Harman Kardon TX20 Owners Manual - Page 4

AM

Antenna:

The

Harman-Kardon

ferrite

loopstick

built

into

the

Serenade

comprises

all

the

antenna

required

for

the

fi

nest

in

noise

-free

local

AM

reception.

In

locations

more

removed

from

metropolitan

areas,

an

outdoor

antenna

may

be

required.

This

should

consist

of

a

single

wire,

as

long

as

is

reasonably

practi-

cal.

It

should

be

kept away

from

large

metal

objects,

power

lines

or

electrical

machinery.

Connect

one

end

of

the

outdoor

antenna

to

the

terminal

marked

"AM"

on

the

Antenna

Terminal

Strip

located

at

the

rear

of

the

chassis.

OPERATING

INSTRUCTIONS

The

Serenade,

Model

TX20

tuner

incorporates

the

following

operating

con-

trols

located

on

the

front

panel.

Viewing

the

instrument

from

the

left

you

will

note

a

FUNCTION

SELECTOR

switch

and

on

the

extreme

right

the

TUNING

control.

The

FUNCTION

SELECTOR

switch

has

4

positions

reading

clockwise:

OFF,

FM

-AFC,

FM

and

AM.

To

operate

turn

the

switch

to

the

desired

operating

position.

This

automatically

turns

the

set

on.

Now

tune

for

the

desired

AM

or

FM

station.

The

volume

level

and

tone

must

be

controlled

by

the

controls

on

your

amplifier.

TECHNICAL

EXPLANATION

OF

THE

CONTROLS

Automatic

Frequency

Control:

(AFC)

FM

Broadcasting,

by

its

very

nature,

eliminates

almost

all

natural

and

man-

made

static.

However,

the

characteristics

of

FM

which

makes

this

possible

also

causes

problems

in

tuning.

The

Serenade

incorporates

a

special

electronic

cir-

cuit

known

as

Automatic

Frequency

Control

that

overcomes

these

problems

and

insures

proper

tuning

even

if

the

manual

tuning

is

not

accurately

done.

There-

fore

AFC

always

keeps

the

station

in

the

center

of

the

channel

and

eliminates

distortion

caused

by

inaccurate

tuning.

The

following

experiment

will

lead

to

an

understanding

of

AFC,

and

the

fuller

enjoyment

of

the

tuner.

Tune

across

the

FM

scale

with

the

Function

Switch

in

the

FM

-AFC

position.

Note

how

the

stations

"pop"

into

place.

Now

tune

to

any

station,

preferably

one

with

a

musical

program.

Defeat

the

AFC

by

turning

the

Function

Selector

Switch

to

the

FM

position,

and

tune

slowly

through

the

station

from

left

to

right.

Notice

there

are

three

distinct

points

where

the

station

sounds

clear,

interspersed

with

points

of

distorted

sound.

The

middle

clear

-sounding

point

is

the

proper

tuning

position

for

the

best

tone

quality

with

minimum

noise

and

interference.

Detune

the

station

so

that

the

sound

is

distorted.

Now

turn

the

Function

Selector

Switch

to

the

FM

-AFC

position,

and

notice

how

the

sound

clears

up.

The

tuning

has

been

readjusted

by

the

operation

of

the

AFC

circuit,

which

automatically

retunes

the

electronic

circuits

to

the

center

of

the

station

channel.

In

order

to

take

maximum

advantage

of

the

benefits

of

AFC,

it

is

suggested

that

fi

ne

tuning

be

done

with

the

Function

Switch

in

the

FM

position.

When

the

switch

is

then

turned

to

the

AFC

position

the

AFC

will

improve

this

care-

ful

tuning

by

a

factor

of

10

to

1.

The

procedure

is

especially

recommended

when

a

weak

station

is

being

tuned

on

a

channel

adjacent

to

a

stronger

one.

This

will

prevent

the

AFC

from

reaching

for

the

powerful

signal

and

skipping

over

the

weaker

one.

If

the

weaker

station

is

tuned

in

without

the

AFC,

when

the

AFC

is

applied

it

will

lock

it

in

permanently.

AM

Operation:

The

AM

portion

of

the

tuner

operates

in

very

much

the

same

manner

as

any

radio

and

the

same

procedure

should

be

followed

in

tuning.

Harman Kardon TX20 Owners Manual - Page 4

understanding

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