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О

ІСОМ

SERVICE

MANUAL

VHF/UHF

FM

TRANSCEIVER

IC-Q7A

IC-Q7E

Icom

Inc.

INTRODUCTION

This

service

manual

describes

the

latest

service

information

for

the

IC-Q7A/IC-Q7E

at

the

time

of

publication.

MODEL

VER

SION

SYMBOL

|

eee

=

ლოძის

To

upgrade

quality,

all

electrical

or

mechanical

parts

and

internal

circuits

are

subject

to

change

without

notice

or

oblig-

ation.

DANGER

NEVER

connect

the

transceiver

to

an

AC

outlet

or

to

a

DC

power

supply

that

uses

more

than

3.5

V.

Such

a

connection

could

cause

a

fire

hazard

and/or

electric.

DO

NOT

expose

the

transceiver

to

rain,

snow

or

any

liquids.

DO

NOT

reverse

the

polarities

of

the

power

supply

when

con-

necting

the

transceiver.

DO

NOT

apply

an

RF

signal

of

more

than

20

dBm

(100mW)

to

the

antenna

connector.

This

could

damage

the

trans-

ceiver's

front

end.

ORDERING

PARTS

Be

sure

to

include

the

following

four

points

when

ordering

replacement

parts:

1.

10-digit

order

numbers

2.

Component

part

number

and

name

3.

Equipment

model

name

and

unit

name

4.

Quantity

required

SAMPLE

ORDER:

8930046580

LCD

Contact

IC-Q7

LOGIC

UNIT

5

pieces

8810009560

Screw

PH

BO

М2х6

ZK

.1C-Q7

Chassis

10

pieces.

Addresses

are

provided

on

the

inside

back

cover

for

your

convenience.

REPAIR

NOTES

Make

sure

a

problem

is

internal

before

disassembling

the

transceiver.

DO

NOT

open

the

transceiver

until

the

transceiver

is

disconnected

from

its

power

source.

DO

NOT

force

any

of

the

variable

components.

Turn

them

slowly

and

smoothly.

DO

NOT

short

any

circuits

or

electronic

parts.

An

insulated

turning

tool

MUST

be

used

for

all

adjustments.

DO

NOT

keep

power

ON

for

a

long

time

when

the

transceiver

is

defective.

DO

NOT

transmit

power

into

a

signal

generator

or

a

sweep

generator.

ALWAYS

connect

a

30

dB

to

40

dB

attenuator

between

the

transceiver

and

a

deviation

meter

or

spectrum

analyzer

when

using

such

test

equipment.

READ

the

instructions

of

test

equipment

thoroughly

before

connecting

equipment

to

the

transceiver.

oo

ROLL

Mo

e

SECTION

SECTION

SECTION

SECTION

SECTION

SECTION

SECTION

SECTION

SECTION

SECTION

SECTION

4-1

4-2

4-8

4-4

4-5

5-1

5-2

5-3

5-4

9-1

9-2

10

11

11-1

11-2

TABLE

OF

CONTENTS

SPECIFICATIONS

INSIDE

VIEWS

DISASSEMBLY

INSTRUCTIONS

CIRCUIT

DESCRIPTION

RECEIVER

CIRCUITS

и.

cee

loas

RR

E

a

TRANSMITTER

CIRCUITS

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

РЦЕСІНСІЛТӘ;

армарзанаа

арағын

а

СЫНЫН

Иа

POWER

SUPPLY

CIRCUITS

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

PORT

ALLOCATIONS

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

ADJUSTMENT

PROCEDURES

PREPARATION

„х

ee

REC

I

Rege

ао

ЛОН

PLL,

ADJUSTMENT

....

аа

л

санч

ით

დაბ

A

თაბი

Td

RECEIVER

ADJUSTMENT

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

TRANSMITTER

ADJUSTMENT

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

PARTS

LIST

MECHANICAL

PARTS

AND

DISASSEMBLY

CABINET

PARIS:

„2:2

22:5

Бу

uve

ка

көле

терен

ез

SEMI-CONDUCTOR

INFORMATION

BOARD

LAYOUTS

LOGIC

UNIT:

лор

ое

Бйр»

кузи

а

кары

eat

aap

aaa

REUNIT

fics

seca

ean

alone

eed

be

8

а

Rude

Sese

გრ

BLOCK

DIAGRAM

VOLTAGE

DIAGRAM

LOGIC

UNIT

а

ke

Ege

qa

Rey

жа

MRE

aie

eie

ace

ЕР

HISUNIT.

5а

ы

Dose

Ба

obs

ұлық

ы

Es

AL

ES

etos

As

SECTION

1

SPECIFICATIONS

@

GENERAL

*

Frequency

range

U.S.A.

Version

|

Transmit

(MHz)

144

—

148

440

—

450

Receive

(MHz)

30.0

—

823.995

849.0

—

868.995

894.0

—

1309.995*

Europe

144

–

146

430

—

440

30.0

—

1309.995*

Italy,

Asia

TWN

136

–

174*

430

—

440

144

–

148

430

—

440

30.0

–

1309.995*

30.0

—

1309.995”

144

—

148

430

—

450

30.0

-

1309.995*

*'

Specifications

guaranteed

144

—

148

MHz

*

Specifications

guaranteed

30

—

1300

MHz

*

Mode

*

No.

of

memory

channels

*

Frequency

stability

*

Tuning

steps

*

Anntena

Impedance

*

Power

supply

requirement

:

*

Polarity

*

Frequency

resolution

*

Current

drain

(at

3.0

V

DC)

:

Receive

Transmit

*

Usable

temperature

range

:

*

Dimensions

(projections

not

included)

*

Weight

(with

antenna

and

battely)

*

MIC/SP

connector

8

TRANSMITTER

*

Output

power

(at

3.0

V

DC)

:

*

Modulation

system

*

Max.

freq.

deviation

*

Spurious

Emissions

:

ЕЗ

(FM)

:

200

channels

:

x6

ppm

max.

(-10'C

to

+60°C)

:

5,

6.25,

10,

12.5,

15,

20, 25,

30,

50,

and

100

kHz

:50

Q

2

x

AA(R6)

Ni-Cd

or

alkaline

cell

:

Negative

ground

:

5

kHz,

6

kHz

Standby

95

mA

(typical)

Max

audio

170тАҰА

(typical)

Power

saved

38

mA

(typical)

VHF

440

mA

(typical)

UHF

380

mA

(typical)

—10'C

to

+60°C

-14°F

to

+140°F

:

58(W)

x

86(H)

x

27(D)

mm

9962(VV)

x

838(Н)

x

1V6(D)

in

:

170

(g);

6

oz

:

4-conductor

3.5(d)

mm

(18°);

2

kQ/8

Q

VHF

350

mW

UHF

300

mW

:

Variable

reactance

modulation

:

x5

kHz

:

less

than

-40

dB

Ш

RECEIVER

*

Receiver

system

:

Tripple

super

heterodyne

*

Intermediate

frequency

— :

1st

266.7

MHz

2nd

19.65

MHz

3rd

450

kHz

*

Sensitivity"

032

118.0

—

136.0

(except

spurious

points;

typical

values)

247.0

–

330.0

330.0

—

380.0

*FM

and

WFM

are

measured

at

12

dB

SINAD;

AM

is

measured

at

10

dB

S/N.

*

Squelch

sensitivity

:

less

than

0.18

pV

144

–

148

MHz

430

-

450

MHz

less

than

0.22

uV

*

Selectivity

:

FM,

AM

more

than

15

КН2/-6

dB

less

than

30

КН2/-60

dB

WFM

more

than

150

kHz/—6

dB

:

100

mW

typical

at

10

%

dis-

tortion

with

an

8

Q

load

*

Audio

output

power

All

stated

specifications

are

subject

to

change

without

notice

or

obligation.

1-1

SECTION2

INSIDE

VIEWS

è

LOGIC

UNIT

AF

power

amplifier

(IC15:

TA31056F)

AF

mute

switch

(Q37:

28J144)

+3.2

regurater

-

(IC4:

S-81332HG)

AF

filter

(030:

XP6501)

+3

гедигаіег

———

— —

Wai

|

(IC3:

ХС62РРЗОО2МН)

1

*

RF

UNIT

TOP

VIEW

BOTTOM

VIEW

end

mixer

(IC10:

uPC2757T-E3)

1st

mixer

(IC1:

uPC2757T-E3)

IF

amplifier

(Q5:

25C5231)

-

FM

IF

IC

(IC2:

ТАЗ1136ЕМ)

Tx

amplifier

Tx

amplifier

хаг

сїгсий

circuit

УСО

circuit

PLL

circuit

PLL

IC

(IC3:

wPD3140GS)

PLL

reference

oscillator

(X1:

CR-583

19.200MHz)

SECTION

3

DISASSEMBLY

INSTRUCTIONS

*

REMOVING

THE

REAR

PANEL

е

REMOVING

THE

LOGIC

UNIT

(D

Unscrew

2

screws,

(А).

(D

Unscrew

2

screws,

(6),

(2

Remove

the

rear

panel

in

the

direction

of

the

arrow.

(2)

Unsolder

2

points,

CI,

and

then

remove

the

LOGIC

unit.

Rear

panel

e

REMOVING

THE

RF

UNIT

(D

Unscrew

1

screw,

(8),

(2

Remove

1

knob,

(O.

Unscrew

2

nuts,

©

апа

©.

(3)

Unsolder

5

points,

©,

and

then

remove

the

RF

unit.

SECTION

4

CIRCUIT

DESCRIPTION

4-1

RECEIVER

CIRCUITS

4-1-1

ANTENNA

SWITCHING

CIRCUIT

(RF

UNIT)

The

RF

signals

from

the

antenna

connector

pass

through

the

antenna

switching

circuit

(D3,

D6,

D9).

The

passed

signals

are

then

applied

to

either

Duplexer

or

RX

band

switching

cir-

cuit.

4-1-2

DUPLEXER

CIRCUIT

(RF

UNIT)

The

transceiver

has

a

duplexer

(low-pass

and

bandpass

fil-

ters)

on

the

frist

stage

from

the

antenna

switcing

diode

to

separate

the

signals

into

VHF

and

UHF

signals.

*

RF

signals

below

175.0

MHz

The

RF

signals

below

175.0

MHz

are

passed

through

the

low-pass

filter

(L57-L59,

С8-С11,

C67)

and

are

applied

to

the

VHF

RF

circuit.

•

RF

signals

330.0

МН2--469.995

MHz

The

330

MHz-469.995

MHz

RF

signals

are

passed

through

the

bandpass

filter

(13-15,

C21-C24,

C218)

and

are

applied

to

the

UHF

RF

circuit.

4-1-3

VHF/UHF

RF

CIRCUIT

(RF

UNIT)

The

VHF/UHF

RF

circuit

amplifies

the

received

signals

with-

in

the

range

of

frequency

coverage

and

filters

out-of-band

signals.

(1)

VHF

RF

CIRCUIT

The

filtered

signals

from

the

low-pass

filter

circuit

are

ampli-

fied

at

the

VHF

RF

amplifier

(Q14)

through

the

Tx/Rx

swich-

ing

diode

(D15),

and

are

then

passed

through

the

two

stages

of

tunable

bandpass

filters

(D1,

D2,

L28,

L1).

The

filtered

sig-

nals

are

applied

to

the

1st

mixer

circuit

(IC1,

pin

1)

via

the

band

switching

diode

(D25).

(2)

UHF

RF

CIRCUIT

The

filtered

signals

from

the

bandpass

filter

circuit

are

ampli-

fied

at

the

UHF

RF

amplifier

(Q35)

via

the

Tx/Rx

switching

diode

(D27)

and

are

passed

through

the

two

stage

of

tunable

bandpass

filters

(D4,

D5,

L61,

L60).

The

filtered

signals

are

applied

to

the

1st

mixer

circuit

via

the

band

switching

diode

(D29).

The

filtered

signals

are

applied

to

the

1st

mixer

circuit

(IC1,

pin

1).

The

tunable

bandpass

filters

employ

varactor

diodes

(D1,

D2,

D4,

D5)

to

tune

the

center

frequency

of

the

RF

passband

for

wide

bandwidth

receiving

and

good

image

response

rejec-

tion.

These

diodes

are

controlled

by

the

CPU

(LOGIC

unit;

IC11,

pin

9).

4-1-4

RX

BAND

SWITCHING

CIRCUIT

(RF

UNIT)

The

signals

from

the

antenna

connector

pass

through

the

antenna

switching

circuit

(D6,

D9).

The

signals

are

then

applied

to

the

RX

RF

circuit

via

RX

the

band

switching

circuit

(D11,

D13,

D31)

which

suppress

out-of-band

signals.

4-1-5

RX

RF

CIRCUIT

(RF

UNIT)

The

RX

RF

circuit

amplifies

the

received

signals

within

the

range

of

frequency

coverage

and

filters

out-of-band

signals.

(1)

470.0

MHz-1026.995

MHz

signals

RF

signals

(470

MHz-1026.995

MHz)

from

a

band

switching

circuit

(011)

pass

through

a

bandpass

filter

(L7,

L8,

L42,

C32, C33,

C35-C39,

C145)

and

are

amplified

at

an

RF

amplifier

(Q24).

The

amplified

signals

are

then

applied

to

the

1st

mixer

circuit

(IC1)

through

the

band

switching

diode

(D32).

(2)

30.0

MHz-117.995

MHz,

175

MHz-329.995

MHz

The

30.0

MHz

–

117.995

MHz,

175

MHz

–

329.995

MHz

sig-

nals

pass

through

a

low-pass

filter

(L9,

L10,

C40-C43)

via

the

band

switching

diode

(D13),

and

are

then

amplified

at

the

RF

amplifier

(Q36).

The

amplified

signals

are

applied

to

the

1st

mixer

circuit

(IC1)

via

the

band

switching

diode

(D34).

(3)

1027.0

MHz-1309.995

MHz

The

1027.0

MHz-1309.995

MHz

signals

pass

through

a

bandpass

filter

(L11,

L12,

L43,

C4,

C5,

C45

–

C51)

via

the

band

switching

diode

(D13),

and

are

then

amplified

at

the

RF

amplifier

(Q36).

The

amplified

signals

are

applied

to

the

1st

mixer

circuit

(IC1)

via

the

band

switching

diode

(D36).

4-1-6

1ST

MIXER

CIRCUIT

(RF

UNIT)

The

1st

mixer

circuit

converts

the

received

RF

signals

to

a

fixed

frequency

of

the

1st

IF

signal

with

a

PLL

output

fre-

quency.

By

changing

the

PLL

frequency,

only

the

desired

fre-

quency

will

pass

through

the

bandpass

filter

at

the

next

stage

of

the

1st

mixer.

The

filtered

RF

signals

are

mixed

with

1st

LO

signals

at

the

1st

mixer

(IC1)

to

produce

a

266.7

MHz

1st

IF

signal.

The

1st

IF

signal

is

output

from

pin

6,

and

passed

through

the

band-

pass

filter

(ҒІ1)

to

suppress

unwanted

harmonic

compo-

nents.

The

filtered

1st

IF

signal

is

applied

to

the

2nd

mixer

circuit.

The

1st

LO

signals

are

generated

at

the

V

VCO

(Q32,

D45)

or

U

VCO

(Q28,

Q30,

D54)

circuit

(according

to

the

receiving

frequency),

and

are

applied

to

the

1st

mixer

(IC1,

pin

3)

directly

or

passing

through

the

doubler

circuit

(Q31)

after

being

amplified

at

the

buffer

amplifier

(IC4,

Q40).

4-1-7

1ST

IF

AND

2ND

MIXER

CIRCUITS

(RF

UNIT)

The

2nd

mixer

circuit

converts

the

1st

IF

signal

to

a

2nd

IF

signal.

The

filtered

266.7

MHz

1st

IF

signal

from

the

bandpass

filter

(ҒІ1)

is

mixed

with

the

2nd

LO

signal

at

the

2nd

mixer

(ІС10)

to

produce

a

19.65

MHz

2nd

IF

signal.

The

2nd

IF

signal

passes

through

(except

WFM

mode)

or

bypasses

(WFM

mode)

the

bandpass

filter

(FI3),

and

is

then

amplified

at

the

buffer

amplifier

(Q5).

The

amplified

signal

is

applied

to

the

demodulator

circuit.

|

4-1-8

DEMODULATOR

CIRCUITS

(RF

UNIT)

The

demodulator

circuit

converts

the

2nd

IF

signal

into

AF

signals.

The

19.65

MHz

2nd

IF

signal

from

the

buffer

amplifier

(Q5)

is

applied

to

the 3rd

mixer

section

of

the

FM

IF

IC

(IC2,

pin

16),

and

is

then

mixed

with

the

3rd

LO

signal

for

conversion

into

a

450

kHz

3rd

IF

signal.

IC2

contains

the

3rd

mixer,

limiter

amplifier,

quadrature

detector

and

S-meter

detector,

etc.

A

frequency

from

the

PLL

reference

oscillator

is

used

for

the

3rd

LO

signal

(19.20

MHz).

(1)

FM

mode

The

3rd

IF

signal

is

output

from

FM

IF

IC

(IC2,

pin

3)

and

passes

through

the

ceramic

bandpass

filter

(F12).

The

filtered

signal

is

fed

back

and

amplified

at

the

limiter

amplifier

section

(pin

5),

then

demodulated

into

AF

signals

at

the

quadrature

detector

section

(pins

10,

11)

and

detector

coil

(L21).

The

demodulated

AF

signals

are

output

from

pin

9

and

are

applied

to

the

AF

circuit

(LOGIC

unit).

(2)

WFM

mode

The

3rd

IF

signal

from

the 3rd

mixer

bypasses

the

ceramic

fil-

ter

(Fl2)

and

fed

back

to

the

limiter

amplifier

section

(pin

5).

е

2nd

IF

AND

DEMODULATOR

CIRCUITS

R56

AF

signal

'WFMS"

7095

The

amplified

signal

is

demodulated

at

the

quadrature

detec-

tor

section

(pins

10,

11)

and

detector

coil

(L21).

The

AF

sig-

nals

are

output

from

pin

9

and

are

applied

to

the

AF

circuit

(LOGIC

unit).

By

connecting

R55

to

R54

in

parallel,

the

output

characteris-

tics

of

pin

12,

"RSSI",

change

gradually.

Therefore,

the

FM

IF

IC

can

detect

WFM

components.

(3)

AM

mode

The

filtered

3rd

IF

signal

from

the

bandpass

filter

(Fl2)

is

amplified

at

the

3rd

IF

amplifier

(Q1).

The

amplified

IF

signal

is

applied

to

the

AM

detector

circuit

(Q4)

to

convert

into

AF

signals,

and

the

signals

are

applied

to

the

AF

circuit

(LOGIC

unit).

4-1-9

AF

AMPLIFIER

CIRCUIT

(LOGIC

UNIT)

The

AF

amplifier

circuit

amplifies

the

demodulated

AF

sig-

nals

to

drive

a

speaker.

While

in

FM

mode,

AF

signals

from

the

demodulator

circuit

(RF

unit)

are

passed

through

the

de-emphasis

(R118,

C66,

C68)

and

bandpass

filter

(Q30)

and

are

then

applied

to

the

pre-amplifier

(Q31).

While

in

AM

mode,

AF

signals

are

pass

through

the

band-

pass

filter

(Q30)

and

are

then

applied

to

the

pre-amplifier

(Q31).

While

in

WFM

mode,

AF

signals

are

applied

to

the

pre-ampli-

fier

(Q31)

directly.

The

pre-amplified

AF

signals

pass

through

the

AF

mute

switch

(Q37),

and

are

then

applied

to

the

electronic

volume

control

circuit

(IC14,

pin

6).

The

level

controlled

AF

signals

are

output

from

pin

7

and

are

applied

to

the

AF

power

ampli-

fier

(IC15,

pin

1)

via

the

buffer

amplifier

(Q36).

The

power

amplified

AF

signals

are

applied

to

the

internal

speaker

via

the

[EXT

SP]

jack.

3rd

IF

filter

50

kH

Х1

19.2

MHz

IC2

TA31136F

2nd

IF

(19.65

MHz)

from

Q5

"SDET"

signal

to

the

IC11

(Logic

unit)

"RSSI"

signal

to

the

CPU

O

WFM

pin

7

(Logic

unit)

Q41

16242

The

electronic

volume

control

circuit

controls

AF

gain,

there-

fore,

the

AF

output

level

is

according

to

the

[VOL]

setting

and

also

the

squelch

conditions.

4-1-10

SQUELCH

CIRCUIT(LOGIC

AND

RF

UNITS)

*

NOISE

SQUELCH

The

noise

squelch

circuit

cuts

out

AF

signals

when

no

RF

signals

are

received.

By

detecting

noise

components

in

the

AF

signals,

the

squelch

circuit

switches

the

AF

mute

switch.

A

portion

of

the

AF

signals

from

the

FM

IF

IC

(IC2,

pin

9)

are

applied

to

the

active

filter

section

(IC2,

pin

8).

The

active

fil-

ter

section

amplifies

and

filters

noise

components.

The

fil-

tered

signals

are

applied

to

the

noise

detector

section

and

output

from

IC2

(pin

13)

as

the

“SDET”

signal.

The

“SDET”

signal

from

IC2

(pin

13)

passes

through

the

noise

detector

(LOGIC

unit;

IC1),

and

is

then

applied

to

the

CPU

(LOGIC

unit;

IC11,

pin

12)

via

"SQL"

line.

The

CPU

ana-

lyzes

the

noise

condition

and

outputs

the

“AMUTE”

signal

to

AF

mute

switch

(Q37).

Even

when

the

squelch

is

closed,

the

AF

mute

switch

(Q37)

opens

at

the

moment

of

emitting

beep

tones.

*

TONE

SQUELCH

The

tone

squelch

circuit

detects

AF

signals

and

opens

the

squelch

only

when

receiving

a

signal

containing

a

matching

subaudible

tone

(CTCSS).

When

tone

squelch

is

in

use,

and

a

signal

with

a

mismatched

or

no

subaudible

tone

is

received,

the

tone

squelch

circuit

mutes

the

AF

signals

even

when

noise

squelch

is

open.

A

portion

of

the

AF

signals

from

the

FM

IF

IC

(IC2,

pin

9)

passes

through

the

low-pass

filter

(LOGIC

unit;

IC9)

to

remove

AF

(voice)

signals

and

is

applied

to

the

CTCSS

decoder

inside

the

CPU

(LOGIC

unit;

IC11,

pin

8)

via

the

“АТОМЕ”

line

to

control

the

AF

mute

switch.

4-2

TRANSMITTER

CIRCUITS

4-2-1

MICROPHON

AMPLIFIER

CIRCUIIT

(LOGIC

UNIT)

The

microphone

amplifier

circuit

amplifies

the

audio

signals

from

the

microphone,

within

+6

dB/octave

pre-emphasis

characteristics

(300

Hz—3

kHz),

to

a

level

needed

for

the

modulation

circuit.

The

microphone

amplifier

circuit

is

used

for

both

the

VHF

and

UHF

bands.

The

AF

signals

from

the

microphone

are

amplified

at

the

microphone

amplifier

(Q12)

and

the

limiter

amplifier

(Q2)

which

has

a

negative

feedback

circuit

for

+6

dB/octave

pre-

emphasis.

The

amplified

signals

are

applied

to

the

low-pass

filter

(Q7)

to

filler

out

RF

components

and

are

then

applied

to

the

RF

unit

as

the

"MOD"

signal.

4-2-2

MODULATION

CIRCUIT

(RF

UNIT)

The

modulation

circuit

modulates

the

VCO

oscillating

signal

(RF

signal)

using

the

microphone

AF

signals

e

VVCO

The

applied

signals

from

the

limiter

amplifier

changes

the

reactance

of

D45

to

modulate

the

oscillated

signal

at

the

VVCO

circuit

(Q32).

The

modulated

signal

is

amplified

at

the

buffer

amplifiers

(IC4,

Q40)

and

is

then

applied

to

the

drive

amplifier

circuit

for

VHF

band.

*

UVCO

The

applied

signals

from

the

limiter

amplifier

changes

the

reactance

of

D54

to

modulate

the

oscillated

signal

at

the

UVCO

circuit

(Q28, Q30).

The

modulated

signal

is

amplified

at

the

buffer

amplifiers

(IC4,

Q40)

and

is

then

applied

to

the

drive

amplifier

circuit

for

UHF

band.

4-2-3

DRIVE/POWER

AMPLIFIER

CIRCUITS

(RF

UNIT)

The

amplifier

circuit

amplifies

the

VCO

oscillating

signal

to

the

output

power

level.

*

VHF

PA

The

signal

from

the

buffer

amplifiers

(IC4,

Q40)

is

passed

through

the

Tx/Rx

switch

(023),

and

is

amplified

at

the

driver

amplifiers

(023,

013)

and

the

power

amplifiers

(09-012)

to

obtain

350

mW

of

RF

power.

The

amplified

signal

is

passed

through

the

antenna

switching

circuit

(D16)

and

low-pass

filter,

and

is

then

applied

to

the

antenna

connector.

*

UHF

PA

The

amplified

signal

from

IC4,

Q40

passes

through

the

Tx/Rx

switch

(D28),

and

is

amplified

to

300

mW

of

RF

power

at

the

driver

amplifiers

(Q22,

Q21)

and

the

power

amplifiers

(Q17-Q20).

The

signal

is

applied

to

the

antenna

connector

via

the

anten-

na

switching

circuit

(D40).

4-3

PLL

CIRCUITS

4-3-1

PLL

CIRCUIT

(RF

UNIT)

A

PLL

circuit

provides

stable

oscillation

of

the

transmit

fre-

quency

and

the

receive

1st/2nd

LO

frequencies.

The

PLL

cir-

cuit

compares

the

phase

of

the

divided

VCO

frequency

to

the

reference

frequency.

The PLL

output

frequency

is

controlled

by

the

divided

ratio

(N-data)

of

a

programmable

divider.

An

oscillated

signal

from

the

1st

VCO

via

the

buffer

amplifiers

(IC4,

043)

is

applied

to

the

PLL

IC

(ІСЗ,

pin

19)

and

is

prescaled

in

the

PLL

IC

based

on

the

divided

ratio

(N-data).

The

reference

signal

is

generated

at

the

reference

oscillator

(X1)

and

is

also

applied

to

the

PLL

IC

(pin

16).

The PLL

IC

detects

the

out-of-step

phase

using

the

reference

frequency

and

outputs

it

from

pin

13.

The

output

signal

is

passed

through

the

loop

filter

(Q2,

Q45)

and

is

then

applied

to

the

VCO

circuit

as

the

lock

voltage.

4-3-2

1ST

VCO

CIRCUIT

(RF

UNIT)

The

1st

VCO

circuit

contains

a

separate

V

VCO

(Q32,

D45)

and

U

VCO

(Q28,

Q30,

D54).

The

oscillated

signal

is

ampli-

fied

at

the

buffer

amplifiers

(IC4,

Q40),

and

is

then

applied

to

the

Tx/Rx

switching

circuit

(D23,

D28, 042,

043,

D44).

Then

the

Tx

and

Rx

signals

are

applied

to

the

pre-driver

(Q23:

for

VHF,

Q22:

for

UHF)

and

1st

mixer

(IC1)

respectively.

A

portion

of

the

RF

signal

from

buffer

amplifier

(IC4)

is

ampli-

fied

at

the

buffer

amplifier

(Q43),

and

is

then

fed

back

to

the

PLL

IC

(IC3

pin

19)

as

the

comparison

signal.

4-3-3

2ND

LO

VCO

CIRCUIT

(RF

UNIT)

The

2nd

LO

VCO

circuit

generates

the

2nd

LO

frequencies,

and

the

signals

are

applied

to

the

2nd

mixer

circuit.

The

generated

signals

from

the

2nd

VCO

(Q6,

D17)

are

applied

to

the

2nd

mixer

(IC10,

pin

3),

then

mixed

with

the

1st

IF

signal.

An

oscillated

signal

from

the

2nd

VCO

passes

through

the

low-pass

filter

(C154,

C250

—

C252,

L69)

and

is

applied

to

the

PLL

IC

(IC3,

pin

2),

and

is

then

output

from

pin

8.

e

2nd

LO

VCO

circuit

037,

053

Ripple

filter

АЗУ

to

the

2nd

mixer

(IC10)

*

PLL

circuit

Loop

Q2,

045

|

filter

4-4

POWER

SUPPLY

CIRCUITS

VOLTAGE

LINE

LINE

|

DESCRIPTION

The

voltage

from

the

attached

battery.

Common

13

V

converted

from

BATT

line

by

the

DC-DC

convertors

(IC10

and

D3, D5,

D15).

The

output

voltage

is

applied

to

the

PLL

circuit

(RF

unit).

VHF

transmit

2V

controlled

by

the

+2.0

switch

VHT2V

|e

from

the

+2V

regulator

(Q21,

Q32)

using

VP

the

"TXV"

signal

from

CPU

(IC11).

UHF

transmit

2V

controlled

by

the

+2.0

switch

UHT2V

|

(028)

from

the

+2V

regulator

(021,

Q32)

using

the

"TXU"

signal

from

CPU

(IC11).

язу

|

Receive

ЗУ

controlled

by

the

R3S

regulator

cir-

cuit

(Q4)

using

the

“RX”

signal

from

CPU

(IC11).

Common

3V

converted

by

the

+3S

regulator

cir-

43S

|сий

(Q3,

039)

using

the

“+3$С”

signal

from

CPU

E

1).

Common

3V

controlled

by

the

+3V

regulator

cir-

43V

|

сий

(Q6)

using

the

“РОМЕНС”

signal

from

CPU

E

(IC11).

Transmit

3V

controlled

from

+3V

line

by

the

3V

regulator

circuit

(Q5).

to

transmitter

circuit

—

to

1st

mixer

circuit

>.

Programmable

9

Prescaler

13

[Phase

[detector

tothe

FMIFIC

17

Programmable

Гу

PSTB

Shift

register

15

CLK

DATA

|

divider

16

}

х1

Са