

frequency

dial

vernier

and

BALANCE

COARSE

and

FINE

controls

for

minimum

Model

333A/334A

Section

III

n.

p.

meter

indication.

Set

METERRANGE

switch

3-21.

DISTORTION

MEASUREMENT

OF

АМ

RF

down-scale

as

necessary

to

keep

meter

in-

CARRIERS

(334A

only).

dication

on

scale.

"rV

Repeat

step

m

until

no

further

reduction

in

meter

indication

can

be

obtained.

DO

NOT

EXCEED

MAXIMUM

INPUT

я

)

it

З

4

Observe

distortion

either

in

percentage

or

VOLTAGES

LISTED

ON

REAR

PANEL.

dB,

as

indicated

by

meter

deflection

and

METER

RANGE

switch

setting.

For

example,

if

meter

indicates

0.4

and

METER

RANGE

a.

Turn

instrument

on

and

mechanically

zero

setting

is

1%,

distortion

measured

is

0.4%

meter

according

to

procedure

in

Paragraphs

of

fundamental.

Similarly,

if

meter

indi-

3-15

and

3-16.

cates

-6

dB

and

METER

RANGE

setting

is

-40

dB,

distortion

measured

is

-46

dB

from

b.

Set

NORM.-R.F.

DET.

switch

to

R.

F.

DET.

fundamental.

c.

Connect

input

signalto

R.

Е.

INPUT

terminal

on

rear

panel.

SUUS

d.

Refer

to

Paragraph

3-19

for

manual

distort-

In

MANUAL

mode

the

accuracy

ion

measurement;

refer

to

Paragraph

3-20

of

distortion

measurements

is

for

automatic

distortion

measurement.

affected

by

frequency

stability

of

the

input

signal,

An

inaccuracy

——

NOTE

in

distortion

indications

occurs

when

the

frequency

drift

of

the

If

no

meter

deflection

can

be

input

signal

exceeds

the

bandwidth

obtained

with

an

RF

input,

diode

ACRI

should

be

checked.

А

spare

diode

is

located

on

the

outside

of

the

A4

shield.

of

the

rejection

curve.

If

desired,

rms

voltage

of

input

signal

can

be

measured

by

setting

FUNCTION

switch

to

3-22.

VOLTAGE

MEASUREMENT.

VOLTMETER,

and

setting

METER

RANGE

switch

to

obtain

an

on-scale

indication.

a.

Turn

instrument

on

and

mechanically

zero

meteraccordingto

procedure

in

Paragraphs

3-15

and

3-16,

3-20.

AUTOMATIC

MODE.

Ce

d.

|

Et

(

Perform

steps

athroughlof

Paragraph

3-19.

b.

Set

NORM.-R.

F.

DET.

switch

to

NORM,

i

та

Adjust

frequency

dial

vernier

and

BALANCE

c.

Set

FUNCTION

switch

to

VOLTMETER.

COARSE

and

FINE

controls

for

minimum

d.

Set

METER

RANGE

switch

to

a

range

meter

indication.

exceeding

amplitude

of

signal

to

be

mea-

sured.

When

meter

indication

is

less

than

10%

of

SET

LEVEL

indication,

set

MODE

switch

to

е,

Connect

signal

to

be

measured

to

INPUT

AUTOMATIC.

(Н

fundamental

cannot

be

terminals.

manually

nulled

below

10%

of

SET

LEVEL

indication,

automatic

mode

cannot

be

used).

f.

Set

METER

RANGE

switch

to

give

a

reading

as

close

to

full

scale

as

possible,

and

00-

Set

METER

RANGE

switch

down-scale

to

serve

meter

indication.

obtain

on-scale

meter

indication.

g.

The

dB

scale

of

the

333A/334A

is

calibrated

Observe

distortion

either

in

percentage

or

in

dBm,

such

that

0

dBm

=

1

milliwatt

dissi-

dB,

as

indicated

by

meter

deflection

and

pated

by

600

ohms.

Therefore,

a

dBm

mea-

METER

RANGE

switch

setting.

For

example,

surement

must

be

made

across

600

ohms.

if

meter

indicates

0.4

and

METER

RANGE

However,

dB

measurements

across

other

setting

is

10,

distortion

measured

is

0.

4%

impedances

can

be

converted

to

dBm

by

use

of

fundamental.

Similarly,

if

meter

indicates

of

the

Impedance

Correction

Graph

of

Fig-

-6

dB

and

METER

RANGE

setting

is

-40

dB,

ure

3-3.

For

example:

to

convert

a

-30

dB

distortion

measured

is

-46

dB

from

funda-

reading

across

200

ohms

to

dBm,

locate

the

mental.

200

ohm

impedance

line

at

the

bottom

of

the

graph.

Follow

the

impedance

line

to

the

If

desired,

rms

voltage

of

input

signal

can

be

heavy

black

line,

and

read

the

meter

correc-

measured

by

setting

FUNCTION

switch

to

tion

at

that

point.

The

correction

for

200

VOLTMETER,

and

setting

METER

RANGE

ohms

is

+5

dBm;

thus

the

corrected

reading

switch

to

obtain

an

on-scale

indication.

is

-25

dBm.

3-3

Section

Ш

3-23,

METER

INDICATION.

3-24.

The

333A/334A

meter

is

calibrated

to

indicate

in

both

dB

and

volts.

It

is

interesting

to

notethat

the

METER

RANGE

markings

differ

from

most

ac

volt-

meter

range

markings.

On

most

ac

voltmeters

(600

ohms)

0

dB

corresponds

to

the

1

volt

range.

This

is

not

true

inthe

case

of

the

333A/334A.

Since

the

instru-

ment

is

primarily

a

distortion

analyzer,

measurements

are

in

dB

(relative

measurement)

rather

than

in

dBm

(absolute

measurement).

Zero

dB

оп

the

333A/334A

corresponds

to

0.3

volt

range

rather

than

the

1

volt

range.

This

allows

210

dB

greater

dynamic

range

of

distortion

measurements.

3-25.

If

measurements

are

to

be

made

in

dBm,

10

dB

must

be

subtracted

from

the

METER

RANGE

setting.

Thus

0

dB

becomes

the

-10

dBm

range

for

absolute

power

measurements.

Zero

dBm

is

equal

to

1

milli-

watt

dissipated

by

any

impedance

andinthis

particular

case

is

600

ohms.

The

«10

DECIBELS

marking

on

the

meter

face

indicates

that

when

voltmeter

measurements

are

being

made,

the

indication

(METER

RANGE

plus

meter

indication)

is

10

dB

greater

than

when

power

(dBm)

measurements

are

being

made.

3-26.

In

short,

when

distortion

and

voltage

measure-

ments

are

being

made,

utilizethe

instrument

METER

RANGE

and

meter

scale

as

they

exist.

For

absolute

power

measurements

in

dBm,

simply

subtract

10

dB

from

the

METER

RANGE

setting.

3-27.

USE

OF

OUTPUT

TERMINALS.

3-28.

In

VOLTMETER

and

SET

LEVEL

functions,

the

333A/334A

can

be

used

as

a

low

distortion,

wide-band

amplifier.

А

portion

of

the

meter

input

(0.1

V

rms

open

circuit

forfullscale

meter

deflection

is

provided

at

the

OUTPUT

terminals.

3-29.

In

DISTORTION

function,

the

distortion

(0.1

V

rms

open

circuit

forfull

scale

deflection)

is

provided

atthe

OUTPUT

terminals

for

monitoring

purposes.

NOTE

The

INPUT

Y

terminal

and

the

OUTPUT

d

terminal

shouldnot

be

connected

directly

together

when

making

low

level

measurements.

These

terminals

are

isolated

from

each

other

by

1

ohm

which

reduces

the

effects

of

common

mode

voltages.

Model

333A

/334А

3-30.

333A/334A

WITH

OPTION

01.

3-31.

Operating

procedures

for

the

333A/334A

with

OptionOlarethe

same

asforthe

standard

instrument.

The

only

difference

between

the

standard

and

optional

instrument

is

that

the

Option

01

has

a

special

meter

and

meter

amplifier

whichis

compensated

to

respond

to

VU

(volume

unit)

characteristics.

|

3-32.

MANUAL

NULLING.

3-33.

Since

the

frequency

and

balance

controls

are

rather

sensitive

in

the

MANUAL

mode,

the

following

information

is

suppliedto

simplify

nulling

the

333A/334A

іп

the

MANUAL

mode,

When

nulling

the

3334/3344

in

the

MANUAL

mode,

connect

the

equip-

ment

as

shown

below

and

adjust

the

333A/334A

fre-

quency

and

balance

controls

for

the

waveform

shown

in

step

a

below,

Additional

waveforms

are

provided

to

simplify

nulling.

а.

www

No

harmonic

distortion,

Frequency

and

balance

adjustment

correct,

b.

7

Frequency

and

balance

control

im-

properly

adjusted,

с.

Frequency

approximately

correct;

balance

incorrect.

d.

CLLD

Balance

approximately

correct;

fre-

quency

incorrect,

e.

COX

2

Second

harmonie

predominant;

fre-

quency

and

balance

adjusted,

f.

--77---.

Second

harmonie

predominant;

fre-

quency

and

balance

adjusted;

phase

changed.

ge

7“-----”

Second

harmonic

predominant;

fre-

quency

and

balance

adjusted;

phase

changed,

һ

CXX

Third

harmonic

predominant.

i.

n

2

pee

incorrect;

meter

reading

off

Scale.

h

P

AE.

Frequency

incorrect;

meter

reading

off

scale.