kenwood tk-8102 Service Manual

UHF FM TRANSCEIVER

TK -8 102H

SERVICE MANUAL

© 2001-11 PRINTED IN JAPAN
B51-8611-00 (N) 851

Chassis
(A10-4048-11)

Cabinet
(A01-2181-01)

Modular jack
(E08-0877-05)

Front glass
(B10-2668-03)

Key top
(K29-9065-01)

CONTENTS

Panel assy
(A62-0942-03)

GENERAL .................................................. 2

OPERATING FEATURES .......................... 3

REALIGNMENT ......................................... 7

DISASSEMBLY FOR REPAIR ................... 9

CIRCUIT DESCRIPTION .......................... 10

SEMICONDUCTOR DATA ...................... 15

DESCRIPTION OF COMPONENTS ........ 17

PARTS LIST ............................................. 19

EXPLODED VIEW.................................... 25

PACKING ................................................. 26

ADJUSTMENT ........................................ 27

TERMINAL FUNCTION ........................... 32

PC BOARD VIEWS

DISPLAY UNIT (X54-3340-20) ............ 33

TX-RX UNIT (X57-6390-20) ................ 35

SCHEMATIC DIAGRAM.......................... 41

BLOCK DIAGRAM ................................... 45

LEVEL DIAGRAM .................................... 47

SPECIFICATIONS .................................... 49

TK -8 102H

GENERAL

INTRODUCTION

SCOPE OF THIS MANUAL

This manual is intended for use by experienced techni­cians familiar with similar types of commercial grade com­munications equipment. It contains all required service in­formation for the equipment and is current as of this publica­tion date. Changes which may occur after publication are
covered by either Service Bulletins or Manual Revisions,
which are issued as required.

ORDERING REPLACEMENT PARTS

When ordering replacement parts or equipment informa­tion, the full part identification number should be included.
This applies to all parts : components, kits, and chassis. If
the part number is not known, include the chassis or kit
number of which it is a part and a sufficient description of
the required component for proper identification.

PERSONNEL SAFETY

The following precautions are recommended for person­nel safety :

• DO NOT transmit if someone is within two feet (0.6

meter) of the antenna.

• DO NOT transmit until all RF connectors are secure and

any open connectors are properly terminated.

• SHUT OFF this equipment when near electrical blasting

caps or while in an explosive atmosphere.

• All equipment should be properly grounded before

power-up for safe operation.

• This equipment should be serviced by only qualified tech-

nicians.

PRE-INSTALLATION CONSIDERNATIONS

1. UNPACKING

Unpack the radio from its shipping container and check
for accessory items. If any item is missing, please contact
KENWOOD immediately.

2. LICENSING REQUIREMENTS

Federal regulations require a station license for each ra­dio installation (mobile or base) be obtained by the equip­ment owner. The licensee is responsible for ensuring trans­mitter power, frequency, and deviation are within the limits
permitted by the station license.

Transmitter adjustments may be performed only by a li­censed technician holding an FCC first, second or general
class commercial radiotelephone operator’s license. There
is no license required to install or operate the radio.

3. PRE-INSTALLATION CHECKOUT
3-1. Introduction

Each radio is adjusted and tested before shipment. How­ever, it is recommended that receiver and transmitter opera­tion be checked for proper operation before installation.

3-2. Testing

The radio should be tested complete with all cabling and
accessories as they will be connected in the final installa­tion. Transmitter frequency, deviation, and power output
should be checked, as should receiver sensitivity, squelch
operation, and audio output. Signalling equipment operation
should be verified.

4. PLANNING THE INSTALLATION
4-1. General

Inspect the vehicle and determine how and where the
radio antenna and accessories will be mounted.

Plan cable runs for protection against pinching or crush­ing wiring, and radio installation to prevent overheating.

4-2. Antenna

The favored location for an antenna is in the center of a
large, flat conductive area, usually at the roof center. The
trunk lid is preferred, bond the trunk lid and vehicle chassis
using ground straps to ensure the lid is at chassis ground.

4-3. Radio

The universal mount bracket allows the radio to be
mounted in a variety of ways. Be sure the mounting surface
is adequate to support the radio’s weight. Allow sufficient
space around the radio for air cooling. Position the radio
close enough to the vehicle operator to permit easy access
to the controls when driving.

4-4. DC Power and wiring

1. This radio may be installed in negative ground electrical

systems only. Reverse polarity will cause the cable fuse

to blow. Check the vehicle ground polarity before installa-

tion to prevent wasted time and effort.

2. Connect the positive power lead directly to the vehicle

battery positive terminal. Connecting the Positive lead to

any other positive voltage source in the vehicle is not rec-

ommended.

3. Connect the ground lead directly to the battery negative

terminal.

4. The cable provided with the radio is sufficient to handle

the maximum radio current demand. If the cable must be

extended, be sure the additional wire is sufficient for the

current to be carried and length of the added lead.

2

GENERAL / OPERATING FEATURES

TK -8 102H

5. INSTALLATION PLANNING – CONTROL STATIONS
5-1. Antenna system

Control station. The antenna system selection depends
on many factors and is beyond the scope of this manual.
Your KENWOOD dealer can help you select an antenna sys­tem that will best serve your particular needs.

5-2. Radio location

Select a convenient location for your control station radio
which is as close as practical to the antenna cable entry
point. Secondly, use your system’s power supply (which
supplies the voltage and current required for your system).
Make sure sufficient air can flow around the radio and power
supply to allow adequate cooling.

SERVICE

This radio is designed for easy servicing. Refer to the
schematic diagrams, printed circuit board views, and align­ment procedures contained in this manual.

NOTE

If you do not intend to use the 3.5-mm jack for the exter­nal speaker, fit the supplied speaker-jack cap to stop dust
and sand getting in.

OPERATING FEATURES

1. Controls and Functions

1-1. Front Panel

q

we tr

u

1-2. Microphone

o

y

i

Antenna
connector

Speaker
jack cap

Power input
connector

q (Power) switch

Press to switch the transceiver ON. Press and hold for
approximately 1 seconds to switch the transceiver OFF.

w ▲ key

Press to increase the volume level.

e ▼ key

Press to decrease the volume level.

r ● key

PF (Programmable Function) key. The default setting of
this key is None (no function). The programmable func­tions available for this key are listed below.

key

t

PF (Programmable Function) key. The default setting of
this key is Monitor. Other programmable functions avail­able for this key are listed below.

y 1/ 2/ 3/ 4 keys

Press to select a channel from 1 to 4.

u Microphone jack

Insert the microphone plug into this jack (the micro­phone is an optional accessory).

i Speaker

Internal speaker.

o PTT switch

Press this switch, then speak into the microphone to call
a station.

1-3. Auxiliary Programmable Functions

• Emergency • Scan On/OFF

• Key Lock • Talk Around

• Monitor • Temporary Delete

• None (no function)

3

TK -8 102H

OPERATING FEATURES

1-4. Display

Indicator Description

Light while transmitting.
Lights when a signal is detected on
the currently selected channel.
Lights while the function programmed
onto its corresponding key is activated.
Lights while the function programmed
onto its corresponding key is activated.
Lights to display the currently selected
channel (1~ 4)

1-5. Rear panel

2. Operation Features

The TK-8102H is a UHF FM radio designed to operate in
conventional format. The programmable features are sum­marized.

3. Transceiver Controls and Indicators

3-1. Front Panel Controls

All the keys on the front panel are momentary-type push
buttons. The functions of these keys are explained below.

• POWER key

Transceiver POWER key. When the power is switched
off, all the parameters are stored in memory. When the
power is switched on again, the transceiver returns to the
previous conditions.

• CHANNEL keys

• MONITOR key (Programmable)

• ● key (Programmable)

• VOLUME UP/DOWN key

When the key is pressed, the volume level is increased/
decreased and repeats if held for 200ms or longer.

Antenna
connector

External
speaker
jack

Power input
connector

• BUSY/TX LED

The BUSY indicator (Green LED) shows that the channel
is in use. The TX indicator (Red LED) shows that you are
transmitting.

3-2. Programmable Keys

The FPU (KPG-70D) enables programmable keys to se­lect the following functions.

• Emergency

• Key Lock

• Monitor

• Scan ON/OFF

• Talk Around

• Temporary Delete

•None

• Emergency

Pressing this key for longer than 1 second causes the
transceiver to enter the emergency mode. The transceiver
jumps to the programmed “Emergency channel” and trans­mits for 25* seconds.

The transceiver disables mic mute while transmitting.
After finishing transmission, the transceiver receivers for 5*
seconds. The transceiver Mute* the speaker while receiv­ing. Following the above sequence, the transceiver contin­ues to transmit and receive.
* Default value.

4

OPERATING FEATURES

TK -8 102H

• Key lock

Pressing this key causes the transceiver to accept entry
of only the [Vol Up/Down]*, [Key lock], Microphone [PTT],
[Monitor], [Emergency], and [Power] keys.
* Programmable

• Monitor

Used to release signalling (press once) or squelch (press
and hold for approximately two seconds) when operating as
a conventional. It is also used to reset option signalling.

• Scan ON/OFF

Press this key starts scanning. Pressing this key stops
scanning.

• Talk around

Press this key, the transceiver uses the receive fre­quency and the tone for transmission.

The operator can call the other party directly (without re­peater). Press this key again, the talk around function goes
off.

• Temporary delete

The “Add” channel contained in the scan sequence, and
“Delete” channel is not contained. In the scan mode, this
key switches the channel delete temporarily (Press and hold
for approximately one second).

When the transceiver is turned off, the transceiver exits
the scan or switches the scan function off.

■ Revert channel

The revert channel is used to transmit during scanning

and set by the programming software (KPG-70D).

1) Selected channel
The transceiver reverts to the channel before scanning or
the channel that you changed during scan.

2) Selected with talkback
The transceiver reverts to the selected channel prior to
scan initiation.
However, if a call is received on a channel other then the
selected channel and PTT is pressed before scanning re­sume, the transceiver “talks back” on the current receive
channel.

■ Scan end

When you press the key programmed to the scan func-

tion during scan mode, the scan ends.

The indicator next to the programmed key LED turns off.

■ Temporary delete

It is possible to delete channel temporary during scan.

When scan stops on unnecessary channel for example by
interference of the other party, activate the delete function
(for example press and hold the key for approximately one
second), then that channel is deleted temporarily and scan
re-start immediately.

The temporary deleted channels return to pre-set delete/

add channels, when the transceiver is turned off or the scan
function is switched off.

• None

Sounds error operation beep, and no action will occur.
Use this function when the transceiver is required to be
more simple operated.

4. Scan Operating

■ SCAN start condition

Two or more channels must be added to all channels that
can be scanned. The transceiver must be in normal receive
mode (PTT off).

When you activate the key programmed to the scan ON/
OFF function, the scan starts. The indicator next to the pro­grammed key LED blinks.

■ Scan stop condition

The scan stops temporarily if the following conditions are
satisfied.

1) A carrier is detected, then QT/DQT matches on channels

for which receive the QT/DQT is set by the programming

software.

2) A carrier is detected on the channels for which receiving

QT/DQT is not set by the programming software or when

the monitor (signalling cancel) function is activated.

5. Details of Features

■ Time-out timer

The time-out timer can be programmed in 30 seconds
increments from 30 seconds to five minutes and off. If the
transmitter is transmitted continuously for longer than the
programmed time, the transmitter is disabled and a warning
tone sounds while the PTT button is held down. The warn­ing tone stops when the PTT button is released.

■ PTT ID

PTT ID provides a DTMF ANI to be sent with every time
PTT (beginning of transmission, end of transmission, or
both).

You can program PTT ID “on” or “off” for each channel.
The contents of ID are programmed each Radio.

The timing that the transceiver sends ID is program­mable.

BOT : DTMF ID (Beginning of TX) is sent on beginning of

transmission.

EOT : DTMF ID (End of TX) is sent on end of transmis-

sion.

Both : DTMF ID (Beginning of TX) is sent on beginning of

transmission and DTMF ID (End of TX) is sent on end of

transmission.

5

TK -8 102H

OPERATING FEATURES

■ Off hook decode

If the Off hook decode function has been enabled, re­moving and replacing the microphone on the hook has no
effect for decoding QT/DQT and option signalling.

■ “TOT” pre-alert

The transceiver has “TOT” pre-alert timer. This param­eter selects the time at which the transceiver generates
“TOT” pre-alert tone before “TOT” is expired.

“TOT” will be expired when the selected time passes
from a TOT pre-alert tone.

■ “TOT” re-key time

The transceiver has “TOT” re-key timer. This timer is the
time you can not transmit after “TOT” exceeded. After
“TOT” re-key time expired you can transmit again.

■ “TOT” reset time

The transceiver has “TOT” reset timer. This timer is the
minimum wait time allowed during a transmission that will
reset the “TOT” count.

“TOT” reset time causes the “TOT” to continue even
after PTT is released unless the “TOT” reset timer has ex­pired.

■ Clear to transpond

The transceiver waits the transpond of DTMF if channel
is busy until channel open. This feature prevents the inter­ference to other party.

6. Option Signalling (DTMF)

Built-in DTMF decoder is available for option signalling.

It is possible to use individual call, group call, Stun.

If the option signalling matches, a predetermined action
will occur.

If option signalling matches on a channel is set up with
option signalling, the channel LED will flash and option sig­nalling will be released. The transpond or alert tone will
sound.

While option signalling matches (or if option signalling is
deactivated when you are transmitting), you can mute or
unmute QT/DQT/Carrier.

SP unmute

Carrier None None Carrier Sounds

Carrier+DTMF

QT/DQT Yes None Carrier Not Sounds

QT/DQT+DTMF

Note :

When QT/DQT is not used, QT/DQT and QT/DQT+DTMF

can not be selected.

When DTMF is not used, Carrier+DTMF and QT/

DQT+DTMF can not be selected.

Channel setting

QT/DQT

DTMF condition

Yes Carrier Sounds

None Yes Carrier Not Sounds

Yes Carrier Not Sounds

Yes Yes Carrier Not Sounds

RX condition Speaker

Carrier+DTMF Sounds

Carrier+DTMF Sounds

Carrier+QT/DQT Sounds

Carrier+QT/DQT Sounds
Carrier+QT/DQT+DTMF
Carrier+DTMF Not Sounds

Carrier+QT/DQT Not Sounds
Carrier+QT/DQT+DTMF
Carrier+DTMF Not Sounds

Sounds

Sounds

■ Auto Reset

If option signalling matches a group set up with option
signalling, option signalling is released. After matching op­tion signalling, option signalling will temporarily reset auto­matically.

■ Stun

If the stun code matches, a predetermined action will oc­cur. Whether option signalling is activated or not, when
stun matches on any channel, the transceiver will become
TX inhibited or TX/RX inhibited. While stun is active, if the
stun code + “#” code is received, stun will deactivate.

When stun matches, transpond will function. Alert will
not be output.

■ SP Unmute

You can select the type of SP Unmute system for each

channel. The selection is as follows.

Carrier, QT/DQT:
Channel with this option will not check ID Code in order

to open its speaker.

Carrier+DTMF, QT/DQT+DTMF:
Channel that is set with this option will have to check for

ID Code in order to open its speaker.

Default:
Carrier, QT/DQT.

6

7. Audible User Feedback Tones

The transceiver outputs various combinations of tones to
notify the user of the transceiver operating state.

Refer to the help file on the KPG-70D, regarding the func­tions that are not listed below.

■ Stun on tone

When a stun code is received, transpond tone sounds.

■ Stun off tone

When a stun release code is received, transpond tone
sounds.

TK -8 102H

User mode

PC mode

Data program­ming mode

PC test mode

PC tuning mode

Clone mode

OPERATING FEATURES / REALIGNMENT

■ Group call tone

Sounds when a group call with the correct DTMF option
signalling is received, repeats 7 times. You can select yes or
no in the Alert tone level setting.

■ Individual call tone

Sounds when an individual call with the correct DTMF
option signalling is received. You can select yes or no in the
Alert tone level setting.

■ Key input error tone

Sounds when a key is pressed but that key cannot be
used. You can select yes or no for the optional feature's
warning tone.

■ Transpond tone

Sounds when an individual call with the correct DTMF
option signalling is received. For group calls, only the group
tone will sound, not the transpond tone.

■ Pre alert tone

Sounds prior to the TOT TX inhibit activation. If TOT pre
alert is set, the tone sounds at the amount of time pro­grammed, before the TOT expires (TOT time – TOT pre alert
time = Pre alert tone sounding time). You can select yes or
no for the optional feature's warning tone.

■ Transmit protection

The final FET is protected against heat while transmitting
by making the radio cuts down TX power when the tempera­ture of the final FET becomes higher than reference. After
that, if the temperature continue to rise, transmission is
stopped. The final FET is also protected against over voltage
by having the radio to check that the voltage of power sup­ply connected to the radio is not higher than about 17V
when the radio is turned on, otherwise it can not transmit.
In both cases when transmission is stopped, a beep will
continue to sound until the PTT key is released.

REALIGNMENT

1. Modes

Mode Function

User mode For normal use.
PC mode Used for communication between the

radio and PC (IBM compatible).
Data programming Used to read and write frequency data
mode and other features to and from the radio.
PC test mode Used to check the radio using the PC.

This feature is included in the FPU.
PC tuning mode Used to tune the radio using the PC.
Clone mode Used to transfer programming data from

one radio to another.

2. How to Enter Each Mode

Mode Operation

User mode Power ON
PC mode Received commands from PC
Clone mode [1]+Power ON (Two seconds)

3. PC Mode

3-1. Preface

The TK-8102H transceiver is programmed using a per­sonal computer, a programming interface (KPG-46) and pro­gramming software (KPG-70D).

The programming software can be used with an IBM PC
or compatible. Figure 1 shows the setup of an IBM PC for
programming.

7

TK -8 102H

REALIGNMENT

3-2. Connection Procedure

1. Connect the TK-8102H to the personal computer with the
interface cable.

2. When the Power is switched on, user mode can be en­tered immediately. When the PC sends a command, the
radio enters PC mode.
When data is transmitted from transceiver, the red LED
blink.
When data is received by the transceiver, the green LED
blink.
In the PC mode, 4CH LEDs, [MON] LED and [●] LED are
turned on.

Notes :

• The data stored in the personal computer must match
model type when it is written into the EEPROM.

• Attach the interface cable, then change the TK-8102H to
PC mode.

3-3. KPG-46 Description

(PC programming interface cable : Option)

The KPG-46 is required to interface the TK-8102H to the

computer. It has a circuit in its D-subconnector (25-pin) case
that converts the RS-232C logic level to the TTL level.

The KPG-46 connects the modular microphone jack of

the TK-8102H to the computers RS-232C serial port.

IBM-PC

KPG-46

4. Clone Mode

Programming data can be transferred from one radio to
another by connecting them via their modular microphone
jacks. The operation is as follows (the transmit radio is the
master and the receive radio is the slave).

Note :

Clone mode should enabled.

1. Turn the master TK-8102H power ON with the [1] key

held down. The TK-8102H [●] LED is turned on.

2. Power on the slave TK-8102H.

3. Connect the cloning cable (No. E30-3382-05) to the

modular microphone jacks on the master and slave.

4. Press the [●] key on the master TK-8102H transceiver.

The data of the master is sent to the slave. While the

master is sending data, [TX] LED blinked. While the slave

is receiving the data, 4 LEDs, [MON] LED, [●] LED are

turned on and [BUSY] LED blinked. When cloning of data

is completed, the master [TX] LED turned off, and the

slave automatically operates in the User mode. The slave

can then be operated by the same program as the mas-

ter.

5. The other slave can be continuously cloned. Carry out

the operation in step 2 to 4.

4-1. Adding the data password.

If the data password is set in the optional feature menu,
you must enter the password (Master transceiver) to acti­vate a clone mode.

you can use 1, 2, 3, and 4 to configure the password. The
maximum length of the password is 10 digits.

KPG-70D

TK-8102H

Fig. 1

3-4. Programming Software Description

The KPG-70D programming disk is supplied in 3-1/2" disk
format. The software on this disk allows a user to program
TK-8102H radio via a programming interface cable (KPG-46).

3-5. Programming With IBM PC

If data is transferred to the transceiver from an IBM PC
with the KPG-70D, the destination data (basic radio informa­tion) for each set can be modified.

1. [1]+Power ON.

2. [1]~[4] LED, and MON LED are turned ON.

3. Enter the password using [1]~[4] keys.

4. Press [MON] key.

5. If the password matches, the transceiver enters a clone
mode. Otherwise, transceiver beeps and returns to the
password input mode.

Clone cable
(E30-3382-05)

Fig. 2

8

DISASSEMBLY FOR REPAIR

Tabs

Tabs

TK -8 102H

1. When you remove the panel, turn the transceiver up side
down. Detach the panel by lifting the tabs as shown be­low.

Tabs

Fig. 1

2. To remove the cabinet, first turn the transceiver up side
down. Detach the cabinet by prying the tabs as shown
below.

3. To remove the display unit PCB, detach the PCB by lifting
at the indents of the PCB as shown below.

Indents

Fig. 3

4. When mounting the front panel, match the 4 tabs of the
chassis with the panel, being sure they attach securely.

Tabs

Fig. 2

Tabs

Fig. 4

9

TK -8 102H

CIRCUIT DESCRIPTION

Frequency Configuration

The receiver utilizes double conversion. The first IF is

49.95MHz and the second IF is 450kHz. The first local oscil­lator signal is supplied from the PLL circuit.

The PLL circuit in the transmitter generates the neces-

sary frequencies. Figure 1 shows the frequencies.

ANT

ANTSWRF

POWER

AMP

AMP

RF

AMP

1st

MIX

MCF

49.95MHz

RX

TX

1/2

CF 450kHz

IF SYSTEM

50.4MHz

X3

multiply

TCXO

PLL/VCO

AF
PA

16.8MHz

MIC

AMP

SP

MIC

Fig. 1 Frequency configuration

Receiver System

The receiver is double conversion superheterodyne. The

frequency configuration is shown in Figure 1.

Item Rating

Nominal center frequency 49.95MHz
Pass bandwidth ±5.0kHz or more at 3dB
35dB stop bandwidth ±20.0kHz or less
Ripple 1.0dB or less
Insertion loss 5.0dB or less

Guaranteed attenMuation

Terminal impedance 350Ω / 5.5pF

80dB or more at fo±1MHz
Spurious : 40dB or more within fo±1MHz

Table 1 Crystal filter (L71-0591-05) : XF1

Item Rating

Nominal center frequency 450kHz
6dB bandwidth ±6.0kHz or more
50dB bandwidth ±12.5kHz or less
Ripple 2.0dB or less
Insertion loss 6.0dB or less
Guaranteed attenuation 35.0dB or more within fo±100kHz
Terminal impedance 2.0kΩ

Table 2 Ceramic filter (L72-0993-05) : CF1

■ Front-end RF Amplifier

An incoming signal from the antenna is applied to an RF
amplifier (Q26) after passing through a transmit/receive
switch circuit (D803 and D804 are off) and a BPF (L36, L38
L48, L49 and varactor diodes: D25, D26, D28). After the
signal is amplified (Q26), the signal is filtered by a BPF (L30,
L32 and varactor diodes: D21, D22) to eliminate unwanted
signals before it is passed to the first mixer.

The voltage of these diodes are controlled by tracking the
CPU (IC6) center frequency of the band pass filter. (See Fig.

2)

■ First Mixer

The signal from the RF amplifier is heterodyned with the
first local oscillator signal from the PLL frequency synthe­sizer circuit at the first mixer (Q21) to create a 49.95MHz
first intermediate frequency (1st IF) signal. The first IF signal
is then fed through two monolithic crystal filters (MCFs :
XF1) to further remove spurious signals.

■ IF Amplifier

The first IF signal is amplified by Q19, and the enters IC5
(FM processing IC). The signal is heterodyned again with a
second local oscillator signal within IC5 to create a 450kHz
second IF signal. The second IF signal is then fed through a
450kHz ceramic filter (Wide : CF1, Narrow : CF2) to further
eliminate unwanted signals before it is amplified and FM de­tected in IC5.

Item Rating

Nominal center frequency 450kHz
6dB bandwidth ±4.5kHz or more
50dB bandwidth ±10.0kHz or less
Ripple 2.0dB or less
Insertion loss 6.0dB or less
Guaranteed attenuation 60.0dB or more within fo±100kHz
Terminal impedance 2.0kΩ

Table 3 Ceramic filter (L72-0999-05) : CF2

10

CIRCUIT DESCRIPTION

AF

Filter

D/A

CONV.

D/A

CONV.

IC3 IC10

IC3

DEO

AF PA

IC101 SP

IF IC

IC5

Q18

NOISE AMP

D18IC5 IC6

AF

RSSI

DET

CPU

IF

SYSTEM

SQIN

RSSI

CF1 (Wide)

TK -81 02H

ANT

D801~
D804

ANT

SW

L36,38,48,49

IC3

D/A

D25,26,28

BPF

TV

CPU

Q26

RF AMP

L30,32
D21,22

BPF

1st local

OSC (VCO/PLL)

Q21
MIX

Fig. 2 Receiver system

■ Wide/Narrow Changeover Circuit

The Wide port (pin 92) and Narrow port (pin 91) of the
CPU is used to switch between ceramic filters. When the
Wide port is high, the ceramic filter SW diodes (D13, D15)
cause CF1 to turn on to receive a Wide signal.

When the Narrow port is high, the ceramic filter SW diodes
(D13, D15) cause CF2 to turn on to receive a Narrow signal.

IC5

IF_IN MIX_O

CF1

(Wide)

IF System

R73

Wide
IC6 92pin

R77

CF2 (Narrow)

XF1

MCF

Q19

IF AMP

X1

TCXO

IC5

IF system

Q6

X3 multiply

IC3

D/A CONVERTER

DEO

■ AF Signal System

The detection signal from IF IC (IC5) goes to D/A con­verter (IC3) to adjust the gain and is output to AF filter (IC10)
for characterizing the signal. The AF signal output from IC10
and the DTMF signal, BEEP signal are summed and the re­sulting signal goes to the D/A converter (IC3). The AFO out­put level is adjusted by the D/A converter. The signal output
from the D/A converter is input to the audio power amplifier
(IC101). The AF signal from IC101 switches between the
internal speaker and speaker jack (J1) output.

Narrow
IC6 91pin

Fig. 3 Wide/Narrow changeover circuit

CF2

(Narrow)

R74

D13 D15

R78

FIg. 4 AF signal system

■ Squelch Circuit

The detection output from the FM IF IC (IC5) passes
through a noise amplifier (Q18) to detect noise. A voltage is
applied to the CPU (IC6). The CPU controls squelch accord­ing to the voltage (SQIN) level. The signal from the RSSI pin
of IC5 is monitored. The electric field strength of the re­ceive signal can be known before the SQIN voltage is input
to the CPU, and the scan stop speed is improved.

Fig. 5 Squelch circuit

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TK -8 102H

CIRCUIT DESCRIPTION

PLL Frequency Synthesizer

The PLL circuit generates the first local oscillator signal

for reception and the RF signal for transmission.

■ PLL

The frequency step of the PLL circuit is 5 or 6.25kHz. A

16.8MHz reference oscillator signal is divided at IC1 by a
fixed counter to produce the 5 or 6.25kHz reference fre­quency. The voltage controlled oscillator (VCO) output sig­nal is buffer amplified by Q15, then divided in IC1 by a dual­module programmable counter. The divided signal is com­pared in phase with the 5 or 6.25kHz reference signal in the
phase comparator in IC1. The output signal from the phase
comparator is filtered through a low-pass filter and passed
to the VCO to control the oscillator frequency. (See Fig. 6)

■ VCO

The operating frequency is generated by Q11 in transmit
mode and Q10 in receive mode. The oscillator frequency is
controlled by applying the VCO control voltage, obtained
from the phase comparator, to the varactor diodes (D10 and
D12 in transmit mode and D9 and D11 in receive mode).
The TX/RX pin is set low in receive mode causing Q12 and
Q7 to turn Q11 off, and turn Q10 on. The TX/RX pin is set
high in transmit mode. The outputs from Q10 and Q11 are
amplified by Q15 and sent to the RF amplifiers.

■ Unlock Circuit

During reception, the 8RC signal goes high, the 8TC sig­nal goes low, and Q29 turns on. Q31 turns on and a voltage
is applied to the collector (8R). During transmission, the
8RC signal goes low, the 8TC signal goes high and Q30
turns on. Q33 turns on and a voltage is applied to 8T.

The CPU in the control unit monitors the PLL (IC1) LD
signal directly. When the PLL is unlocked during transmis­sion, the PLL LD signal goes low. The CPU detects this
signal and makes the 8TC signal low. When the 8TC signal
goes low, no voltage is applied to 8T, and no signal is trans­mitted.

8C

8R 8T

Q31

SW

Q29

SW

8RC

IC6

CPU

Q33

SW

Q30

SW

LD

8TC

IC1

PLL

PLL lock
: LD “H”

PLL

DATA

16.8MHz

IC1 : PLL IC

REF

OSC

1/N

1/M

5kHz/6.25kHz

Phase

comparator

5kHz/6.25kHz

LPF

Charge

pump

Fig. 6 PLL circuit

D10,12

D9,11

Fig. 7 Unlock circuit

Q11

TX VCO

Q15

BUFF

AMP

Q10

RX VCO

Q7,12

T/R SW

Q3

AMP

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CIRCUIT DESCRIPTION

IC3

D/A

converter

IC1

PLL

IC9

DTMF

DECO.

IC6

CPU

DTMDAT
DTMCLK
DTMSTD

DAST

CNTDT

CNTCK

PLLE
DT
CK

TK -81 02H

Transmitter System

■ Outline

The transmitter circuit produces and amplifies the de­sired frequency directly. It FM-modulates the carrier signal
by means of a varicap diode.

■ Power Amplifier Circuit

The transmit output signal from the VCO passes through
the transmission/reception selection diode (D19) and ampli­fied by Q39, Q23, Q800 and Q801. The amplified signal
goes to the final amplifier (Q101) through a low-pass filter.
The low-pass filter removes unwanted high-frequency har­monic components, and the resulting signal is goes the an­tenna terminal.

■ APC Circuit

The automatic transmission power control (APC) circuit
detects part of a final amplifier (Q101) output with a diode
(D805, D806) and applies a voltage to IC800. IC800 com­pares the APC control voltage (PC) generated by the D/A
converter (IC3) and DC amplifier (IC4) with the detection
output voltage. IC800 generates the voltage to control
Q800, Q801 and Q101 and stabilizes transmission output.

The APC circuit is configured to protect over current of
Q800, Q801 and Q101 due to fluctuations of the load at the
antenna end and to stabilize transmission output at voltage
and temperature variations.

Control Circuit

The CPU carries out the following tasks:

1) Controls the WIDE, NARROW, TX/RX outputs.

2) Adjusts the AF signal level of the AF filter (IC10) and turns
the filter select compounder on or off.

3) Controls the DTMF decoder (IC9).

4) Controls the display unit.

5) Controls the PLL (IC1).

6) Controls the D/A converter (IC3) and adjusts the volume,
modulation and transmission power.

Fig. 10 Control circuit

■ Memory Circuit

The transceiver has an 8k-bit EEPROM (IC7). The

EEPROM contains adjustment data. The CPU (IC6) controls
the EEPROM through three serial data lines.

D19

CONVERTER

Q39

RF

AMP

3pin

D/A

M62363FP

Q23
PRE

DRIVE

AMP

IC4

PC

DC

IC3

AMP

MIC/IDC

NJM2100V

MIC KEY

INPUT

IC3 Q11

Q800

DRIVE
AMP1

Q801

DRIVE
AMP2

IC800

APC

CONTROL

Fig. 9 APC circuit

IC22IC21(1/2)MIC

Splatter

FILTER

NJM2904V

IC6

CPU

784214GC

VCO

2SK508NV

(K52)

NJM2902V

CONVERTER

Q15

BUFFER

2SC5108

(Y)

Q101

FINAL

AMP

IC4

SUM AMP

IC3

D/A

M62363FP

D801~804

ANT

SW

CONVERTER

M62363FP

Q20

RF

2SC5108

(Y)

D805
D806

IC3

D/A

LPF

POWER

DET

RF AMP

2SC5110

ANT

Q39

(O)

IC4

BUFFER

NJM2902V

DRIVE AMP

2SC3356(R24)

Q23
PRE

EEPCK

IC6

CPU

EEPDT

EEPWP

IC7

EEPROM

Fig. 11 Memory circuit

Q800

DRIVE
AMP 1

2SK2596

Q801

DRIVE
AMP 2

2SK3075

ANT

IC101

FINAL AMP
2SK3478-22

X1

TCXO

16.8MHz

IC1

PLL

MB15A02

Q3

RF AMP

2SC4649

(N,P)

Fig. 8 Transmitter system

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