Panasonic RF-2800LBS Manuale

ORDER

No.

RD8003-T1030

Technical

Information

Radio

Poriable

ado

RF-2800LBS

RF-2900LBS

Subject:

Frequency

Counter

Circuit

Table

of

Contents

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Outline

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Counter

Signal

Circuit...........

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page

5

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Signal

Selector

Circuit

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page

6

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Matsushita

Electric

Trading

Co.,

Ltd.

Panasonic

P.O.

Box

288,

Central

Osaka,

Japan

RF-2800/RF-2900

Frequency

Counter

Circuit

4

|.

Outline:

The

RF-2800/RF-2900

displays

the

frequency

of

the

received

broadcast

by

counting

the

frequency

of

the

local

oscillator

and

scaling

accordingly.

Figure

1

is

a

block

diagram

for

the

receiver.

The

following

relationships

exist

between

the

reception

frequency

(fs),

the

local

oscillator

frequency

(fo),

the

intermediate

frequency

(fi)

and

the

display

frequency

(fo).

(A)

fs+fi=fo...(1)

.

(B)

fo=fs=fotfi...

(2)

LOCAL

OSC

.,

CONVERSION

COMMAND

DEVICE

Fig.

1

With

reference

to

figure

1,

for

example

Reception

frequency

(fs)=10

MHz

Intermediate

frequency

(fi)=455

kHz

Under

these

conditions,

the

local

oscillator

frequency

(fo)

must

be,

according

to

formula

(1),

10.455

MHz

(called

“upper

local

oscillation’’)

or

9.545

MHz

(called

“lower

local

oscillation’’).

Thus,

if

10.455

MHz

is

used

as

the

local

oscillator

signal:

Display

frequency

(fo)=

10.455

(fo)

—

0.455

(f)=

10

MHz

(fs)......

(3)

Therefore,

the

display

frequency

is

equivalent

to

the

reception

frequency.

The

subtraction

of

the

0.455

MHz

(fi)

is

accomplished

by

the

conversion

command

device

to

the

counter.

if

the

unit

were

designed

to

use

the

lower

local

oscillator

frequency,

a

signal

(preset

frequency=

+

0.455

MHz)

would

be

applied

to

the

counter

in

order

to

add

0.455

MHz.

At

the

same

time,

in

models

which

use

different

frequency,

such

as

2

MHz,

for

the

intermediate

frequency

(fi),

a

conversion

signal

is

applied

to

the

counter

in

order

to

add

(or

subtract)

2

MHz,

so

that

the

reception

frequency

will

be

correctly

displayed.

In

short,

the

conversion

signal

must

be

equal

to

+fi.

-

ll.

Block

Diagram

Figure

2

is

a

chart

of

the

reception

frequency,

local

oscillator

frequency

and

intermediate

frequency

for

each

band.

Intermediate

Local

Osc.

Frequency

(MHz)

Frequency

(MHz)

Frequency

(MHz)

10.7

98.2

~

118.7

LW

0.150

~

0.410

0.605

~

0.865

8.0

~

16.0

2.

|

10.0

16.0

~

30.0

2

|

18.0

Fig.

2

Because,

the

upper

local

oscillator

frequency

is

used

the

conversion

signal

is

subtracted

from

the

counter

circuit

for

each

band.

As

can

be

understood

from

the

table

in

figure

2,

an

intermediate

frequency

of

10.7

MHz

is

used

for

the

FM

band.

Because

the

upper

local

oscillator

frequency

is

used,

the

reception

frequency

is

displayed

after

10.7

MHz

has

been

subtracted

from

the

local

oscillator

frequency.

For

the

LW,

MW

bands,

455

kHz

is

subtracted

from

the

local

oscillator

frequency.

For

the

SW

bands,

2

MHz

is

subtracted

from

the

local

oscillator

frequency.

Figures

3

and

4

are

block

diagrams

which

include

the

RF,

Local

Oscillator,

IF

and

Counter

circuits.

The

subtraction

is

accomplished

through

logic

signals

applied

to

pins

3,

4,

5

and

6

of

IC902.

ANT

F

RF

AMP

IF

;

\F

AMP

'

IF

AMP

LOCAL

OSC

C101

Q103

3

1101

COUNTER

BUFFER

e164

PRE-AMP

(3)

River

AM

CIRCUIT

Q901,0902

1C901

0000

FM

Circuit

0

O

©

is

COUNTER

O

AMP

(2)

Ree

DISPLAY

O

si7

Q907

1c902

2)

Swt/Swe/Sw3

TUNING

CIRCUIT

L410,L109,

L108

CIRCUIT

£102

EP

NOTE:

1.8902

terminal

Nos.

3.4.5,6:for

Preset

L.

condition

in

terminals

3,4..5

and-6):—10.7MHz

2.

$1:Band

Selector

FMLW/MW/SW1/SW2/SW3

Fi

ig.

3

FM

Section

Block

Diagram

shown

at

FM

position

C101

FM

O

==

©

.

SW

2nd

MIX

2)

T102

—™

1102

15

O

RF

AMP

Q108

:

SWITCHING

Ei

Q105,

Q106

000000

“oO

l

O

TUNING

O

CIRCUIT

a

COUNTER

PRE-AMP

G}

oriver

(8)

AMP

@}

circuit

DISPLAY

Nore

Q901,0902

Ic901

a908

1C902

$1

Band

Selector

o

FM/LW/MW/SW1/SW2/SW3

(Q)@&E)

shown

in

MW

position.

OSC

COILS

L118,L117,

L1t6,0115.

L114

IC902

terminals

'3)..4),.5':and

6,

For

Preset

Fig.4

LW/MW/SW

Section

Block

Diagram

lll.

Preset

Selector

Circuit

Figure

5

shows

the

relationship

between

the

preset

terminals

(3,

4,

5

and

6)

of

IC902

and

the

preset

frequency.

Preset

terminal

Band

|

Preset

Frequency

(MHz)

Fig.

5

Figure

6

shows

the

preset

selector

circuitry.

COUNTER

CIRCUIT

IC902

CONNECTER

CP2-CS2

$1-9

:

O

LW

MW

SW1SW2SW3

a

or

oy

DISPLAY

Preset

terminal

A.

For

FM:

(a)

Terminal

6

of

IC902

becomes

an

‘'L”

level.

(through

connectors

1—-L120—Pin

7-+GRND)

(b)

Terminal

5

of

IC902

becomes

an

‘'L"

level.

(through

S1—9

.—Connector

2.)

(c)

Terminal

4

of

C902

becomes

an

“'L”’

level.

(through

S1—-9—»

D106—+Connector

3)

(d)

Terminal

3

of

IC902

is

set

at

an

‘‘L”’

level.

(through

S1—9->Connector

4)

As

a

result,

(refer

to

the

table

in

figure

5)

the

counter

circuit

subtracts

10.7

MHz

from

the

local

oscillator

frequency

(the

input

signal),

and

the

result

is

displayed

as

the

reception

frequency.

B.

Inthe

same

way,

for

the

LW,

MW

and

SW

bands

the

condition

of

each

preset

terminal

is

changed

by

the

band

selector

(S1—9)

consenquently,

the

preset

frequency

shown

in

the

table

in

figure

5

is

obtained,

and

the

correct

reception

frequency

is

displayed.

IV.

Counter

Signal

Circuitry

Figure

7

shows

the

counter

signal

circuitry.

A.

For

each

band,

the

local

oscillator

signal

from

the

local

oscillator

circuitry

is

selected

(FM,

LW,

MW

or

SW)

by

SW-A,

and

is

supplied

to

terminal

3

of

the

driver

circuit

(IC901).

B.

This

signal

is

frequency

divided

(1/8)

by

IC901,

and

is

output

from

terminal

8.

At

the

same

time,

a

signal

(frequency

divided

by

1/80)

is

output

from

terminal

9.

DRIVER

CIRCUIT

C901

COUNTER

CIRCUIT

IC902

Counted

Frequency

from

Local

OSC

(9)

X'tat

OUT

FM:

98.2--118.7

MHz

LW:

605~865

kHz

MW:

987~2.072

kHz

Preset

DISPLAY

terminal

SW1:

5.2--

10.0

MHz

SW2:

10~18

MHz

SW3:

18~

32

MHz

C.

These

two

output

signals

are

selected

(by

SW-B):

the

1/8

frequency

divided

output

(from

terminal

8)

for

the

LW,

MW

band

and

SW:~SWSs

bands,

and

the

1/80

frequency

divided

output

(from

terminal

9)

for

the

FM

band

are

applied

to

the

input

terminal

(terminal

2)

of

the

counter

circuit

(IC902).

D.

These

frequencies

are

converted,

by

!C902,

into

the

original

local

oscillator

frequencies.

Moreover,

depending

upon

the

signal

applied

to

the

preset

terminals,

the

necessary

frequency

for

each

band

is

subtracted

from

the

derived

local

oscillator

frequencies

and

the

resulting

frequency

is

supplied

to

the

display.

V.

Signal

Selector

Circuitry

Figure

8

shows

the

signal

selector

circuitry

for

the

counter.

A.

For

the

FM

band,

since

the

band

selector

(S1-9)

is

in

the

‘‘FM”’

position,

the

base

of

each

transistor

(Q904,

Q905

and

Q906)

becomes

an

‘‘L”’

level,

consenquently,

Q904

and

Q905

turn

on,

and

Q906

turns

off.

As

a

result,

the

signal

from

the

FM

band

local

oscillator

flows

as

shown

below,

and

is

counted

at

the

counter

circuitry.

FM

Local

osc

+

C902

—

Q901

—»

Q902

-»

C908

—

IC901(3)

—

IC901(9)

+

C914—»

Q907

—

IC902(2)

In

this

case

instance,

the

local

oscillator

circuitry

for

the

LW,

MW

and

SW

bands

does

not

function

(refer

to

figures

3,

4

and

the

+B

selector).

The

signal

(AM)

from

the

1/8

frequency

divider

is

output

from

terminal

8

of

|C901.

However,

because

Q905

is

turned

on

thus

shorting

its

collector

to

emitter

junction,

the

base

to

emitter

junction

of

Q908

is

also

shorted,

therefore,

the

signal

current

can

not

flow

to

the

counter

circuit.

NOTE:

é

ot

$1-8:

Band

Selector

Sw3

Se

te

a

FM/LW/MW/SW1/SW2/SW3

CLP

UP

Ail

FS.

shown

at

FM

position.

@)

+

G):

ee

»)

|

cp2

CONNECTOR

'

©

6)

O|

a

R908

DRIVER

CIRCUIT

—>

Q904

1c901

/8

R901

COUNTER

CIRCUIT

Ic902

FM

BAND

C902

Q901

Q902

LOCAL

OSC

i)

(Sh

CIRCUIT

ss

el

c303

AM

BAND

LOCAL

Osc].

CIRCUIT

R907

(2)

INPUT

Fig.

8

B.

For

the

LW,

MW

and

SW:~SWs

bands,

Si-9

is

open,

the

base

(Q904,

Q905

and

Q906)

become

an

‘‘H”

level,

consenquently

Q904

and

Q905

turn

off,

and

Q906

turns

on.

As

a

result,

transistor

Q907

turns

off

(base

to

emitter

junction

shorted

by

Q906)

which

results

in

Q901

turning

off.

Therefore,

the

signal

from

the

AM

local

oscillator

circuit

flows

as

shown

below,

and

is

supplied

to

the

counter

circuitry

(IC902).

AM

local

osc

—

C903

—

Q902

—

C908

—

1C901(3)

—

1C901(8)

—

C912

—.

Q908

—.

IC902(2)

In

this

case,

the

local

oscillator

circuitry

for

the

FM

band

does

not

function.

The

above

is

a

description

of

the

operation

of

the

frequency

counter

circuitry

for

models

RF-2800/RF-2900.

The

frequency

counter

circuitry

for

other

models

is

similar.

Refer

to

RF-4900

Technical

Information

(Order

No.

RD8002-T

1028),

because

the

counter

circuitry

for

models

RF-2800/RF-2900

uses

the

same

LSI

as

model

RF-4900.

|

RD

®

x!

Printed

in

Japa

EM/LVW/MW/SW

6-BAND

PORTABLE

RADIO

Mi

SPECIFICATIONS

Frequency

Range:

FM

LW

MW

SW:

SW2

SWs3

Intermediate

FM

87.5~108

MHz

150~410

kHz

(2000~731m)

525~1610

kHz

(571~186m)

3.2~8

MHz

(93.8-~37.5m)

8~16

MHz

(37.5~18.7m)

16~30

MHz

(18.7~10m)

10.7

MHz

Frequency:

AM

(LW,

MW

&

SW)

455

kHz

Sensitivity

:

FM

LW

MW

SW;

SW2

SWs

2.5uV

(S/N

26

dB),

2uV

(3

dB

down

limitter

sens.)

704V/m

(S/N

6

dB),

600zV/m

(S/N

26

dB)

302V/m

(S/N

6

dB),

400“V/m

(S/N

26

dB)

1.8uV

(S/N

6

dB),

192V

(S/N

26

dB)

0.82V

(S/N

6

dB),

92V

(S/N

26

dB)

1.24V

(S/N

6

dB),

134V

(S/N

26

dB)

Power

Output:

3W

DC

Maximum

National

Panasonic

Power

Source:

Power

Consumption:

Speaker:

Dimensions:

Weight:

Impedance:

ORDER

NO.

RD7803-1549

ervice

Manual

Radio

RF-2800LBS

AC

110~125V/220—~240V

50-60

Hz

or

9V

(Six

‘‘D”

Size

Flashlight

Batteries)

(National

UM-1

or

equivalent)

11W

(AC

Only)

10

cm

(4’’)

PM

Dynamic

Speaker

381(Wide)

x

246(High)

x

120(Deep)mm

(15°

x

942"'

x

43")

2.3

kg.

(8

Ib.

10

oz.)

without

batteries

Speaker

2.0.0...

.....ccccceccccue

suas

BQ

Earphone

Jack.....................

ixe)

Multiplex

Out

Jack

.........

10k.

(40mV)

FM

Antenna

Terminal

.........

752

Phono

Jack..................

500k

(50mV)

Recording

Out

Jack

......

80ka2

|

100mvV)

Specifications

are

subject

to

change

without

notice

for

further

improvement.

Matsushita

Electric

Trading

Co.,

Ltd.

P.O.

Box

288,

Central

Osaka,

Japan

M@

TO

REMOVE

CABINET

COVER

1.

Remove

the

battery

cover.

2.

Remove

the

six

(6)

screws

(nos.

1~6)

for

the

cabinet

cover,

tf

as

shown

in

fig.

1.

.

Remove

the

cabinet

cover.

.

Pull

out

sockets

from

PC

board.

.

To

reassemble,

reverse

the

above

procedure.

M@

TO

REMOVE

PC

BOARD

(IF,

RF

Circuit)

1.

Onno

7.

8.

Remove

the

cabinet

cover.

(Refer

to

cabinet

cover

removal

instruction.)

.

Remove

the

band

knob.

(To

remove

the

knob,

wind

a

cord

around

the

control

and

pull

it

outward.)

.

Turn

the

tuning

knob

fully

counter-clockwise.

.

Pull

out

the

sockets

from

PC

board.

.

Unsolder

lead

from

PC

board.

Remove

the

eight

(8)

screws

(nos.

1~8)

for

the

PC

board,

as

shown

in

fig.

2.

Remove

the

PC

board.

To

reassemble,

reverse

the

above

procedure

and

note

the

followings.

Notes

1.

2.

Turn

the

tuning

knob

fully

counter-clockwise.

Turn

the

tuning

capacitor

shaft

fully

counter-clockwise.

M@

TO

REMOVE

FREQUENCY

COUNTER

1.

o

Remove

the

PC

board

(IF,

RF

circuit).

(Refer

to

PC

board

removal

instruction.)

.

Remove

the

two

(2)

screws

(nos.

1

&

2)

for-the

frequency

counter,

as

shown

in

fig.

3.

.

Remove

the

frequency

counter.

To

reassemble,

reverse

the

above

procedure.

@

TO

REMOVE

PC

BOARD

(Frequency

Counter)

1.

Remove

the

frequency

counter.

(Refer

to

frequency

counter

removal

instruction.)

2.

Remove

the

four

(4)

screws

(nos.

1~4)

for

the

frequency

counter

cover,

as

shown

in

fig.

4.

3.

Remove

the

two

(2)

screws

(nos.

1

&

2)

for

the

PC

board,

as

shown

in

fig.

5.

4.

Remove

the

PC

board.

5.

To

reassemble,

reverse

the

above

procedure.

Screw

No.1

(XTN3+6F)

Screw

No.2

XTN3-+6F)

Fig.

5

[2]

rr-2800LBS

Screw

No.1(CA17)

Screw

No.2(CAi7)

Screw

No.3

(CA17)

Screw

No.4

(CA)

Screw

No.5

(CAt7)

~~

Screw

No.6

(CAi7)

Fig.

1

Screw

No.1

Screw

No.2

Screw

No.3

Screw

No.4

(XTN3-+6F)

(XTN3+6F)

(XTW3-++10F)

(XTW3+10F)

a

Screw

No.5

Screw

No.6

Screw

No.7

Screw

No.8

(XTW3-++10F)

(XTW3-+10F)

(XTW3+10F)

—

(XTW3-++-10F)

Fig.

2

Screw

No.

1

Screw

No.2

Screw

No.3

Screw

No.4

(XTW3+10F) (XTW3+10F)

(XTW3-++10F)

(XTW3+-10F)

acre

Screw

No.5

Screw

No.6

Screw

No.7

Screw

No.8

(XTW3+10F)

(XTW3-+-10F)

(XTW3+10F)

—

(XTW3-++10F)

Fig.

3

Screw

No.1

Screw

No.3

(XTN3+6F)

XTN3+6F)

:

Screw

No.4

Screw

No.2

XTN3-+-6F)

(XTN3-+6F)

Fig.

4

M@

TO

REMOVE

DIAL

SCALE

CHASSIS

1.

Remove

the

PC

board

(IF,

RF

circuit).

(Refer

to

PC

board

removal

instruction.)

Remove

the

tuning

knob.

Remove

the

six

(6)

screws

(nos.

3~8)

for

the

dial

scale

chassis,

as

shown

in

fig.

3.

Remove

the

dial

scale

chassis.

M

TO

REMOVE

DIAL

MECHANISM

1.

Remove

the

dial

scale

chassis.

(Refer

to

dial

scale

removal

instruction.)

2.

Remove

the

dial

belt,

as

shown

in

fig.

7.

3.

Remove

the

two

(2)

screws

(nos.

1

&

2)

for

the

dial

mech-

anism,

as

shown

in

fig.

6.

4.

To

reassemble,

reverse

the

above

procedure

and

note

the

followings.

Notes

1.

Turn

the

tuning

shaft

fully

counter-clockwise.

2.

Set

the

dial

scale

at

the

position,

as

shown

in

fig.

7.

3.

Attach

the

dial

belt.

4.

Refer

to

dial

scale

removal

instruction.

@

TO

REMOVE

DIAL

SCALE

1.

Remove

the

dial

scale

chassis.

(Refer

to

the

dial

scale

chassis

removal

instruction.)

2.

Remove

the

one

(1)

screw

for

the

dial

scale

spring,

as

shown

in

fig.

7.

3.

Remove

the

dial

scale.

4.

To

reassemble,

reverse

the

above

procedure

and

note

the

followings.

Notes:

1.

Loosen

the

two

(2)

screws

(nos.

1

&

2)

for

the

dial

scale

gear,

as

shown

in

fig.

8.

2.

Set

the

catch

of

dial

scale

gear

to

the

start

point

of

dial

scale,

as

shown

in

fig.

9.

3.

Turn

the

tuning

shaft

fully

counter-clockwise.

4.

After

mounting

the

PC

board

(IF,

RF

circuit),

turn

the

dial

scale

by

pushing

the

catch

of

dial

scale

and

set

the

start

point

of

dial

scale

to

the

catch

of

cabinet,

as

shown

in

fig.

10.

5.

Tighten

the

two

(2)

screws

(nos.

1

&

2)

for

the

dial

scale

gear,

as

shown

in

fig.

10.

Screw

No.1

Catch

of

Cabinet

Start

Ponint

(XXAR3H6S)

Fi

Bie

S.

se

Screw

No.2

(XXAR3H6S)

Fig.

10

Seiew

No.1

‘a

Sorew

No.2

(XTW3-++10F)

(XTW3+10F)

Fig.

6

0d.

Screw

(XTN23-+6C)

:

a

ae

in

OS

Dial

Belt

©

Sg

ae’

ge

.

5

RSGBIBS

eas

Fig.

7

Screw

No.1

Screw

No.2

(XXAR3H6S)

Kw

|

qed

-|

SWI

|

SW2'

Syvads

2

My

Catch

Start

Point

Fig.

9

RF-2810L-BS

[3]

M@

TO

REMOVE

PC

BOARD

(AF

Circuit)

Srey

:

een

(

Subp

:

e

XTW3-+10F

XTW3-+10F,

1.

Remove

the

dial

scale

chassis.

(Refer

to

the

dial

scale

(

)

chassis

removal

instruction.)

2.

Remove

the

six

(6)

knobs

for

the

RADIO,

LIGHT,

BAND

WIDTH,

VOLUME,

BASS

and

TREBLE.

3.

Remove

the

five

(5)

screws

(nos.

2, 3, 5,

6

&

7)

for

the

PC

board,

as

shown

in

fig.

11.

.

Unsoider

lead

from

PC

board.

.

Pull

out

sockets

from

PC

board.

.

Remove

the

PC

board.

:

.

To

reassemble,

reverse

the

above

procedure.

NOOO

Screw

No.4

“Screw

No.5

Screw

No.6

Screw

No.7

(XTW3-++H10F)

(XTW3-+10F)

(XTW3-F10F)

(XTW3-+10F)

@

TO

REMOVE

PC

BOARD

(Control

Circuit)

1.

Remove

the

dial

scale

chassis.

(Refer

to

the

dial

scale

Fig.

11

chassis

removal

instruction.)

2.

Remove

the

three

(3)

knobs

for

the

SW

CAL,

RF

GAIN

and

Indicator

PITCH.

(To

remove

those

control

knobs

wind

a

cord

around

the

control

and

pull

it

outward.)

3.

Remove

the

two

(2)

screws

(nos.

1

&

4)

for

the

PC

board.

.

Remove

the

PC

board.

5.

To

reassemble,

reverse

the

above

procedure.

>

@

TO

REMOVE

INDICATOR

1.

Remove

the

PC

board

(AF

circuit).

(Refer

to

PC

board

removal

instruction.)

2.

Unsolder

the

terminal

of

indicator,

as

shown

in

fig.

12.

3.

Remove

the

indicator.

4.

To

reassemble,

reverse

the

above

procedure.

M@

HOW

TO

REPLACE

CHIP

1.

Remove

solder

for

chip

completely.

Cc

:

;

Pe

|

Color

|

Original

Parts

Name

Service

Parts

Name

2.

Remove

chip

by

nippers,

as

shown

in

fig.

13.

hie

Resistor

Garbon

Fegictor

3.

Use

tube

for

service

parts

as

shown

in

fig.

14

and

solder

)

service

parts

according

to

following

table.

(please

refer

Blue

Shi

Sapa

rerarie

Capecner

to

Circuit

Board

Wiring

View

for

the

value

of

resistor

and

capacitor).

Ceramic

Capacitor

Carbon

Resistor

Fig.

13

Fig.

14

[4]

pr-2800LBs

Panasonic RF-2800LBS Manuale

Manuali Radio popolari di altre marche