Kenwood TH-28E Service Manual

144MHz FM TRANSCEIVER
~TH-28A/E
SERVICE MANUAL
© 1992-5 PRINTED IN JAPAN
KENWOOD >
B51-8170-00(0) 1209
——— CONTENTS
CIRCUIT
DESCRIPTION
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2
DESCRIPTION
OF
COMPONENTS.
.........-2s0000
13
SEMICONDUCTOR
DATA
....sscssesesscseceesessessneerens
16
PARTS
LIST
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22
EXPLODED
VIEW
sssesssssscssssscssseceseeseeateatsueesnneens
37
-
PACKING
vicccssescsssssessssseccssnessssesessesesesstansatesneeennes
38
ADJUSTMENT
oiscssssssscsscccsssscssessscesssnseseeessteserenees
39
POWER
MODULE
INSTALLATION
METHOD
.........
43
TERMINAL
FUNCTION.
.....c.ssscsssscsseieceesesessneeeees
44
(190
0445-05)
PC
BOARD
VIEWS
TX-RX UNIT : IF (X57-404X-XX) (A/2). essen 45
TX-RX-UNIT-; RF-(X57-404X-XX)}(B/2) 49 —
.
CONTROL
UNIT
(X53-340X-XX)
(A/5)
.-e-s-
53
Coe
1634-13)
:
KM,
M2,
X,
P
CONTROL
UNIT
:
CHARGER
(X53-340X-XX)
(B/S)
......
55
(A02-1634-13)
:
T,
E,
E2,
3,
£6
CONTROL
UNIT
:
PTT
(X53-340X-XX)
(C/5)
sseessssssensee
55
Knob
ENC)
CONTROL
UNIT
:
VOL/SOL
(X53-340X-XX)
(D/5)
......-
56
Knob
(VOL
(K29-4774-04)
CONTROL
UNIT
:
ENCODER
(X53-340X-XX)
(E/5)
s..sesssn
56
({K29-4772-04)
VCO
(X58-3870-XX)
«
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SCHEMATIC DIAGRAM. ...ssecsesscssssensessesseestenssanss
BLOCK DIAGRAM. ...sseseesssssssesssssssetseeeee eeeeeesseeees
Knob
(SQL)
LEVEL
DIAGRAM
....eeccesecsseteceesesestiereeseesnenecenvess
(K29-4773-04)
(K29-4775-13)
Knob (LOCK)
(K29-4777-04)
Front glass
(B10-1179-04)
Knob
(K29-4776-03)
Knob (Key top)
(K29-4778-03)
PHOTO is TH-28A
RRS ne ens nape spent
BC-15A (RAPID CHARGER)
HMC-2 (HEAD SET WITH VOX & PTT) ..eseeeeeeeees 66
ME-1 (MEMORY EXPANSION UNIT) .........004+ 68
PB-13 (Ni-Cd BATTERY) ...ssssscsccssssseeeesseseessssnees 68
PB-14
(Ni-Cd
BATTERY)
wessssssssstssseeeseseeeeeeeee
69
PB-17 (HIGH POWER BATTERY PACK)... 70
PB-18 (LONG LIFE BATTERY PACK) ........--.+++ 70
PG-2W (DC CORD) o.eescsescssessesstsssesseesesserseeeacees 71
PG-3H (FILTERED CIGAR LIGHTER CORD) ....... 71
SMC-31, 32, 33 (SPEAKER MICROPHONE) ....... 72
TSU-7/CTCSS UNIT (X52-3170-00) .....seeeeeeeens 73
BH-6 (SWIVEL MOUNT) o....ecsssesssccssseseeeessseerseeens 75
HB-2 (HAND STRAP) n.ccessessseccsecssecssscseevecseseseeees 75
SC-30, 33, 34 (SOFT CASE) ciescsssccecsseesseeeeees 75
WR-2 (WATERPROOF CASE) ......sssscceeesesseeseeees 75
SPECIFICATIONS oo... eessseesseesseesssees BACK COVER

Kenwood TH-28E Specifications

General

Brand	Kenwood
Model	TH-28E
Category	Transceiver
Language	English

Summary

CIRCUIT DESCRIPTION

Frequency Configuration

Details the frequency configuration using diagrams and tables.

Receiver System

IF, AF, and Squelch Circuits

Explains IF amplifier, AF amplifier, and squelch/mute control circuits.

S-meter and Transmitter System

Details S-meter circuit and transmitter system including mic, modulator, and output.

APC and Power Control

Details automatic power control and output power selector circuits.

Economic Low-Power Circuit

PLL and VCO Circuits

Explains the Phase Locked Loop and Voltage Controlled Oscillator circuits.

Digital Control Circuit

Reset and Backup Circuits

Power Supply Circuit

Details the Ni-Cd charging circuit and power selector circuit.

Battery Save and Remote Control Circuits

Supplied Circuits (CTCSS, DTMF)

Details CTCSS, DTMF, BEEP, and TONE signal processing circuits.

DESCRIPTION OF COMPONENTS

Control Unit Components

TX-RX Unit Components

SEMICONDUCTOR DATA

Microprocessor (HD404629A24H)

Terminal connection diagram and function details for the microprocessor.

EEPROM, Power Amplifier, and Microphone Amplifier ICs

PLL IC (MB1505PF-G-BND)

FM Receiver IC (MC33720)

PARTS LIST

Power and Battery Components

Semiconductors and ICs

EXPLODED VIEW

Exploded View Diagram

ADJUSTMENT

Required Test Equipment

TX/RX Common and PLL Adjustments

Details common TX/RX adjustments and PLL circuit calibration.

TX Adjustments

Covers adjustments for reference frequency, power, and deviation.

VHF RX Adjustments

Details adjustments for the VHF receiver section.

UHF RX Adjustments

Details adjustments for the UHF receiver section.

PC BOARD VIEWS

TX-RX Unit Boards

Control Unit and VCO Boards

BLOCK DIAGRAM

Receiver and Transmitter Block Diagrams

Level Diagram

HMC-2 (HEAD SET WITH VOX & PTT)

HMC-2 PC Board Views and Circuit Diagram

SPECIFICATIONS

General Specifications

Covers general specifications like frequency, mode, impedance, and temperature.

Transmitter Specifications

Details transmitter output power, deviation, and spurious radiation.

Receiver Specifications

Lists receiver circuitry, sensitivity, selectivity, and audio output.