Wavetek 180 User manual

I

INSTRUCTION

MANUAL

MODELS

180

AND

180

LF

SWEEP/FUNCTION

GENERATORS

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WVas/'

WARRANTY

All

Wavetek

instruments

are

warranteed

against

defects

in

material

and

workmanship

for

a

period

of

one

year

after

date

of

manufacture.

Wavetek

agrees

to

repair

or

replace

any

assembly

or

component

(except

batteries)

found

to

be

defective,

under

normal

use,

during

this

period.

Wavetek's

obligation

under

this

warranty

is

limited

solely

to

repairing

any

such

instrument

which

in

Wavetek's

sole

opinion

proves

to

be

defective

within

the

scope

of

the

warranty

when

returned

to

the

factory

or

to

an

authorized

service

center.

Transportation

to

the

factory

or

service

center

is

to

be

prepaid

by

purchaser.

Shipment

should

not

be

made

without

prior

authorization

by

Wavetek.

This

warranty

does

not

apply

to

any

products

repaired

or

altered

by

persons

not

authorized

by

Wavetek,

or

not

in

accordance

with

instructions

furnished

by

Wavetek.

If

the

instrument

is

defective

as

a

result

of

misuse,

improper

repair,

or

abnormal

conditions

or

operations,

repairs

will

be

billed

at

cost.

Wavetek

assumes

no

responsibility

for

its

product

being

used

in

a

hazardous

or

dangerous

manner

either

alone

or

in

conjunction

with

other

equipment.

High

voltage

used

in

some

instruments

may

be

dangerous

if

misused.

Special

disclaimers

apply

to

these

instruments.

Wavetek

assumes

no

liability

for

secondary

charges

or

consequential

damages

and,

in

any

event,

Wavetek's

liability

for

breach

of

warranty

under

any

contract

or

otherwise,

shall

not

exceed

the

purchase

price

of

the

specific

instrument

shipped

and

against

which

a

claim

is

made.

Any

recommendations

made

by

Wavetek

for

use

of

its

products

are

based

upon

tests

believed

to

be

reliable,

but

Wavetek

makes

no

warranty

of

the

results

to

be

obtained.

This

warranty

is

in

lieu

of

all

other

warranties,

expressed

or

implied,

and

no

representative

or

person

is

authorized

to

represent

or

assume

for

Wavetek

any

liability

in

connection

with

the

sale

of

our

products

other

than

set

forth

herein.

INSTRUCTION

MANUAL

MODELS

180

AND

180

LF

SWEEP/FUNCTION

GENERATORS

\\^\VETEK

Box

651,

San

Diego,

Calif.,

714-279-2200

3/77

CONTENTS

SECTION

1

GENERAL

DESCRIPTION

1.1

THE

MODELS

180

AND

180LF

1.2

SPECIFICATIONS

SECTION

2

INITIAL

PREPARATION

2.1

UNPACKING

INSPECTION

2.2

PREPARATION

FOR

USE

2.3

ELECTRICAL

ACCEPTANCE

CHECK

2.4

CHANGING

THE

OUTPUT

IMPEDANCE

.

..

.

SECTION

3

OPERATION

3.1

CONTROLS

AND

CONNECTORS

.

3.1.1

Power/Frequency

Controls

3.1.2

Amplitude

Controls

3.1.3

Function

Selections

3.1.4

Sweep

Controls

3.2

OPERATION

3.2.1

Signal

Termination

3.2.2

Manually

Controlled

Operation

3.2.3

Voltage

Controlled

Operation

3.2.4

Sweep

Generator

Operation

SECTION

4

CIRCUIT

DESCRIPTION

4.1

VOLTAGE

CONTROLLED

GENERATOR

(VCG)

4.2

FREQUENCY

CONTROL

4.3

WAVEFORM

OUTPUT

4.4

SWEEP

CIRCUITS

4.5

CRYSTAL

CONTROL

SECTION

5

CALIBRATION

5.1

FACTORY

REPAIR

5.2

REQUIRED

TEST

EQUIPMENT

5.3

REMOVING

GENERATOR

COVER

5.4

CALIBRATION

SECTION

6

TROUBLESHOOTING

6.1

FACTORY

REPAIR

6.2

TROUBLESHOOTING

CHART

6.3

TROUBLESHOOTING

INDIVIDUAL

COMPONENTS

SECTION?

PARTS

AND

SCHEMATICS

7.1

DRAWINGS

7.2

ORDERING

PARTS

7.3

ADDENDA

1-1

2-1

3-1

3-2

3-3

3-4

4-1

4-2

5-1

6-1

7-1

1

SECTION

GENERAL

DESCRiPTION

1.1

THE

MODELS

180

AND

180LF

The

Wavetek

Model

180

Sweep/Function

Generator

is

a

precision

source

of

sine,

triangle,

and

square

waveforms.

Frequency

of

the

waveforms

is

manually

and

remotely

variable

from

0.1

Hz

to

2

MHz.

The

generator

can

repeti

tively

sweep

from

one

frequency

to

a

higher

frequency,

with

controllable

rate

and

range

of

sweep.

Amplitude

of

the

waveforms

is

variable

from

10V

peak-to-peak

into

50f2

down

to

30

mV

p-p.

DC

reference

of

the

waveforms

can

be

offset

positively

and

negatively.

A

voltage

representing

generator

frequency,

a

fixed

amplitude

pulse

train

of

that

frequency,

and

a

voltage

ramp

representing

frequency

sweep

rate

are

provided

as

front

panel

outputs.

The

Wavetek

Model

180LF

(Low

Frequency)

Sweep/Func

tion

Generator

is

identical

to

the

Model

180

except

for

frequency

range:

0.01

Hz

to

200

kHz.

1.2

SPECIFICATIONS

The

specifications

(available

waveforms,

frequencies,

and

amplitudes),

operating

modes,

precision

(accuracy),

and

purity

(quality)

are

listed

in

the

following

paragraphs.

1.2.1

Versatility

Output

Signals

Sine

%

,

triangle

ramp

^

and

DC.

square

""Lj

,

TTL

pulse

J~L

Control

Generator

operates

in

continuous

and

sweep

modes.

Fre

quency

controlled

manually

or

with

external

voltage.

Frequency

Range

0.1

Hz

to

2

MHz

(180);

0.01

Hz

to

200

kHz

(180LF).

Operating

Frequency

Ranges

Model

180:

XI

0.1

Hz

to

2

Hz

X

10

0.1

Hz

to

20

Hz

X100

0.2

Hz

to

200

Hz

X

IK

2

Hz

to

2

kHz

XIOK

20

Hz

to

20

kHz

X

100K

200

Hz

to

200

kHz

X

1M

2

kHz

to

2

MHz

Model

180LF:

X.I

0.01

Hz

to

0.2

Hz

X

I

0.01

Hz

to

2

Hz

X

10

0.02

Hz

to

20

Hz

X100

0.2

Hz

to

200

Hz

X

IK

2

Hz

to

2

kHz

X10K

20

Hz

to

20

kHz

X

100K

200

Hz

to

200

kHz

Main

Output

Sine,

triangle

and

square

waveforms

and

DC

are

selectable.

HI

(0

dB)

and

LO

(-20

dS)

BNC

outputs

are

available

for

simultaneous

usage;

outputs

may

be

varied

to

HI

(—30dB)

and

LO

(—50

dB)

by

amplitude

control.

HI

output

provides

20V

peak-to-peak

max

open

circuit

(10V

peak-to-peak

max

into

50n

load).

LO

output

provides

IV

peak-to-peak

max

into

50n

load.

Both

output

impedances

are

50^2.

DC

Offset

and

DC

Output

DC

offset

of

waveform

and

DC

output

selectable

and

variable

through

HI

and

LO

BNC

outputs.

HI

output

±10V

max

(±5V

into

50n

load)

as

offset

or

Vdc

output.

LO

output

±1V

max

into

50n

load

as

offset

or

Vdc

output.

Waveform

offset

limited

to

±10

Vp

HI

and

±1

Vp

LO

(both

open

circuit

voltages).

Pulse

Output

TTL

pulse

(50%

duty

cycle)

at

generator

frequency.

Drives

up

to

20

TTL

loads.

GCV

Output

0

to

+2V

(nominal,

open

circuit)

proportional

to

frequency

of

main

generator.

Output

impedance

600J2.

VCG

—

Voltage

Controlled

Generator

Input

VCG

voltage

as

well

as

control

settings

select

generator

frequency.

Frequency

may

be

dc-programmed

or

ac-mod-

ulated

by

external

0

to

2V

signal.

Input

impedance

is

2

kS7.

VCG

input

can

change

generator

output

1000:1

on

all

ranges

except

X

10

Hz

and

X

1

Hz

ranges

(Model

180)

and

X

1

Hz

and

X

.1

Hz

(Model

180LF).

VCG

Input

Signal

Bandwidth;

100

kHz.

VCG

Slew

Rate:

O.IVZ/JS.

1-1

Sweep

Output

Ramp

waveform

output

with

5V

peak

into

open

circuit.

Output

impedance

600n.

1.2.2

Operating

Modes

Continuous

Operates

as

standard

VCG.

Frequency

of

main

generator

determined

by

dial/range

setting

and

VCG

input

voltage.

Sweep

Main

generator

is

frequency

modulated

by

internal

sweep

generator.

When

swept,

main

generator

frequency

rises

from

frequency

set

by

the

dial

and

range

setting

to

a

frequency

set

by

sweep

width

control.

Sweep

Rate:

30

ms

to

20s

(nominal)

continuously

adjustable

by

single

turn

control

on

front

panel.

Sweep

Width:

Up

to

1:1000

adjustable

on

all

ranges

except

X

1

Hz

and

X

10

Hz

ranges

(Model

180)

and

X

.1

Hz

and

X

1

Hz

(Model

180LF).

1.2.3 Horizontal

Precision

Dial

Accuracy

Model

180:

±3%

of

full

scale

for

0.1

Hz

to

2

MHz.

Model

180LF:

±3%

of

full

scale

for

0.01

Hz

to

200

kHz.

Time

Symmetry

Models

180

and

180LF,

as

applicable:

±1%

on

all

but

X

1M

range.

1.2.4

Vertical

Precision

Amplitude

Change

With

Frequency

(Sine)

Models

180

and

180LF,

as

applicable:

Less

than

±0.1

dB

on

all

ranges

thru

X

100K.

Less

than

±0.5

dB

on

X

1M

range.

1.2.5

Waveform

Purity

(Models

180

and

180LF,

as

applicable)

Sine

Distortion

Less

than

0.5%

on

X

100,

X

1K,

X

10K

ranges

(typically

0.2%).

Less

than

1.0%

on

X

1,

X

10,

X

TOOK

ranges

(typically

0.5%).

All

harmonics

30

dB

down

on

X

1M

range.

Square

Wave

Rise

and

Fall

Time

Less

than

75

nanoseconds.

Triangle

Linearity

Greater

than

99%

to

200

kHz.

1.2.6

Environmental

Specifications

apply

at

25°C

±5°C.

Instrument

will

operate

from

0°C

to

+50°C.

1.2.7

Mechanical

Dimensions

11%

in./28.6

cm

wide;

4

in./10.2

cm

high;

lOVa

in./26.7

cm

deep.

Weight

6.5

lb/2.9

kg

net;

9.5

lb/4.3

kg

shipping.

1.2.8

Power

105

to

125V

or

200

to

250V,

50

Hz

to

400

Hz.

Less

than

15

watts.

NOTE

AH

specifications

apply

when

frequency

dial

is

between

0.1

and

2.0,

amplitude

is

at

10V

p-p

and

output

is

from

HI

BNC

into

500.

load.

1-2

2

SECTION

INITIAL

PREPARATION

2.1

UNPACKING

INSPECTION

After

carefully

unpacking

the

instrument,

inspect

the

ex

ternal

parts

for

damage

to

knobs,

dials,

indicators,

surface

areas,

etc.

If

there

is

damage,

file

a

claim

with

the

carrier

who

transported

the

instrument.

Retain

the

shipping

con

tainer

and

packing

material

for

use

in

case

reshipment

is

required.

2.2

PREPARATION

FOR

USE

Before

connecting

the

instrument

to

line

power,

check

that

the

rear

panel

115/230V

switch

is

set

to

the

value

nearest

the

line

voltage

and

that

the

fuse

is

correct

for

the

switch

setting.

Check

that

the

plug

on

the

power

cord

is

the

mate

for

the

line

receptacle.

2.3

ELECTRICAL

ACCEPTANCE

CHECK

This

checkout

procedure

provides

a

general

verification

of

generator

operation.

Should

a

malfunction

be

found,

refer

to

the

Warranty

in

the

front

of

this

manual.

An

oscilloscope,

BOH

coax

cable,

and

a

50f2

feedthru

are

needed

for

this

procedure

(figure

2-1).

Preset

the

generator

front

panel

controls

as

follows:

Control

Position

FREQMULT

PWR

OFF

Frequency

Dial

l.Q

Function

AMPLITUDE

Full

clockwise

DC

OFFSET

OFF

SWEEPWIDTH

OFF

SWEEP

RATE

9

o'clock

Perform

the

steps

in

table

2-1;

monitor

the

50n

OUT

HI

connector

at

the

oscilloscope.

2.4

CHANGING

THE

OUTPUT

IMPEDANCE

The

output

impedance

is

normally:

HI

50n@10Vp-p

LO

50J2

@

1V

p-p

Attenuation

is

normally

0

-

30

dS.

Lowest

possible

ampli

tude

is

—50

dB.

If

simultaneous

BOOH

and

50n

output

impedances

are

desired:

MODEL

180

50L2„

LOAD

OUT®

Clh

OSCILLOSCOPE

Figure

2-1.

Acceptance

Check

Setup

1.

Change

value

of

R145

from

49912

to

604S2.

2.

Remove

R147.

The

result

is:

HI

5012

@

10V

p-p

LO

60012

@

10V

p-p

(low

power)

Attenuation

is

0

-

30

dB.

Lowest

possible

amplitude

is

—30

dB.

Square

wave

rise

and

fall

is

<

150

ns.

If

5012

and

any

other

impedance

greater

than

60012

are

desired,

replace

R145

with

resistor

of

that

value.

If

50

dB

of

attenuation

control

is

desired

in

a

modified

instrument,

change

R121

from

33.212

to

1.812.

Waveform

quality

above

20

kHz

will

be

considerably

impaired

at

-50

dB

compared

to

a

standard

instrument.

2-1

Table

2-1.

Acceptance

Check

Step

Control

Position/Operation

Observe

at

50SJ

OUT

1

FREQMULT

X

1

(Model

180)

X

.1

(Model

180LF)

1

Hz,

10V

p-p

sine

wave

(Model

180)

0.1

Hz,

10V

p-p

sine

wave

(Model

180LF)

2

FREQ

MULT

X

1,

X

10,

X

100,

- - -

X

1M

(as

applicable)

Frequency

increases

by

a

decade

for

every

change

of

switch

position

3

FREQ

MULT

X

IK

4

Function

Triangle

wave

5

Function

"b

Square

wave

6

AMPLITUDE

ccw

Decrease

in

waveform

amplitude

7

DC

OFFSET

cw

Positive

slew

of

waveform

from

full

negative

offset

8

DC

OFFSET

ccw

Negative

slew

of

waveform

g

DC

OFFSET

OFF

10

AMPLITUDE

Full

cw

11

Dial

Full

cw

12

SWEEP

WIDTH

Full

cw

Frequency

of

waveform

repetitively

sweeps

2-2

3

SECTION

OPERATiON

3.1

CONTROLS

AND

CONNECTORS

The

generator

front

panel

controls

and

connections

shown

in

figure

3-1

are

keyed

by

circled

numbers

to

the

following

descriptions.

3.1.1

Power/Frequency

Controls

(T)

FREQMULT/PWR

OFF

Power

is

turned

on

when

frequency

range

is

selected

at

the

FREQ

MULT

(Hz)

control.

The

ranges

multiplied

by

frequency

dial

settings

deter

mine

output

frequency.

The

frequency

dial

index

lights

when

power

is

turned

on.

(2)

Frequency

Dial

Frequency

dial

settings

multiplied

by

frequency

range

determine

output

frequency.

VCG

IN

Connector

Voltage

controlled

generator

input

(VCG

IN)

dc

excursions

proportionally

control

frequency

within

a

selected

range.

Positive

inputs

increase

frequencies

set

by

the

frequency

dial

and

range

control;

nega

tive

inputs

decrease

the

frequencies.

GCV

OUT

Connector

Generator

controlled

voltage

output

(GCV

OUT)

dc

excursions

of

OV

to

about

2V

proportionally

represent

output

frequency

within

a

given

range.

3.1.2

Amplitude

Controls

@

DC

OFFSET

Rotating

the

DC

OFFSET

control

clockwise

offsets

dc

center

reference

of

waveform

positive;

when

POWER/FREQUENCY

FREQ

UlTiH/t

SWEEP

WiOTH

SWEEP

AMPLITUDE

©

@

®

SWEEP/FUNCTION

a'VEEPRATE

DC

Of

\

^

iiv

F

\

/

OFF

\GCV

jTSiNeBP

PULSE

OUT

/

OUT

(TTLI

I

ENERATt

DEL

180

FUNCTIONS

Figure

3-1.

Model

180

Controls

and

Connectors

3-1

counterclockwise,

negative.

When

OFF,

the

wave

form

is

balanced

around

signal

ground

(figure

3-2).

TTL

PULSE

Figure

3-2.

Output

Waveforms

@

AMPLITUDE

Rotating

the

AMPLITUDE

control

fully

clockwise

provides

maximum

peak-to-peak

output

at

the

50n

OUT

connectors;

counterclockwise

for

up

to

30

dB

attenuation

of

output

amplitude.

50n

OUT

Connectors

Maximum

output

of

10V

p-p

signals

into

a

5012

load

(20V

p-p

open

circuit)

is

provided

at

the

50n

OUT

HI

connector,

and

20

dB

below

(1/10

or

a

1V

p-p

maximum)

of

that

level

at

the

5012

OUT

LO

connector.

3.1.3

Function

Selections

(D

%

Tj

,

and

DC

(Waveforms)

Sine

'V

,

triangle

'V

,

and

square

""L

wave

forms

are

selected

by

the

larger

of

the

two

concen

tric

controls;

the

DC

position

provides

a

dc

voltage

output

of

the

waveform

center

reference

level

at

the

5012

OUT

connectors.

@

TTL

PULSE

OUT

Connector

A

fixed

amplitude

Transistor-Transistor

Logic

(TTL)

square

pulse

train

of

the

output

frequency

is

provided

at

the

PULSE

OUT

(TTL)

connector.

(TTL

levels

are

OV

to

0.4V

for

a

logic

low

and

2.4V

to

5V

for

a

logic

high.)

The

output

can

drive

up

to

20

TTL

loads.

The

pulse

train

can

also

be

used

as

a

synchronizing

reference

for

the

main

output

@

.

Phase

of

the

waveforms

relative

to

the

TTL

pulse

is

shown

in

figure

3-2.

3.1.4

Sweep

Controls

@

SWEEP

WIDTH/OFF

Main

output

(at

5012

OUT

HI

or

LO)

frequency

sweep

is

turned

on

when

SWEEP

WIDTH

is

rotated

past

OFF.

Rotation

of

the

control

varies

the

peak

amplitude

of

an

internal

ramp

signal

(seen

at

GCV

OUT)

whose

voltage

controls

the

frequency

of

the

main

generator

(seen

at

5012

OUT).

See

figure

3-3.

.

SWEEP

TIME

GCV

OUT

5012

OUT

SWEEP

START

FREQUENCY

SET

BY

FREQUENCY

DIAL

SWEEP

WIDTH

SWEEP

STOP

FREQUENCY

SET

BY

SWEEP

WIDTH

Figure

3-3.

Effect

of

Sweep

on

Output

Frequency

SWEEP

OUT

Connector

The

sweep

generator

ramp

is

available

at

the

SWEEP

OUT

connector.

Amplitude

is

OV

to

5V

peak

(60012

source

impedance).

SWEEP

RATE

Rotation

of

SWEEP

RATE

controls

duration

of

the

sweep

voltage

ramp,

and

thus

frequency

of

sweep

repetition.

3.2

OPERATION

Operation

can

be

quite

varied

but

is

described

here

as

manual,

voltage

controlled

or

sweep

controlled.

The

gen

erator

is

ready

to

operate

as

soon

as

a

frequency

multiplier

is

selected;

however,

when

output

is

critical,

allow

Vi

hour

warm

up.

3.2.1

Signal

Termination

Proper

signal

termination,

or

loading,

of

the

generator

con

nectors

is

necessary

for

its

specified

operation.

For

example,

the

proper

termination

of

the

main

output

is

shown

in

figure

3-4.

Placing

the

50

ohm

terminator,

or

50

ohm

resistance,

in

parallel

with

a

higher

impedance,

matches

the

receiving

instrument

input

impedance

to

the

generator

3-2

output

impedance,

thereby

minimizing

signal

reflection

or

power

loss

on

the

line

due

to

impedance

mismatch.

MODEL

180

RECEIVING

INSTRUMENT

OUTPUT

IMPEDANCE

5on

OUTPUT

RG58

OR

EQUIVALENT

50r2

LOAD,

EFFECTIVE

CIRCUIT

RESISTANCE

-AAA^

1

(SIGNAL

LOAD)

V.

Figure

3-4.

Signal

Termination

The

input

and

output

impedances

of

the

generator

con

nectors

are

listed

below:

Connector

50S2

OUT

HI

50^2

OUT

LO

PULSE

OUT

(TTL)

SWEEP

OUT

VCG

IN

GCVOUT

Impedance

50^2

son

60on

2kn

60on

•The

PULSE

OUT

connector

can

drive

up

to

20

Transistor-Transistor

Logic

(TTL)

loads

(low

level

between

OV

and

0.4V.

and

high

level

between

2.4V

and

5V).

3.2.2

Manually

Controlled

Operation

For

basic

operation,

select

the

waveform

to

be

output,

and

set

the

output

signal

frequency

and

amplitude.

The

following

steps

demonstrate

manual

control

of

the

function

generator:

Step

Co

ntrol

/Co

n

nector

1

50n

OUT

2

FREQMULT

3

Frequency

Dial

4

Waveform

Selector

5

DC

OFFSET

6

AMPLITUDE

Setting

Connect

circuit

to

either

HI

or

LO

output

(Ref:

paragraph

3.2.1).

Set

to

desired

range

of

frequency.

Set

to

desired

frequency.

Set

to

desired

waveform.

See

figure

3-5.

Select

desired

amplitude.

TRIANGLE

WAVEFORM

FROM

HI

OUTPUT

INTO

50I2

load

•f6V

OV

-5V

GDC

OFFSET

POSITIVE

DC

OFFSET

NEGATIVE

DC

OFFSET

+5V

—

n—

EXCESSIVE

POSITIVE

OFFSET

OR

LOADING

EXCESSIVE

NEGATIVE

OFFSET

OR

LOADING

Figure

3-5.

DC

OFFSET

Control

3.2.3

Voltage

Controlled

Operation

as

a

voltage

controlled

function

generator

(VCG)

is

as

for

a

manually

controlled

function

generator,

only

the

frequency

within

particular

ranges

is

additionally

controlled

with

dc

levels

(±2V

excursions)

injected

at

the

VCG

IN

connector.

Perform

the

steps

given

in

paragraph

3.2.2,

only

set

the

frequency

dial

to

determine

a

reference

from

which

the

frequency

is

to

be

voltage

controlled:

1.

For

frequency

control

with

positive

dc

inputs

at

VCG

IN,

set

the

dial

for

a

lower

frequency

limit.

2.

For

frequency

control

with

negative

dc

inputs

at

VCG

IN,

set

the

dial

for

an

upper

frequency

limit.

3.

For

modulation

with

an

ac

input

at

VCG

IN,

center

the

dial

at

the

desired

center

frequency.

Do

not

exceed

the

maximum

dynamic

range

of

the

selected

frequency

range.

Figure

3-6

is

a

nomograph

with

examples

of

the

frequency

dial

effect

as

a

reference

for

VCG

IN

voltages.

Example

1

shows

that

with

OV

VCG

input,

frequency

is

as

determined

by

the

main

dial

setting,

1.0

in

this

example.

Example

2

shows

that

with

a

positive

VCG

input,

output

frequency

is

increased.

Examples

shows

that

with

a

negative

VCG

input,

output

frequency

is

decreased.

(Note

that

the

50S2

OUT

Frequency

Factor

column

value

must

be

multiplied

by

a

frequency

range

multiplier

to

give

the

actual

50^2

OUT

frequency.)

3-3

MAIN

DIAL

SETTING

2.0

1.8-f-

1.6

1.4

1.2--

1.0

.8--

.6

.4

.2

.002-'-

VCG

IN

VOLTAGE

-2.0-|-

-1.6

-

-1.2--

-

.8

-

.4^

^

,

EXAMPLE

1

X

U-t-

\

+

.4--

\

+1.2-

S-?!.

son

OUT

FREQUENCY

FACTOR

-.002

-.2

-.4

-.6

-.8

-1.0

--1.2

-1.4

-1.6

+1.6-1-

\

-1.8

-2.0

+2.0-'-

Figure

3-6.

VCG

Voltage-to-Frequency

Nomograph

The

up

to

1000:1

VCG

sweep

of

the

generator

frequencies

available

in

each

range

results

from

a

2V

excursion

at

the

VCG

IN

connector.

With

the

frequency

dial

set

to

2.0,

excursions

between

—2V

and

OV

at

VCG

IN

provide

the

up

to

1000:1

frequency

sweep.

With

the

dial

set

to

.002,

excursions

between

OV

and

+2V

at

VCG

IN

provide

the

up

to

1000:1

sweep

within

the

set

frequency

range.

3.2.4

Sweep

Generator

Operation

as

a

sweep

generator

is

like

operation

as

a

manual

function

generator,

only

the

frequency

is

automatically

and

repetitively

swept

from

the

set

frequency

to

a

higher

fre

quency.

Actually,

an

internally

generated

positive-going

voltage

ramp

{available

at

the

SWEEP

OUT

connector)

can

be

modified

in

amplitude

and

used

like

a

VCG

input

voltage

to

sweep

the

output

frequency

(see

figure

3-3).

Perform

the

steps

in

paragraph

3.2.1

and

the

following

steps

for

use

as

a

sweep

generator:

Step

Control/Connector

SWEEP

WIDTH

SWEEP

RATE

Setting

As

desired.

This

determines

the

upper

frequency

of

the

sweep.

As

desired.

This

determines

the

speed

of

the

sweep.

NOTE

Nonlinear

operation

results

when

the

VCG

input

voltage

is

excessive;

that

is,

when

the

attempted

generator

frequency

exceeds

the

range

setting

(2

times

the

multiplier

setting)

or

in

the

other

direction,

1/1000th

of

the

range

setting.

To

monitor

the

ramp

generator,

use

the

SWEEP

OUT

connector.

To

monitor

the

frequency

of

the

main

generator,

use

the

GCV

OUT

connector,

which

is

a

voltage

proportional

to

the

generator

frequency.

3-4

4

SECTION

CIRCUIT

DESCRIPTION

4.1

VOLTAGE

CONTROLLED

GENERATOR

(VCG)

As

shown

in

figure

4-1,

the

VCG

summing

amplifier

sums

the

currents

from

the

frequency

dial,

sweep

generator,

crystal

control

and

VCG

input

connector.

The

VCG

sum

ming

amplifier

is

an

inverting

amplifier

whose

output

current

is

used

to

control

a

positive

current

source

and

a

negative

current

source.

The

currents

from

the

two

current

sources

are

equal

and

opposite

polarity

and

the

magnitudes

are

directly

proportional

to

the

current

of

the

VCG

sum

ming

amplifier

output.

The

diode

gate,

which

is

controlled

by

the

hysteresis

switch.

Is

used

to

switch

the

positive

current

or

the

negative

current

to

the

integrating

capacitor

selected

by

the

frequency

multiplier.

If

the

positive

current

is

switched

into

the

capacitor,

the

voltage

across

the

capacitor

will

increase

linearly

to

generate

the

positive

slope

of

the

triangle

wave.

If

the

current

is

negative,

the

voltage

across

the

capacitor

will

decrease

linearly

to

produce

the

negative

slope.

0,

HYSTERESIS

SWITCH

BUFFER^

The

triangle

buffer

amplifier

is

a

unity

gain

amplifier

whose

output

is

fed

to

the

hysteresis

switch

as

well

as

to

the

sine

converter.

The

hysteresis

switch

has

two

voltage

limit

points

(+1.25V

and

—1.25V).

(See

figure

4-2.)

During

the

time

the

output

voltage

of

the

triangle

buffer

amplifier

is

increasing,

the

output

voltage

of

the

hysteresis

switch

is

positive,

but

when

the

output

voltage

of

the

triangle

amplifier

reaches

+1.25V,

it

triggers

the

hysteresis

switch

causing

the

switch

output

to

become

negative.

Once

the

control

voltage

into

the

diode

gate

becomes

negative,

it

will

switch

the

positive

current

out

and

switch

the

negative

current

in

to

the

integrating

capacitor,

starting

a

linear

decrease

of

the

voltage

across

the

capacitor.

When

the

decreasing

voltage

reaches

-1.25V,

the

output

of

the

hys

teresis

switch

will

switch

back

to

positive,

reversing

the

process.

This

action

generates

the

triangle

waveform

as

shown

in

figure

4-2.

Since

the

output

of

the

hysteresis

switch

isa

square

wave,

the

result

is

simultaneous

generation

of

a

square

wave

and

triangle

wave

at

the

same

frequency.

4.2

FREQUENCY

CONTROL

The

output

frequency

is

determined

by

the

magnitude

of

the

integrating

capacitor

selected

by

the

frequency

multiplier

and

the

magnitude

of

the

positive

and

negative

current

sources

(figure

4-1).

Since

the

current

magnitudes

are

linearly

proportional

to

the

sum

of

the

VCG

current,

the

output

frequency

will

also

be

linearly

proportional

to

the

current

sum.

ni-

+1.25V

-1.25

V

wv

^0.91

SQUARE

WAVE

TRIANGLE

B

WAVE

Figure

4-2.

Simplified

Timing

Diagram

Figure

4-3.

Current

Divider

4-1

By

using

current

division,

the

magnitude

of

the

capacitor

is

effectively

increased,

allowing

the

generation

of

lower

fre

quencies.

Figure

4-3

is

the

simplified

diagram

showing

current

divider

operation.

By

reducing

integration

current

precisely

by

a

factor

of

10

while

holding

triangle

wave

amplitude

constant,

it

is

possible

to

extend

the

lower

fre

quency

range

by

a

factor

of

10

with

fixed

capacitance

C.

Since

points

A

and

B

are

at

the

equipotential

points,

constant

current

output

I

can

be

divided

by

resistance

ratio

of

R

and

9R.

Then,

Integration

current

of

capacitor

C

is

reduced

to

0.1

I.

The

lower

current

extends

the

frequency

range

of

the

function

generator

by

a

factor

of

10.

The

same

theory

is

applied

to

extend

the

frequency

range

by

a

factor

of

100.

4.3

WAVEFORM

OUTPUT

The

inverted

output

of

the

hysteresis

switch

is

fed

to

the

TTL

buffer

amplifier

and

also

the

square

wave

shaper

(figure

4-1).

The

square

wave

shaper

consists

of

a

shaping

circuit

which

limits

the

output

swing

to

±1.25

volts.

The

output

signal

from

the

triangle

buffer

amplifier

is

applied

to

the

sine

converter,

which

uses

a

diode-resistor

network

with

linear

sections

to

shape

a

sine

wave.

The

sine,

triangle

or

square

waveform

is

fed

to

the

summing

amplifier

through

the

waveform

selector

switch.

The

output

of

summing

amplifier

is

fed

through

the

amplitude

control

to

the

output

amplifier.

The

output

amplifier

is

an

inverting

amplifier

whose

output

is

capable

of

driving

10V

p-p

into

son

load

from

50n

source

impedance.

4.4

SWEEP

CIRCUITS

Sweep

rate

control

determines

the

amount

of

integrating

current

fed

to

the

positive

input

of

the

sweep

integrator

(figure

4-1).

The

output

voltage

increases

linearly

as

the

sweep

circuit

capacitor

is

charged

to

form

the

positive

slope

of

the

ramp.

As

the

ramp

output

reaches

the

preset

level

of

+5V,

the

peak

detector

turns

on

while

the

positive

feedback

circuit

holds

the

positive

output

state.

The

large

flyback

current

Ip

is

fed

to

the

negative

input

of

the

sweep

integra

tor

while

overcoming

minute

integrating

current

Ir.

Thus,

the

ramp

output

decreases

rapidly

toward

the

negative

voltage,

forming

the

negative

slope

of

the

ramp.

When

the

negative

slope

reaches

zero

volts,

the

zero

detector

turns

on,

the

peak

detector

is

unlatched

and

the

flyback

current

source

is

turned

off,

allowing

the

output

voltage

to

increase

linearly.

4-2

5

SECTION

CALIBRATION

I

5.1

FACTORY

REPAIR

Wavetek

maintains

a

factory

repair

department

for

those

customers

not

possessing

the

necessary

personnel

or

test

equipment

to

maintain

the

instrument.

If

an

instrument

is

returned

to

the

factory

for

calibration

or

repair,

a

detailed

description

of

the

specific

problem

should

be

attached

to

minimize

turnaround

time.

5.2

REQUIRED

TEST

EQUIPMENT

Voltmeter

Distortion

Analyzer

Oscilloscope

50n

(±0.1%)

Load

Counter

(6

digit)

5.3

REMOVING

GENERATOR

COVER

Remove

the

four

screws

in

the

lower

cover,

place

the

instrument

on

its

feet

and

lift

off

the

top

cover.

5.4

CALIBRATION

After

referring

to

the

following

preliminary

data,

perform

calibration,

as

necessary,

per

table

5-1.

If

performing

partial

calibration,

check

and

adjustments

for

applicability.

1.

Unless

otherwise

noted,

all

measurements

made

at

the

50n

OUT

connector

should

be

terminated

Into

a

50n

«1%,

1W)

load.

2.

Before

connecting

the

unit

to

an

ac

source,

check

the

ac

line

circuit

to

make

sure

the

115/230

volt

switch

is

set

at

the

correct

position

(see

paragraph

2.2).

3.

Start

the

calibration

by

setting

the

front

panel

switches

as

follows:

Dial

2.0

FREQMULT

X

IK

SWEEPWIDTH

OFF

SWEEP

RATE

ccw

DC

OFFSET

OFF

Function

\

AMPLITUDE

cw

4.

Allow

the

unit

to

warm

up

at

least

30

minutes

for

final

calibration.

Table

5-1.

Calibration

Chart

Step

Check

Tester

Gal

Points

Control

Setting

Adjust

Desired

Results

Remarks

1

Power

supply

regulation

Voltmeter

TP2

(TPl

ground)

R9

+15±0.01V

2

TP3

-15±0.05V

3

Distortion

analyzer

(50fi

terminated)

5on

OUT

HI

R78

R103

Minimum

distortion

5-1

Table

5-1.

Calibration

Chart

(Continued)

Step

Check

Tester

Gal

Points

Control

Setting

Adjust

Desired

Results

Remarks

4

VCG

null

Scope

(50n

terminated)

FREQIVIULTX

100K

Function

""L

Dial

full

cw

Scope

vert

2V/div

Scope

horiz

.5

ms/div

R43

Minimum

fre

quency

shift

Adjust

generator

dial

for

1

full

square

on

scope.

Alternately

short

and

open

VCG

IN

BNC

while

adjust

ing

R43.

5

Horizontal

symmetry

Scope

X

10

on

R47

Maximum

sym

metry

Alternately

switch

scope

triggering

from

positive

to

negative

slope

while

adjusting

R47.

6

Dial

0.1

FREQMULTX

10

Scope

sweep

O.ls/div

DC

triggering

R66

Maximum

sym

metry

For

180LF,

FREQ

MULT

X

1.

Scope

sweep

Is/div.

7

Frequency

accuracy

Counter

(5012

terminated)

Dial

2.0

FREQ

MULT

X

1

thru

X

10K

R39

Best

frequency

accuracy

over

X

1

thru

X

10K

8

FREQMULT

X

1M

Function

\

^

C19

Best

frequency

accuracy

for

all

waveforms

9

DC

level

Voltmeter

(5012

terminated)

FREQMULT

X

IK

Function

DC

Amplitude

ccw

R125

0

±20

mVdc

1

5-2

6

SECTION

TROUBLESHGOTiNG

6.1

FACTORY

REPAIR

Wavetek

maintains

a

factory

repair

department

for

those

customers

not

possessing

the

necessary

personnel

or

test

equipment

to

maintain

the

instrument.

If

an

inistrument

is

returned

to

the

factory

for

calibration

or

repair,

a

detailed

description

of

the

specific

problem

should

be

attached

to

minimize

turnaround

time.

6.2

TROUBLESHOOTING

CHART

Troubleshooting

charts

are

given

in

figure

6-1.

The

charts

do

not

cover

every

possible

trouble,

but

will

be

an

aid

In

systematically

isolating

faulty

components.

6.3

TROUBLESHOOTING

INDIVIDUAL

COMPONENTS

6.3.1

Transistor

1.

A

transistor

is

defective

if

more

than

one

volt

is

mea

sured

across

its

base

emitter

junction

in

the

forward

direction.

2.

A

transistor

when

used

as

a

switch

may

have

a

few

volts

reverse

bias

voltage.

3.

If

the

collector

and

emitter

voltages

are

the

same,

but

the

base

emitter

voltage

is

less

than

500

mV

forward

voltage

(or

reversed

bias),

the

transistor

is

defective.

4.

A

transistor

is

defective

if

its

base

current

is

larger

than

10%

of

its

emitter

current

(calculate

currents

from

voltage

across

the

base

and

emitter

series

resistors).

In

a

transistor

differential

pair

(common

emitter

stages),

either

their

base

voltages

are

the

same

in

normal

operating

condition,

or

the

one

with

less

forward

voltage

across

its

base

emitter

junction

should

be

off

(no

collector

current);

otherwise,

one

of

the

transistors

is

defective.

6.3.2

Diode

1.

A

diode

is

defective

if

there

is

greater

than

one

volt

(typically

0.7

volt)

forward

voltage

across

it.

6.3.3

Operational

Amplifier

(e.g.,

UA741C,

LM318)

1.

The

"+"

and

"

inputs

of

an

operational

amplifier

will

have

less

than

15

mV

voltage

difference

when

operating

under

normal

conditions.

2.

If

the

output

voltage

stays

at

maximum

positive,

its

"+"

input

voltage

should

be

more

positive

than

its

"

input

voltage,

or

vice

versa;

otherwise,

the

operational

amplifier

is

defective.

6.3.4

Capacitor

1.

Shorted

capacitors

have

zero

volts

across

their

termi

nals.

2.

Opened

capacitor

can

be

located

(but

not

always)

by

using

a

good

capacitor

connected

in

parallel

with

the

capacitor

under

test

and

observing

the

resulting

effect.

SYSTEM

CHECK

50^2

OUT

BAD

1

f

TURN

DC

OFFSET

&

SWEEP

OFF

ALL

FUNCTIONS

BAD

V

GOOD

'V

BAD

\good

Ti

BAD

YES

r

SELECT

APR

R

OX

±2v

nL

AT

JUNCTION

^

CR20,22

APPROX

±1V

\

AT

R119

WIPER

WITH

AMPLITUDE

CW

?

PPRO

GO

TO

GENERATOR

LOOP

CHECK

SW2

A

&

B

&

IC10CKT

REMOVE

R120

APPROX

±1V

\

SET

WAVEFORM

TO

L

CHECK

CR20

-

23

&

SW2

A

&

B

AT

JUNCTION

CR21,

23

OK

?

CHECK

CR20-

23

&

021

CKT

CHECK

023

-

29

CIRCUIT

REINSTALL

R120;

^

NO,

CHECK

R119

WITH

AMPLITUDE

CW

?

REINSTALL

Figure

6-1.

Troubleshooting

Chart

(Sheet

1

of

4)

6-2

GENERATOR

LOOP

CHECK

NO

±1.25V

'V

AT

6

106

REGULATED

<+

&

-

15

Vdc

AT

TP2

&

TP3

115/220V

SWITCH

&

POWER

CONNECTION

'

OK

?

+24

Vdc

ON

C2

(+)

8,^-24

Vdc

ON

C1

(-)

YES

GO

TO

POWER

SUPPLY

REGULATOR

CHECK

DIODES

CRl

-4

OK

YES

CHECK

XFMR

<

ROTATE

DIAL

FROM

TOP

TO

BOTTOM;

+15V

T0~15

mV

SHIFT

AT

E6

r

WIRING

E5

-7

OK

YES

DIAL

POTENTIO

METER

BAD

<

ROTATE

DIAL;

0

Vdc

WITH

NO

SHIFT

AT

3IC4

^ES

ROTATE

DIAL;

APPROX

-15V

TO

lOV

SHIFT

AT

PINS7.4,2

&

+15V

TO

+10V

SHIFT

AT

PINS

10,13

IC5

?

^^ES

^±2

Vdc

ATJUNCTION

&

--+1.25

Vdc*

AT

JUNCTION

CR11.CR13

?

PROBLEM

IN

IC4

CIRCUIT

&

PNP

AT

PINS?

ICS

OK

PROBLEM

IN

ICS

CIRCUIT

CHECK

018

•

20

CR14,

15

&

IC7

CIRCUIT

CR10-

13

&

SW1

A,

B,C

OK

SAME

Vdc

AT

PINS

3,

8

ICS

CIRCUIT

OK

+1.25

Vdc

AT

8

ICS

CHECK

GIB

-

20,

CR14,

15

&

IC7

CIRCUIT

YES

CHECK

CR14,

15

THE

TOP

OR

BOTTOM

OF

THE

SQUARE

AND

TRIANGLE

WAVEFORMS.WHICH

INDICATES

A

LOCKED

UP

GENERATOR

Figure

6-1.

Troubleshooting

Chart

(Sheet

2

of

4)

6-3

POWER

SUPPLY

REGULATOR

CHECK

^NO

REGULATED

+

&^

-IBVdc

AT

TP2

8<TP3;

V

FUSE

OK

y

UYES

+15

Vdc

REG

NEAR

OV

YES

NO

YES

NO

+15

Vdc

REGULATOR

IS

ASSUMED

TO

BE

IN

CURRENT-LIMIT

MODE

-15

Vdc

REG

NEAR

OV

+15

Vdc

REGULATOR

IS

ASSUMED

TO

BE

DEFECTIVE

YES

NO

-15

Vdc

REGULATOR

IS

ASSUMED

TO

BE

IN

CURRENT-LIMIT

MODE

R1

&

03

OK

-15

Vdc

REGULATOR

IS

ASSUMED

TO

BE

DEFECTIVE

YES

R13

&

07

OK

YES

05

-8

&

iC2

CKT

OK

YES

"-24

Vdc

UNREGULATED

\

GOOD

/

+15

Vdc

^

PARTIALLY

REGULATED

'^1

•

4>

CR5

&

IC1

CKT

OK

ISOLATE

LOW

Z

BY

LIFTING

+15V

JUMPERS

ISOLATE

LOW

Z

BY

LIFTING

-15V

JUMPERS

Figure

6-1.

Troubleshooting

Chart

(Sheet

3

of

4)

6-4

Wavetek 180 User manual

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