Kenwood TK-7108H Service Manual

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VHF FM TRANSCEIVER

TK-7108H

SERVICE MANUAL

Chassis	Cabinet	Front glass	Panel assy
(A10-4048-11)	(A01-2181-01)	(B10-2668-03)	(A62-0942-03)

Modular jack	Key top
(E08-0877-05)	(K29-9065-01)

CONTENTS

GENERAL ..................................................	2	ADJUSTMENT ........................................	27
OPERATING FEATURES ..........................	3	TERMINAL FUNCTION ...........................	32
REALIGNMENT .........................................	7	PC BOARD
DISASSEMBLY FOR REPAIR ...................	9	DISPLAY UNIT (X54-3340-20) ............	33
CIRCUIT DESCRIPTION ..........................	10	TX-RX UNIT (X57-6383-01) ................	35
SEMICONDUCTOR DATA ......................	15	SCHEMATIC DIAGRAM ..........................	41
COMPONENTS DESCRIPTION ..............	17	BLOCK DIAGRAM ...................................	45
PARTS LIST .............................................	19	LEVEL DIAGRAM ....................................	47
EXPLODED VIEW ....................................	25	SPECIFICATIONS ....................................	49
PACKING .................................................	26

TK-7108H

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 powerup for safe operation.

•This equipment should be serviced by only qualified technicians.

PRE-INSTALLATION CONSIDERNATIONS

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.

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.

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 installation 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 recommended.

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.

TK-7108H

GENERAL / OPERATING FEATURES

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

OPERATING FEATURES

1. Controls and Functions

1-1. Front Panel

q w e

r t

1-2. Microphone

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.

Antenna	Speaker
connector	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 func-

tions available for this key are listed below.

t key

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. When using the Group function, press to select a channel from 5 to 8.

u Microphone jack

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

i Speaker Internal speaker.

oPTT switch

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

1-3. Auxiliary Programmable Functions

•	Emergency	•	None (no function)
•	Group	•	Scan On/Off
•	Key Lock	•	Talk Around
•	Monitor	•	Temporary Delete

TK-7108H

OPERATING FEATURES

1-4. Display

2. Operation Features

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 to display the currently selected channel (1~ 4 or 5~8).

1-5. Rear panel

Antenna	External
connector	speaker
	jack

Power input connector

The TK-7108H 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

•Group

•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.

TK-7108H

OPERATING FEATURES

• 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.

■ 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 resume, 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.

■ Temporary delete

• None

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

• Group

If Group has been programmed onto a key, press the Group key to select the second group of channels. While active, the LED beside the key lights. At this time, press a key from 1 to 4 select a channel from 5 to 8. To return to channels 1 through 4, press the Group key again.

Note : You cannot use the Group function while operating in Emergency mode.

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.

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.

TK-7108H

OPERATING FEATURES

■ 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 transmission.

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.

■ “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

■ 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	Channel setting		RX condition	Speaker

	QT/DQT	DTMF		condition

Carrier	None	None	Carrier	Sounds

		Yes	Carrier	Sounds

			Carrier+DTMF	Sounds

Carrier+DTMF	None	Yes	Carrier	Not Sounds

			Carrier+DTMF	Sounds

QT/DQT	Yes	None	Carrier	Not Sounds

			Carrier+QT/DQT	Sounds

		Yes	Carrier	Not Sounds

			Carrier+QT/DQT	Sounds

			Carrier+QT/DQT+DTMF	Sounds

			Carrier+DTMF	Not Sounds

QT/DQT+DTMF	Yes	Yes	Carrier	Not Sounds

			Carrier+QT/DQT	Not Sounds

			Carrier+QT/DQT+DTMF	Sounds

			Carrier+DTMF	Not Sounds

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.

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.

■ 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.

TK-7108H

OPERATING FEATURES / REALIGNMENT

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.

■ 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.

REALIGNMENT

1. Modes

	User mode
	User mode


			Data program-
	PC mode		Data program-
	PC mode		ming mode
			ming mode


	Clone mode		PC test mode	PC tuning mode
	Clone mode		PC test mode	PC tuning mode

	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.

■ 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.

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-7108H 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.

TK-7108H

REALIGNMENT

3-2. Connection Procedure

1.Connect the TK-7108H 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-7108H to PC mode.

3-3. KPG-46 Description

(PC programming interface cable : Option)

The KPG-46 is required to interface the TK-7108H 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-7108H to the computers RS-232C serial port.

IBM-PC

KPG-46

KPG-70D

TK-7108H

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-7108H 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.

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-7108H power ON with the [1] key held down. The TK-7108H [●] LED is turned on.

2.Power on the slave TK-7108H.

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-7108H 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 master.

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.

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

TK-7108H

DISASSEMBLY FOR REPAIR

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

Tabs

Indents

Fig. 1

Fig. 3

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

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

Tabs

Fig. 4

Fig. 2

TK-7108H

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 necessary frequencies. Figure 1 shows the frequencies.

ANT

CF 450kHz

1st

MCF

MIX 49.95MHz

ANT

IF SYSTEM

AMP

50.4MHz

multiply

16.8MHz

TCXO

1/2

PLL/VCO

MIC

POWER

AMP

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 (D804 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

	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	80dB or more at fo±1MHz

		Spurious : 40dB or more within 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	60.0dB or more within fo±100kHz

Terminal impedance	2.0kΩ

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

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.

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