Kirisun FP420 Service Manual

FP420 Service Manual

Contents

Chapter 1 Overview ........................................................................................................... 2

Chapter 2 External View and Functional Keys ............................................................... 3

Chapter3 Circuit Description ............................................................................................ 6

Chapter 4 Function Description and Parameter Settings ........................................... 16

Chapter5 Disassembly for Repair .................................................................................. 18

Chapter 6 Adjustment ...................................................................................................... 26

Chapter7 Major Specification ......................................................................................... 27

Chapter 8 Service and Test Equipment ......................................................................... 28

Chapter 9 Troubleshooting ............................................................................................. 29

Appendix1 Abbreviation.................................................................................................. 31

Appendix 2 Electronic Parts List ................................................................................... 31

Appendix 3 Spare Parts List (Structure Part) ............................................................... 39

Appendix 4 Accessories reference List ........................................................................ 41

Figure1 FP420 Schematic Pane Diagram ...................................................................... 42

Figure2 FP420 Top Board Position Mark Diagram ....................................................... 48

Figure3 FP420 Bottom Board Position Mark Diagram................................................. 49

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FP420 Service Manual

Chapter 1 Overview

1.1 Introduction

This manual applies to the service and maintenance of FP420 FM portable radios, and is intended for use by engineers and professional technicians that have been trained by Kirisun. It contains all the required service information for the equipment. Kirisun reserves the right to modify the product structure and specifications without notice in order to enhance product performance and quality. You can also contact your local dealer or us to get the latest service manual.

Please read this manual before repairing the product.

1.2 Safety Precautions * Electromagnetic Energy Exposure

Radios will generate and radiate electromagnetic energy during transmit mode.

Kirisun radio is designed to comply with a number of national and international standards for human exposure to radio frequency electromagnetic energy.

In order to obtain best performance, and to guarantee that the electromagnetic radiation does no harm to you, always keep the radio in a vertical position to the ground and make sure that the microphone is 2-5cm from your mouth while using.

* Electromagnetic Interference

In order to avoid electromagnetic interference, please turn off the radio in the place where such post prompts you to do so, e.g. hospital, health care center, airport and etc.

* Explosive Atmosphere

It’s prohibited to use the radio in the following places:

Any area with a potentially explosive atmosphere, e.g. orlop deck of the ship, storage and transportation equipment for fuel and chemical, where the air with chemical substance, particle or iron dust.

Any place near blasting sites or area with electrical blasting cap.

It is also prohibited to change or charge the battery in any area with a potentially explosive atmosphere.

* Antenna

If the antenna has been damaged, do not use the radio. Damaged antenna may cause light burning to skin.

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FP420 Service Manual

* Replacement Parts

All components used for repair should be supplied by Kirisun.

Components of the same type available on the market are not surely able to be used in this product and we do not guarantee the quality of the product using such components.

1.3 Service

All the Kirisun products are subject to the service warranty.

The warranty of the host is 18 months. The warranty of the accessories, including battery, charger, earphone, antenna and adapter, is 6 months. However, in one of the following cases, charge free service will not be available.

* No valid warranty card or original invoice.

* Malfunction caused by disassembling, repairing or reconstructing the radio by users without permission.

* Wear and tear or any man-made damage such as mechanical damage, burning or water leaking.

* Product’s serial number has been damaged or the product trademark is difficult to identify.

After the warranty expires, lifetime service is still available. We also provide service components to service stations and staffs.

Chapter 2 External View and Functional Keys

2.1 External View and Functional Keys

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FP420 Service Manual

Figure 2.1

1

○

Antenna

2

○

PTT

Press the key and talk to make a call; release the key to listen

3

○

PF Button

The button can be assigned different functions through PC software by your dealer. Details refer to the following “Programmable Key” in this instruction.

4

○

Speaker

Output the voice

5

○

Channel Knob

Rotate to choose 1—16 channels.

6

○

On/Off Key and Volume Knob

Clockwise rotate the knob to turn on the radio, and counterwise rotate the knob until there is a click sound to turn off the radio.

Rotate the knob to adjust the volume when the radio is on.

7

○

LED Indicator

When transmitting signal it indicates red, when receiving signal it indicates green. It flashes when the power is not enough.

8

○

Microphone

Input the voice

9

○

External Connector

Open the cover to connect external speaker and microphone.

10

○

Belt Clip

11

○

Pushing Buckle

2.2 Functional Keys Operation Instruction Programmable Keys

Below keys can be set through PC software by dealers:

Long press key and short press key can be set: PFkey

Long press key can be set：Menue Key/ Cancel Key

NOTE：

Short press：Press down and release instantly.

Long press：Press down and keep 2 seconds to release.

Available functions to be chosen:

None：No feature will be assigned.

Power level adjustment: Switch between high/low power

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FP420 Service Manual

Moniter: If the current analog channel is with CTCSS/CDCSS, press the key to squelch mode to cancel the CTCSS/CDCSS function. Press the key again to return to the original status.

Emergency alarm open: Start the Emergency Alarm function to seek help.

Emergency alarm close: Finish the Emergency Alarm function.

Squelch open/close: Open/close the squelch function to receive weak signal on analog channels.

Scan: Check activity of other channels. Press the key to open/close this function.

Whisper: When the whisper function is on, others can hear clearly even speakomg in a low voice.

Aler tone on/off: Open/close the alert tone.

2.3LED Indicator

Red LED lights on: the radio is transmitting.

Green LED lights on: the radio is receiving.

Red LED flashes: low battery, the battery needs to be charged.

2.4 Basic Operation Turn On/Off the radio

Clockwise rotate the knob to turn on the radio, and counterwise rotate the knob until there is a click sound to turn off the radio.

Selecting a channel

Each channel in your radio can be programmed to analog channel or digital channel. Under the Home Screen, turn the Channel Knob to select a channel.

Adust the volume

Rotate the knob to adjust the volume when the radio is on.

Make a call

On a digital channel, choose one of the following procedures to make a call:

a. Enter Contacts menu, select one contact and then press and hold the PTT Button, speak to the MIC.

b. Enter Call Log menu, and then enter Call Out or Call In item, select one contact, press the PTT Button and speak to the MIC.

c. Under the Home Screen, press the PTT Button and speak to the MIC. The call out number is the default contact number of this channel, which can be programmed by the dealer, or set through menu.

d. Under the Home Screen, input the number manually, then press the PTT Button and

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FP420 Service Manual

LPF

RDA1846 ANT

LT1801A

AF AMP

MIC

12.8MHZ

Q501 Q503

LNA

32.768KHz

FLASH

18.432MHz

APC

speak to the MIC.

On an analog channel, press the PTT Button and speak to the MIC.

Receiving a call

When receiving the signal, the signal strength will be indicated on LCD. While on digital channels, when receiving private call/group call/all call, the radio will output the voice. While on the analog channels, when receiving analog signal and the CTCSS/CDCSS matches, the radio will output the voice.

Anserwing a call

While using digital channels, press PTT within call holding time after receiving the call

to answer the call. If you didn’t answer back during call holding time, you should start a

new call to call back. The call holding time can be set through PC software by dealers.

While using analog channels, press PTT to answer the call directly.

Chapter3 Circuit Description

3.1 Preface

This radio is FM portable radio equipment.

3.2 Frequency Configuration

The reference frequency of RD1846S is generated by 12.8MHz crystal oscillator X500 TCXO.

3.3 Principle of Receiver (RX)

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FP420 Service Manual

LPF

ANT SW

RDA1846

LT1801A

POWER SW

AFAMP

LNA

Figure 3.3 Principle of Receiver

Receiver is mainly used in receiving, selecting, amplifying, transforming, demodulating etc. and other processing like audio signal amplifying, filtering. Audio part mainly is used to post emphasis, amplify and filter audio signal.

Receiver Front End

Low noise amplifier is located in the receiver front-end, mainly used in amplifying small radio frequency signal, in order to provide certain intensity and SNR of RF signal for subsequent signal processing.

Signals from the antenna transmission (RX/TX) switch (D502 D501, D503, D504), are sent to Q507 3SK318 and peripheral components consisting of low noise amplifier (LNA) for enlarging. The enlarged signal will be sent into IC4 (RDA1846S) to demodulate into output audio signal. 3sk318 noise coefficient is 1.4 db, G about 18 db.

There is input and output match for LNA. Input match adopts best noise figure while output use maximum power to match, i.e., the amplifier output impedance adjusted to the load impedance (typically 50 ohm); Input and output impedance of the low noise pipe is usually high impedance, so the matching circuit using inverted L

Receiver audio signal processing

Audio signal from IC4 (RDA1846S) processed through LT1801, then through the volume potentiometer, to the audio power amplifier U600 (TDA2822).

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LPF

RDA1846S

ANT SW

12.8MHZ

Q501

Q500

Q503

Q502

APC

Audio power amplifier

U600 and peripheral components makes up the audio power amplifier circuit

Q601 base is the control end. High level: U2 begins to make audio; Low level: closed.

Receive audio signals, voice signals, alarm sound signals are summarized and sent to speaker through audio power amplifier. Among them, the alarm sound will not be limited by volume control. The speaker impedance: 16 ohms.

3.4 Principle of Transmitter (TX)

Power amplifier and antenna switch principle diagram

Modulated signal from IC4 (RDA1846S), enlarged via Q502, Q503, Q501, are sent to Q500 power amplifier, and then transmitted through receiving toggle sending into the low pass filter. LPF will improve as much as possible to harmonic stray signal attenuation in certain condition of fluctuations in performance. Q500 output power: 4W

Q502 2sc5108 pre-amplifier, mainly to preliminary enlarge output RF signal of RDA1846S, to provide a certain intensity of the amplifier after excitation signal.

Q503 2sc3356 pre-push RF amplifier is mainly used to provide a certain level of intensity of excitation signal for subsequent amplifier, so as to guarantee the driving amplifier can output enough power, to push the last stage power amplifier.

Q501 RD01 promote RF amplifier, is mainly used to promote the last stage power amplifier, to ensure the output power of the last stage power amplifier to achieve the rated output power of the transmitter. The output is about 0.5 W, G about 14 db.

Q500 RD07, end RF power amplifier, is part of the important and critical level. The output power and efficiency level at the end power amplifier are almost equal to transmitter output power and efficiency. The stability of the last stage amplifier basically

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FP420 Service Manual

IC100

5T 5R

IC102

3.3V IC102

1.8V

1.8V:MCU;BASEBAND;LCD

3.3V:MCU;BASEBAND;LCD

5T:AF; BASEBAND, RF

5R:RF

represents the stability of the transmitter also. Output is 0.8W, G about 12db.

Q500 Q501 grid bias is controlled by APC circuit. Change the gate bias voltage, can easily control the size of the transmitter output power.

APC (automatic power control) circuit

This circuit changes the gate bias voltage by testing the change of the input to the power amplifier drain current and changes the output power by changing the gain.

R520 R521, R522 are power amplifier current detection, U502A is the current sampling amplifier power amplifier. U502B is the comparison power amplifier.

If the transmitter output power is too large, the power amplifier current increase, U502A output rise, U502B output voltage drops, applied to Q500, Q501 bias voltage to drop, lower the transmitter output power, vice versa. In this way, the transmitter output power is stable under different working conditions.

MCU achieves the goal of setting power by changing the input to the voltage on the U502B.

Transmitter speech signal processing

MIC signal is sent through the inside and outside MIC switch circuit into No. 11 feet of IC4 (RDA1846S) to modulate the carrier.

3.5 Principle of power

The machine uses 7.4 V batteries. Transmitter power amplifier circuit (Q500, Q501) and receiver audio processing (U600) directly uses the battery. All the other circuits are powered by constant 5 V power supply.

IC100: 5T switch, controlled by MCU.

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5T: supply power for front-end transmitter

5 R: supply power for receiver RF amplifier, audio signal processing unit etc.

IC102:3C switch controlled by MCU, Provide 3.3 V

3C: receive 3V electricity controlled by power save, supply power for RDA1846S.

IC102: Provide VCC1.8V

3.6 IC characteristics

RDA1846S features:

3.6.1. Fully integrated CMOS RF front-end

3.6.2, High linearity and low noise amplifier and mixer

3.6.3. Low intermediate frequency receiving channel

Automatic DC offset calibration circuit

High performance analog/digital converter and digital/analog converter

Fully integrated receive filters

The digital AGC

The frequency modulation demodulation technology based on digital signal processing technology

3.6.4 Direct frequency synthesis pathway

Direct frequency synthesis frequency modulation

Emission filter based on digital signal processing technology

FM digital gain adjustable

Digital voice activation emission control

3.6.5. High-performance decimal PLL frequency synthesizers

Complete piece RF VCO

The complete piece inside the loop filter

Low phase noise

Extremely fast phase lock time

High frequency resolution, frequency is adjustable

The built-in crystal frequency error calibration circuit

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FP420 Service Manual

Pin NO

I/O

Port Name

function

E11

IO

SIRIN

SECRET_IO(Reserved for Encryption chip)

D11

IO

SIROUT

POW_C（Soft switch on power control）

M4

IO

RXD1

RXD(Download program)

J4

IO

TXD1

TXD(Download program)

L4

IO

RXD2

EFUNC1(function key)

K4

IO

TXD2

EFUNC2(function key, monitor key)

A16

IO

SCLK0

GPS Enable Pin

A15

IO

SSN0

TX_LED(Transmitter indication)

B11

IO

SRX0

RX_LED(Receiver indication)

A11

IO

STX0

LAMP(keypad light)

N4

IO

SIMCK

PTT KEY(PTT)

R4

IO

SIMIO

EXT_PTT（PTT for earpiece）

P4

IO

SIMRST

Soft boot detection ( use this if you have any other functions. Otherwise, please use POW_ON

A8

IO

RFSO

RFIF Three line SPI serial data output module

E9

IO

RFSN0

RFIF Modules chosen line of three SPI piece inside signal is 0

C12

IO

AON

HEADSET_DET(headset detect)

B15

IOU

KB0

KB The keyboard scan input/output signals [0-7], includes alarm and two function keys. It is highly recommended to refer to the design the of hardware keyboard circuit to make it easier for compatibility

B14

IOU

KB1

B13

IOU

KB2

B12

IOU

KB3

C16

IOU

KB4

C15

IOU

KB5

C14

IOU

KB6

C13

IOU

KB7

3.6.6. Ultra low power sleep mode

3.6.7. Three line serial digital interface control

3.7 semiconductor devices

MCU instructions Table 3.7 the microprocessor (LT1801A) port

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FP420 Service Manual

T3

IO

LCDCRD

LCD_RD

R3

IO

LCDCRS

LCD_RS

P3

IO

LCDCWR

LCD_WR

M3

IO

LCDCS0

LCD_CS

N3

IO

LCDCS1

LCD_RST

K1

IO

LCDC0

LCD_D0

L1

IO

LCDC1

LCD_D1

M1

IO

LCDC2

LCD_D2

A14

IO

SCLK1

SPEAKER_POP/AGC_PD（AGC enable chip）

B16

IO

SSN1

APC

A13

IO

SRX1

A12

IO

STX1

RX_SW

A9

IO

PWM0

MOTO_EN 或 LAMP(Keypad light)

E10

IO

PWM1

LCD_BACK

E7

-

GPO0

P_UL（Indicate frequency lock state）

D7

GPO1

5T（TX power control）

C7

GPO2

5R（RX power control）

B7

GPO3

5C（Radio frequency (RF) public power control）

CPU please don't use these 4 pins

D9

IO

RFSN1

P_PS（PLL lock indicator）

C9

IO

RFSN2

TX-SW

B5

IO

OSCEN

SPEAKER_EN

B8

IO

RFSCLK

RFIF (Three line SPI clock module )

P6

IO

NC

N1

IO

LCDC3

LCD_D3

P1

IO

LCDC4

LCD_D4

R1

IO

LCDC5

LCD_D5

T1

IO

LCDC6

LCD_D6

K2

IO

LCDC7

LCD_D7

L2

IO

LCDC8

LCD_D8

M2

IO

LCDC9

LCD_D9

N2

IO

LCDC10

LCD_D10

P2

IO

LCDC11

LCD_D11

R2

IO

LCDC12

LCD_D12

T2

IO

LCDC13

LCD_D13

K3

IO

LCDC14

LCD_D14

L3

IO

LCDC15

LCD_D15

G3

AI

Simulation of the ADC module voltage input range is 0 to 3 v

VO or VOX

F3

AI

battery voltage detection

E3

AI

RSSI

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FP420 Service Manual

D3

AI

BUSY

F5

AO

RFIF

（ AUXDA ）

Simulation of DAC module input voltage range of 1.15-2.15 V

VCCN(TCXO reference voltage)

E5

AO

RFIF

（ AUXDA ）

Simulation of DAC module voltage input

range is 0 to 3 v

TV/PC

D1

AI

RX_I+

Simulation of the ADC module for single-ended input voltage range 1 VPP, difference of 2, pp

AFDET

C1

AI

RX_I-

B1

AI

RX_Q+

Simulation of the ADC module for single-ended input voltage range 1 VPP, difference of 2, pp

A1

AI

RX_Q-

A2

IO

TX_I+

Simulation of DAC module voltage output range of single-ended 1 VPP, difference 2 VPP

MOD1

B2

IO

TX_I-

A4

IO

TX_Q+

Simulation of DAC module voltage output range of single-ended 1 VPP, difference 2 VPP

MOD2

B4

IO

TX_Q-

G2

IO

CODEC 16 Ohm 耳机 headphones negative output

CODEC 16 Ohm Headphones differential negative output H2

IO

CODEC 16 Ohm headphones positive

output

CODEC 16 Ohm Headphones difference negative output H5

IO

CODEC The microphone bias voltage

MIXBIAS

J2

IO

SPEAKER Linear output

SPEAKER Linear output E2

AI

MIC input input amplitude=96mv when 24dB open; input

MIC2(headphone MIC input)

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FP420 Service Manual

amplitude=1.53V after closed

F2

AI

MIC input input amplitude=96mv when 24dB open; input amplitude=1.53V after closed

MIC1(headphone MIC input)

L5

D10

RXD0 (for GPS)

C10

TXD0 (for GPS)

B10

RTS0 (for GPS)

A10

CTSO (for GPS)

R5

K5

GPIO0_12 Hard boot detection

L7

L8

L9

L10 -

AVDD

1

Power supply

SCLK

2

Clock input for serial control bus

SDIO

3

Data input/output for serial control bus

AVDD

4

Power supply

XTAL1

5

Oscillator pin 1

XTAL2

6

Oscillator pin 2,control interface select

MODE

7

When MODE = VL, I2C Interface is select; When MODE = VH, SPI Interface is select

SENB

8

Latch enable (active low) input for serial control bus

AFOUT

9

Audio signal output to speaker

NC*

10

No connection

MIC_IN

11

MIC input

Cc

12

Compensation capacitor connection

AVDD

13

Power supply

NC*

14

No connection

RFIN

15

RF signal input

AVDD

16

Power supply

NC*

17

No connection

RFOUT

18

RF signal output

RDA1846S port

Page 14 of 50

FP420 Service Manual

NC*

19

No connection

NC*

20

No connection

AVDD

21

Power supply

PABIAS

22

PA bias supply for PA

AVDD

23

Power supply

PDN

24

Chip enable, high active; Chip sleep, low active

GPIO7

25

Gpio7/vox(When Gpio7=VH, vox is active; else VL)

GPIO6

26

Gpio6 / sq (When Gpio6=VH, sq is active; else VL)

GPIO5

27

Gpio5 / txon (When Gpio5=VH, txon is active; else VL)

GPIO4

28

Gpio4 / rxon (When Gpio4=VH, rxon is active; else VL)

GPIO3

29

Gpio3 / sdo (Gpio3=VH or VL, it is the output register data in 4 wire

control Interface mode)

GPIO2

30

Gpio2 / int (When Gpio2=VH, int is active; else VL)

GPIO1

31

Gpio1 / code_in / code_out (Gpio1=VH or VL, it is the input/output code data)

GPIO0

32

Gpio0 / css_in / css_out (Gpio0=VH or VL, it is the input/output CTCSS/CDCSS

signal)

Item

Model No.

Functions

U500

NJM2904

APC，

U400

LT1801A

MCU

IC200

24LC512

E2PROM ， Storage channel frequency data, set parameters, debugging status parameters

U201

TDA2822

Receiver audio power amplifier

Q500

RD07S2B

end of TX power amplifier

Q504

DTA144EE

APC output switch

Q507

3SK318

Receiver high power

Q200

DTC144EE

Red LED drive

Q201

DTC144EE

Green LED drive

Q501

RD01MUS1

Transmitter power amplifier

Q202

DTC144EE

Audio power amplifier control switch

U404

XC6204B502MR

The adjustable 5 R, 5 T voltage output

IC102

LN2407

1.8V output voltage adjustment

IC103

LN2407

3.3V output voltage adjustment

Q600

FMMT717

Audio output control switch

3.8 semiconductor devices functional description

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FP420 Service Manual

Q205

DTC144EE

MIC Switch

Q501

2SC5108

TX 1st amplifier

Q503

2SC3356

TX 2st amplifier

Chapter 4 Function Description and Parameter

Settings

4.1TOT

This function forbids you from occupying the channel for a long time. If the continuous transmitting time exceeds the setting time by dealer, the radio sends out a warning tone and stops transmitting. Release the PTT key to stop the warning tone. After a period of time, which is set by dealer, you can transmit again. And if the radio is programmed with pre-alert function by the dealer, the radio will send out an alert before the time out timer expires

4.2 Scan

During scan, the radio checks and stops on a busy channel. Then the radio continues scanning until the channel is not busy for a while (this time is set by dealer, which is named as Scan Hold Time).

Steps to start scanning: press the Scan shortcut key  select “Start” item. The radio scans the channels in the current scanning list one by one. During scan, press the Cancel key or scan shortcut key to stop.

◆Scan revert channel

During scan, press the PTT key to make the radio transmit on a default channel. The channel can be programmed by your dealer.

4.3Kill、Revive

This function allows one radio to receive the kill and revive signaling from another radio. The radio to be killed cannot make or receive calls. The radio can only revive through CPS sends a revive order. After revived, the radio can work normally again. This function is used to manage the unauthorized usage of the radio, prevent misappropriating the radio which is lost

4.4Emergency

If you are in danger and this function is enabled, you can press Emergency Alarm On shortcut key to send an emergency alarm.

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FP420 Service Manual

The means of sending emergency alarm are decided by the following parameters: Alarm Type, which defines the audio and visual reaction when the radio sends an alarm; Alarm Mode, which defines the content sent to the other members when the radio sends an alarm. The above parameters can be programmed by dealer.

To turn off the Emergency Alarm, press the programmed Emergency Alarm Off shortcut key.

Alarm Type:

◆None: No alarm function (Default setting); you cannot send an emergency alarm.

◆Siren Only: The radio only emits siren locally.

◆Regular: The radio provides audio and visual indication that it is in Emergency

mode and can receive the signal from others;

◆Secret: No audio and visual indication. And the radio cannot receive the signal from

others;

◆Secret with voice to follow: No audio and visual indication. But the radio can receive

the signal from others.

Alarm Mode:

◆Emergency Alarm: The radio sends out an emergency alarm, and then exits the

emergency alarm status automatically.

◆Emergency Alarm w/ Call: An emergency alarm is sent, after which an emergency

call can be transmitted by pressing the PTT Button.

◆Emergency Alarm w/ Voice to Follow: The radio sends out an emergency alarm, and

then sends out background tone periodically and automatically through emergency call.

Note:

Emergency Alarm: The radio sends out a signal to alert other member.

Emergency Call: A priority call on channel, so as to make sure the successful communication under emergency condition.

4.5 Parameter Setting(PC Mode)

The radio parameter have been programmed in the factory.The user can reset the radio parameters such as working frequency, channels, digital functions, QT/DQT, and auto scaning.We designed a user-friendly and convenient programming software CPSc to set parameters on the radio. The programming steps are as following:

Install the programming software of FP420

B． Connect the radio to the computer serial port with the specified programming cable,see figure4.5

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FP420 Service Manual

Computer(RS232 or USB)

Specifiled programming cable

Radio(Speaker/MIC socket)

Figure4.5

C．Turn on the radio power

D．Click the CPSc to run the programming software.

E．Click read to read the data from radio.

G．About more details, please refer to help file or programming instrunction manual.

Chapter5 Disassembly for Repair

The radio is a piece of precision communication equipment. Please be careful when disassembling the radio during service. The instructions for the disassembly are as follows.

5.1 Disassemble the Battery

Removing the Battery

Make sure the radio has been turned off,

When you remove the battery, ①push the battery latch upwards ②battery will upspring③remove it away from the radio. ④If the radio with belt, pls pull up the battery.

Installing the Battery

If the radio with belt, ①pls upspring the belt. ②Install the two bulges at the bottom of the battery pack with the corresponding slots at the rear bottom of the radio. ③Push the top part of the battery towards the radio to lock it until a click is heard.

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FP420 Service Manual

Notice:

Do not short-circuit the battery terminals or dispose of batteries in fire.

Do not attempt to disassemble the case of the battery.

5.2 Installing/Removing the Antenna

Installing: Hold the base of the antenna and turn the antenna clockwise into the connector on the top of the radio until it’s tightened.

Removing: Hold the base of the antenna and turn the antenna anti-clockwise and remove it.

5.3 Installing/Removing the Belt Clip

Match the grooves of the belt clip to the rear top of the battery, fixed it with two 2.5x6.5 screws. Loosen the two screws fixing clip, you can remove the clip.

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FP420 Service Manual

Installing an optional headset

When you use an external headset, to open outward headphones cover in the upper right of the radio, plug the external headphone cable into the headset port.

5.4 Removing the Back Cabinet from the Chassis

(1) Remove the antenna;

(2) Remove two screws on the knob and the screw on the antenna;

(3) Remove the two screws on the back cabinet;

(4) Remove those four screws on the Al alloy bracket;

(5) Insert the flat-bladed screwdriver into the slot of Al alloy bracket; lift it so as to separate the Zinc alloy bracket from the chassis, and then push the Al alloy bracket away from the chassis, and take the soft flat cable away from the socket. Using the soldering iron to separate the speaker connecting cable.

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FP420 Service Manual

5.5 Removing the PCB Board from the Chassis

(1) Screw off screws on the main board (2) Take down the waterproof cushion in top and use the soldering iron to cut off the antenna connecting point, and then separate the main board (include PTT PCB) from the aluminium alloy chassis.

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FP420 Service Manual

After the demolition of the above, you can make the appropriate repairs and debugging against fault conditions.

5.6 Exploded view

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FP420 Service Manual

No. Part Code

Part Name

Specifications

Unit

1

7MHP-4038-06A-W0

FP420 Headphone cover

TPU; Black; texture

1

2

7MJS-4038-01A-W0

FP420 spindle

SUS304;nature color, BaYang, Non-lead

1

3

7MHP-4038-01A-W0

FP420 Surface shell

PC+ABS; Black; texture

1

4

7MHB-7069-01A-W0

PT7800 Microphones waterproof pad

DY-E002A Breathable film,φ6.6xφ4.4,

1

5

7GCB-S4002-01A

4700 Speaker dust –proof

No anti-cloth; black; Xinlongda; non-lead

1

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FP420 Service Manual

cover

6

7PLJ-4038-E01A

S760 Trademark stickers

Transparent PC

1

7

7MHR-4038-01A-W0

FP420 Side silicone key

Silica gel; black; Laser carving; PT Orange21C;

1

8

7NRC-060090035-W 1

FP420 Coding nut

Brass, diameter M6mm, OD

φ9mm, thick 3.5mm, black nickel

plated

1

9

7NRC-090115025-G1

3208 nut

Brass, diameter M9mm, OD φ11.5mm, 2.5mm thick

1

10

8ATX-400470-WU

FP420 Antenna

428649,Φ=40mm,H=4.5mm

1

11

7MHR-4038-03A-WC

FP420 Light pipe

Silica gel; transparent; high light; MingKun; Non-lead

1

12

7MHP-4038-05A-W0

FP420 PTT Cover

Double Color

1

13

4SS7-3525-016-100B

7200 Speaker

Φ40mm，1W，Non-lead

1

14

7MHS-4038-02A-W

FP420PTT keypad metal dome

φ5mm,SUS301 Round metal

dome;

1

15

7MHJ-4038-03A-W

FP420 Double-sided adhesive side key board

3M9448

1

16

7MHR-1727-09A-W3

558 radio mic sets

Silica, hardness 40, orange, no surface treatment

1

17

7MDC-4057-02A-G

FP420 Battery SLC

Material: Brass; nickel-plated gold-covered

4

18

7MHR-4038-04A-W0

FP420 Top waterproof pad

Silica gel; black; polishing

1

19

7MHP-4038-03A-W0

FP420 Volume knob

ABS; Black; texture, white-oil

1

20

7MHS-1140-01A-W

3118/3208 Knob retainer

Spring steel

2

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FP420 Service Manual

21

7MHP-4038-04A-W0

FP420 Coding knob

ABS; Black; texture, white-oil

1

22

3CR7-SMA-50JF-4

RF coaxial connectors

SMA-J, Flange mounting,used for 7200

1

23

7MDZ-1737-04A-J5

KB-58L sticker 1

Dark green paper,8*35mm,thick

0.2mm, single Side with plastic

2

24

6BPM-784043-07415 0-A

Li-poly battery pack (FP420)

Li-poly battery pack 78mm* 40mm*4.3mm×2,7.4V,1500mAh

1

25

7GCM-360075040-J

KB-36L Foam pad

Black foam,36*7.5*4mm, single Side with plastic

1

26

7MHP-4038-02A-W0

FP420 Top Cover

PC+ABS; Black; texture,

1

27

7SMF-020080M-MHH T-N1

M2*8 Plum-type Thick Head Machine Screw

Iron and hard, Φ2mm * 8mm

thick plum-type nickel-plated machine Metric Coarse, drop-resistant treatment

1

28

6SS3-BJ4038-A

KBJ-17 Belt

1

29

7MDP-4057-01A-W0

KB-460 Battery top shell

PC+ABS; Black; texture,

1

30

6PD7-4057-DPA

KB-460 Battery charging board

PCB,29.4X11.3MM, Thickness:

0.6MM,2 layers

1

31

7MHP-4038-10A-W0

FP420 Power on Right hook

POM; Black; high light

1

32

7MHC-4038-01A-Z

FP420 Power on splinter

T=0.20 Spring steel; black zinc plated; Xinchengda; Non-lead

1

33

7MHP-4038-09A-W0

FP420 Power on left hook

POM; Black; high light

1

34

7MHP-4038-08A-W0

FP420 Power on Push Button

PC+ABS; Black; texture,

1

35

7SMF-020080M-MHH T-N1

M2*8 Plum-type Thick Head Machine Screw

Iron and hard, Φ2mm * 8mm

thick plum-type nickel-plated machine Metric Coarse, drop-resistant

1

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FP420 Service Manual

treatment

36

7MDP-4057-02A-W0

KB-460 Battery case back

PC+ABS; Black; texture,

1

37

7MHR-4038-02A-W0

FP420 main Waterproof gasket

Silica gel; black; high gloss

1

38

7MHR-4038-05A-W0

FP420 Bomb-pin socket

Silica gel; black; polishing

1

39

7MHL-4038-01A-W

FP420 Aluminum

ADC12;

1

40

7MHP-4038-07A-W0

FP420 Headphone jack waterproof pad

TPU; Black; texture,

1

41

7SMF-020040M-SZY B-N

M2*4 Cross round flat head Machine Screw

Iron and hard,Φ2mm*4mm Cross round flat head Nickel-plated machine, Metric Coarse, plus drop-resistant treatment

8

6.1 Method of Adjustment

During the servicing, it is necessary to test and adjust the radio’s technical parameters

after changing components.

6.1.1 Components needed for the adjustment

(1) Antenna connector converter

(2) Universal connector

6.1.2 Adjustment Method in PC Testing Mode

Tx Part

A.Tx Frequency

Chapter 6 Adjustment

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FP420 Service Manual

Frequency

(136-174) MHz

(400-470)MHz

The Tx frequency is the standard frequency ± 100Hz.

B. Power

a. High Power is 3.5-5.0W.

b. Low Power is 0.5-1.5W.

C. Voltage

Voltage is 6.5V.

Rx Part

A. Max Volume

Set RF of the comprehensive tester to be the center frequency, the single strength to be 1mV and the modulation deviation to be 3.0kHz/1.5kHz (wide/narrow band), and

then in PC mode, adjust the value of “Max. Volume” to make the audio power to be

1.0-1.2W.

B. Squelch

a. Set the RF signal of the comprehensive tester to be -121dBm, and the deviation

3.0kHz/1.5kHz（wide/narrow band）.In PC mode, adjust the SQL of the 5 frequency points, and save it when the data is stable.

b. Set the RF signal of the comprehensive tester to be -123dBm, and the deviation

3.0kHz/1.5kHz（wide/narrow band）.In PC mode, adjust the SQL of the 5 frequency points, and save it when the data is stable.

Chapter7 Major Specification

7.1 General Specification

Page 27 of 50

Usable sensitivity (12dB SINAD)

-121dBm

Squelch On sensitivity

≤0.18uV

Adjacent Channel Selectivity

≥70dB/≥60dB

Intermodulation Rejection

≥65dB

Spurious response rejection

≥70dB

Audio output power

1W，Balance @ Distortion ≤5, 16Ω

Rx current consumption

≤400mA

Tx power

4.0W/1.0W @7.4V DC

Frequency stability

≤±2.5ppm

Max. modulation deviation

±3kHz/±1.5kHz

Modulation distortion

(300~3000Hz)

≤3% Adjacent channel Tx power

≥60dB/≥55dB

Spurious Tx

≥70 dB

Tx current consumption

≤1.4A @ 7.4V DC

Model

FP420

Number of Control Channel

16 Zones x 16 Channels

Channel spacing

25kHz/12.5kHz

Operating voltage

7.4V, cathode grounded

Operating temperature

-25°C ~ +55°C

Antenna impedance

50 Ω

Microphone impedance

2.2 Ω

Battery (Standard)

Li-ion Battery: DC 7.4V, 1500mAh, Operating time: 12.5h (5: 5: 90 cycle)

Size (H*W*D)

116 mm x54 mm x30 mm

Weight (g)

240 (with battery and antenna)

7.2 RX Part

FP420 Service Manual

7.3 TX Part

Chapter 8 Service and Test Equipment

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FP420 Service Manual

No.

Equipments

Specifications

1

Standard signal generator

Frequency range: 400-470MHz Modulation: FM and external modulation Output: -127dBm/0.1 uV to ＞-47dBm/1mV

2

Power meter

Output impedance: 50 Ω Operative frequency: 400-470MHz Measuring range: around 10W

3

Deviation meter

Frequency range: 400-470MHz

4

Digital voltmeter

Measuring range: DC 10mv – 10v Input impedance: load high input impedance to Min. circuit

5

Oscilloscope

Current to 30MHz

6

High sensitivity frequency counter

Measuring range: 50Hz – 10KHz Frequency stability: 0.2 ppm or lower

7

Ammeter

5A

8

Audio frequency voltmeter

Frequency range: 50Hz – 10KHz Voltage range: 1mv – 10v

9

Audio frequency generator

Frequency range: 50Hz – 5KHz or higher Output: 0- 1v

10

Distortion tester

Capacity: 3% or lower @ 1KHz Input power level: 50mV to 10vms

11

Spectrum analyzer

Measuring range: DC – 1GHz or higher

12

Path generator

Center frequency: 50KHz – 600MHz Output voltage: 100mv or higher

13

16 Ω dummy load

Around 16Ω, 3W

14

Adjustable power supply

5v – 10v, around 5A

During the servicing and test process, the following equipments and apparatus will be used:

Chapter 9 Troubleshooting

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FP420 Service Manual

No.

Problems

Causes and solutions

1

Power ON failure

A. The battery pack may be out of power. Please charge it or change a new one B. Power switch in failure. Change a new one. C.MCU in failure. Change the IC. D. Zener diode Q45 is broken. Change a new IC.

2

PPL unlocked (beeping)

A. The PLL crystal oscillator X500 is broken. Please change it. B. The RDA1846 is broken. Please change it.

3

Cannot talk to or hear other radios

A. The frequency of the radio’s current channel is not

the same with that of the other radio. Please reselect a channel. B. The CTCSS/DCS is not the same. Please reset it. C. The radio is out of the effective communication range.

4

No signal

A. The antenna is in poor contact. Please fasten it. B. Low sensitivity, fine tuning “Regulating Mode” C. The squelch level is too high, so the squelch cannot be opened. Please adjust the squelch level.

5

The indicator lights red while transmitting, but no voice is heard by the recipient.

A. The power amplifying tube is broken, so there is no power output. Please change it. B. The MIC is broken. Please change it. C. The operational amplifier U600 is broken. Please change it.

6

The indicator lights green while receiving, but no sound is heard.

A. The speaker is broken. Please change it. B. The audio power amplifier U600 is broken. Please change it. C. The switch diode Q601 is broken. Please change it.

7

The programming is abnormal

A. The programming cable is not correctly connected to PC. Please check the cable connection. B. The Computer’s RS-232 serial port output is

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FP420 Service Manual

abnormal. Please check the computer. C. The earphone jack of the radio is in poor contact. Please check the earphone jack. If it is abnormal, please change it.

Part No.

Name

Specification

Q’ty

Pulg-in Position

6SS2-4038-HMB

S760 mainboard patches parts

S760 mainboard patches parts, no Pb

1

6SS1-4038-HMB

S760-02 mainboard patches parts (Version D)

400-470MHZ,S760-02 mainboard patches parts, no Pb

1

0SS1-4038-HMD

S760 mainboard patches parts

S760 mainboard patches parts,1846S, no Pb

1

Appendix1 Abbreviation

AMP amplify, amplifier ANT antenna APC automatic power control BPF band pass filter CTCSS continuous tone control squelch system DCS Digital code squelch DEMOD demodulation HPF high pass filter IDC instantaneous deviation control IF intermediate frequency LED Light-Emitting Diode LNA low noise amplifier LPF low pass filter MCU micro control unit MIC microphone MOD modulation MONI monitor PLL phase lock loop PTT push-to-talk SPK speaker TCXO temperature control X’ oscillator UL un-lock VCO voltage control oscillator

Appendix 2 Electronic Parts List

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FP420 Service Manual

3CF1-BL112-30RU

FFC/FPC connector

0.5mm spacing,30 Pin, horizontal type

1

J201 1DP1-BV08C

R protected diode

BV08C

2

D600,D601

1DR1-NSR1020MW2T1 G

Surface mounting schttky diode

NSR1020MW2T1G, No Pb

2

D101,D102

1DS1-DA2S10100L

R Surface mounting switch diode

DA2S10100L

1

D505

1DS1-HSC277

R Surface mounting switch diode (production halts)

HSC277,1608

1

D502

1DS1-HVC131

R Surface mounting switch diode (production halts)

HVC131(P1),1608

2

D500,D501

1DZ1-HZU5ALL

R Surface mounting constant voltage diode (production halts)

HZU5ALL,2012,5V

1

D504 1IL1-NJM2904V

R Surface mounting linearity IC

Double arithmetic amplification NJM2904V,TSSOP-8

2

IC301,IC500

1IM1-AT24C512C

Surface mounting memorizer IC 1IM1-AT24C512BN (replaceable)

AT24C512C, manufacture:ATMEL, no Pb

1

IC200

1IM1-DS28E10P

Surface mounting memorizer IC

Encryption chip, DS28E10P+, no Pb

1

U201

1IM1-M36LOT7050T3ZA Q

Surface mounting memorizer IC

M36LOT7050T3ZAQF, no Pb

1

U401

1IP1-LT1801A

Baseband process module

1 U400

1IS1-MP2359

Surface mounting power

supply IC

MP2359,6PIN,1.2A 24V,1.4MHz,TSOT-23-6

2

IC102,IC103

1IS1-RDA1846S

Surface mounting exclusively IC

RDA1846S,PLL module IC ， 5*5mm，32PIN,QFN32, no Pb

1

U500

1IS1-TDA2822

E R Surface mounting exclusively IC

TDA2822

1

U600

1IS1-XC6204B502MR

R Surface mounting constant voltage IC

Constant voltage integration 5V,SOT-23-5

1

IC100 1TF1-2SK1824

R FET

2SK1824(B1)

1

Q506

1TF1-3SK318

R dual-gate fet

3SK318(YB-)

1

Q507

1TF1-RD01MUS2

E R FET

1 Q501

1TF1-RD07MUS2B

E R FET

Mitsubishi, RD07MUS2B, no Pb

1

Q500

1TF1-ST2302

R FET

ST2302,SOT-23

2

Q602,Q603

1TT1-2SA1586

R Surface mounting triode

2SA1586

1

Q605

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FP420 Service Manual

1TT1-2SC3356-R24

R Surface mounting triode

2SC3356-R24,SOT23,NPN

1

Q503

1TT1-2SC5108-Y

R Surface mounting triode

2SC5108-Y(MC),NPN

1

Q502

1TT1-DTA144EE

R Surface mounting triode

Digital triode, DTA144EE-SMD

1

Q504

1TT1-DTC144EE

R Surface mounting triode

Digital triode, DTC144EE(26),SOT323

9

Q1,Q101,Q103,Q200,Q201, Q505,Q601,Q604,Q606

1TT1-FMMT717TA

R Surface mounting triode

FMMT717A,PNP,SOT23

1

Q600

1TT1-KTA1298-Y

R Surface mounting triode

KTA1298-Y,SOT23

2

Q100,Q102

2CC1-10-C0G500-101J

R flake multilayer capacitor

1005,100P±5%,50V,C0G

19

C3,C4,C5,C7,C8,C9,C10,C1 1,C24,C225,C237,C238,C23 9,C240,C241,C242,C243,C5 21,C543

2CC1-10-C0G500-151J

R flake multilayer capacitor

1005,150P±5%,50V,C0G

2

C301,C561

2CC1-10-C0G500-180J

R flake multilayer capacitor

1005,18P±5%,50V,C0G

1

C520

2CC1-10-C0G500-220J

R flake multilayer capacitor

1005,22P±5%,50V,C0G

3

C313,C314,C518

2CC1-10-C0G500-470J

R flake multilayer capacitor

1005,47P±5%,50V,C0G

2

C558,C560

2CC1-10-C0G500-4R0C

R flake multilayer capacitor

1005,4P±0.25P,50V,C0G

7

C315,C316,C317,C318,C319 ,C320,C321

2CC1-10-C0G500-5R0C

R flake multilayer capacitor

1005,5P±0.25P,50V,C0G

1

C310

2CC1-10-X7R100-105K

R flake multilayer capacitor

1005,1μF±10%,10V,X7R

4

C219,C220,R606,R607

2CC1-10-X7R160-104K

R flake multilayer capacitor

1005,100nF±10%,16V,X7R

29

C16,C100,C101,C111,C114, C117,C127,C223,C224,C228 ,C229,C300,C302,C303,C30 4,C305,C306,C307,C309,C3 11,C312,C322,C323,C324,C 325,C400,C601,C608,C616

2CC1-10-X7R160-333K

R flake multilayer capacitor

1005,33nF±10%,16V,X7R

1

C583

2CC1-10-X7R250-223K

R flake multilayer capacitor

1005,22nF±10%,25V,X7R

1

C584

2CC1-10-X7R500-102K

R flake multilayer capacitor

1005,1000P±10%,50V,X7R

11

C120,C124,C226,C512,C536 ,C545,C547,C562,C563,C57 3,C581

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FP420 Service Manual

2CC1-10-X7R500-103K

R flake multilayer capacitor

1005,10nF±10%,50V,X7R

11

C110,C112,C115,C126,C308 ,C529,C539,C540,C548,C60 0,C612

2CC1-10-X7R500-471K

R flake multilayer capacitor

1005,470P±10%,50V,X7R

76

C1,C29,C34,C40,C42,C44,C 46,C48,C50,C52,C102,C104, C113,C118,C122,C128,C130 ,C201,C202,C203,C204,C20 6,C207,C208,C209,C210,C2 11,C213,C214,C215,C217,C 218,C221,C222,C230,C231, C232,C233,C234,C326,C332 ,C519,C522,C523,C526,C52 7,C528,C530,C531,C532,C5 33,C535,C537,C

2CC1-16-C0G500-120J

R flake multilayer capacitor

1608,12P±5%,50V,C0G

1

C507

2CC1-16-C0G500-1R0C

R flake multilayer capacitor

1608,1P±0.25P,50V,C0G

1

C534

2CC1-16-C0G500-1R5C

R flake multilayer capacitor

1608,1.5P±0.25P,50V,C0G

1

C504

2CC1-16-C0G500-220J

R flake multilayer capacitor

1608,22P±5%,50V,C0G

1

C502

2CC1-16-C0G500-270J

R flake multilayer capacitor

1608,27P±5%,50V,C0G

1

C510

2CC1-16-C0G500-2R0C

R flake multilayer capacitor

1608,2P±0.25P,50V,C0G

1

C503

2CC1-16-C0G500-3R0C

R flake multilayer capacitor

1608,3P±0.25P,50V,C0G

2

C514,C516

2CC1-16-C0G500-3R5C

R flake multilayer capacitor

1608,3.5P/3.6±0.25P,50V,C0G

1

C505

2CC1-16-C0G500-4R0C

R flake multilayer capacitor

1608,4P±0.25P,50V,C0G

1

C501

2CC1-16-C0G500-5R0C

R flake multilayer capacitor

1608,5P±0.25P,50V,C0G

2

C513,C515

2CC1-16-C0G500-6R0D

R flake multilayer capacitor

1608,6P±0.5P,50V,C0G

1

C509

2CC1-16-C0G500-8R0C

R flake multilayer capacitor

1608,8P±0.25P,50V,C0G

1

C508

2CC1-16-X7R500-471K

R flake multilayer capacitor

1608,470P±10%,50V,X7R

1

C511

2CC1-20-X7R6R3-475K

R flake multilayer capacitor

2012,4.7uF±10%,6.3V,X7R(GRM 219R6J475KE19D)

2

C27,C542

2CC1-20-Y5V160-106Z

flake multilayer capacitor

2012,10uF+80%/-20%,16V,Y5V

18

C2,C103,C108,C116,C121,C 123,C131,C200,C205,C212,

Page 34 of 50

FP420 Service Manual

C216,C227,C582,C602,C606 ,C615,C119,C129

2CT1-TS35-100-470M

R Surface mounting Tantalum capacitor

3528,47μF±20%,10V,TS

Series(Grade B)

1

C605

2LH1-R401R5-R03-05

R Surface mounting Air Coil

Wire diameter: φ0.40, Inner

diameter: φ1.5, 3 circles, Pin

hight: 0.5mm, clockwise circling

4

L500,L501,L503,L505

2LH1-R401R5-R04-05

R Surface mounting Air Coil

Wire diameter: φ0.40, Inner

diameter: φ1.5, 4 circles, Pin

hight:: 0.5mm, clockwise circling

1

L502

2LH1-R401R5-R08-05

R Surface mounting Air Coil

Wire diameter: φ0.40, Inner

diameter: φ1.5, 8 circles,

clockwise circling, high Pin

1

L507

2LH1-R501R5-L05-05

R Surface mounting Air Coil

Wire diameter: φ0.50, Inner

diameter: φ1.5, 5 circles,

anticlockwise, high Pin

1

L506 2LL1-16-12NJ

R multi-layer inductance

1608,12nH±5%(MLG1608B12NJ/ LL1608-FH12N)

1

L511 2LL1-16-18NJ

R multi-layer inductance

1608,18nH±5%(MLG1608B18NJ)

1

L509

2LL1-16-3N3S

multi-layer inductance

1608,3.3nH±0.3nH(MLG1608B3 N3S)

1

L504

2LW1-16UC-270J

R Surface mounting wire wound inductance

1608, 27nH±5%, Ceramic core (C1608CB-27NJ)

2

L3,L6

2LW1-16UC-680J

R Surface mounting wire wound inductance

1608,68nH±5%, Ceramic core (C1608CB-68NJ)

1

L516 2LW1-20UC-221J

R Surface mounting wire wound inductance

2012,220nH±5%, Ceramic core (LQN21AR22J/LQW2BHNR22J0 3L)

1

L508 2LW1-25UC-103J

R Surface mounting wire wound inductance

2520,10μH±5%, Ceramic core

(FLM2520-100J)

1

L520

2LW1-35UF-473K

Surface mounting wire wound inductance

3.5*3.0*2.1,47UH±10％ ,CD32-47 0K,no Pb

2

L107,L110

2RE1-10-1502