Kirisun PT4208 User manual

PT4208 Service Manual
1
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 higher 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 light 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 appearance
/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”,“”, and “科
立讯”.
Contents
Chapter 1 Overview..............................................................................................................2
Chapter 2 External View and Functional Keys ....................................................................2
Chapter 3 Circuit Description...............................................................................................3
Chapter 4 Mode Introduction ...............................................................................................9
Chapter 5 Assembly and Disassembly for Maintenance.................................................... 11
Chapter 6 Adjustment.........................................................................................................12
Chapter 7 Specifications.....................................................................................................16
Chapter 8 Troubleshooting .................................................................................................16
Chapter 9 KBC-70C Charger .............................................................................................17
Appendix 1 Abbreviations..................................................................................................18
Appendix 2 Electronic Parts List .......................................................................................18
Appendix 3 Structural Parts List ........................................................................................29
Appendix 4 Accessories .....................................................................................................31
Figure 1 PT4208 Block Diagram .......................................................................................32
Figure 2 PT4208 Schematic Circuit Diagram (420-470MHz) ..........................................33
Figure 3 PT4208 Main Board Top Layer Position Mark Diagram (420-470MHz)...........34
Figure 4 PT4208 Main Board Bottom Layer Position Mark Diagram (420-470MHz).....35
Figure 5 PT4208 Main Board Top Layer Position Value Diagram (420-470MHz) ..........36
Figure 6 PT4208 Main Board Bottom Layer Position Value Diagram (420-470MHz) ....37
Figure 7 PT4208 Main Board Top Layer Layout (420-470MHz) .....................................38
Figure 8 PT4208 Main Board Bottom Layer Layout (420-470MHz) ...............................39
Figure 9 PT4208 Schematic Circuit Diagram (136-174MHz) ..........................................40
Figure 10 PT4208 Main Board Top Layer Position Mark Diagram (136-174MHz).........41
Figure 11 PT4208 Main Board Bottom Layer Position Mark Diagram (136-174MHz)...42
Figure 12 PT4208 Main Board Top Layer Position Value Diagram (136-174MHz) ........43
Figure 13 PT4208 Main Board Bottom Layer Position Value Diagram (136-174MHz) ..44
Figure 14 PT4208 Main Board Top Layer Layout (136-174MHz) ...................................45
Figure 15 PT4208 Main Board Bottom Layer Layout (136-174MHz) .............................46
Figure 16 KBC-70C Schematic Circuit Diagram ..............................................................47
Figure 17 KBC-70C Top Layer Position Value Diagram ..................................................48
Figure 18 KBC-70C Top Layer Position Mark Diagram...................................................49
Figure 19 KBC-70C Bottom Layer Position Value Diagram ............................................50
Figure 20 KBC-70C Bottom Layer Position Mark Diagram.............................................51
Figure 21 KBC-70C Layout ...............................................................................................52

PT4208 Service Manual
2
Chapter 1 Overview
1.1 Introduction
This manual applies to the service and maintenance of
PT4208 series portable radios, and is intended for use by
engineers and professional technicians that have been trained
by Kirisun. It contains all 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
log on our website www.kirisun.com to download the latest
service manual or contact your local dealer or us.
Please read this manual before repairing the product.
1.2 Service Attentions
* Safety
Do not contact the antenna connector or PCB with your
skin directly.
Do not reverse the battery polarity.
It may cause harm to the radio if signal input on the
antenna connector is larger than 20 dBm (100mW).
Do not turn on the radio before the antenna and load
connection is completed.
If the antenna has been damaged, do not use the radio.
Damaged antenna may cause light burning on skin.
* Explosive Atmosphere
It’s prohibited to use or repair the radio in the following
places:
Hospital, health center, and airport.
Any area with a potentially explosive atmosphere (e.g.
orlop deck of the ship, storage and transportation equipment
for fuel and chemical etc.)
Any place near blasting sites or area with electrical
blasting cap.
* 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.
If you want to apply for any component from Kirisun,
please fill in an application form as below.
e.g.
Component Application Form
Radio Model Component Position
Mark
Model/
Specifications Parts No. Qty
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 not be available.
* No valid warranty card or original invoice.
* Malfunction caused by disassembling, repairing or
restructuring 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
See Figure 1.
Figure 1
2.2 Functional Keys
1. LED Indicator
Lights red while transmitting; lights green while

PT4208 Service Manual
3
receiving; flashes red while in low battery power.
2. Channel Selector Knob
Rotate the knob to select channel 1-16.
3. On/Off/Volume Control Knob
Rotate clockwise to turn on the radio, and keep turning
to adjust the volume. To turn off the radio, rotate the knob
anticlockwise till a sound of click is produced.
4. PTT (Push-To-Talk) Key
Press the PTT key and talk to the microphone to send the
voice to the recipient.
5. Side Key 2 (Programmable key)
6. Side Key 1 (Programmable key)
7. Top Key (Programmable key)
8. Speaker/Microphone Jack
Jack for connecting external speaker or external
microphone to the radio.
Chapter 3 Circuit Description
3.1 Frequency Configuration
Figure 3.1 Frequency Configuration
The reference frequency of the frequency synthesizer is
provided by crystal oscillator X4 (TCXO, 16.8MHz). The
receiver adopts double mixing. The first IF is 49.95MHz and
the second IF is 450kHz. The first local oscillator signal of
the receiver is generated by the frequency synthesizer. The
second local oscillator signal adopts the third harmonic
(50.4MHz) of the crystal oscillator X4 (TCXO, 16.8MHz).
Transmitter signal is directly produced by the frequency
synthesizer.
3.2 Principle of Receiver (RX)
Figure 3.2 Principle of Receiver
Front end
The signal coming from the antenna passes through the
RX/TX switch circuit (D1, D2, D4 and D5), and passes
through a BPF (C37, C227, L8, L15, C70, C126, D30, C218,
L9, C230, C128, D26, C217, L10, C229, C127 and D24) to
remove unwanted out-of-band signal, and is routed to the
low noise amplifier (LNA) consists of Q20 and its peripheral
components where it is amplified.
Output signal from the LNA passes through a BPF (L7,
C228, C47, D23, C219, L6, C182, C124, D22, C216, L5,
C132, C32 and D21) and goes to the first mixer (Q19).
PWM wave is output from pin 12 of the MCU. The wave
is filtered and rectified into adjustable voltage, which can
control the center frequency of the band pass filter through
changing capacity of the varactor diode (D21, D22, D23,
D24, D26 and D30).
First mixer
The receiving signal from LNA is mixed with the first
local oscillator signal from the frequency synthesizer to
produce the first IF signal (49.95MHz). Then the first IF
signal passes through crystal filter (XF1 and XF2) to remove
the adjacent channel signal and signal outside the adjacent
channel.
IF circuit
The first IF signal from the crystal filter is amplified by
the first IF amplifier (Q21), and is routed to the IF
processing IC (IC5, TA31136).
IF IC consists of the second mixer, second local
oscillator, IF amplifier, limiter, discriminator, and noise
amplifier.
The 16.8MHz frequency produced by TCXO (X4) is
multiple-amplified and then adopts the third harmonic
(50.4MHz) as the second local oscillator signal source. The
second local oscillator signal (50.4MHz) is mixed with the
first IF signal (49.95MHz) in IC5 to generate the second IF
(450kHz). And then the second IF signal is amplified and
limited in IC5, filtered in the ceramic filter (CF1, 450kHz),
and demodulated in IC5. After that, the demodulated signal
is routed to the audio circuit to output audio signal.

PT4208 Service Manual
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Figure 3.3 IF System
Audio signal processing
The voice signal processing circuit of the receiver
consists of IC6 and its peripheral circuits. After being
amplified in IC6-C, voice signal from IC5 is sent to IC4
(CTCSS signaling filtering circuit) and IC6-D respectively.
The signal is then amplified, deemphasized and filtered by
other units of IC6 to remove HF and LF components
contained in the audio frequency, with only voice
components within 300~3000Hz left. The resulting signal is
then routed to Q9 for amplifying. The amplified signal is
adjusted in volume potentiometer and then is routed to the
audio power amplifier (IC8).
Figure 3.4 Audio Processing of Receiver
Squelch circuit
The demodulated signal from IC5 goes to the selective
noise amplifier consists of noise amplifier within IC5, C211,
R99, R100, C107 and R94 to remove the noise component.
The resulting signal is then amplified in Q7 and
demodulated in D17 and is routed to the MCU. MCU
identifies level of the noise and controls the squelch.
Audio power amplifier
The audio power amplifier circuit consists of IC8 and its
peripheral components.
The received audio signal, voice alert signal, alert tone
signal and warning tone signal are collected and pass
through the audio amplifier where it is amplified and output
to drive the speaker. The warning tone has no volume
limitation.
When AFCO is in high level, Q35 turns on, IC8 starts to
operate, and the speaker sounds. Speaker impedance: 16.
Q38: RX audio signal switch
Q51: Warning tone switch
Q25: Alert tone switch
CTCSS signal filtering
Demodulated audio signal from IC5 may contain CTCSS
(Continuous Tone Control Squelch System) or DCS (Digital
Code Squelch) signal. The spectrum components of
CTCSS/DCS are within 67-250Hz. The filtering circuit
consists of IC4 can remove signals outside the CTCSS/DCS
spectrum, which enables the MCU to decode CTCSS/DCS
more accurately.
3.3 Principle of Transceiver (TX)
TX power amplification
Figure 3.5 Principle of Power Amplification and Antenna
Switch
The modulated RF signal from VCO is amplified in Q2,
Q3 and Q12, and is routed to Q11 for power amplification.
Grid bias of Q11 and Q12 is controlled by the APC
circuit. Through changing the grid bias voltage, the Tx
output power can be controlled conveniently.
APC (Automatic Power Control)
Figure 3.6 APC Circuit
R167, R168 and R169 are used to test the power
amplification current. IC3A is the sampling amplifier for the
power amplification current. IC3B is the power comparator
amplifier.
If the Tx output power is too high, the power
amplification current and IC3A output will increase; IC3B
output voltage will decrease, so the bias voltage of Q11 and
Q12 will also decrease, which causes the Tx output power to
be lowered, and vice versa. Thus the output power of Tx can
keep stable under different working conditions.
MCU can set the power through changing the voltage

PT4208 Service Manual
5
input to IC3B.
Tx voice signal processing
TCXO
VCO
MCU
CTCSS/DCS
MIC
MIC Amp Pre-Emphasis
IC7A IC7B
IC7C,IC7D
Figure 3.7 Audio Circuit of Tx
The Tx voice signal processing circuit consists of IC7
and its peripheral components. After being amplified, limited
and filtered, the voice signal from MIC is routed to VCO for
modulation together with CTCSS/DCS signal.
The AGC circuit is consisting of D13, D308 and Q24.
When signal from MIC is too large, the AGC circuit will
lower the signal strength to make sure that no distortion
happens to the signal.
Q34 is the power switch of the voice processing circuit.
It is controlled by MCU. Power supply of IC7 will be turned
on when the radio is transmitting.
J2 is the jack for external MIC. When using external
MIC, the internal MIC will be turned off automatically. But
the internal PTT is still effective.
3.4 Principle of Frequency Synthesizer
1
Nr
1
N
Control Circuit Charge
UL
Detect
Pump
TCXO
DCS Mod
Freq Adj
to MCU VCCN
Data
CK
LE
to MCU
VCO
RX
TX
D3,D6
Q4
Q5
MOD in
Figure 3.8 Frequency Synthesizer
The radio adopts PLL type frequency synthesizer.
The frequency synthesizer consists of reference oscillator,
voltage control oscillator (VCO), programmable divider,
phase comparator, and low pass filter.
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, which consists
of programmable reference divider, programmable
swallowing divider, phase comparator, and charge pump.
The low pass filter consists of R244, C193, R202, R40,
C207, R141, C205, R2 and C204. The reference frequency is
provided by X4 (TCXO, 16.8MHz).
The reference frequency from TCXO (Temperature
Controlled Crystal Oscillator) is divided by the
programmable reference divider in IC1 to produce reference
frequency of 5kHz or 6.25kHz (determined by the preset
channel frequency and is controlled by MCU).
The oscillation frequency from VCO goes to IC1 where
it is divided by the programmable swallowing divider and is
then compared with the reference frequency to obtain the
error signal. The signal is then filtered by a low pass filter
and is routed to VCO to change the oscillation frequency of
the VCO, enabling the frequency to reach the set value. Then
the VCO is locked.
N=F
VCO/FR
N: Times of frequency division
F
VCO: Oscillation frequency of VCO
F
R: Reference frequency
Unlock detection: When PLL is unlocked, Pin 14 of IC
will output the low level signal to MCU. Then MCU
prohibits the Tx from transmitting and makes an alert tone.
Q6: Power filter, which provides more purified power for
PLL to reduce noise of the frequency synthesizer.
3.5 Voice Alert Circuit
The radio is provided with voice alert function, which is
especially useful at night or in dark environment.
IC15 is a voice memory chip, which is stored with voices
of channel indication etc. Once the channel selector knob is
switched, the speaker will announce the current channel
number. User can press the preprogrammed “Voice Alert”
key to repeat the current channel number.
If voice alert function is enabled, the speaker will
announce the current channel number once the “Voice Alert”
key is pressed under standby mode. You can switch the voice
type by pressing and holding the “Voice Alert” key while
rebooting the radio. Do it repeatedly to switch the voice type
in the order of “Chinese Male-English Male-Chinese
Female-English Female-No Alert”.
3.6 Power Supply
The radio uses 7.4V, 1700mAh Li polymer battery. The
Tx power amplification circuit (Q11 and Q12) and the Rx
audio power amplifier (IC8) directly adopt the battery for
power supply. Power of other circuits is supplied by 5V
regulated voltage.

PT4208 Service Manual
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IC12: 5V, low dropout, micro-power regulator, which
supplies 5V power with large current for the radio together
with Q10 and Q30.
Q29: 5T switch, which is controlled by MCU.
5T: Supplies power for front end of Tx.
Q31: 5R switch, which is controlled by MCU.
5R: Supplies power for RF amplifier, mixer, IF
processing unit, and audio signal processing unit etc. of Rx.
Q32: 5C switch, which is controlled by MCU.
5C: 5V power supply under SAVE control. 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 Principle of MCU Unit
MCU unit controls the operation of each unit of the radio
so that all functions can be realized.
Communicate with external PC.
Access the status data of the radio.
Control the PLL to generate Rx and Tx local oscillator
frequencies.
Obtain status parameters of current channel.
Control status of LED indicator.
Control power supply for each unit.
Check the actions of each functional key.
Generate CTCSS signal.
Generate DCS signal.
Generate power control signal.
Perform CTCSS decoding.
Perform DCS decoding.
Testandcontrol the squelch.
Control content of voice alert.
Memory (E2PROM, AT24C08):
The memory is stored with channel data, CTCSS/DCS
data, other data for function setting, and parameter adjusting
data.
CTCSS/DCS signal encoding and decoding:
The CTCSS/DCS signal (output from pin 12) generated
by MCU is filtered by R155, R156, C242 and C243. Then
the resulting signal is divided into two parts and sent to VCO
and TCXO respectively for modulation.
The CTCSS/DCS signal from the receiver is decoded by
MCU (pin 49). MCU checks if the CTCSS/DCS signal in the
receiving signal matches the preset value of the radio, and
determines whether to open the speaker or not.
Power adjustment:
Output from pin 42 of the MCU passes through
integrating filter (R161, C317, R206, and C318), and is
routed to the APC unit to control the output power of the
transmitter.
CTCSS signal
CTCSS (Continuous Tone Control Squelch System) is a
squelch control system which is modulated on carrier and is
guided by a continuous sub-audio signal. If CTCSS is set,
the communication between the transmitting and receiving
radios can be realized only when the two radios has set the
same CTCSS frequency. In doing this, disturbance from
other signals can be avoided.
PT4208 has 39 groups of standard CTCSS frequencies
for your selection. See table 3.1.
The CTCSS signal is generated by MCU, and is passed
through low pass filter consists of RC to remove high
frequency components (above 300Hz). Then the resulting
signal is routed to VCO for modulation.
Table 3.1 CTCSS Frequencies
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
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 signal

PT4208 Service Manual
7
DCS (Digital Code Squelch), which is used to control
squelch, is a series of continuous digital codes modulated on
carrier together with voice signal. If DCS is set, the speaker
can be opened only when the radio receives signal with the
same DCS to avoid disturbance of unwanted signals.
PT4208 has 83 standard codes (inverted and
non-inverted) for your selection. See table 3.2.
DCS signal is produced by MCU (in waveform of PWM).
It passes through the low pass filter consists of RC to
remove the high frequency components (above 300Hz).
Then the resulting signal is sent to VCO and TCXO for
modulation, with HF components of the DCS signal being
modulated by VCO, and the LF components of the DCS
signal being modulated by TCXO.
The DCS signal coming from the receiver is routed to
MCU for decoding. MCU checks if the DCS code in the
received signal matches the preset DCS of the radio, and
determines whether to open the speaker or not.
Table 3.2 DCS Codes
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 Semiconductor Data
Refer to table 3.3 for descriptions of each pin.
Table 3.3 Definition of CPU Pins
No. Port name Pin Name I/O Function
1 TOPKEY P33 I Top key detect
2 UPKEY P34 I Up key detect
3 MODE I Connect the 4.7K resistor with VCC,
programming test point
4 PTT P43 I [PTT] input
5 DNKEY P44 I Down key detect
6 RST I Reset input, programming test point
7 XOUT O Oscillator
8 VSS I GND
9 XIN I Oscillator（7.3MHz）
10 VCC I 5V CPU power input
11 SHIFT P54 O Clock beat shift. H：On
12 TO0 P53 O (PWM) BPF tuning output
13 TO1 P52 O (PWM) QT/DQT output
14 VDEVC2 P51 I Deviation switch 2 of VHF
15 VDEVC1 P50 I Deviation switch 1 of VHF
16 NC Connect the pull-down resistor with VSS
17 PABC P26 O Final power supply H：On
18 OSCSI P25 I VCO crystal select and connect the
pull-down resistor with VSS. H: 13, L:
16.8
19 WNTC P24 O Wideband/Narrowband control.
H: Wideband L: Narrowband
20 ENC0 P23 I Encoder input
21 ENC2 P22 I Encoder input
22 ENC3 P21 I Encoder input
23 ENC1 P20 I Encoder input
24 PS P17 O PLL power-saving control. H: Normal L:
Power Saving
25 NC Connect the pull-down resistor with VSS
26 NC Connect the pull-down resistor with VSS
27 NC P86 Connect the pull-down resistor with VSS
28 SDA P85 I/O E2PROM data line
29 SCL P84 O E2PROM clock line
30 UL P83 I
I (TRFI)
PLL unlock detect pin
H: Locked L: Unlocked
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: Locked
35 5MC P45 O Power control except CPU and E2PROM
L：On
36 INT P66 I Power detect input
37 TXD P67 O RS-232C output, programming test point
38 RXD P65 I RS-232C input, programming test point
39 AFCO P64 O AF amplification power
H: On
40 RX P63 O TX/RX VCO select H: Receiving
41 GLED P31 O Green LED control H: On
42 APC P30 O (PWM) TX: Automatic power control output
43 RLED P36 O Red LED control H: On
44 SAVE P32 O
O
Battery saving control. H：Supply power,
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
50 RSSI I (A/D7) Signal strength detect
51 BUSY P01 I (A/D6) Busy signal input
52 MANDO
WN
P02 I (A/D5) Man-down switch detect
53 BATT P03 I (A/D4) Battery voltage detect
54 NC Connect the pull-down resistor with VSS
55 W588C P62 O Voice alert switch. H: Channel No.
reporting
56 AC P61 O Alarm switch control. H: Controlled by
Volume Switch
The power level must be low in case of
emergency alarm
57 BUSY_V P05 I Voice alert circuit busy detect
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 VCC
62 AVCC I Connect with VCC
63 DATA_V P37 O Voice alert data

PT4208 Service Manual
8
64 SCLK_V P35 O Voice alert clock
Table 3.4 Function Description of Semiconductor
Components
Position
Mark Model Function Description
IC1 MB15E03 Frequency synthesizer
IC4 NJM2904 APC, voltage comparison, driving
IC5 TA31136 Rx second local oscillator, second IF
amplification, limitation, demodulation, and
noise amplification
IC6 NJM2902 Amplification and filtering of demodulation
signal of receiver.
IC7 NJM2902 MIC amplification, limitation and filtering
IC8 TDA8541 Audio frequency power amplification of
receiver
IC9 AT24C08 E2PROM, memorizes channel frequency data,
function setting parameters and adjusting
status parameters
IC10 R5F212A8 MCU
IC11 PST9140NR MCU reset circuit
IC12 HT7150-1 LDO, low-power voltage regulator
IC15 W588A080 Voice storage IC
Q2 2SC5108 First amplification of transmitter
Q3 2SC3356 Second amplification of transmitter
Q4 2SC5108 VCO buffer amplifier
Q5 2SC5108 VCO buffer amplifier
Q6 2SC4617 VCO power filter
Q7 2SC4738 Noise amplifier
Q9 2SC4617 Audio frequency signal amplification of
receiver
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 mixer
Q20 3SK318 Receiver high power amplifier
Q21 KTC4082 1st IF Amplifier
Q22 DTC144EE Red LED Driving
Q23 DTC144EE Green LED Driving
Q24 2SK1824 Voice alert 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. Disconnect on
Emergency
Q36 2SK1824 Receiver audio output switch
Table 3.5 Function Description of Diodes
Position
Mark Model Function Description
D1 MA77 Transmitter antenna switch diode
D2 MA77 Transmitter antenna switch diode
D3 HSC277 VCO output switch
D4 HSC277 Antenna toggle switch
D5 HSC277 Antenna toggle 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 Green
LED
Receiving indicator
D25 MA2S111 APC single diode
D28 Red LED Transmitting indicator
D29 Green
LED
Receiving indicator
Table 3.6 Features of Crystal Filter XF1, XF2
Item Rated Value
Nominal center frequency 49.95MHz
Passband width ±7.5kHz or higher
40dB stop bandwidth ±20.0kHz or lower
Pulse 1.0dB or lower
Insertion loss 3.0dB or lower
Guarantee attenuation 80dB or higher
Terminal impedance ---
Table 3.7 Features of CF1 LTVPC450EB
Table 3.8 Schematic Diagram for Packaging of
Semiconductor Devices
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
Item Rated Value
Nominal center frequency 450kHz
6dB bandwidth ±6kHz or higher
50dB bandwidth ±12.5kHz or lower
Pulse 2.0dB or lower
Insertion loss 6.0dB or lower
Guarantee attenuation 35.0db or higher
Terminal impedance 2.0k

PT4208 Service Manual
9
Chapter 4 Mode Introduction
Mode Introduction
Mode Function How to enter
User Mode For normal use Power ON
Data
Programming
Mode
Used to read and write
frequency data and
other features to and
from the radio
Received commands
from PC. See below for
further information.
PC Test Mode Tune the radio
parameters by PC
Received commands
from PC. See below for
further information.
PC
Mode
Firmware
Programming
Mode
Upgrade the radio
when new features are
released
Press and hold the top
key for over 2 seconds
while turning the radio
power ON, and received
commands from PC
Wired Clone Mode
Used to transfer
programming data
from one radio to
another
Press and hold side key 2
for over 2 seconds while
turning the radio power
ON
* User Mode
You can enter User Mode (conventional communication
mode) by turning the radio power ON. Under this mode,
users 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, the radio’s
operating frequency, channels, CTCSS/DCS, scan, and other
functional parameters should be reprogrammed. Therefore,
Kirisun 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
PC are as follows:
A. Install KSP4208 on the computer.
B. Connect the radio to the serial port of the PC with
the special programming cable. Refer to the figure
below.
Figure4.1
C. Turn the computer power ON.
D. Turn the radio power ON.
E. Run the KSP4208 programming software by
double clicking on its executive program.
F. Click “Program” in the main menu of KSP4208,
and click “Read from radio” in the pull-down menu
to read parameters of the radio to the computer;
click “Write to radio” in the pull-down menu to
write parameters in the computer to the radio.
G. The following parameters can be set by using
KSP4208 according to requirements of the user:
Radio Information:
Radio Model (model/frequency range), Serial Number,
Embedded Information, MCU Version, Hardware Version,
etc.
Radio Configuration:
(1) Key Assignment: Side Key 1 (Up Key), Side Key 2
(Down Key), and Top Key can be set as long/short key and
the hold time can be defined.
(2) Miscellaneous
1. Wired Clone Mode
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) Scan
Scan Function option, Priority Channel, Revert Channel,
Tx Dwell Time, Dropout Delay Time, Lookback Time.
(4) Emergency settings
Channel Parameters
(1) Rx Frequency and Tx Frequency (Step:
2.5KHz/5KHz/6.25KHz)
(2) Rx Signaling and Tx Signaling
a) None
b) CTCSS (60~260Hz @ 0.1Hz step)
c) DCS (-777~777@octal number)
(3) Busy Channel Lockout (BCL)
(4) Beat Shift
(5) Channel Spacing: 25KHz/12.5KHz (Wide/Narrow)
(6) Scan Add/Delete
(7) Tx Power (High/Low)
(8) Clear Tail Tone
(9) CALL1 and CALL2 encode
(10) PTT ID Keyup Telegram, PTT ID Dekey Telegram
DTMF Setting
DTMF Encoder Template
Computer
(RS232 serial port) Programming cable
Radio
(Earphone/Program
ming interface)

PT4208 Service Manual
10
DTMF Encoder Sequences (1~12)
Please refer to the “Help” document of KSP4208 for
details.
Note:
1. Please firstly read data of the radio and back up the data
before editing the parameters on KSP4208.
2. If the radio cannot function normally after being written in
with the edited data, please rewrite the backup data into the
radio.
3. “Model Information” is important for the radio; users
should not modify it.
* PC Test Mode
Connect the radio to the serial port of the computer with
the special programming cable. Refer to figure 4.1.
Warning: Before entering the PC Test Mode, please firstly
connect a 50HF load to the antenna connector of the radio
or connect the radio to a general test set.
With the KSP4208 programming software, you can enter
the Tuning Mode under PC Test Mode to tune 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) Five frequency points for SQL9 On (Wideband)
(5) Five frequency points for SQL9 Off (Wideband)
(6) Five frequency points for SQL9 On (Narrowband)
(7) Five frequency points for SQL9 Off (Narrowband)
(8) Five frequency points for SQL1 On (Wideband)
(9) Five frequency points for SQL1 Off (Wideband)
(10) Five frequency points for SQL1 On (Narrowband)
(11) Five frequency points for SQL1 Off (Narrowband)
(12) Five frequency points for QT (67.0Hz) Deviation
(Wideband)
(13) Center frequency point for QT (67.0Hz) Deviation
(Narrowband)
(14) Five frequency points for QT (151.4Hz) Deviation
(Wideband)
(15) Center frequency point for QT (151.4Hz) Deviation
(Narrowband)
(16) Five frequency points for QT (254.1Hz) Deviation
(Wideband)
(17) Center frequency point for QT (254.1Hz) Deviation
(Narrowband)
(18) Five frequency points for DQT Deviation (Wideband)
(19) Center frequency point for DQT Deviation
(Narrowband)
(20) Five frequency points for Rx Sensitivity
(21) Center frequency of DTMF Deviation (Wideband and
Narrowband)
(22) Tx Low Voltage
(23) Rx Low Voltage
* Firmware Programming Mode
The radio is in possession with an internal Flash ROM
which can be upgraded when new features are released.
Procedure:
1. Press and hold the Top Key for over 2 seconds while
turning the radio power ON. The LED will light orange
and the radio enters the Firmware Programming Mode.
2. Run the firmware programming software KMU on PC.
3. Connect the radio to the computer by the programming
cable.
4. Select a COM port and load the firmware upgrading file.
Then click on “E.P” to start downloading.
5. If the communication ends successfully, turn the radio
power OFF to exit.
6. If you want to continue programming other radios,
repeat steps 1 to 5.
* Wired Clone Mode
If the wired clone function is enabled, the radio can enter
the Wired Clone Mode. After entering this mode, the radio
will not exit automatically. The user needs to reboot the
radio if he wants the radio to return to the User Mode.
The operation is as follows:
1. Press and hold Side Key 2 for over 2 seconds while
turning the radio power ON to enter the Wired Clone
Mode. The radio will enter User Mode if wired clone
function is disabled.
2. Connect the slave radio to the master radio by the
cloning cable (KCL-01) and turn on the power of the
slave radio.
3. Press Side Key 1 on the master radio to start cloning.
Then the red LED on the master will light. The data of
the master is sent to the slave. While the slave is
receiving the data, the LED lights green. When cloning
of data is completed, the red LED on the master will go
out, and the slave radio will reboot automatically.

PT4208 Service Manual
11
4. The other slaves can be continuously cloned. Carry out
the operation in step 3.
Note: The user can enable or disable the wired clone
function through PC programming software. Once the wired
clone function is disabled, the radio cannot enter the Wired
Clone Mode.
Chapter 5Assembly and Disassembly for
Maintenance
The radio is a kind of sophisticated communication
equipment with precise structure and small size. You should
assemble and disassemble it carefully during the
maintenance. The instructions for the assembly and
disassembly are as follows.
5.1 Install/Remove the battery
1) Install the battery
Insert the two protrusions at the lower end of the battery
into the holes at the lower end of the shell of the radio.
Press down the upper part of the battery until the latch on
the radio completely bounces out and locked.
2) Remove the battery
Press the back of the battery slightly, and push the latch
upward. Then remove the battery from the radio.
Note:
* Never short the terminals of the battery.
* Do not throw the battery into fire.
* Do not remove the housing of the battery by yourself.
5.2 Install/Remove the belt clip
Slide the guide rails on the belt clip along the guide slots
on the rear of the battery with proper strength until the belt
clip is hooked. When removing the belt clip, lift the sheet
metal on the top of the belt clip with your finger nail or a
tool while pushing the belt clip upward.
5.3 Remove the front cabinet from the chassis
1) Pull out the knobs and screw off the antenna;
2) Remove the two nuts of the knobs and one nut of the
antenna with a special tool;
3) Screw off the screw on the earphone jack cover with a
cross screwdriver, and then remove the rubber cover;
4) Remove the two rubber plugs on the screws of the coping;
screw off the screws by a hexagonal screwdriver, and then
take off the coping;
5) Remove the two fixing screws at the lower part of the Al
chassis by a hexagonal screwdriver;
6) Insert a flat-blade screwdriver into the slot at the bottom
of the Al chassis, and prize up it. Then pull the Al chassis
backward to remove it from the front cabinet. Please be
careful not to break the cable of the speaker.
Refer to Figure 5.5.

PT4208 Service Manual
12
Figure5.5
5.4 Remove the main board from the Al chassis
1) Remove the screws from the PCB board by a cross
screwdriver;
2) Remove the solder of the antenna terminal with a
soldering iron. Then take off the main board.
Refer to Figure 5.6
Figure5.6
After the aforesaid disassembly, you can repair and
adjust the radio according to its actual malfunction.
1
2
3
4
5
6
8
9
10
17 18 19 20 21 22
11 12 13
14
15
16
23 24 25
27
28 29 30 31
7
26 32 33 34
35
37
36
Figure 5.7 Exploded View
No. Part No. Description PCS
1 710-420470-R06 Antenna 1
2 201-004208-R07 Channel Selector Knob 1
3 201-004208-R06 Volume Knob 1
4 203-003208-R09 Circlip 2
5 203-007200-R07 Nut for Antenna Socket 1
6 203-000558-R02 Nut for Knob 2
7 201-004208-R09 Light Guide 1
8 201-004208-R01 Front Cabinet 1
9 201-004208-R08 Earphone Jack Cover 1
10 301-25080J-R01 Screw M2.5*8.0 1
11 202-004208-R01 Main Waterproof 1
12 201-004208-R02 Coping 1
13 301-25050J-R01 Screw M2.5*5.0 2
14 202-007200-R07 Rubber Plug 2
15 203-000558-R05 Spring for Battery Latch 1
16 201-004208-R03 Battery Latch 1
17 204-003208-R02 Dust-proof Net for Speaker 1
18 202-004208-R02 Rubber PTT Key 1
19 201-004208-R04 PTT Key 1
20 121-100000-R20 Speaker 1
21 301-20040G-R01 Screw M2.0*4.0 12
22 602-04208X-HXX Main Board 1
23 201-004208-R05 POGO Pin Socket 1
24 203-004208-R02 Earphone Plate 1
25 203-000558-R07 Antenna Socket 1
26 204-004208-R02 Dust-proof Net for MIC 1
27 202-007200-R06 POGO Pin Waterproof 1
28 203-004208-R01 Al Chassis 1
29 301-20080G-R02 Screw M2.0*8.0 2
30 204-007200-R03 Sponge for POGO Pin 1
31 706-0KB70B-R01 Battery 1
32 202-004208-R03 MIC Rubber Waterproof 1
33 120-100000-007 Plastic-packaged Wire 1
34 120-100000-008 Plastic-packaged Wire 1
35 202-003208-R07 Heat Exchange Silicone
Rubber Washer
1
36 204-006500-R02 MIC Socket Guardian 1
37 204-0KB36L-R03 Sponge Cushion 1
Chapter 6 Adjustment
Before test/adjustment, make sure all equipment has
been well connected to the ground!
Before test/adjustment, make sure the antenna output
terminal has been correctly connected to corresponding
equipment or load!
The transmitter output terminal must be terminated with

PT4208 Service Manual
13
an RF power attenuator and connected to a standard signal
generator (SSG)/frequency counter/deviation
meter/spectrum analyzer！
Make sure no transmission operation is being conducted
while measuring the receiver!
During the adjustment/test/maintenance, make sure
reliable anti-static measures are taken for human body and
equipment.
6.1 Equipment and Software Required for Test and
Adjustment
Equipment and software listed in Table 6.1 are required
for test and adjustment of PT4208.
Table 6.1 Equipment and Software Required for Test and
Adjustment
No. Name Major Specifications
1 Computer P2 or above, IBM compatible PC, WINDOWS
98/ME/2000/XP Operating System
2 Programming
software KSP4208
3 Programming
cable
4 Clone cable KCL01
5 DC regulated
power supply
Output voltage:7.5V
Output current:5A
6 RF power meter
Measurement range: 0.5-10W
Frequency range: 100MHz-500MHz
Impedance: 50
SWR1.2
7 Frequency
counter
Frequency range: 0-1600MHz
Frequency accuracy: better than ±1×10-6
Sensitivity: better than 100mV
8 Deviation meter Frequency range: DC600MHz
Measurement range: 0-±5kHz
9 DMM Input impedance: above 10M/V DC, capable of
measuring voltage, current and resistance.
10 Audio signal
generator
Frequency range:2-3000Hz
Output level: 1-500mV
11 RF power
attenuator
Attenuation: 40dB or 50dB
Supporting power : higher than10W
12 Standard signal
generator
Frequency range:10MHz-1000MHz
Output level: 0.1uV-32mV (-127dBm~-17dBm)
13 Oscilloscope Frequency range: DC~20MHz
Test range: 10mV-20V
14 Audio frequency
voltmeter Test range: 10mV-10V
Recommendation: Item 6, 7, 8, 10, 11, and 12 listed in
the table can be replaced by HP8920 general test set.
Figure 6.1 External Speaker/MIC Plug
6.2 Adjustment Items
After changing components during the maintenance, it is
necessary to test the radio and adjust its technical parameters.
The following part is going to introduce the adjustment
items.
Some parameters can be adjusted by use of KSP4208
programming software (in the Tuning Mode). The adjustable
parameters are as follows:
1) 6250Hz stability/2500Hz stability
2) Tx high power/low power
3) BATT Tx low voltage /Rx low voltage
4) SQL9/SQL1 On/Off
5)
QT DEV
6) DCS DEV
7) DTMF DEV
8) Rx sensitivity
Steps for adjustment:
a. Enter PC Test Mode. Refer to Chapter 4.
b. Click “Edit” in the main menu of KSP4208
programming software, and then click “Entry Tuning” in the
pull-down menu to enter the Tuning Mode.
c. Then the “Tuning Item List” screen will pop up.
Double click the item you want to adjust, and then you can
adjust the parameters.
d. Exit the PC Test Mode after adjustment.
6.3 Adjustment
6.3.1 VCO
Disable the “Battery Save” function, and set the Rx
frequency to the low frequency point (see Table 6.2). Under
the receiving status, measure the voltage of PD by DMM.
Then adjust the PD voltage to be 0.7V±0.3V by tuning the
trimming capacitor C180.
Set the Tx frequency to the high frequency point (see

PT4208 Service Manual
14
Table 6.2), and press the PTT key. Then measure the voltage
of PD by DMM. The resulting voltage should be lower than
4.5V.
Table 6.2 High/Center/Low Frequency Point for PT4208
Low Freq Point Center Freq Point High Freq Point
PT4208(1) 136.125 MHz 145.125 MHz 173.975 MHz
PT4208(2) 400.125MHz 425.125MHz 449.975MHz
PT4208(3) 420.125MHz 445.125MHz 469.975MHz
6.3.2 PLL frequency
In the Tuning Mode, double click the “6250Hz
stability/2500Hz stability” item to enter. Adjust the
parameter within the adjusting range of 0-255 to make the
Tx frequency be the rated value (with error within ±200Hz).
6.3.3 Tx power
In the Tuning Mode, double click the Tx “High power”
item to enter. Adjust the five frequency points of “Lowest”,
“Low”, “Mid”, “High” and “Highest” within the adjusting
range of 0-255 to make the Tx power be higher than 4W.
Meanwhile, observe the operating current, and make sure
that the current is no larger than 1.7A.
In the Tuning Mode, double click the Tx “Low power”
item to enter. Adjust the five frequency points of “Lowest”,
“Low”, “Mid”, “High” and “Highest” within the adjusting
range of 0-255 to make the Tx power be higher than 1W.
See Table 6.5 for detailed parameters.
6.3.4 Tx low voltage/Rx low voltage for BATT
Firstly, adjust the power voltage to be 6.8V. Double click
the “Tx low voltage/Rx low voltage” in the Tuning Mode.
Click “Begin” to let the software test automatically. When
the value changes no more or only changes a little, click
SAVE to exit.
6.3.5 Max. deviation
Input audio signal (100mV, 1000Hz) to the MIC jack of
the radio. Adjust the potentiometer VR2 to make the Max.
deviation be ±4.5kHz.
6.3.6 DCS Tx signal waveform and deviation
In the Tuning Mode, double click the “DCS DEV” item
to enter. Adjust the potentiometer VR1 and observe the
demodulation signal (the waveform should be smooth and
similar to square wave). Click wideband, and adjust the five
frequency points of “Lowest”, “Low”, “Mid”, “High”, and
“Highest” to make the deviation be 0.8kHz. Then click
narrowband, and adjust the five frequency points to make the
deviation be 0.4kHz.
6.3.7 CTCSS deviation
In the Tuning Mode, double click the “QT(67.0) DEV”
item to enter. Click wideband, and adjust the five frequency
points of “Lowest”, “Low”, “Mid”, “High”, and “Highest” to
make the deviation be 0.75kHz. Then click narrowband, and
adjust the value to make the deviation be 0.35kHz.
In the Tuning Mode, double click the “QT(151.4) DEV”
item to enter. The tuning method is the same as that of
“QT(67.0) DEV”.
In the Tuning Mode, double click the “QT(254.1) DEV”
item to enter. The tuning method is the same as that of
“QT(67.0) DEV”.
6.3.8 Rx sensitivity
In the Tuning Mode, double click the “Sensitivity” item
to enter. Adjust the five frequency points of “Lowest”,
“Low”, “Mid”, “High”, and “Highest” within the adjusting
range of 0-255 to make the sensitivity be the highest.
See Table 6.4 for detailed parameters.
6.3.9 Rx squelch
In the Tuning Mode, double click the “SQL9 On” item to
enter. Click wideband and use the following method to
adjust the five frequency points of “Lowest”, “Low”, “Mid”,
“High”, and “Highest” respectively. Firstly, click one of the
frequency points, and adjust the RF signal frequency of the
test equipment to be the same with the receiving frequency
of that frequency point, and adjust the signal level to be
-116dBm. Then adjust the frequency of the modulation
signal to be 1kHz and the deviation to be 3kHz. Click
“Begin”, the programming software will adjust the value
automatically. When the value keeps stable, click “OK”, the
adjustment of that frequency point is completed. Then click
the next frequency point to do the adjustment. After all of the
five frequency points are adjusted, use the same method to
adjust the five frequency points of the narrowband. The only
difference is that the frequency of the modulation signal
should be 1kHz, and the deviation should be 1.5kHz.
In the Tuning Mode, double click the “SQL9 Off” item
to enter. Click wideband and use the following method to
adjust the five frequency points of “Lowest”, “Low”, “Mid”,

PT4208 Service Manual
15
“High”, and “Highest” respectively. Firstly, click one of the
frequency points, and adjust the RF signal frequency of the
test equipment to be the same with the receiving frequency
of that frequency point, and adjust the signal level to be
-118dBm. Then adjust the frequency of the modulation
signal to be 1kHz and the deviation to be 3kHz. Click
“Begin”, the programming software will adjust the value
automatically. When the value keeps stable, click “OK”, the
adjustment of that frequency point is completed. Then click
the next frequency point to do the adjustment. After all of the
five frequency points are adjusted, use the same method to
adjust the five frequency points of the narrowband. The only
difference is that the frequency of the modulation signal
should be 1kHz, and the deviation should be 1.5kHz.
In the Tuning Mode, double click the “SQL1 On” and
“SQL1 Off” item to enter respectively. Use the same method
stated above to do the adjustment. The only difference is that
the RF signal level for “SQL1 On” should be 123dBm, and
the RF signal level for “SQL1 Off” should be 125dBm.
6.4 Adjustment Description
See Table 6.3, 6.4, and 6.5.
Table 6.3 VCO
Item Test Condition Test
Equipment
Measurement
Terminal
Adjustment
Parts Requirement Remark
Setting BATT terminal
voltage: 7.5V DMM PD
CH: Rx low freq
point C180 0.7V±0.3V Adjustment
VCO lock
voltage CH: Tx high freq
point
Lower than
4.5V Observation
Table 6.4 Receiver Section
Item Test Condition Test
Equipment
Measure
ment
Terminal
Adjustment
Parts Requirement Remark
Audio level
Test freq: Mid freq
point
Antenna input:
RF OUT: -53dBm
(501V)
MOD: 1kHz
DEV: ±3.0kHz
Audio load: 16
(Turn the
volume knob
clockwise to
the end) Audio
power ＞
0.3W
Internal speaker
power ＞1.2W
Sensitivity
CH: Mid freq point
CH: Low freq point
CH: High freq point
RF OUT: -119dBm
(0.25V)
MOD: 1kHz
DEV: ±3.0kHz
PC Tuning
Mode
SINAD: 12dB
or higher
CH: Rx center freq
point
Normal
squelch on
after
adjustment
Level 9
RF OUT: -116dBm
SQL On
sensitivity
Level 1
RF OUT: -123dBm
RF signal
generator
Oscilloscope
Audio
frequency
voltmeter
Distortion
meter
/General test
set
Speaker
connector
PC Tuning
Mode Normal
squelch on
after
adjustment
Table 6.5 Transmitter Section
Item Test condition Test equipment Measuring
terminal
Adjustment
parts Requirement Remark
Tx
frequency Frequency counter / General test set
PC Tuning
Mode Within ±200Hz
DCS
waveform
(balance)
Oscilloscope /
General test set
Antenna
VR1
Smooth and
similar to square
wave

PT4208 Service Manual
16
Power Power: 7.5V
Power meter/
General test set
Ammeter
PC Tuning
Mode Adjust to 4W Within
±0.2W
Max
modulation
deviation
CH：Tx center freq point
AG：1kHz/220mV VR2 Adjust to ±4.5kHz ±200Hz
Modulation
sensitivity
CH：Tx center freq point
AG：1kHz/22mV
Deviation meter/
General test set
Deviation
checked should
be
2.2kHz~3.6kHz
CTCSS
DEV CTCSS：67Hz Deviation meter/ General test set
PC Tuning
Mode
Adjust to
±0.75kHz ±50Hz
DCS DEV DCS：023N Deviation meter/
General test set
PC Tuning
Mode
Adjust to
±0.75kHz ±50Hz
Low
battery Battery terminal: 6.8V PC Tuning Mode
Indicator flashes
after adjustment
Chapter 7 Specifications
Technical Parameters PT4208
7.1 General Specifications
(136 ~ 174) MHz (400 ~ 450) MHz
Frequency
(350 ~ 390) MHz (420 ~ 470) MHz
Number of Channels 16
Channel Spacing W:25 kHz /N:12.5kHz
Operating Temperature -25℃~ +55℃
Antenna Impedance 50
Frequency Stability ±2.5ppm
Battery (Standard
Configuration)
Lithium Polymer Battery: 1700mAH 7.4V
Dimension (W×H×D) 54mm × 119mm × 34mm
Weight 157g (Radio only);
255g: with antenna and 1700mAh Lithium
Polymer Battery
330g: with antenna and 1350mAh Ni-MH
Battery
7.2 Receiver
Sensitivity (12dB
SINAD)
0.25V(W) / 0.28V(N)
Adjacent Channel
Selectivity
W: 70dB / N:60dB
Intermodulation
Interference
65dB
Audio Output Power 1W (16)
Audio Distortion 5%
7.3 Transmitter
Transmitting Power 4W(UHF) / 5W(VHF)
Modulation Mode W:16KF3E / N:11KF3E
Clutter and Harmonic -36 dBm
Residual FM
（300~3000Hz）
W:-45 dB / N:-40dB
Audio Distortion
（300~3000Hz）
5%
Adjacent Channel
Power
W:70dB / N:60dB
Max. Deviation W:＜±5kHz / N:＜±2.5kHz
Chapter 8 Troubleshooting
No. Problem Causes and Solutions
1 Power on
Failure
A. Unreliable connection between the battery and the
radio, please reinstall the battery.
B. The fuse of the power supply is burnt out. Please
change it.
C. Power switch in failure, please change it.
D. The battery is out of power. Please charge it or
change a new one.
E. The CPU is broken, please change the IC.
2 PLL
unlocked
(Beeping)
A. Channel frequency goes beyond the limit, please
reset the channel data.
B. The PLL crystal oscillator X4 is broken. Please change
it.
C. The oscillator transistor is broken. Please change
it.
D. The PLL IC1 is broken. Please change it.
3 No talkback 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 receiving
signal
A. The antenna is in poor contact. Please fasten the
antenna until secure.
B. The high-frequency amplifying tube Q20 is
broken. Please change it.
C. The squelch level is too high and the squelch cannot be
opened. Please reset the squelch level.
D. The mixing tube Q19 is broken. Please change it.

PT4208 Service Manual
17
E. The FM processing chip IC5 is broken. Please
change it.
5 The
transmitting red
light is on, but
no voice is
heard by the
recipient.
A. Power module Q11 is broken, so there is no power
output, please change the module.
B. The microphone is broken, please change it.
6 The receiving
green light is
on, but no voice
is heard.
A. The speaker is broken. Please change it.
B. The audio power amplifier IC8 is broken. Please
change it.
Chapter 9 KBC-70C Charger
9.1 General
Function: Intelligent rapid charging
Applicable battery: KB-70B (1700mAH, 7.4V Li-ion battery)
/ KB-70A (1350mAH, 7.2V Ni-MH Battery)
Identification for battery type: External
Input power: DC12V, 500mA, ripple < 500mV
9.2 Operating Environment
Temperature: -5℃± 2℃~ +55℃± 2℃
Humidity: 95%@40℃
9.3 Safety Requirement
Comply with CCC, CE, UL and other safety
requirements.
9.4 Specifications
* Idling input current: 15mA
* Charging terminal maximum idling voltage: 96% ~ 97% of
the input voltage
* Rapid charging current: 410 ± 25mA
* Max. charging time of Ni-MH battery: 285 minutes ± 15
minutes
* Max. charging time of Li-ion battery: 510 minutes ± 30
minutes
* Max. charging voltage: 9.6V ± 0.2V
* Highest battery temperature: +50℃± 2℃
* Specified voltage for charged battery:
Ni-MH battery: Pre-charge when the voltage is lower than
5.5 ± 0.1V. When the battery voltage reaches 6.5 ± 0.1V, the
charging turns to rapid charging. Or pre-charge when the
voltage is lower than 8.3V ± 0.1V. When the battery voltage
reaches 9.6V ± 0.2V, the battery will be deemed as full and
the charging will stop.
Li-ion battery: Pre-charge when the voltage is lower than
6.5 ± 0.1V. When the voltage reaches 6.5 ± 0.1V, the
charging turns to rapid charging.
* During the charging process, battery voltage, battery
temperature rise, - V△, charging time, max. battery
temperature will be checked.
* Min. battery voltage:
Ni-MH battery: 5.5V ± 0.1V
Li-ion battery: 6.5V ± 0.1V
* Pre-charge current for battery:
Ni-MH battery: 180mA ± 10mA
Li-ion battery: 90mA ± 10mA
* Pre-charge time: 15 ~ 20 minutes
* Check the battery voltage during the pre-charging process,
when the voltage reaches the threshold of the battery, the
charging will turn to rapid charging.
* Conditions for stopping charging:
Normal conditions: The battery is fully charged. Ni-MH
battery: - V△= 30mV ~ 60mV
Abnormal conditions:
(1) The battery temperature is higher than the limit.
(2) The battery voltage is higher than the limit.
(3) The charging time exceeds the limit.
(4) In the pre-charging process, the battery voltage fails to
reach the min. voltage allowed for normal battery.
* Status of the charger after the charging is finished: Ni-MH
battery enters trickle charging status (current: 30mA ±
10mA).
* Charging efficiency:
After being charged under normal temperature, the
battery capacity should not be lower than 90% of its actual
capacity.
After being charged under high temperature, the battery
capacity should not be lower than 70% of its actual capacity.
After being charged under low temperature, the battery
capacity should not be lower than 80% of its actual capacity.
* Other functions:
1. Charging indication
2. Abnormal charging indication
3. Pre-charging function for over-discharged battery
4. Trickle charging function for Ni-MH battery

PT4208 Service Manual
18
5. Output short circuit protection function (the current for
short circuit is lower than 10mA)
9.5 LED Status Table
Charger Status LED Status
Charging
Indicator
(red)
Power
Indicator
(green)
Indicator for
abnormal battery
temperature
(yellow)
Standby/Unconnect
ed with Battery / Light /
Pre-charge Flash / /
Rapid charge Light / /
Charging completed / Light (Ni-MH) /
Charger output
short circuit / / /
Abnormal
charging status / / Light
9.6 Descriptions
Face the charger, from left to right:
Red LED: Charging indication
Green LED: Power indication or charging completion
indication
Yellow LED: Abnormal charging indication
BAT-: Charging output cathode
DECT: Battery type detection
Suspended: Ni-MH battery
Grounded: Li-ion battery
TEMP: Battery temperature detection. In the battery pack,
there is a thermosensitive resistor (model: NTC103J)
between the output terminal and the ground to detect the
battery temperature.
BAT+: Charging output anode
Appendix 1 Abbreviations
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
E2PROM: Electrical Erasable Programmable Read Only
Memory
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
RX: Receiver
SPK: Speaker
TCXO: Temperature Controlled Crystal Oscillators
TX: Transmitter
UL: Un-lock
VCO: Voltage Control Oscillator
Appendix 2 Electronic Parts List
Electronic Parts List (420-470MHz)
No. Part No. Description Unit Qty. Position Mark
1 101-04208U-R04 PT4208PCB, FR-4, 1.2mm, PT4208U-081224, ROHS pcs 1
2 102-0R8C2A-R01 MCU / R8C/2A, R5F212A8SNFP, PLQP-64, ROHS pcs 1 IC10
3 102-9140NR-R01 Reset IC / PST9140NR, ROHS pcs 1 IC11
4 102-A31136-R01 IF(MF) modulation IC / TA31136FN, SSOP, ROHS pcs 1 IC5
5 102-AT2408-R01 Memory IC / AT24C08BN-SH, ROHS pcs 1 IC9
6 102-B15E03-R01 PLL IC / MB15E03SL, PLL,16-PIN, SSOP, ROHS pcs 1 IC1
7 102-DA8541-R01 AUDIO, AMP / TDA8541, SO8, ROHS pcs 1 IC8
8 102-HT7130-R01 Voltage regulator IC / HT7130-1, SOT-89, ROHS pcs 1 IC14
9 102-HT7150-R01 Voltage regulator IC / HT7150-1, ROHS pcs 1 IC12
10 102-M2902V-R01 Operational amplifier/ NJM2902V, OP-AMP, ROHS pcs 3 IC4, IC6, IC7

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19
11 102-M2904V-R01 Operational amplifier/ NJM2904V, OP-AMP, ROHS pcs 1 IC3
12 103-00MA77-R01 Chip switch diode / MA77, 0805, ROHS pcs 1 D1
13 103-0MA360-R01 Chip variable capacitor diode/ 0805,
MA360(PANASONIC), ROHS
pcs 1 D12
14 103-0MA742-R01 Chip switch diode / MA742(PANASONIC), ROHS pcs 1 D17
15 103-1SR154-R01 Chip diode, / 1SR154-400(ROHM), ROHS pcs 1 D33
16 103-1SS372-R01 Chip switch diode / 1SS372(TOSHIBA), ROHS pcs 1 D13
17 103-1SV325-R01 Chip variable capacitor diode / 1SV325, ROHS pcs 4 D8, D9, D10, D11
18 103-A2S111-R01 Chip switch diode / 0603,
MA2S111(PANASONIC), ROHS
pcs 3 D15, D16, D25
19 103-DAN222-R01 Chip switch diode / DAN222, (ROHM), ROHS pcs 1 D308
20 103-HSC277-R01 Chip diode / Waveband switch, HSC277(HITACHI),
ROHS
pcs 5 D3, D4, D5, D6, D7
21 103-HVC350-R01 Chip variable capacitor diode / 0603,
HVC350B(HITACHI), ROHS
pcs 6 D21, D22, D23, D24, D26, D30
22 103-HZU5AL-R01 Chip Voltage regulator diode / HZU5ALL(HITACHI),
ROHS
pcs 1 D14
23 103-L190YG-R01 Chip LED / 0603, green, H19-213SYGC,ROHS pcs 2 D20, D29
24 103-MHC190-R02 Chip LED / 0603,red,19-21SURC/S530-A2/TR8,
ROHS
pcs 1 D28
25 104-A144EE-R01 Chip triode / DTA144EE(ROHM),ROHS pcs 3 Q17, Q34, Q40
26 104-C144EE-R01 Chip triode / DTC144EE(ROHM),ROHS pcs 11 Q8, Q22, Q23, Q26, Q27, Q35, Q39, Q42, Q44, Q52, Q101
27 104-C144EU-R01 Chip triode / DTC144EUA(ROHM),ROHS pcs 1 Q18
28 104-KRX102-R01 Chip triode / KRX102U,with,bias,resistor,ROHS pcs 1 IC2
29 104-MT717T-R01 Chip triode / FMMT717TA,ROHS pcs 1 Q30
30 104-SA1586-R01 Chip triode / 2SA1586,ROHS pcs 1 Q43
31 104-SC1623-R01 Chip triode / 2SC1623,ROHS pcs 1 Q10
32 104-SC3356-R01 Chip triode / 2SC3356,R24,ROHS pcs 1 Q3
33 104-SC4617-R01 Chip triode / 2SC4617(S)(ROHM),ROHS pcs 4 Q6, Q7, Q9, Q37
34 104-SC4919-R01 Chip triode / 2SC4919, MUTING,
CIRCUIT(SANYO), ROHS
pcs 1 Q24
35 104-SC5108-R01 Chip triode / 2SC5108Y(TOSHIBA), ROHS pcs 3 Q2, Q4, Q5
36 104-TA1298-R01 Chip triode / KTA1298(Y),ROHS pcs 3 Q29, Q31, Q32
37 104-TC4082-R01 Chip triode / KTC4082,(KEC),ROHS pcs 2 Q1, Q21
38 105-2SJ243-R01 Chip FET(field-effect transistor) / 2SJ243,ROHS pcs 1 Q16
39 105-2SK508-R01 Chip FET(field-effect transistor) / 2SK508NV(K52),
ROHS
pcs 2 Q14, Q15
40 105-3SK318-R01 Chip FET(field-effect transistor) / 3SK318,ROHS pcs 2 Q19, Q20
41 105-RD01MU-R01 Chip FET(field-effect transistor) / RD01MUS2,ROHS pcs 1 Q12
42 105-SK1588-R01 Chip FET(field-effect transistor) / 2SK1588(NEC),
ROHS
pcs 1 Q102
43 105-SK1824-R01 Chip FET(field-effect transistor) / 2SK1824,ROHS pcs 7 Q13, Q25, Q33, Q36, Q38, Q41, Q51
44 105-SK3476-R01 Chip FET(field-effect transistor) / 2SK3476,ROHS pcs 1 Q11
45 106-0BA010-R01 Knob switch / SKHLLBA010,ROHS pcs 1 K1
46 106-454548-R01 Touch switch / 4.5*4.5*4.8,ROHS pcs 2 K2, K4
47 106-ED0873-R01 3208/558 Carbon encoder switch /
ED0873-16-16HC-F18(9), BAND, ROHS
pcs 1 SW2
48 106-LBE010-R01 Chip touch switch / SKRTLBE010,ROHS pcs 1 K3
49 108-450C24-R02 Chip phase frequency detector/ JTBM450CX24,
ROHS
pcs 1 CD1
50 108-CF450G-R02 Chip porcelain filter/ LTWC450G, 450kHz±5kHz,
ROHS
pcs 1 CF1
51 108-XF4995-R01 Chip IF filter / 49.95MHz±7.5KHz,U-5*2,ROHS pair 2 XF1, XF2
52 109-040000-R01 Chip resistor / 0402,0R±5%,ROHS pcs 13 C67, C166, C250, R7, R24, R141, R182, R183, R217, R241, R260, R261, R278
53 109-040100-R01 Chip resistor / 0402,10R±5%,ROHS pcs 7 R95, R96, R98, R101, R127, R200, R283
54 109-040101-R01 Chip resistor / 0402,100R±5%,ROHS pcs 8 R58, R4, R12, R89, R90, R128, R180, R240
55 109-040102-R01 Chip resistor / 0402,1K±5%,ROHS pcs 24 R97, R37, R38, R41, R42, R47, R48, R49, R50, R69, R129, R130, R131, R150,
R152, R157, R191, R199, R226, R234, R256, R262, R280, R281
56 109-040103-R01 Chip resistor / 0402,10K±5%,ROHS pcs 25 R29, R92, R100, R109, R110, R117, R119, R120, R121, R122, R123, R133, R136,
R137, R138, R139, R140, R194, R203, R228, R254, R264, R266, R268, R275
57 109-040104-R01 Chip resistor / 0402,100K±5%,ROHS pcs 26 C170, R279, R6, R43, R79, R80, R84, R102, R103, R104, R107, R113, R115,
R116, R154, R158, R174, R197, R235, R236, R243, R247, R249, R257, R272,