Trio CASA VT-150 User manual

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2

CHANNEL

SOLID

STATE

VOLT

METER

VT-15[]

INSTRUCTION

MANUAL

~TRIO

I

"

I

"I

I

1.

2.

).

4.

CONTENTS

FEATURES

...........................................

SPECIFICATIONS .....................................

CIRCUIT DESCRIPTION

OPERATING

INSTRUCTIONS

.............................

Page

2

3

5

7

5.

CAUTION

ON

HANDLING

THE

SET

•••••••••••••..••••••.••

12

6.

BLOCK

DIAGRAM,

SCHEMATIC

DIAGRAM

&

DRAWING

OF

EXTERNAL

VIEW

....•••..•.........

13

FEATURES

2~~~~------------------------------------------------

FEATURES

The

model

VT-150

is

a

2-channel

solid-state

voltmeter

with

an

r.m.s.

scale.

It

provides

facilities

to

make

an

accurate

and

stable

voltage

measurement

from

a

minute

voltage

of

1

mV

up

to

300

V

with

'frequencies

of

10

Hz

to

500

kHz.

The

model

VT-150

has

an

extremely

high-sensitivity.

So,

it

may

also

be

used

for

measurement

of

the

noise

of

power

source

and

others,

not

to

speak

of

general

measurements.

Further,

it

may

be

used

as

a

high-gain

amplifier.

FEATURES

**

All

solid-state

circuitry

provides

minimum

warm-up

time

and

small

power

consumption.

**

2-pointer

meter

promises

more

effective

uses

of

a

space

com-

paring

with

those

provided

by

two

sets

of

conventional

voltmeter.

**

Frequency

bandwidth

of

10

Hz

to

500

kHz

and

voltage

range

of

1

mV

to

JOO

V

available

for

various

uses.

**

Metal-film

resistor

with

a

low

temperature

coefficient

and

less

secular

change

employed

as

attenuator

resistor.

**

Voltage

regulator

circuit

provided

in

power

supply

circuit.

**

Voltage

scale

graduated

in

r.m.s.

values

of

sine

wave

voltages,

dB

and

dBm

scales

-

easy

means

provided

specifically

for

measure-

ment

of

S/N

and

so

on.

**

Monitor

output

terminals

provided

for

connection

of

an

oscil-

loscope

and

the

likes.

VOLTMETER

Voltage

range

Accuracy

dB

dBm

Frequency

response

(Reference

of

1kHz)

Input

impedance

Change

due

to

power

Source

voltage

vari-

ation

Temperature

coef-

ficient

Operating

temper-

ature

Rated

Max.

input

voltage

Channel

isolation

SPECIFICATIONS 3

2 SPECIFICATIONS

1mV

full

scale

to

300V

full

scale

in

12

range

(0.001/0.003/0.01/0.03/0.1/0.J/1/3/10

30/100/300)

-80

to

+50 dB

(0

dB

= 1V)

-80

to

+52

dB

(0

dB =

1mW,

6oo

Q)

=3%

of

full

scale

reading

(At

1

kHz)

±10%

from

10Hz

to

500kHz

±

5%

from

20Hz

to

250kHz

=

3%

from

20Hz

to

100kHz

1M

Q

shunted

by

45

PF

or

less

Within

±0.5%

of

full

scale

reading

against

±10%

variation

of

power

source

voltage

DC

component

±400V

AC

component

300Vr.m.s.

for

0.3V

range

or

.:

lower

500Vr.m.s.

for

1V

range

or

higher

80

dB

or

more

(When

each

channel

operated

separately,

with

range

set

at

1V

and

one

of

channels

input

terminal

open)

50

dB

or

more

(When

both

channel

co-operated,

with

range

set

at

1V

and

one

of

channels

input

terminal

open)

MONITOR

OUTPUT

CHARACTERISTIC

Gain

Output

voltage

Approx.

40 dB

:

Approx.

1V

4

SPECIFICATIONS

Frequency

response

Output

impedance

Distortion

facter

S/N

POWER

REQUIREMENT

DIMENSIONS

WEIGHT

ACCESSORIES

Within

:2

dB

from

10Hz

to

500kHz

(Reference

of

1kHz)

Approx.

600Q

1o/o

or

less

at

full

scale

reading

(At

1kHz)

40

dB

or

more

at

full

scale

reading

AC100V,

117V,

2JOV (:10o/o)

50/60Hz

5W

MAX.

W140(144)

x

H200(225)

X

D235(277)mm

Dimensions

in

( )

are

those

which

contain

all

protrusions.

J.?Kg

(7

.lbs)

2

test

leads

(CA-36)

with

a

dual

banana

plug.

2

plugs

with

M

type

binding

post

Two

0.5A

and

0.2A

fuses

One

instruction

manual

CIRCUIT

DESCRIPTION 5

3

CIRCUIT

DESCRIPTION

See

the

block

diagram

and

the

circuit

diagram

shown

in

page

13.

ATTENUATOR

(I)

When

the

12-

range

selector

switch

is

set

to

any

range

of

0.001V

to

O.JV

range,

the

output

voltage

of

this

attenuator

becomes

equal

to

the

input

voltage.

When

the

switch

is

set

to

1V

range,

the

input

voltage

is

at-

tenuated

60

dB

by

voltage

divider

resistors

R101

and

R10J.

The

frequency

compensating

trimmer

capacitors

is

adjusted

properly

at

a

frequency

of

100kHz.

AMPLIFIER

(I)

Amplifier

(I)

consists

of

a

high-input

impedance

circuit

employing

an

FET(2SK1J-Y).

It,

consisting

mainly

of

Q1(2SK1J-Y)

and

Q5(2SC458(LG)C),

forms

an

amplifier

circuit

having

a

gain

of

20

dB

with

a

negative

feedback

of

13

dB

provided

to

insure

said

gain.

QJ(2SA562-Y)

is

the

transistor

inserted

to

compensate

the

drift

of

Q1

owing

to

variation

of

the

temperature.

While,

Q7(2SC458(LG)C)

is

an

emitter

follower

which

connects

the

output

of

this

amplifier

to

the

second

attenuator.

Diodes

D1

and

DJ(1S2075{K))

are

those

inserted

to

protect

Q1.

ATTENUATOR

(

II)

Attenuator

(II)

provides

facilities

to

divide

all

input

voltage

into

approx.

0.01V

for

application

of

its

output

to

the

amplifier.

In

other

words

this

attenuator

exerts

an

attenuation

of

up

to

50

dB

to

the

input

voltages

on

ranges

of

0.001

to

O.JV.

When

the

12

range

selector

switch

is

set

to

1V

range,

the

input

voltage

is

attenuated

60

dB

by

the

attenuator

(I),

so

that

this

at-

tenuator

is

connected

to

the

circuit

for

0.001V

range.

AMPLIFIER

(II)

The

Darlington

circuit

comprising

Q9

and

Q11

receives

the

6

CIRCUIT

DESCRIPTION

output

of

attenuator

(II)

with

a

high

impedance

and

delivers

its

out-

put

through

transistor

Q11

serving

as

an

emitter

follower

with

a

low

output

impedance

to

the

stage.

This

amplifier

provides

a

gain

of

approx.J8

dB

at

1kHz

with

a

negative

feedback

of

about

22

dB

provided

to

insure

said

gain.

The

amplifier,

operating

in

combination

with

amplifier

(I),

forms

an

amplifier

circuit

providing

an

overall

gain

of

58

dB

and

an

overall

negative

feedback

of

35

dB.

RECTIFIER

The

rectifier,

consisting

of

a

full-wave

rectifier

circuit,

applies

the

DC

voltage

directly

in

proportion

to

the

mean

value

of

input

voltages

to

the

meter

to

deflect

its

pointer.

METER

The

meter

is

a 1

rnA,

2-pointer

DC

meter

with

an

internal

resistance

of

200

Q.

It

is

provided

with

2

magnets

within

a

single

case

and

gives

indications

equivalent

to

those

of

two

sets

of

a

voltmeter.

It

has

a

voltage

scale

graduated

in

r.m.s.

values

of

sine

wave

voltages

(0

to

10

and

0

to

J)

and

dB

and

dBm

scales

graduated

as

10

= 0

dB

and

1

mW

(600

Q) = 0

dBm

respectively.

POWER

SUPPLY

The

power

supply

is

of

the

series

regulator

tape.

It

keeps

the

output

voltage

to

a

constant

value

by

regulating

the

voltage

by

transistor

Q1

(2SD90)

under

control

of

transistor

Q2

(2SC~58

C

),

which

compares

the

reference

voltage

provided

by

diode

D2

(ZB1-12)

to

the

voltage

obtained

by

detecting

the

output

voltage

and

applies

the

difference

voltage

thus

obtained

to

transistor

Q1.

It

supplies

a

DC

voltage

of

23

V

as

+B

supply

to

the

circuit.

OPERATING INSTRUCTIONS 7

4 OPERATING

INSTRUCTIONS

1.

OPERATING

OF

CONTROLS

ON

THE

PANEL

This

voltmeter

is

provided

with

the

controls

on

the

pe1nel

shown

in

the

table

below

and

external

view.

REF.

NO.

MARKING

ON

PANEL DESCRIPTION

(

1)

(NEON

LAMP)

Neon

lamp

which

lights

when

POWER

;:,",witch

is

turned

to

ON.

(2)

POWER

Power

ON-OFF

switch

Throwing

this

switch

in

the

upper

position

turns

on

the

set.

(3)

CH

1 & 2

Attenuator

having

12

positions

to

provide

an

attenuation

to

the

input

voltage

in

10

dB

step.

It

serves

as

the

voltage

range

selector

switch

for

CH1

and

CH2,

when

the

voltmeter

is

set

for

operating

CH1

and

CH2

co-operated.

(4)

CH

2

Attenuator

having

12

positions

to

provide

an

attenuation

to

the

input

voltage

in

10

dB

step.

It

serves

as

the

voltage

range

selector

switch

for

CH2.

(5)

INPUT 1

CHi

input

terminal

(6)

INPUT 2

CH2

input

terminal

·--····~····

"'

..

<

(

7)

GND

Grounding

terminal

(8)

GND

Grounding

terminal

S OPERATING INSTRUCTIONS

REF.

NO.

MARKING

ON

PANEL DESCRIPTION

(9)

CH

2 SELECTOR

In

the

right-

hand

position

of

this

switch

it

allows

the

CH2

attenuator

(4)

to

select

a

voltage

range

for

channel

2.

In

the

left-hand

position,

the

switch

causes

the

set

t_o

operate

CH1

and

CH2

simultaneously

and

allows

the

CH1 & 2

attenuator

(J)

to

select

a

voltage

range

for

both

CH1

and

CH2.

(

10)

Mechanical

zero

adjustment

for

the

pointer

provided

for

channel

CHi.

(

11)

Mechanical

zero

adjustment

for

the

pointer

provided

for

channel

CH2.

(

12)

CH

1

OUTPUT

Monitor

output

terminal

which

provided

for

connecting

CH1

signal

under

measurement

to

an

oscilloscope

and

others

to

observe

the

waveform.

(

13)

CH

2

OUTPUT

Monitor

output

terminal

which

provided

to

observe

CH2

signal

in

the

same

manner

as

CH1 OUTPUT.

(

14)

Power

source

selector

switch

for

AC

100,

117

or

230

v,

50

or

60

Hz.

(.15)

Fuse

(

16)

Power

cord

Trio CASA VT-150 User manual

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