Kenwood TK-7102 User Manual

VHF FM TRANSCEIVER

TK-7102

SERVICE MANUAL

TK -7 102TK -7 102

© 2001-5 PRINTED IN JAPAN
B51-8584-00 (S) 283

Cabinet
(A01-2178-02)

Front glass
(B10-2668-03)

Key top
(K29-9065-01)

Panel assy
(A62-0942-03)

CONTENTS / GENERAL

CONTENTS

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

OPERATING FEATURES ......................................... 4

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

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

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

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

DESCRIPTION OF COMPONENTS ....................... 16

PARTS LIST ............................................................ 18

EXPLODED VIEW ................................................... 24

PACKING ................................................................. 25

ADJUSTMENT ........................................................ 26

PC BOARD VIEWS

DISPLAY UNIT (X54-3340-20) ........................... 31

TX-RX UNIT (X57-6290-20) ............................... 33

SCHEMATIC DIAGRAM ......................................... 39

BLOCK DIAGRAM................................................... 43

LEVEL DIAGRAM.................................................... 45

TERMINAL FUNCTION .......................................... 47

SPECIFICATIONS.................................BACK COVER

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.

2 47

2

GENERAL

TK-7102

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.

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.

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.

Antenna connector

speaker jack cap

Power input

connector

3

TK-7102

External

speaker jack

Power input

connector

Antenna connector

OPERATING FEATURES

1. Controls and Functions

1-1. Front Panel

q

we tr

u

1-2. Microphone

o

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 (page 5). 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.

y

1-4. Display

i

Indicator Description

Light while transmitting.

Lights when a signal is detected on

the currently selected channel.

Lights while the function pro-

grammed onto its corresponding key

is activated.

Lights while the function pro-

grammed onto its corresponding key

is activated.

Lights to display the currently se-

lected channel (1~ 4)

1-5. Rear panel

1-3. Auxiliary Programmable Functions:

• Emergency • Scan On/OFF

• Key Lock • Talk Around

• Monitor • Temporary Delete

• None (no function)

4

OPERATING FEATURES

TK-7102

2. Operation Features

The TK-7102 is a VHF 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.

• 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.

• 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 fre-

quency 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.

• 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.

■ 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 re-

sume, the transceiver "talks back" on the current receive

channel.

■ Scan end

When you press the key programmed to the scan func­tion during scan mode, the scan ends.

The indicator next to the programmed key LED turns off.

5

TK-7102

OPERATING␣ FEATURES

■ 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.

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.

■ 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.

■ 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

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.

SP Unmute

Carrier None

Carrier+DTMF

QT/DQT Yes

QT/DQT+DTMF

Channel Setting

QT/DQT DTMF Condition

None Yes

Yes Yes

RX Condition

None Carrier Sounds

Carrier Sounds

Yes

Carrier+DTMF Sounds

Carrier Not Sounds

Carrier+DTMF Sounds

Carrier Not Sounds

None

Carrier+QT/DQT

Carrier Not Sounds

Carrier+QT/DQT

Yes

Carrier+QT/DQT+DTMF

Carrier+DTMF Not Sounds

Carrier Not Sounds

Carrier+QT/DQT

Carrier+QT/DQT+DTMF

Carrier+DTMF Not Sounds

Speaker

Sounds

Sounds

Sounds

Not Sounds

Sounds

■ "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.

6

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.

■ 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.

OPERATING␣ FEATURES / REALIGNMENT

User mode

PC mode

Data program­ming mode

PC test mode

PC tuning mode

Clone mode

TK-7102

■ 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.

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.

■ 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.

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)

■ 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.

3. PC Mode

3-1. Preface

The TK-7102 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.

3-2. Connection Procedure

1. Connect the TK-7102 to the personal computer with the

interface cable.

2. When the Power is switched on, user mode can be en-

tered 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 [

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-7102 to

PC mode.

] LED are

7

TK -7102

REALIGNMENT

3-3. KPG-46 Description

(PC programming interface cable : Option)

The KPG-46 is required to interface the TK-7102 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-7102 to the computers RS-232C serial port.

KPG-46

IBM-PC

KPG-70D

Fig. 1

TK-7102

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-7102 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.

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.

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.

Cloning cable
(E30-3382-05)

Fig. 2

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-7102 power ON with the [1] key held

down. The TK-7102 [

2. Power on the slave TK-7102.

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

modular microphone jacks on the master and slave.

4. Press the [

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

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

ceiving the data, 4 LEDs, [MON] LED, [

on and [BUSY] LED blinked. When cloning of data is com-

pleted, the master [TX] LED turned off, and the slave au-

tomatically operates in the User mode. The slave can

then be operated by the same program as the master.

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

the operation in step 2 to 4.

] key on the master TK-7102 transceiver. The

8

] LED is turned on.

] LED are turned

DISASSEMBLY FOR REPAIR

TK -7102

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

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

indents

Fig. 3

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

tabs

tabs

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

tabs

tabs

Fig. 2

Fig. 4

9

TK-7102

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.

1/2

CF 450kHz

IF SYSTEM

50.4MHz

X3

multiply

TCXO

PLL/VCO

AF

AMP

16.8MHz

MIC

AMP

SP

MIC

ANT

ANTSWRF

AMP

PA

AMP

AMP

TX

1st

MIX

MCF

49.95MHz

RX

TX

Fig. 1 Frequency configuration

Receiver System

The receiver is double conversion superheterodyne. The

frequency configuration is shown in Figure 1.

■ 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 (D31 is off) and a band pass filter (L36, L38
and varactor diodes: D25, D26). After the signal is amplified
(Q26), the signal is filtered through a band pass filter (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 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 attenuation 80dB or more at fo±1MHz

Spurious : 40dB or more within fo±1MHz

Terminal impedance 350Ω / 5.5pF

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

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 55.0dB or more within fo±100kHz
Terminal impedance 2.0kΩ

Table 3 Ceramic filter (L72-0994-05) : CF2

CF1 (Wide)

10

ANT

D30,31

ANT

SW

IC3

D/A

L36,38
D25,26

BPF

TV

CPU

Q26

RF AMP

L30,32

D21,22

BPF

1/2 divider

1st local

OSC (VCO/PLL)

Q21
MIX

IC23

XF1

MCF

Q19

IF AMP

X1

TCXO

Fig. 2 Receiver system

CF2 (Narrow)

IC5

MIX,IF,DET

Q6

X3 multiply

IC3

AF AMP

DEO

CIRCUIT DESCRIPTION

TK-7102

■ 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

R78

IF System

R73

R77

Wide
IC6 92pin

Narrow
IC6 91pin

IF_IN MIX_O

CF1

(Wide)

CF2

D13 D15

(Narrow)

R74

Fig. 3 Wide/Narrow changeover circuit

■ AF Signal System

The detection signal from IF IC (IC5) goes to AF amp (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 (IC16).
The AF signal from IC16 switches between the internal
speaker and speaker jack (J1) output.

■ 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.

IF

SYSTEM

Q18

NOISE AMP

AF

RSSI

D18IC5 IC6

DET

SQIN

RSSI

CPU

Fig. 5 Squelch circuit

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)

IC5

IF IC

IC3 IC10

DEO

AF

AMP

Filter

AF

IC3

D/A

CONV.

FIg. 4 AF signal system

IC102 SP

AF PA

■ 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 buffer amplifiers.

11

TK-7102

CIRCUIT DESCRIPTION

IC1 : PLL IC

5kHz/6.25kHz

1/N

PLL

DATA

16.8MHz

REF

OSC

1/M

Phase

comparator

5kHz/6.25kHz

Charge

pump

Fig. 6 PLL circuit

■ 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

Q33

SW

LPF

D10,12

D9,11

Q11

TX VCO

Q10

RX VCO

Q15

BUFF

AMP

Q7,12

T/R SW

Q3

RF AMP

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 to a specified level of the power module (IC101) by the
drive block (Q23 and Q25). The amplified signal goes to a
low-pass filter. The low-pass filter removes unwanted high­frequency harmonic components, and the resulting signal is
goes the antenna terminal.

Q29

SW

8RC

IC6

CPU

Fig. 7 Unlock circuit

MIC/IDC

NJM2100V

MIC KEY

INPUT

IC3 Q11

D/A

CONVERTER

M62363FP

X1

TCXO

16.8MHz

Splatter

FILTER

NJM2904V

784214GC

VCO

2SK508NV

(K52)

IC1

PLL

MB15A02

Q30

SW

LD

IC22IC21(1/2)MIC

IC6

CPU

8TC

PLL

PLL lock
: LD "H"

BUFFER

2SC5108

BUFFER

2SC4649

(N,P)

IC1

IC4

SUM AMP

NJM2902V

IC3

D/A

CONVERTER

M62363FP

Q15

(Y)

Q3

IC3

D/A

CONVERTER

M62363FP

IC23
1/2

DIVIDER

UPB1509GV

BUFFER

NJM2902V

Q20

BUFFER
2SC4649

(N,P)

IC4

Q23

RF AMP

2SC3357

Q25

RF AMP

2SC2954

IC101

POWER AMP

M67741H-32

ANT

12

Fig. 8 Transmitter system