Kirisun PT4208 User manual

PT4208ServiceManual
Dangerous!
Do not connect the AC power or DC power over
8.6V with any connector or terminal of the radio.
Otherwise it will cause fire, electric shock or
damage to the radio.
Warning!
Do not reverse power connection.
It may cause harm to the radio if signal input on
the antenna connector is bigger than 20 dBm
(100mW).
Do not turn on the power before the antenna or
load connection is completed.
If the antenna has been damaged, do not use the
radio. Damaged antenna may cause lightly burning
on skin.
Though the radio is waterproof, it's better to
avoid putting it in rain or snow, or any other liquid
to ensure its life and performance.
Statement!
Kirisun Electronics (Shenzhen) Co., Ltd owns
the copyright of KSP4208 software.
Unauthorized Duplication of KSP4208 software
is strictly prohibited.
Kirisun Electronics (Shenzhen) Co., Ltd owns
the copyright of the MCU software.
Kirisun Electronics (Shenzhen) Co., Ltd owns
the copyright of the radio outward/structure/circuit
design.
Kirisun Electronics (Shenzhen) Co., Ltd owns
the copyright of this service manual. Unauthorized
publication is prohibited.
Kirisun Electronics (Shenzhen) Co., Ltd owns
the trademarks “KIRISUN”, “”, “科立讯”.
Contents
Chapter 1 Overview……………………………………………………………………1
Chapter 2 Radio Overview……………………………………………………………..1
Chapter 3 Circuit Introduction………………………………………………………….2
Chapter 4 Mode Introduction…………………………………………………………..8
Chapter 5 Maintenance, Assembly and Disassembly…………………………………10
Chapter 6 Overall Debugging…………………………………………………………12
Chapter 7 Major Specifications……………………………………………………….15
Chapter 8 Trouble Shootings and Solutions ………………………………………….15
Chapter 9 KBC-70C Charger…………………………………………………………16
Appendix 1 Abbreviations………………………………………………………….…17
Appendix 2 Electronic components list……………………………………………….18
Appendix 3 Damageable components list……………………………………………..23
Appendix 4 Framework components list……………………………………………...25
Appendix 5 Accessories……………………………………………………………….26
Figure 1 PT4208 Schematic Circuit Diagram (420-470MHz)………………………..27
Figure 2 PT4208 Main Board Schematic Circuit Diagram (420-470MHz)…………..28
Figure 3 PT4208 Top Main Board Position Mark Diagram (420-470MHz)………….29
Figure 4 PT4208 Bottom Main Board Position Mark Diagram (420-470MHz)……...30
Figure 5 PT4208 Top Main Board Numerical Value Diagram (420-470MHz)……….31
Figure 6 PT4208 Bottom Main Board Numerical Value Diagram (420-470MHz)…...32
Figure 7 PT4208 Top Main Board Circuit Connection Diagram (420-470MHz)…….33
Figure 8 PT4208 Bottom Main Board Circuit Connection Diagram (420-470MHz)...34
Figure 9 PT4208 Main Board Schematic Circuit Diagram (136-174MHz)…………..35
Figure 10 PT4208 Top Main Board Position Mark Diagram (136-174MHz)………...36
Figure 11 PT4208 Bottom Main Board Position Mark Diagram (136-174MHz)…….37
Figure 12 PT4208 Top Main Board Numerical Value Diagram (136-174MHz)……...38
Figure 13 PT4208 Bottom Main Board Numerical Value Diagram (136-174MHz)….39
Figure 14 PT4208 Top Main Board Circuit Connection Diagram (136-174MHz)…...40
Figure 15 PT4208 Bottom Main Board Circuit Connection Diagram (136-174MHz).41
Figure 16 KBC-70C Schematic Circuit Diagram……………………………………..42
Figure 17 KBC-70C Top Main Board Numerical Value Diagram…………………….43
Figure 18 KBC-70C Top Main Board Position Mark Diagram……………………….44
Figure 19 KBC-70C Bottom Main Board Numerical Value Diagram………………...45
Figure 20 KBC-70C Bottom Main Board Position Mark Diagram…………………...46
Figure 21 KBC-70C Circuit Connection Diagram……………………………………47

PT4208ServiceManual
Chapter 1 Overview
1.1 Introduction
This manual applies to the service and maintenance of
PT4208 portable radios, and is for the engineers and
qualified technicians that have been trained by our company.
In this manual you can find all the information of product
service. Kirisun reserves the rights to modify the product
construction and specifications without notice in order to
enhance product performance and quality. You can also log
on our website www.kirisun.com to download the latest
service manual or contact your local dealer or us.
1
Please read this manual before repairing the product.
1.2 Attention
Safety
Do not contact the antenna connector or PCB with your
skin directly.
Do not reverse the battery.
It may cause harm to the radio if signal input on the
antenna connector is bigger than 20 dBm (100mW).
Do not turn on the radio before the antenna or load
connection is completed.
If the antenna has been damaged, do not use the radio.
Damaged antenna may cause lightly burning on skin.
Electromagnetism Interference
It’s prohibited to use or repair the radio in the following
places:
Hospital, health center, airport
Any area with a potentially explosive atmosphere (e.g.
orlpo deck of the ship, fuel and chemical storage and
transport devices etc.)
Any place near blasting areas or area with blasting cap.
Components Replacement
All the components used in repair service should be
supplied by Kirisun.
Other components of the same models 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.
Please fill in the following form if you want to apply for
any component from Kirisun.
Component Application
Radio Model Component No. Model/
Specifications
Material Serial No. Quantity
PT4208-02 FET Q3 RD01MUS1 105-RD01MU-R01 1
PT4208-02 Triode Q49 2SC5108（Y）104-SC5108-001 1
1.3 Service
All the Kirisun products are subject to the service
warranty.
After-sales service will be provided, and the length of
warranty is stated by Kirisun. The radio and its accessories
are all in the warranty. However, in one of the following
cases, charge free service will be not available.
· No valid service warranty or original invoice.
· Malfunction caused by disassembling, repairing or
reconstructing the radio by the users without permission.
· Wear and tear or any man-made sabotage such as
mechanical damage, burning or water leaking.
· Product serial number has been damaged or the product
trademark is difficult to identify.
Beyond the warranty time, lifetime service is still
available with paid. And we also provide service
components to service stations and staffs.
Chapter 2 Radio Overview
2.1 External view
See Figure 1.
Figure 1
Functional buttons description:
1. LED Indicator
Solid red: The radio is transmitting.
Solid green: The radio is receiving.
Blinking red: The radio is in low battery.

PT4208ServiceManual
2. Channel Selector Knob
Rotate the knob to select channels 1-16.
3. Power/Volume Control Knob
Rotate clockwise to turn on the radio, keep turning to
adjust the volume. To turn off the radio, just turn the
knob anticlockwise till a sound of click is produced.
4. PTT (PUSH-TO-TALK) Key
Press the PTT key and talk towards the MIC to send the
voice to the recipient.
5. Side Key 1 (programmable key)
6. Side Key 2 (programmable key)
7. Top Key (programmable key)
8. Speaker/MIC Connector
Connecting external speaker or MIC.
Chapter 3 Circuit Introduction
3.1 Frequency Structure
Figure 3.1: Frequency Structure Diagram
The reference frequency of frequency synthesizer is
provided by 16.8MHz crystal oscillator X4 TCXO. The
receiver adopts quadric mixing mode. The first IF is
49.95MHz, and the second IF is 450kHz. The first local
oscillation signal of the receiver is produced by frequency
synthesizer and the second local oscillation signal selects the
3rd harmonic (50.4MHz) of 16.8MHz crystal oscillator X4
TCXO. The signal of transmitter is produced by frequency
synthesizer directly.
3.2 Principles of Receiver（RX）
Figure 3.2: Principle of Rx
Front End of Receiver
Signals from the antenna are filtered by BPF which
consists of C37, C227, L8, L15, C70, C126, D30, C218, L9,
C230, C128, D26, C217, L10, C229, C127 and D24 via
RX/TX switch (D1, D2, D4 and D5). After being filtered out
the useless out-of-band signals, the signals are amplified by
LNA consisting of Q20 and external components.
Signals from LNA are filtered again by BPF which
consists of L7, C228, C47, D23, C219, L6, C182, C124, D22,
C216, L5, C132, C32 and D21 before entering the 1st mixer
(Q19).
The PWM wave is output by MCU composed of 12 pins
and then commutated to adjustable voltage after filtering to
change the capacity of varactor diode D21, D22, D23, D24,
D26 and D30 to control the center frequency of BPF.
1st mixer
The first IF (49.95MHz) signal is produced after mixing
of the receiving signal from LNA and the 1st local oscillation
signal from frequency synthesizer. The first IF signal is
filtered to get rid of adjacent channel and other useless
signals by crystal filter (XF1, XF2).
IF Circuit
The 1st IF signal from crystal filter is amplified by the
first IF amplifier (Q21) before being sent to the IF
processing IC ( IC5，TA31136).
IF IC consists of the 2nd mixer, 2nd local oscillator, IF
amplifier, limiter, frequency discriminator and noise
amplifier.
Frequency (16.8MHz) produced by TCXO(X4) is
amplified and then selects the 3rd harmonic (50.4MHZ) as
the second local oscillation signal source. The second IF
signals (450kHz) are generated after signals mixing of the
second local oscillation (50.4MHz) and the first IF signal
(49.95MHz) in IC5. Audio signals are demodulated and
outputted by IC5 after the second IF signals are amplified
and limited in IC5 and then filtered by ceramic filter (CF1
450kHz).
2

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3
Figure 3.3 Schematic Diagram for IF System
Audio Signal Processing of Receiver:
The audio signal processing circuit of receiver consists
of IC6 and the peripheral circuit. Voice signals from IC5 are
sent to IC4（CTCSS signaling filtering circuit）and IC6-D
respectively after being amplified in IC6-C. After that, the
signals are removed of the HF and LF components after
amplification, de-emphasis and filtering by other units of
IC6, and only audit components from 300 to 3000Hz can be
sent to audio power amplifier (IC8) after amplified in Q9
and adjusted by volume potentiometers.
Figure 3.4 Schematic Diagram for Audio Processing of
Receiver
Squelch Circuit
Signals demodulated by IC5 are filtered out the noise
components by frequency selection noise amplifier
composed of IC5 internal noise amplifier, C211, R99, R100,
C107 and R94, and then amplified further by Q7. After that,
the signals are sent to MCU after being demodulated by D17,
and then the noise is identified and the squelch circuit is
controlled by MCU.
Audio PowerAmplification
The audio power amplifying circuit consists of IC8 and
the peripheral components.
The signals are amplified by audio power amplifier to
drive the speaker after collecting the receiving audio signals,
voice prompt signals, alert tone signals and warning tone
signals. The warning tone has no volume limitation.
When AFCO is in high level, Q35 is on, IC8 begins to
work and the speaker sounds. Speaker Impedance: 16ohm
Q38：Receiving audio signals switch
Q51：Warning tone switch
Q25：Alert tone switch
CTCSS Signal Filtering
The audio signals after demodulation in IC5 may contain
CTCSS (continuous tone control squelch system) or DCS
（digital code squelch）signals. The spectrum component of
CTCSS/DCS is 67 to 250Hz. The filtering circuit composed
of IC4 can filter out signals out of CTCSS/DCS spectrum,
which makes MCU decode the CTCSS/DCS more
accurately.
3.3 Principles of Transmitter (TX)
Transmitter PowerAmplifier
Figure 3.5 Schematic Diagram for Power Amplifier and
Antenna Switch
The modulated RF signals from VCO are amplified by
Q2, Q3 and Q12 before the power amplification in Q11.
Gate bias of Q11 and Q12 is controlled by APC circuit,
so the output power of transmitter can be controlled
conveniently by changing the gate bias voltage.
APC（Automatic Power Control）
Figure3.6SchematicDiagramforAPCCircuit
R167, R168 and R169 are power amplification current
detector, IC3A is power amplification current sampling
amplifier and IC3B is power comparison amplifier.

PT4208ServiceManual
If the output power of the transmitter is too large, the
power amplification current and IC3A output will increase,
and the output voltage of IC3B and the bias voltage of Q11
and Q12 will decrease. Finally the output power of
transmitter will decrease and vice versa. Thus, the output
power of transmitter will keep stable under any different
working condition.
MCU can set the power by changing the voltage input to
IC3B.
Audio Signal Processing of Receiver
TCXO
VCO
MCU
CTCSS/DCS
MIC
MIC Amp Pre-Emphasis
IC7A IC7B
IC7C,IC7D
Figure 3.7 Schematic Diagram for Audio Circuit of Receiver
The audio signal processing circuit of receiver consists
of IC7 and the peripheral components. Voice signals from
MIC are sent to VCO for modulation together with
CTCSS/DCS after amplification, limitation and filtering.
AGC circuit consists of D13, D308 and Q24. The signal
amplitude is reduced to ensure no distortion in case of
oversized MIC signal.
Q34, the power switch of voice processing circuit,
controlled by MCU, will give power supply to IC7 only
during transmission.
J2 is the socket for external MIC, and the internal MIC
will disconnect automatically when using external MIC, but
the internal PTT is still effective.
3.4 Principles of Frequency Synthesizer
1
Nr
1
N
Control Circuit Charge
UL
Detect
Pump
TCXO
DCS Mod
Freq Adj
4
to MCU VCCN
Data
CK
LE
to MCU
VCO
RX
TX
D3,D6
Q4
Q5
MOD in
Figure 3.8 Schematic Diagram for Frequency Synthesizer
The PT4208 adopts PLL frequency synthesizer.
Frequency synthesizer consists of reference oscillator,
voltage controlled oscillator (VCO), programmable
frequency divider (PFD), phase comparator and low pass
filter (LPF).
RX VCO Unit consists of Q14, L30, C120, C88, C142,
C180, D8 and D9.
TX VCO Unit consists of Q15, L51, C121, C137, C206,
C194, D10 and D11. D12 is the modulation circuit of VCO.
IC1 (MB15E03) is PLL integrated circuit and contains
programmable parametric frequency divider (PPFD),
programmable swallowing frequency divider (PSFD), phase
comparator and charge pump, etc.
Low pass filter consists of R244, C193, R202, R40,
C207, R141, C205, R2 and C204.
Reference frequency is provided by X4 (TCXO,
16.8MHz).
Reference frequency of TCXO (Temperature-controlled
Crystal Oscillator) is divided by PPFD in IC1 to produce
reference frequency of 5kHz or 6.25kHz (controlled by
MCU based on the set channel frequency).
The oscillation frequency of VCO is compared with
reference frequency to produce error signal after being
divided by PSFD in IC1. The error signal is filtered by low
pass filter before changing the VCO frequency to the set
value in VCO (it is locked).
N=FVCO/FR
N：Division Frequency
FVCO：VCO Oscillation Frequency
FR：Reference Frequency
Un-lock detection: When PLL is out of lock, IC pin14
will output low level signal to MCU，and then MCU prohibit
transmitter from transmitting with a warning tone.
Q6, the power filter, can provide PLL with more purified
power to reduce the noise of frequency synthesizer.
3.5 Voice Prompt Circuit
The radio is equipped with Voice Prompt Function,
which is very useful during night or under dark condition.
The speaker will voice the current channel number when
changing the channel every time because of the voice
memory chip (IC15), which stores channel voice prompts. It
will repeat the current channel number once pressing “Voice
Prompt” key.
The speaker will voice the current channel number under
standby state if the Voice Prompt Function is set and the
“Voice Prompt” key is pressed. Reboot the radio while
pressing the “Voice Prompt” key to switch voice types. Do it

PT4208ServiceManual
repeatedly, then the voice types will be switched in circle in
the order of “Chinese male voice—English male
voice—Chinese female voice—English female voice—No
prompt”.
3.6 Power Supply
The radio use lithium battery (7.4V, 1700mAh), and the
transmitter amplifier circuit (Q11, Q12) and receiver audio
amplifier (IC8) use battery directly for power supply, and
other circuits use regulated voltage (5V).
IC12, micro-power voltage stabilizer of 5V LDO,
provides power (5V) of heavy current for the radio together
with Q10 and Q30.
Q29: 5T switch (controlled by MCU)
5T: supply power for the front end of transmitter
Q31: 5R switch (controlled by MCU)
5R: supply power for RF amplification, mixing, IF
processing and audio signal processing units of the receiver.
Q32: 5C switch (controlled by MCU)
5C: 5V power with power-saving control. It
supplies power for frequency synthesizer.
3.7 MCU Unit:
EEPROM
D/A
chananl
SW
PTT MONI
ALARM
PF1
CTCSS/DCS IN
SQL BATT VCCN
CTCSS/DCS OUT
BEEP
LE DATA CK
to PLL
VIOCE CHIP
TX/RX CONTROL
RXD TXD
to PC
UL
5TC
5RC
SAVE
APC CONTR
SHIFT
IC9
IC10
MCU
Figure 3.9 Schematic Diagram for MCU Unit
MCU controls the operation of every unit to realize all
functions of the PT4208.
Communication with external PC
State data access
Control PLL for the generation, receiving and
transmitting of local oscillation frequency
Access to the current channel state
Control LED status indicator
Control power supply condition of every unit
Detect action of every function key
Produce CTCSS signal
Produce DCS signal
Produce power control signal
Finish CTCSS decoding
Finish DCS decoding
Squelch detection and control
Control voice prompt content
Memory (E2PROM, AT24C08)
Stored with channel data, CTCSS/DCS data and other
function setting data and parameter adjustment data of the
radio.
CTCSS/DCS signal coding and decoding:
CTCSS/DCS signals from MCU (pin12 output) are sent
to VCO and TCXO for modulation respectively after being
filtered by R155, R156, C242 and C243.
CTCSS/DCS signals from receiver are sent to MCU
(pin49) for decoding, and then MCU test if there are
CTCSS/DCS signals with the same setting as the radio to
decide whether to open the speaker or not.
Power Adjustment:
MCU P42 output is sent to APC unit after integral
filtering by R161, C317, R206 and C318 to control the
output power of transmitter.
CTCSS
CTCSS (continuous tone control squelch system,
hereinafter referred to as CTCSS), is a kind of squelch
control system with modulation on carrier and continuous
sub-audio signals as pilot tone. If CTCSS function is set,
talkback can be realized only when both receiving and
transmitting parties have the same CTCSS frequency to
avoid the disturbance of other signals.
The radio has 39 groups of standard CTCSS frequency
for your selection, refer to Table 3.1.
CTCSS signals produced by MCU are sent to VCO for
modulation after being filtered to get rid of the HF
components over 300Hz in low pass filter composed by RC.
Table 3.1 CTCSS Frequency Table
No. Frequency
[Hz]
No. Frequency
[Hz]
No. Frequency
[Hz]
No. Frequency
[Hz]
1 67.0 11 94.8 21 131.8 31 186.2
2 69.3 12 97.4 22 136.5 32 192.8
3 71.9 13 100.0 23 141.3 33 203.5
5

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6
4 74.4 14 103.5 24 146.2 34 210.7
5 77.0 15 107.2 25 151.4 35 218.1
6 79.7 16 110.9 26 156.7 36 225.7
7 82.5 17 114.8 27 162.2 37 233.6
8 85.4 18 118.8 28 167.9 38 241.8
9 88.5 19 123.0 29 173.8 39 250.3
10 91.5 20 127.3 30 179.9
DCS signaling
DCS (Digital code squelch), is a kind of continuous
digital code modulated on carrier with voice signal and used
for squelch control. If DCS function is set, the speaker is
available only when receiving the same DCS code to avoid
the disturbance of unwanted signals.
The radio has 83 kinds of standard codes including
positive and inverse code for your selection, refer to Table
3.2.
DCS signals produced by MCU (PWM waveform) are
sent to VCO and TCXO for modulation (the HF components
of DCS signals are modulated by VCO, while the LF
components by TCXO) after filtered the HF components
over 300Hz in low pass filter composed by RC.
CTCSS/DCS signals from receiver are sent to MCU for
decoding, and then MCU test if there are DCS codes with
the same setting of the radio to decide whether to open the
speaker or not.
Table 3.2 DCS Coding Schedule
023 114 174 315 445 631
025 115 205 331 464 632
026 116 223 343 465 654
031 125 226 346 466 662
032 131 243 351 503 664
043 132 244 364 506 703
047 134 245 365 516 712
051 143 251 371 532 723
054 152 261 411 546 731
065 155 263 412 565 732
071 156 265 413 606 734
072 162 271 423 612 743
073 165 306 431 624 754
074 172 311 432 627
3.8 Description of Semiconductor Devices
The distribution of each pin goes as table 3.3.
Table 3.3 Definition of CPU Base Pin:
No. Port name Pin Name I/O Function
1 TOPKEY P33 I Programmable Top Key Detection
2 UPKEY P34 I Programmable Upper Key Detection
3 MODE I Connect resistor of 4.7K with VCC and
burn the test points
4 PTT P43 I Press [PTT] to input
5 DNKEY P44 I Programmable Lower Key Detection
6 RST I Reset Input and burn the test points
7 XOUT O Oscillator
8 VSS I Grounding
9 XIN I Oscillator（7.3MHz）
10 VCC I CPU Power 5V Input
11 SHIFT P54 O Clock Beat Frequency Shift H：On
12 TO0 P53 O(PWM) BPF Tuner output
13 TO1 P52 O(PWM) QT/DQT Output
14 VDEVC2 P51 I Frequency Offset Switch 2 of VHF
15 VDEVC1 P50 I Frequency Offset Switch 1 of VHF
16 NC Connect Pull-down Resistor with VSS
17 PABC P26 O Supply final power H：On
18 OSCSI P25 I VCO crystal selection and connect
pull-down resistor with VSS H：13，L：
16.8
19 WNTC P24 O Broad/narrowband Control H:
Broad L: Narrow
20 ENC0 P23 I Encoding Input
21 ENC2 P22 I Encoding Input
22 ENC3 P21 I Encoding Input
23 ENC1 P20 I Encoding Input
24 PS P17 O PLL Power-saving Control H ：Normal
L：Power Saving
25 NC Connect Pull-down Resistor with VSS
26 NC Connect Pull-down Resistor with VSS
27 NC P86 Connect Pull-down Resistor with VSS
28 SDA P85 I/O EEPROM Data Line
29 SCL P84 O EEPROM Clock Line
30 UL P83 I
I (TRFI)
PLL Lock Detection Pin
H: Locking L: Un-lock
31 T2IN P82 Reserved：2TONE Input
32 DT P81 O PLL Data Output
33 CK P80 O PLL Clock Output
34 LE P60 O PLL IC Enable Pin H:
Locking
35 5MC P45 O
I
Power control except CPU and EEPROM
L：On
36 INT P66 Power Detection Input
37 TXD P67 O RS-232C Output and burn the test points
38 RXD P65 I RS-232C Input and burn the test points
39 AFCO P64 O Audio Amplification Power
H：On
40 RX P63 O TX/RX VCO Selection H ：
Receiving
41 GLED P31 O Green Indicator Light Control
H：On
42 APC P30 O(PWM) TX: Automatic Power Control Output
43 RLED P36 O Red Indicator Light Control
H：On
44 SAVE P32 O
O
Battery Saving Control H：
Power Supply，L：Power Saving
45 MUTE P13 O Mute Control H: Mic Mute L：
Audio Mute
46 5RC P12 Receiving Power Control L：On
47 5TC O Transmitting Power Control H：On
48 NC P10 Speaker Mute Switch Output
49 TI P00 I(A/D8) QT/DQT Signal Input

PT4208ServiceManual
50 RSSI I(A/D7) Signal Strength Detection
51 BUSY P01 I(A/D6) Busy Signal Input
52 MANDO
WN
P02 I(A/D5) Rewind Switch Detection
53 BATT P03 I(A/D4) Battery Voltage Detection
54 NC Connect Pull-down Resistor with VSS
55 W588C P62 O Voice Prompts Switch H：
Number Reporting
56 AC P61 O Alarm Switch Control H：Controlled
by Volume Switch
It must be low level in case of emergency
alarm
57 BUSY_V P05 I “Busy indicating circuit detection” by
voice prompts
58 VCCN P06 O(D/A0) Frequency Stability Output
59 AVSS I Connect with VSS
60 DTMF P07 O(D/A1) DTMF Output
61 VREF I Connect with VSS
62 AVCC I Connect with VSS
63 DATA_V P37 O Voice Prompt Data
64 SCLK_V P35 O Voice Prompt Clock
7
Table 3.4 Functional description of semiconductor devices
Item Model Function Description
IC1 MB15E03 Frequency Synthesizer
IC4 NJM2904 APC, Voltage Comparison, Driving
IC5 TA31136 Receiver 2nd Local Oscillation, 2nd IF
Amplification, Limitation, Demodulation,
Noise Amplification
IC6 NJM2902 Receiver demodulated signal Amplification,
Filtering
IC7 NJM2902 MIC Amplification, Limitation, Filtering
IC8 TDA8541 Audio Frequency Power Amplification
IC9 AT24C08 E2PROM, Channel Frequency Data Storage,
Function Setting Parameter, Debug Mode
Parameter
IC10 R5F212A8 MCU
IC11 PST9140NR MCU Reset Circuit
IC12 HT7150-1 LDO，Low-power Voltage Regulator
IC15 W588A080 Voice Storage IC
Q2 2SC5108 Transmitter 1st Amplification
Q3 2SC3356 Transmitter 2nd Amplification
Q4 2SC5108 VCO Buffer Amplifier
Q5 2SC5108 VCO Buffer Amplifier
Q6 2SC4617 VCO Power Filter
Q7 2SC4738 Noise Amplifier
Q9 2SC4617 Receiver Audio Frequency signal
Amplification
Q10 2SC1623 5V Voltage Regulation Output Current
Stretching
Q11 RD07MVS1 Transmitter Final Power Amplification
Q12 RD01MUS1 Transmitter Power Amplification Driving
Q17 DTA144EE APC Output Switch
Q19 3SK318 First Level Mixer
Q20 3SK318 Receiver High Power Amplification
Q21 KTC4082 1st IF Amplifier
Q22 DTC144EE Red LED Drive
Q23 DTC144EE Green LED Drive
Q24 2SK1824 Voice Prompts Switch
Q26 DTC144EE 5C Switch
Q29 KTA1298 5T Switch
Q30 KTA1298 5V Voltage Regulation Output Current
Stretching
Q31 KTA1298 5R Switch
Q32 KTA1298 5C Switch
Q34 DTA144EE Power Switch of MIC Amplification Unit
Q35 2SK1824 Receiver Audio Output Switch, Disconnection
on Emergency
Q36 2SK1824 Receiver Audio Output Switch
Table 3.5 Functional description of Diodes
Item Model Function Description
D1 MA77 Transmitter antenna switch diode
D2 MA77 Transmitter antenna switch diode
D3 HSC277 VCO Output Switch
D4 HSC277 Antenna Switch
D5 HSC277 Antenna Switch
D6 HSC277 VCO Output Switch
D7 HSC277 5V Voltage Regulation Output Current
Stretching
D8 HVC376B VCO Oscillation Varactor Diode
D9 HVC376B VCO Oscillation Varactor Diode
D12 MA360 VCO Modulation Diode
D14 HZU5ALL APC Output Voltage-limiting Diode
D15 MA2S111 Unlock Detection Diode
D16 MA2S111 VCO Power Filtering Acceleration Diode
D17 1N4148 Noise Demodulation
D18 1N4148 Noise Demodulation
D20 LED
Green
Receiving Instructions
D25 MA2S111 APC Single Diode
D28 LED Red Transmitting Instructions
D29 LED
Green
Receiving Instructions
Table 3.6：Characteristic of crystal filter (XF1 and XF2)
Item Rated Value
Nominal center frequency 49.95MHz
Pass bandwidth ±7.5khz or higher, but within 3db
40db stop band width ±20.0khz or lower
Ripple 1.0db or lower
Insertion loss 3.0db or lower
Ensure attenuation 80db or higher, but between f0-910khz
Terminal impedance ---
Table 3.7 Performance and characteristic of CF1
LTVPC450EB
Item Rated Value
Nominal center frequency 450kHz
6db band width ±6kHz or higher
50db band width ±12.5kHz or lower
Ripple 2.0db or lower, but between f0±4kHz
Insertion loss 6.0db or lower
Ensure attenuation 35.0db or higher, but between
f0±100kHz
Terminal impedance 2.0k

PT4208ServiceManual
Table 3.8 Schematic diagram for semiconductor devices
packaging
8
3SK318
M: YB-
G1
G2 D
S
G
S
D
CC C
C
B
BB
B
EE
E
E
G
D
S
2SK1824
Mark: B1
2SC5108
M: MC
C
B
E
M: R24
2SC3356
C
B
E
2SC4617
C
B
E
C
B
E
2SC4738 KTC4082
C
B
E
2SC1623
M: L6
KTA1298 DTC144EE
M:16
GND
IN
OUT
HT7150-1
RD01MUS1
D
G
SS
RD07MVS1
RDA0002
1
2
3
DA221
M: K
2SK308NV
DTA144EE
C
B
E
FMMT591
GSD
Chapter 4 Mode Introduction
Mode Introduction
Mode Function How to access
User Mode For normal use Power on
Data
Programming
mode
Reading and writing
frequency data and
other functions
Receive instructions
from the PC
Test Mode Adjust the radio
parameters by PC.
Receive instructions
from the PC
PC
Mode
Firmware
Programming
Mode
Add new functions to
upgrade the software.
Press the top button for
over 2 seconds and turn
on the power at the same
time; Receive
instructions from the
computer
Wired Clone Mode
Used to transfer
programming data
from one radio to
another.
Press side button P1 for
over 2 seconds and turn
on the power at the same
time.
User Mode：
You can enter User Mode (conventional communication
mode) by turning on the power switch. Users in the mode
can use the defined functions of the radio.
Data programming mode:
The radio has been set before leaving the factory.
However, due to different requirements of users, functional
parameters of the radio like working frequency, channels,
CTCSS/DCS and auto scanning, etc. should be reset.
Therefore, the company has specially designed a set of
Chinese/English programming software KSP4208 with
friendly interface, convenient operation and visualized
display for setting functional parameters of the radio.
Steps for setting the functional parameters of the radio by
computer are as follows:
A. Install KSP4208 on the computer.
B. As shown in the figure below, connect the radio to the
serial port of the computer with the special
programming cable （KSPL-09）.
Figure 4-1
C. Turn on the power of the computer.
D. Turn on the power of the radio.
E. Click on KSP4208 program to run KSP4208.
F. In the top menu of KSP4208, click on [Read] to read
the parameters of the radio into the computer; click on
[Write] to write the parameters set in the computer into
the radio.
G. As required by the user, the following parameter
settings can be made with KSP4208:
Radio information:
Radio model (model/ frequency range), serial number,
embedded information, MCU version and hardware version,
etc.
Radio parameters:
(1) Programmable buttons:（P1, P2, P3, P4 and P5 can
be set to long/short button and the long button time
can be defined）
(2) Miscellaneous settings
1. Wired clone mode allowed
2. TOT (Time Out Timer)
3. TOT reset
4. TOT Pre-alert
5. TOT Re-key time
6. Squelch level selection
7. Alert tone
8. Read data password
9. Write data password
(3) Scanning settings
Scan functions selection, priority channel selection,
response channel selection, Tx dwell time, scan hold
time and scan-back cycle time
(4) Emergency alarm settings
Channel parameters:
(1) Channel receiving frequency and transmitting
Computer
(RS232 serial port)
Radio
(Earphone
/Programming port)
Programming
cable

PT4208ServiceManual
9
frequency. (stepping frequency: 2.5KHz / 5KHz /
6.25KHz）
(2) Channel receiving signaling and transmitting
signaling
a) None
b) CTCSS (60~260Hz @ 0.1Hz step)
c) DCS (-777 ~ 777 @ octal number)
(3) Busy channel lockout option
(4) Clock beat frequency shift selection
(5) Channel spacing selection 25KHz/12.5KHz
(Wide/Narrow)
(6) Scanning channel adding/deletion selection
(7) Channel high/low power selection
(8) CTCSS side tone reverse burst selection
(9) Code selection of CALL1 and CALL2
(10) Code selection of PTT ID on-line code and off-line
code
DTMF setting:
(1) DTMF encoding template.
(2) DTMF encoding sequence (group 1~12).
Please refer to the “Help” document of KSP4208 for
details.
Caution:
1. Before editing for the first time, you should read data
on the radio firstly and backup the data.
2. If the radio cannot work normally after being written
in with the editing data, please open the backup data
and rewrite them into the radio.
3. “Model Information” is the important information of
the radio and should not be altered.
Test Mode
According to Figure 4-1, connect the radio to the serial
port of the computer with the special programming cable.
Warning: Before entering the Test Mode, please firstly
connect a high-frequency load of 50 ohm to the antenna
connector of the radio or connect the radio to a
comprehensive tester.
With the KSP4208 Programming Software, you can
enter the adjustment status under Computer Test Mode to
adjust the following parameters of the radio:
(1) Frequency stability
(2) Five frequency points of Tx high power
(3) Five frequency points of Tx low power
(4) Level-9 broadband of squelch level opens five frequency
points
(5) Level-9 broadband of squelch level closes five frequency
points
(6) Level-9 narrowband of squelch level opens five
frequency points
(7) Level-9 narrowband of squelch level closes five
frequency points
(8) Level-1 broadband of squelch level opens five frequency
points
(9) Level-1 broadband of squelch level closes five frequency
points
(10) Level-1 narrowband of squelch level opens five
frequency points
(11) Level-1 narrowband of squelch level closes five
frequency points
(12) Five frequency points of broadband QT(67Hz)
frequency offset
(13) IF points of narrowband QT(67Hz) frequency offset
(14) Five frequency points of broadband QT(151.4Hz)
frequency offset
(15) IF points of narrowband QT(151.4Hz) frequency offset
(16) Five frequency points of broadband QT (254.1Hz)
frequency offset
(17) IF points of narrowband QT(254.1Hz) frequency offset
(18) Five frequency points of broadband DQT frequency
offset
(19) IF points of narrowband DQT frequency offset
(20) Five frequency points of Rx sensitivity adjustment
voltage
(21) IF points of broadband/narrowband DTMF frequency
offset
(22) Transmitting low-voltage alarm
Firmware Programming Mode
The radio is equipped with FLASH ROM internally, when
new features are launched, it can be upgraded.
1. Press top key for over 2 seconds and turn on the power
at the same time. The LED indicator will light up
orange and the radio enters Firmware Programming
Mode.
2. Run computer programming software KMU.
3. Connect the radio and the computer with the
programming cable.
4. Select the COM port to load firmware upgrade file and