Dyna FM-3 - Multiplex Integrator Alignment

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Dynatuners

supplied

with

optional

power transformel'

PB-012

can

be

wired

for

use

with

either

120

or

240 volt,

50

or

60

cycle

AC

power

sources,

as

follows:

BLACK

VIOLET

8

WHITE

t

BLACK

8

WHITE

.

VIOLET

~

240·yolt

VIOLET

:,

aWHITE

,

BLACK

i

aWHITE

~

VIOLET

-(

35(

)

Unsolder

the

1.2

megohm

resistor

from

the

V71

ground

pin

and

eyelet

# 88.

It

can

be

saved

for

future

use

when

realignment

is desired.

36( )

Unsolder

the

green wire from

eyelet

# 88

and

re-

connect

it

to

eyelet

#75

(8).

This

completes

the

alignment

of

your

Dynatuner.

No

further

alignment

should

be

required

unless

there

is a

change

in

tubes

or

components.

When

necessary,

you

have

the

means

of

realigning

it

so

that

your

Dynatuner

will

always

be

at

the

very

peak

of

its

performance

capabilities.

However,

one

word

of

caution

is

in

order-do

not

make

these

adjustments

unnecessarily,

as

the

various

slugs will

eventually

loosen

and

cause

tuning

shifts

to

the

detriment

of

performance.

Alignment

adjustments

should

be

con-

sidered

as a

semi-permanent

type

of

adjustment.

Reassemble

the

tuner,

making

sure

the

COVel'

front flange

slips

between

the

aluminum

front

plate

and

the

steel

panel.

Your

STEREOMATIC

Dynatuner

is now

ready

for long pleas-

urable

use.

120-yolt

For

120

Volt

Operation

1 ( )

Twist

together

the

black

and

black-white

power

transformer

leads.

Connect

both

leads

to

lug

#2

of

the

AC

outlet.

2( )

Twist

together

the

violet

and

violet-white power

transformer

leads.

Connect

both

leads

to

lug

# 2

of

the

fuse

holder

(8-2).

For

240

Volt

Operation

1( )

Twist

together

the

black

and

the

violet power

trans-

former

leads.

Connect

the

black

lead

to lug #2

of

SPECIAL INSTRUCTIONS FOR

OPTIONAL

120-240

VOLT

POWER

TRANSFORMERS

BLACK

32(l

).

Unsolder

the

end

of

the

1.2

megohm

resistor sol-

dered

to

eyelet

#75,

and

temporarily

solder

it

to

\

eyelet

#88.

This

is

the

other

test

point

TP.

33(

\j)

Unsolder

the

green wire

connected

to

eyelet

#75

,and

temporarily

connect

it

to

eyelet

#88

(8).

34

(

')

Adjust

the

top

slug

of

transformer

T73

for maxi-

mum

closing

of

the

STEREOCATOR.

Then

adjust

the

bottom slug of

T73

for

maximum

closing of

the

STEREOCATOR.

Repeat

these

adjustments,

first

with

the

top,

and

then

the

bottom

slug,

until

the

beam

closes

no

further.

To

obtain

a sufficiently weak signal,

it

may

be

nec-

essary

to remove

the

antenna

and

substitute

a

short

piece

of wire.

Shorting

out

half

the

antenna

is

another

alternative.

With

signals

of

this

magnitude

(a

very few

microvolts)

it

will be

noticed

that

the

eye

is

sensitive

to

flutter

as

a

result

of

airplanes

passing

overhead,

or

varying

signal

strength

as

a

result

of

atmospheric

conditions.

Care

must

be

taken

not

to allow

this

sensitivity

to influence

the

actual

/

adjustment

of

C1-B

and

CloD.

30

(J)

Tune

carefully

to a

station

near

88

megacycles

and

adjust

the

two

brass

slugs

in

the

mixer

coil L3

and

the

R.F.

coil

Ll

for

maximum

eye

closing.

The

last

two

adjustments

should

be

repeated,

since

there

is

interaction

between

adjust~ent

of

the

trimmer

capac-

itors

and

the

slugs

of

the

coils.

This

adjustment

of

Ll

and

L3

is

not

critical,

and

may

be

a

broad

peak,

necessitating

an

approximate

center

setting,

but

the

accuracy

of

adjust-

ment

of

Cl-B

and

Cl-n

has

a very definite

correlation

with

the

tuner's

effective

sensitivity,

so

that

extra

care

here

will

be

well

repaid

in

superior

performance.

Alignment

of

the

Multiplex

Integrator

The

basic

Dynatuner

alignment

in

the

preceding

sections

should

be

carried

out

before

aligning

the

multiplex

inte·

grator.

In

particular,

the

discriminator

must

be accurately

aligned

if

maximum

noise

rejection

is

to

be realized,

and

this

becomes

doubly

important

in

stereo

operation,

for

the

effective

sensitivity

and

noise

rejection

of

any

tuner

is

lower

in

stereo

than

in

the

mono

mode.

The

tuner

must

have

an

antenna

connected,

but

it

is

not

necessary

for

an

amplifier

and

speaker

to be

connected

for

this

part

of

the

alignment.

Tune

precisely to a

known

stereo broadcast, for

this

part

of

the

aligrunent

involves

tuning

the

multiplex

transformers

to

the

19KC

pilot

signal

which is

an

integral

part

of

every

stereo

broadcast.

You

can

enjoy

normal

monophonic

reception

prior

to

alignment

of

the

multiplex

integrator,

since

its

adjustments

affect

only

the

separation

of stereo'

programs.

Push

the volume control

"IN"

so

that

it

is

in

the

normal

STEREOMATIC

operating

position.

The

upper

beam

of

V8

is

the

STEREOCATOR.

After

alignment,

it

will be

either

fully

open

or

fully

closed

whenever

you

are

tuned

tCl

a

station,

and

thus

will

illuminate

or

turn

off

the

word

STEREO

printed

on

the

plastic

insert

in

the

front

panel.

Between

stations

the

ambient

noise

may

cause

it

to

flicker,

but

this

is

of

no

consequence.

You

will

be

able

to

see

the

STEREOCATOR

quite

well

dur-

ing

alignment

if

you

look

down

on V8 from above,

but

if

you

wish to

observe

its

operation

more

easily, remove

the

knobs,

front

plate

and

plastic

insert.

31 (

v)

Temporarily

connect

one

end

of

the

1.2

megohm

(brown-red-green)

resistor

R94 to

the

center

ground

pin

of V71

(8).

Temporarily

connect

the

other

end

to

eyelet

#75

(8).

Eyelet

#75

is

one

test

point,

and

is

marked

with

the

letters

TP

on

the

bottom

of

the

board.

Using

the

shoulder

end

of

the

alignment

tool,

adjust

transforme.'

T7l

for

maximum

closing

of

the

STEREOCATOR.

Then

adjust

transformer

T72

for

maximum

closing

of

the

STEREOCATOR.

Repeat

these

adjustments,

first

with

T71

and

then

with

T72,

until

the

beam

closes

no

further.

Usually

only

a

small

adjustment

will be

necessary.

19

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