Kenwood NX-740H, NX-740, NX-740V, NX-740HV Service Manual

SERVICE MANUAL

VHF DIGITAL TRANSCEIVER

RA010<Rev.001>20145SERVICE MANUALB5B-7126-00

NX-740H, NX-740H(V), NX-740

ACC.

1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21

4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-23

5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-29

his product complies with the RoHS directive for the European market.

B5B-7126-00

Note :

Lead free solder used in the board (material : Sn, Ag, In, Bi, melting point : 227 Centigrade)

TABLE OF CONTENTS

This product uses Lead Free solder.

No.RA010<Rev.001>

2014/5

Document Copyrights

Copyright 2014 by JVC KENWOOD Corporation. All rights reserved. No part of this manual may be reproduced, translated, distributed, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, for any purpose without the prior written permission of JVC KENWOOD Corporation.

Disclaimer

While every precaution has been taken in the preparation of this manual, JVC KENWOOD Corporation assumes no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein. JVC KENWOOD Corporation reserves the right to make changes to any products herein at any time for improvement purposes.

Firmware Copyrights

The title to and ownership of copyrights for firmware embedded in KENWOOD product memories are reserved for JVC KENWOOD Corporation. Any modifying, reverse engineering, copy, reproducing or disclosing on an Internet website of the firmware is strictly prohibited without prior written consent of JVC KENWOOD Corporation. Furthermore, any reselling, assigning or transferring of the firmware is also strictly prohibited without embedding the firmware in KENWOOD product memories.

Transceivers containing AMBE+2 Vocoder: The AMBE+2 voice coding technology is embedded in the firmware under the license of Digital Voice Systems, Inc.

1-2 (No.RA010<Rev.001>)

SPECIFICATION

GENERAL

Frequency Range 136 ~ 174MHz

Number of Channels Max. 32ch

Number of Zones 2 zones (Max. 16ch per Zone)

Channel Spacing Analog 12.5kHz

Digital 6.25kHz

Operating Voltage 13.6V DC ±15%

Operating Temperature Range -22°F ~ +140°F (-30°C ~ +60°C)

Frequency Stability ±2.0ppm

Antenna Impedance 50Ω

Dimensions (W x H x D) (Projections not included)

Weight (net) Transceiver only 1.10 kg (2.42 lb)

RECEIVER

Sensitivity Digital 0.28µV

Analog (12dB SINAD) 0.28µV

Selectivity Analog 65dB

Intermodulation Distortion Analog 65dB

Spurious Response Analog 75dB

Audio Output (4Ω impedance) 4W with less than 5% distortion

TRANSMITTER

RF Power Output 5W ~ 50W (NX-740H)

Spurious Response 70dB

FM Hum & Noise Analog 40dB

Audio Distortion Less than 5%

Modulation 11K0F3E, 4K00F1E, 4K00F1D, 4K00F7W, 4K00F2D

Measurements made per TIA/EIA-603 and specifications shown are typical. JVC KENWOOD Corporation reserves the right to change specifications without prior notice or obligation.

160 x 43 x 122.6 mm (6.29 x 1.69 x 4.82 in)

5W ~ 25W (NX-740)

(No.RA010<Rev.001>)1-3

2.1 SYSTEM SET-UP

SECTION 1

PRECAUTION

This service manual does not describe PRECAUTION.

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

2.2 REALIGNMENT

2.2.1 Modes

User mode

PC mode

Merchandise received

Choose the type of transceiver

Transceiver programming

(Option)

KES-3

External speaker

Data programming mode

A personal computer, programming interface (KPG-46A/46U), and FPU (programming software) are required for programming.

KCT-60

Connection cable

Extension cable

KCT-18

Ignition sense cable

Delivery

Frequency range (MHz)

136~174 25W NX-740 M

136~174

(Option)

KCT-36

(Option)

External speaker

RF power

50W

(Option)

KES-5

Type

NX-740H K

NX-740H(V) K

2.2.2 How to Enter Each Mode

Mode Function

User mode Power ON

PC mode Received commands from PC

Clone mode [ ] + Power ON (Two seconds)

Clone mode

PC test mode

PC tuning mode

Mode Function

User mode For normal use.

PC mode Used for communication between the

transceiver and PC (IBM compatible).

PC programming mode

Used to read and write frequency data and other features to and from the transceiver.

PC test mode Used to check the transceiver using the

PC. This feature is included in the FPU.

PC tuning mode Used to tune the transceiver using the

PC.

Clone mode Used to transfer programming data

from one transceiver to another.

1-4 (No.RA010<Rev.001>)

2.2.3 PC Mode

2.2.3.1 Preface

The transceiver is programmed using a personal computer, a programming interface (KPG-46A/46U) and FPU (programming software). The programming software can be used with a PC. Figure 1 shows the setup of a PC for programming.

KPG-46A or KPG-46U + Tuning cable (E30-3383-05)

FPU

D-SUB (9-pin)

KPG-46A

Transceiver

USB

KPG-46U

Transceiver

Fig.1

2.2.3.2 Connection procedure

(1) Connect the transceiver to the computer using the interface

cable.

Note:

You must install the KPG-46U driver in the computer to use the USB programming interface cable (KPG-46U).

(2) When the Power is switched on, you can immediately enter

user mode. When the PC sends a command, the transceiver enters PC mode, and “Pc” is displayed on the LED. When data is transmitting from the transceiver, the red LED blinks. When data is receiving by the transceiver, the green LED blinks.

Note:

The data stored in the computer must match the “Model Name” when it is written into the EEPROM.

2.2.3.3 KPG-46A description (PC programming interface cable: Option)

The KPG-46A is required to interface the transceiver to the computer. It has a circuit in its D-sub connector (KPG-46A: 9-pin) case that converts the RS-232C logic level to the TTL level. The KPG-46A connects the 8-pin microphone connector of the transceiver to the RS-232C serial port of the computer.

2.2.3.4 KPG-46U description (USB programming interface cable: Option)

The KPG-46U is a cable which connects to a USB port on a computer. When using the KPG-46U, install the supplied CD (with driver software) in the computer. The KPG-46U driver runs under Windows XP, Vista, 7 or 8. The latest version of the USB driver is available for download from the following URL: http://www.kenwood.com/usb-com/ (This URL may change without notice.)

2.2.3.5 Programming Software: KPG-175D description

The FPU is the programming software for the transceiver supplied on a CD. This software runs under Windows XP, Vista, 7 or 8 on a PC. The data can be input to or read from the transceiver and edited on the screen. The programmed or edited data can be printed out. It is also possible to tune the transceiver.

2.2.4 Clone Mode

Programming data can be transferred from one transceiver to another by connecting them via their cloning cable. The operation is as follows (the transmit transceiver is the source and the receive transceiver is a target).

Note:

Clone mode should be enabled. (1) Turn the source transceiver power ON with the [ ] key held

down (2 seconds), “cL” is displayed on the LED. (2) Power on the target transceiver. (3) Connect the cloning cable (No. E30-3382-05) to the modu-

lar microphone jacks on the source and target. (4) Press the [S] key on the source transceiver.

The data of the source is sent to the target. While the

source is sending data, red LED blinked.

While the target is receiving the data, “Pc” is displayed and

green LED blinked. When cloning of data is completed, the

source displays “En”, and the source red LED turned off,

and the target automatically operates in the User mode.

The target can then be operated by the same program as

the source. (5) The other target can be continuously cloned. Carry out the

operation in step 2 to 4.

2.2.4.1 Adding the data password.

If the data password is set in the optional feature menu, you must enter the password (Source transceiver) to activate a clone mode. You can use 0~9 to configure the password. The maximum length of the password is 6 digits.

(1) [ ]+Power ON. (2) “PS” is displayed on the LED. (3) If the [ ] and [ ] keys is pressed while “PS” is displayed,

numbers (0 to 9) are displayed flashing. When you press

the [C>] key, the currently selected number is determined.

If you press the [S] key after entering the password in this

procedure, “cL” is displayed if the entered password is cor-

rect. If the password is incorrect, “PS” is redisplayed.

Cloning cable (E30-3382-05)

Fig.2

(No.RA010<Rev.001>)1-5

2.2.4.2 Flow chart (Source transceiver)

Press [ ] key + Power ON for 2 seconds

password*

* Read Authorization password

set?

Start the clone funnction

Yes

Clone mode

[ ]

Shows PS

Enter password

Is entered

password

correct?

Yes

D-sub 15-pin Pin No. Name Molex 15-pin Pin No.

6 FNC1 9

7 FNC2 11

8 FNC3 7

9 FNC4 6

10 FNC5 8

11 FNC6 10

12 5MS NC

13 HR1 13

14 HR2 14

15 GND 3

2.3.2 Horn Alert Function

The Horn alert function (max. 2A drive) is enabled by installing the KCT-60 in the transceiver.

2.3 INSTALLATION

2.3.1 Connection Cable (KCT-60: Option)

The KCT-60 connection cable kit is used to connect the transceiver to a Horn alert cable, KCT-18 (Ignition sense cable), KES5 (External speaker), or through the KCT-36 extension cable.

2.3.1.1 Installing the KCT-60 (Connection cable) in the transceiver

(1) Remove the ACC. cap on the rear of the transceiver. (2) Connect the D-sub connector of the KCT-60 to the D-sub

15-pin terminal of the transceiver.

(3) Connect the 15-pin connector of the KCT-60 to a Horn alert

cable, KCT-18, KES-5, or through a KCT-36 extension cable.

Note:

You must set up using the KPG-175D.

KCT-60

2.3.2.1 Installation Procedure

(1) Remove the ACC. cap on the rear of the transceiver. (2) Connect the D-sub connector of the KCT-60 to the D-sub

15-pin terminal of the transceiver.

(3) Insert the two crimp terminals of the Horn alert cable to pins

13 and 14 of the square plug.

(4) Connect the square plug to the 15-pin connector of the

KCT-60.

(5) Connect the remaining two Horn alert cables to your car

Horn alert signal control. The internal FET switch can be controlled by turning the HA function on/off and by using a signaling decode output. The maximum current of HA is 2A. This FET switch is the open drain circuit. Therefore, a DC power supply is necessary to use the HR1. The voltage range is from 5V to 16V.

1. SB

13. HR1

14. HR2

3. GND

More than 8

(Default)

13. HR1

14. HR2

3. GND

1. SB

More than 8

13. HR1

14. HR2

3. GND

Horn alert cable, KCT-18, KES-5 or through KCT-36 extension cable

2.3.1.2 Terminal function

D-sub 15-pin Pin No. Name Molex 15-pin Pin No.

1SB1

2IGN2

3 PA or

External SP

4DETO 4

5 DATAI 5

1-6 (No.RA010<Rev.001>)

Horn alert cable

Crimp terminal

KCT-60

Square plug

2.3.3 Ignition Sense Cable (KCT-18: Option)

The KCT-18 is an optional cable for enabling the ignition function. The ignition function lets you turn the transceiver power on and off with the car ignition key.

2.3.3.1 Installing the KCT-18 (Ignition sense cable) in the transceiver

(1) The KCT-18 can be installed in the transceiver by the fol-

lowing two methods (Method A, Method B). Method A: The KCT-18 is soldered to the “IGN” pad on the TX-RX unit. Method B: The KCT-18 is connected to the 15-pin connector of the KCT-60 connected to the transceiver.

Installation Procedure: Method A

(1) Remove the two screws on both the right and left sides

of the transceiver, then remove the cabinet and top packing from the transceiver.

(2) Cut the crimp terminal side of the KCT-18 using a pair of

nippers or similar tool.

Cut

(3) Solder the cable side cut in the above step 3 to the “IGN”

pad on the TX-RX unit.

Installation Procedure: Method B

(1) Remove the ACC. cap on the rear of the transceiver. (2) Connect the D-sub connector of the KCT-60 to the D-sub

15-pin terminal of the transceiver.

(3) Insert the crimp terminal side of the KCT-18 to pin 2 of

the square plug.

(4) Connect the square plug to the 15-pin connector of the

KCT-60.

(5) Connect the other side of the KCT-18 to the ignition line

of the car.

Note:

You must set up using the KPG-175D.

KCT-18

Ignition line of the car

KCT-60

Square plug

TX-RX unit Component side

(4) Dress the KCT-18 cable as shown in the figure. The

KCT-18 cable needs to pass through one of two indentations located on the rear panel of the transceiver.

(5) Cut off the projection of the top packing using a pair of

nippers or similar tool. If the KCT-18 cable is dressed to be routed through the indentations on the right side in step 5, the right side of the projection needs to be cut off. If the KCT-18 cable is dressed to be routed through the indentations on the left side, the left side of the projection needs to be cut off. Following is a figure presenting an example for when the right side of the projection is cut off.

Top packing

2.3.4 External Speaker (Option)

2.3.4.1 KES-3

The KES-3 is an external speaker for the 3.5-mm-diameter speaker jack.

Connection procedure

(1) Remove the speaker-jack cap on the rear of the trans-

ceiver.

(2) Connect the KES-3 to the 3.5-mm-diameter speaker jack

on the rear of the transceiver.

(6) Reinstall the top packing. Check the correct fitting of the

top packing, then reinstall the cabinet and two screws for the right and left sides.

(7) Connect the other side of the KCT-18 to the ignition line

of the car.

(No.RA010<Rev.001>)1-7

2.3.4.2 KES-5

External speaker KES-5 can be installed for KCT-60.

Connection procedure

(1) Remove the ACC. cap on the rear of the transceiver. (2) Connect the D-sub connector of the KCT-60 to the D-sub

15-pin terminal of the transceiver.

(3) Insert the two crimp terminals of the KES-5 to pins 3 and

12 of the square plug.

(4) Connect the square plug to the 15-pin connector of the

KCT-60.

Note:

• You must set up using the KPG-175D. Before the external speaker can be used, you must assign one of the keys as “External Speaker”, using the KPG175D.

• This also applicable to public address provide you must assign one of the keys as “Public Address”, using the KPG-175D.

Black lead

KCT-60

Square plug

Black/ White lead

2.3.5 GPS Receiver Connection

2.3.5.1 Connecting the GPS receiver

(1) Soldering position

TX-RX unit

FNC2

DATA OUT

POWER

2.3.6 Extended Function: COM Port 0 and COM Port 1

Location of COM Port 0 and COM Port 1 of the transceiver is shown below.

COM Port 1

COM Port 0

You must configure the transceiver COM Port 0 and COM Port 1 using the KPG-175D. When you set as “Data”, the Function port 1 and 2 will be automatically fixed as Input ports. The reason for this is because function port 1 (TXD) and 2 (RXD) share the same circuit path of TXD and RXD line.

2.3.7 Changing Serial Port Level

2.3.7.1 Change FNC1 (TXD) and FNC2 (RXD) of D-SUB 15pin connector from TTL level to RS-232C level

FNC1 (TXD /6pin ) and FNC2 (RXD /7pin ) of D-SUB 15-pin connector are configured at the TTL level as the default value. But you can change these serial port level to RS-232C level through the RS-232C level converter IC (IC704) by configuring the port.

FNC1 (TXD)

Remove the R761 chip jumper and solder the clip jumper to R767.

TTL level RS-232C level

R761[5] *1 0Ω chip jumper. open

R767[6] *1 open 0Ω chip jumper.

FNC2 (RXD)

Remove the R724 and R762 chip jumpers and solder the chip jumpers to R725 and R756.

TTL level RS-232C level

R724[7], R762[9] *1 0Ω chip jumper. open

R725[8], R756[10] *1 open 0Ω chip jumper.

*1: The value in square bracket [ ] is the silk print number on the TX-RX unit.

GND

TX-RX unit Component side

GND

GROUND

GPS receiver

FNC2

(2) Refer to FNC2 (RXD) of “2.3.7 Changing Serial Port Level”.

1-8 (No.RA010<Rev.001>)

TX-RX unit Component side

2.3.8 Changing of Signal Type

MIC +ve cable (signal line)

MIC -ve cable (GND)

2.3.8.1 Change signal input of D-SUB connector from DI to MIC

The input (5pin) of D-SUB 15-pin connector is configured at the DI as the default value. Remove the R737 chip jumper and solder the chip jumper to R735.

TX-RX unit Component side

2.3.9 Emergency MIC

2.3.9.1 Installation Procedure

(1) Remove the two screws on both the right and left sides of

the transceiver, then remove the cabinet and top packing from the transceiver.

(2) solder the MIC connection cable as below

a) solder the MIC +ve cable (signal line) to EMGMIC

solder pad

b) solder the -ve cable (GND) to GND solder pad

MIC -ve cable (GND)

MIC +ve cable (signal line)

(3) Dress the cable as shown in the figure. The cable needs to

pass through one of two indentations located on the rear panel of the transceiver.

(4) Cut off the projection of the top packing using a pair of nip-

pers or similar tool. If the cable is dressed to be routed through the indentations on the right side in step 4, the right side of the projection needs to be cut off. If the cable is dressed to be routed through the indentations on the left side, the left side of the projection needs to be cut off. Following is a figure presenting an example for when the right side of the projection is cut off.

TX-RX unit Component side

Note:

You must set up using the KPG-175D.

Top packing

(5) Reinstall the top packing. Check the correct fitting of the

top packing, then reinstall the cabinet and two screws for the right and left sides.

(No.RA010<Rev.001>)1-9

2.4 CIRCUIT DESCRIPTION

2.4.1 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

AMP

1st

MIX

MCF

49.95MHz

IF SYSTEM

50.4MHz

Tripler

AF PA

16.8MHz

MIC

AMP

POWER

AMP

TCXO

PLL/VCO

Fig.1 Frequency configuration

2.4.2 Receiver System

The receiver is double conversion superheterodyne. The frequency configuration is shown in Figure 1.

D305,D306 D309,D310

ANT

L512,L513

D504,D505

BPF

IC503

DC OP AMP

Q506

RF AMP

TVC

L507,L508

D502,D503

BPF

OSC (VCO/PLL)

Q503

MIX

1st local

XF500

MCF

Q501

IF AMP

TCXO

IC501

FM IC system

Q500

Tripler

IC709

Baseband IC

Fig.2 Receiver system

2.4.2.1 Front-end RF Amplifier

An incoming signal from the antenna is applied to an RF amplifier (Q506) after passing through a transmit/receive switch circuit (D305, D306, D309 and D310) , BPF (L512, L513, and varactor diodes : D504, D505). After the signal is amplified (Q506), the signal is filtered by a BPF (L507, L508 and varactor diodes : D502, D503) to eliminate unwanted signals before it is passed to the first mixer. The voltage of these diodes are controlled by the TVC according to the channel frequency. (See Figure 2)

2.4.2.2 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 (Q503) to create a 49.95MHz first intermediate frequency (1st IF) signal. The first IF signal is then fed through one pair of monolithic crystal filter (MCF : XF500) to further remove spurious signals.

2.4.2.3 IF Amplifier Circuit

The first IF signal is amplified by Q501, and the enters IC501 (FM processing IC). The signal is heterodyned again with a second local oscillator signal within IC501 to create a 450kHz second IF signal. The second IF signal is fed through a 450 kHz filter in IC501 to further eliminate unwanted signals before it is amplified and FM detected in IC501.

1-10 (No.RA010<Rev.001>)

2.4.2.4 AF Signal System

The detection signal from FM IC (IC501) goes to the baseband IC (IC709) DISC input (pin 16) after pass through IC500 for characterizing the signal.

• Analog signal

The demodulated AF signal pass through IC709 with the signal processing and output at AUDIO (pin26) to the E-Vol before the Audio amplifier (IC719). The AF signal from IC719 switches between the internal speaker and speaker jack (J701) output.

• NXDN (Digital signal)

The recovered 4L-FSK signal obtained from IC501 is decoded in the baseband IC (IC709). Decoded signal is fed into microprocessor (IC714) and converted to PCM audio signal, and return to baseband IC (IC709) for converting to audio signal. This audio signal will output at AUDIO (pin26) to the E-Vol before the Audio amplifier (IC719). The AF signal from IC719 switches between the internal speaker and speaker jack (J701) output.

IC501

IC500

IC709

IC715

IC719

FM IC

AMP

Baseband IC

MCU

(Build in Vocoder)

E-Vol

IC714

AF PA

Fig.3 AF signal system

2.4.2.5 Squelch Circuit

Part of the AF signal goes a rectifier circuit to produce a DC voltage corresponding to the noise level after filtering and amplification. This DC voltage send to MCU (IC714) SQIN input pin. The MCU controls squelch according to the voltage (SQIN) level. The signal from the RSSI pin of IC501 is monitored. The electric field strength of the receive signal can be known before the SQIN voltage is input to the MCU, and the scan stop speed is improved.

Q500

Noise DET

SQIN

IC714

MCU

RSSI

IC501 FM IC

NAMPO

RSSI

Q502

Noise

AMP

Fig.4 Squelch circuit

2.4.3 Transmitter System

2.4.3.1 Outline

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

ANT

IC706MIC

MIC

AMP

D712, Q701

IC709

Baseband

VCO

Q11

BUFF

AMP

Q12

AMP

Q300 IC300

DRIVE

AMP

RF POWER

module

MIC key

input

MCU

IC714

TCXO

16.8MHz

PLL IC

IC2

AMP

Fig.5 Transmitter system

2.4.3.2 Power Amplifier Circuit

The transmit output signal from the VCO passes through the transmission/reception selection diode (D16) and amplified by Q300. The amplified signal goes to the RF power module (IC300) through a low-pass filter. The lowpass filter removes unwanted high-frequency harmonic components, and the resulting signal is goes the antenna terminal.

(No.RA010<Rev.001>)1-11

2.4.3.3 APC Circuit

The automatic transmission power control (APC) circuit detects part of a final amplifier output with a coupler circuit and applies a voltage to IC301. IC301 compares the APC control voltage (APCC) generated by the baseband IC (IC709) and DC amplifier (IC503) with the detection output voltage. IC301 generates the voltage to control IC300 and stabilizes transmission output. The APC circuit is configured to protect over current of Q300 and IC300 due to fluctuations of the load at the antenna end and to stabilize transmission output at voltage and temperature variations.

ANT

LPF

D16

DRIVE AMP

IC300Q300

RF POWER

MODULE

D305,D306 D309,D310

ANT

APCC IC709 pin 32

AMP

IC503

APC

control

IC301

Coupler

circuit

Fig.6 APC circuit and Power amplifier circuit

2.4.4 PLL Frequency Synthesizer

The PLL circuit generates the first local oscillator signal for reception and the RF signal for transmission.

2.4.4.1 PLL Circuit

The frequency step of the PLL is 2.5, 5.0, 6.25 or 7.5 kHz. A 16.8MHz reference signal is divided at IC2 by a fixed counter to produce the reference frequency. The voltage controlled oscillator (VCO) feedback output is divided by a programmable counter in IC2. The 2 signals are phase compared, filtered through a low pass filter and passed to VCO to control the oscillator frequency.

2.4.4.2 VCO Circuit

The operating frequency is generated by Q7 in transmit mode and Q5 in receive mode. The oscillator frequency is controlled by applying the control voltage, which obtained from the phase comparator, to varactor diodes (D5, D6, D9, D10, D11 in transmit mode and D7, D8, D12, D13, D14 in receive mode). The TX/RX pin is set “High” in receive mode causing turn on Q9. And T/R pin is set “Low” in transmit mode causing turn on Q6.

D9,D10,D11

PLL_DATA

MCU

PLL_UL

16.8MHz

IC2: PLL IC

REF

OSC

1/N

1/M

Phase

comparator

Charge

ASTC

pump

IC2

AMP

LPF

D5,D6

D7,D8

Assist

voltage

D12,D13,D14

TX VCO

RX VCO

Q11

BUFF

AMP

Q6,Q9

T/R SW

AMP

Fig.7 PLL and VCO circuit

2.4.4.3 Unlock Circuit

If low level appears at the “LD” pin of IC2, then PLL an unlock condition occurs. It causes the voltage applied to the “PLL_UL” pin of the microprocessor to go low. When the microprocessor detects this condition, the transmitter is disabled by ignoring the push-to-talk switch input signal.

1-12 (No.RA010<Rev.001>)

2.4.5 Control Circuit

The MCU carries out the following tasks:

(1) Controls the FM IC (IC501). (2) Controls the baseband IC (IC709). (3) Controls the PLL (IC2) & TX/RX outputs. (4) Controls IO expender through I2C level converter. (5) Controls the display unit.

PLL IC

PLL_U

PLL_PDN2 PDN RSTN

IC501 FM IC

CSN SCLK SDATA

BLED

RLED

GLED

IC714

MCU

MBL

Fig.8 Control circuit

2.4.5.1 Memory Circuit

The transceiver has an 256k-bit EEPROM (IC716). The EEPROM contains adjustment data. The MCU (IC714) controls the EEPROM through three serial data lines.

IC2

PLL_CLK

PLL_DATA

PLL_LE

LECI

LECE

LECL

IC1

LED Driver

Display unit

LELH

C.DATA R.DATA SCLK IRQ CSN

converterIOexpender

IC714

MCU

IC709

Baseband

I2C level

IC700 IC702

EEP_DATAO EEP_CLK EEP_DATAI EEP_CS EEP_WP

IC716

EEPROM

2.4.5.2 Display Circuit

The MCU (IC714) controls the Display 7-segment LED and LEDs. When power is on, the MCU will use the MBL line to control the key backlight LEDs. When the transceiver is busy, the GLED line goes high, Q1 turns on and the green LED (D23) lights after Q4 turn on. In transmit mode, the RLED line goes high, Q2and Q8 turns on and the red LED (D23) lights. BLED will be set high when the function select (FPU setting) is on, Q6 turn on and the blue LED (D22) lights. The dimmer function is controlled by the switch Q5. The LED driver (IC1) controls the functions of the 7-segment LED through the LEDI, LECE, LECL, LELH lines from the MCU.

IC714

MCU

Fig.9 Memory circuit

LEDM

LEDI LECE LECL LELH

MBL

GLED

RLED

BLED

IC1

LED

driver

Fig.10 Dsplay circuit

Display

7-segment

D1~D5

Key backlight

D23

D22

(No.RA010<Rev.001>)1-13

2.4.5.3 Key Matrix Circuit

The front panel has function keys. Each of them is connected to

KMO1

a cross point of a matrix of the KMI1 to KMO3 ports of the microprocessor. The KMO1 to KMO3 ports are always high, while the KMI1 to KMI3 ports are always low. The microprocessor monitors the status of the KMI1 to KMO3 ports. If the state of one of the ports changes, the microprocessor assumes that the key at the matrix point corresponding to that port has been pressed.

IC714

MCU

KMO2

KMO3

KMI3 KMI2 KMI1

CH UP

VOL DN

VOL UP

Fig.11 Key matrix circuit

2.4.6 Signaling Circuit

2.4.6.1 Encode

(1) Low-speed data (QT, DQT)

Low-speed data is output from pin 40 (LSDO) of the MCU (IC714). The signal passes through a low-pass CR filter. The signal is mixed with the audio signal and goes to the VCO and TCXO (X1) modulation input after signal processing in the baseband IC (IC709).

(2) High-speed data (2-tone)

High-speed data (HSD) is output from pin 41 (HSDO) of the MCU. The signal passes through a low-pass CR filter. TX deviation making an adjustment by microprocessor is applied to the baseband IC (IC709). The signal is mixed with the audio signal and goes to the VCO and TCXO. The side tone is audio ouput of baseband IC(IC709) at the same time to audio power amplifier and then to the speaker.

(3) MSK / DTMF

MSK and DTMF signal is self genarated by the baseband IC(IC709). The TX deviation adjustment is done by the output gain of baseband IC(IC709), and is routed to the VCO. When encoding MSK/DTMF, the microphone-input signal is muted.

TCXO

MOD

VCO

MOD

TCXO

IC1

PLL

VCO

IC714 MCU

LSDO

QT/DQT

HSDO

2-TONE

IC709

Baseband IC

DTMF/

MSK

Fig.12 Encode

CH DN

2.4.6.2 Decode

(1) Low-speed data (QT, DQT)

The demodulated signal from the FM IC (IC501) will input to baseband IC(IC701) to remove frequency above 300Hz. The signal is input to pin 26(LSDI) of the MCU. The MCU digitizes this signal, performs processing such as DC restoration, and decodes the signal.

(2) High-speed data (2-tone)

The demodulated signal from the FM IC (IC501) is amplified by baseband IC and passes through a band-pass filter in IC709 to remove frequency of 3kHz or above and 300Hz or below. The MCU digitizes this signal anddecodes the signal after receive the signal at pin 27(HSDI).

(3) MSK / DTMF

The demodulated signal from theFM IC(IC501) will input to baseband IC(IC709), then the baseband IC will decode and send the decode information to MCU by the data line. The MCU then processes the decoded information.

REPLAY data

DTMF/MSK decode data

LSDI

QT/DQT

HSDI

2-TONE

IC714

MCU

IC501 FM IC

IC709

Baseband IC

DTMF/MSK

decode

Fig.13 Decode

1-14 (No.RA010<Rev.001>)

2.4.6.3 NXDN Receiving

• For Digital Data Mode: The demodulated signal from IC501 (Pin13) feed into baseband IC (Pin 16) for NXDN decoding. The decoded digital data will pass to MCU through C-BUS. MCU determines whether or not to output sound from speaker by checking if the data match.

• For Digital Voice Mode: If the digital data match in MCU, the digital voice payload data will goes into Vocoder in MCU for conversion to PCM. The PCM data will go to baseband IC through SPI input, where it will be converted to analog by DAC. Analog voice will be filtered and finally send to audio amplifier.

IC501

IF IC

IC709 Baseband IC

1613

NXDN decoder

Audio Output

C-BUS

SPI

DAC

7543

112

IC714 MCU

C-BUS

Vocode

To E-Vol

Fig.14 NXDN receiver system

2.4.6.4 NXDN Transmitting

• For Digital Data Mode: The digital data will be generated by MCU, where it wil be pass to baseband IC, through C-BUS for encoding process. The encoded data finally will transmit through TCXO and VCO modulation.

• For Digital Voice Mode: The analog voice from mic will go to ADC (after audio filter) to convert to PCM data. The PCM data will send to Vocoder through SPI output. Vocoder will convert the PCM to NXDN protocol, where it will be sent to baseband through C-BUS. In baseband IC, the data will be encoded and finally transmit through TCXO and VCO modulation.

TCXO

VCO

IC709 Baseband IC

NXDN encoder

Audio Filter

C-BUS

SPI

ADC

7642

113

IC714 MCU

C-BUS

Vocode

From MIC

Fig.15 NXDN transmit system

(No.RA010<Rev.001>)1-15

2.4.7 Power Supply Circuit

• When the power switch on the display unit is pressed, the power port on the display unit which is connected pin 140 (POWKEY), goes low, then pin88 (SBC) goes high, Q718 turns on, SB SW (Q719) turns on and power (SB) is supplied to the transceiver.

• When the DC power supplied to the transceiver, the voltage regulator IC (IC720&IC718) and supply into the MCU VDD and reset voltage detect IC (IC723). IC723 will generate signal (RESET) into the reset terminal on the MCU (IC714) to carry out a power on reset.

• When the DC power voltage deceases from normal voltage, the INT voltage detector IC (IC722) will set to high on MCU port 141 (BATT_INT). If B line becomes less than about 8.5V, MCU will send the backup data to EEPROM (IC716) and go into STOP mode. This circuit has an overvoltage protection circuit. If a DC voltage of 18V or higher is applied to the base of Q712, this voltage turns Q712 on and sets port 141 (BATT_INT) to low. As a result port 88 (SBC) is low, and turns Q719 and Q720 (SB) off.

Q706

IGN

IC714

MCU

BATT

POWKEY

SBC

33MA

33MD

RESET

BATT_INT

IGN

R898

R899

POWER

Fig.16 Power supply circuit

2.5 SEMICONDUCTOR DATA

2.5.1 MCU: 2F405ZGT6KFKA (TX-RX unit IC714)

Port Name I/O Function

No.

1 LEDI O LED Data

2 LECE O LED Enable

3 LECL O LED Clock

4 LELH O LED Latch

5 LERE O LED Reset

6 VBAT - 3.3V

7 ACR_SW O ACR switch for HSDO(D/A) port

8 NC I No connection

9 NC I No connection

10 I2CDT I/O Function P8I/O Expander I2C Data

11 I2CCK I/O Function P7I/O Expander I2C Data

12 EVOL_DACCE O Function P6CE for EVOL

13 EVOL_SCLK O Function P5CLK for EVOL

14 EVOL_DATA O Function P4DATA for EVOL

15 /INT15P I/O Function P3I/O Expander Interrupt

16 VSS - GND

17 VDD - 33MD

18 BEEP O Beep for Side Tone

19 NC I No connection

Q719

Q718

IC723

AV R

IC720

AV R

IC718

AV R

Port Name I/O Function

Q712

IC722

AV R

IC721

AV R

D715

R969R970

No.

20 PCBVER I PCB version identification

21 IFDET I IFDET for ACR improvement

22 DISC_DC

(optional)

I for Discriminator DC Level

Adjustment

23 XIN I Crystal (19.2MHz)

24 NC I No connection

25 RESET I MCU Reset pin

26 LSDI I Low-Speed Data Input

27 HSDI I High-Speed Data Input

28 TEMP_1 I Temperature 1

29 TEMP_2 I Temperature 2

30 VDD - 33MD

31 VSSA - GND

32 VREF+ - 33MA

33 VDDA - 33MA

34 TEST_TX I/O UART_TX for Debug

35 TEST_RX I/O UART_RX for Debug

36 FNC_1(TXD0) I/O Function P1(TXD)

37 FNC_2(RXD0) I/O Function P2(RXD)

38 VSS - GND

1-16 (No.RA010<Rev.001>)

Pin No.

Port Name I/O Function

39 VDD - 33MD

40 LSDO O Low-Speed Data Output

41 HSDO O High-Speed Data Output

42 3CC O 33C Control

43 5CC O 5C Control

44 SQIN I Squelch Input

45 RSSI I RSSI Input

46 BATT I Battery Voltage

47 CVIN I VCO Lock Voltage

48 BOOT_1 I Test Point to enable Bootloader

49 TEST_1 I/O Test Point 1 for Debug

50 TEST_2 I/O Test Point 2 for Debug

51 VSS - GND

52 VDD - 33MD

53 PLL_DATA O PLL IC Data

54 PLL_LE O PLL IC Enable

55 PLL_CLK O PLL IC Clock

56 PLL_PDN2 O PLL IC Power Down

57 PA O Public Address

58 AMP_SW O AF amplifier

59 9TC O 9T Control

60 BSFT O Beat Shift

61 VSS - GND

62 VDD - 33MD

63 KMO3 O Key Matrix Output 3

64 KMO2 O Key Matrix Output 2

65 KMO1 O Key Matrix Output 1

66 KMI1 I Key Matrix Input 1

67 KMI2 I Key Matrix Input 2

68 KMI3 I Key Matrix Input 3

69 TXD2 O 2nd UART for DE15

70 RXD2 I 2nd UART for DE15

71 VCAP_1 - 2.2uF

72 VDD - 33MD

73 CML_CSN O C-BUS Chip Select

74 CML_SCLK O C-BUS Clock

75 CML_RDATA I C-BUS Reply Data

76 CML_CDATA O C-BUS Command Data

77 EEP_DATAO O EEPROM Data Out

78 EEP_DATAI I EEPRON Data In

79 EEP_SCLK O EEPROM Clock

80 EEP_CS O EEPROM Chip Select

81 EEP_WP O EEPROM Write Protect

82 BUCNT1 O PTT/TXD buffer control

83 VSS - GND

No.

84 VDD - 33MD

85 MKEYI I DTMF MIC key input

86 BUCNT2 O DTMF MIC buffer control

87 PLL_UL I PLL Unlock Detect

88 SBC O SB Control

89 MKEYO O DTMF MIC Key output

90 9RC O 9R Control

91 PTT I PTT

92 HOOK I Hook

93 ASTSW O Assist Speed-up Switch

94 VSS - GND

95 VDD - 33MD

96 FM_SDATA O FM IC Data In/Out

97 FM_RSTN O FM IC Hardware Reset

98 FM_SCLK O FM IC Clock

99 FM_CSN O FM IC Chip Select

100 FM_PDN O FM IC Power Down

101 TXD O Serial Data to Mic Jack

102 RXD I Serial Data from Mic Jack

103 TXRX O TX / RX Switch

104 HORN O Horn Alert

105 SWDIO I/O SWDIO for SWD

106 VCAP2 - 2.2uF

107 VSS - GND

108 VDD - 33MD

109 SWCLK I/O SWCLK for SWD

110 CML_SSOUT I Audio Codec Chip Select

111 CML_EPSCLK I Audio Codec Clock

112 CML_EPSO O Audio Codec Data Out

113 CML_EPSI I Audio Codec Data In

114 NC I No connection

115 LEDM O LED Dimmer

116 MBL O Panel and Mic Key Backlight

117 FNC_4 (CTS0) I Function P4(CTS)

118 FNC_3(RTS0) O Function P3(RTS)

119 NC I No connection

120 VSS - GND

121 VDD - 33MD

122 33BC O BB IC power supply control

123 MIC1MUTE O Internal Mic Mute

124 MIC2MUTE O External Mic Mute

125 SP_MUTE O Speaker Mute

126 SIM1 I Shimuke port 1

127 SIM2 I Shimuke port 2

128 NC O No connection

Port Name I/O Function

(No.RA010<Rev.001>)1-17

+ 37 hidden pages

Kenwood NX-740H, NX-740, NX-740V, NX-740HV Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Document Copyrights

Disclaimer

Firmware Copyrights

SPECIFICATION

2.1 SYSTEM SET-UP

2.2 REALIGNMENT

2.3 INSTALLATION

2.4 CIRCUIT DESCRIPTION

2.5 SEMICONDUCTOR DATA