SPECIFICATIONS................................. BACK COVER
TH-K4AT/K4E
CN2
CN9
CN6
x
x
c
c
v
m
b
,
,
.
ç
√
µ
∫
∫
∫
∫
∫
Ω
/
∫
≈
~
≤
n
z
TX-RX unit (B/3)
TX-RX unit (C/3)
TX-RX unit (A/3)
DISASSEMBLY FOR REPAIR
How to remove the case assembly from the
chassis
1. Remove two screws (z) holding the chassis.
2. Pull out two knobs (
3. Pull out the SP and MIC parts of the cap from jacks (
4. Turn the unit over with the bottom of the chassis facing
upwards, and remove the chassis (
assembly (
5. Remove the speaker lead (
the TX-RX PC board (TX-RX unit A/3).
b
).
) and remove two round nuts (c).
x
) from the case
n
) from the connector (CN2) of
m
v
).
How to remove the PC board
■ Numeric key PC board (TX-RX unit B/3)
1. Remove three screws (,) on the numeric key PC board.
2. Lift the numeric key PC board and remove it from the
■ PTT PC board (TX-RX unit C/3)
3. Remove one screw on the PTT PC board (/).
4. Pull the PTT PC board to the left and remove it from the
■ TX-RX PC board (TX-RX unit A/3)
5. Remove the SP/MIC jack cover (≈).
6. Remove two screws (
7. Remove two screws (
8. Remove eight screws (
9. Absorb solder from the antenna terminal (
Note: Do not melt the shadow plate (
10.Remove the TX-RX PC board from the chassis, then remove
connector (CN9) of the TX-RX PC board (
.
).
connector (CN6) of the TX-RX PC board (TX-RX unit A/3)
(
Ω
).
) holding the shield
ç
cover (antenna terminal section).
) holding the shield
√
cover (final amplifier section).
board.
with a solder absorber.
) on the TX-RX PC
∫
µ
moving the tip of the solder absorber close
to the antenna terminal.
the encoder volume FPC (
of the TX-RX PC board.
) from the flat cable connector
≤
~
) when
)
2
TH-K4AT/K4E
DISASSEMBLY FOR REPAIR
Soldering the antenna terminal
1. With the shield cover removed from the antenna terminal
section, install two screws on the PC board and bring the
PC board into contact with the chassis (
2. Solder the antenna terminal with a soldering iron (
z
).
).
x
x
z
3. Remove the two screws installed in step 1 above, and install
the two screws again on the PC board together with the
shield cover (
c
).
c
4. Apply the tips of soldering irons to all the four pins of the final
FET at the same time (
the final FET (
). (Two persons should be required to do this.)
v
v
5. Remove all PC boards from the chassis.
6. Confirm that there is no space between the radiation plate
installed on the foil side of the TX-RX PC board (TX-RX unit
A/3) and the PC board (
the radiation plate and PC board, eliminate it by applying
the tip of the soldering iron to the radiation plate.
), heat them sufficiently, and remove
c
c
). If there is any space between
b
b
Radiation plate
TX-RX PC board
Replacing the final FET (Q12)
1. Remove the two screws holding the shield cover of the
final FET section (
2. Remove solder from the shield cover completely with a
solder absorber.
3. Remove the shield cover (
z
).
).
x
z
x
This illustration is
M2 type.
7. Apply the tip of the soldering iron to the installation side of the
radiation plate of the TX-RX PC board, put a little amount of
solder to the radiation plate that is seen through a square hole
in the final FET installation section and melt the solder (
8. When the solder in step 7 is melted, place the final FET on
the PC board by aligning it with the silk of the final FET
installation section of the PC board (
m
).
n
).
m
n
9. Release the soldering iron and confirm that the final FET
and radiation plate have been soldered.
10.Solder the four pins of the final FET with the soldering iron.
11.Install all the PC boards.
12.Reinstall the shield cover removed in step 3 above in its
original position and install two screws.
13.Solder the shield cover to the PC board.
14.
Install the chassis on the case assembly and assemble them.
15.Readjust transmission power.
Note: Since the FET is sensitive to static electricity, always
wear a grounding band. Use a highly insulated ceramic
heater solder iron.
3
TH-K4AT/K4E
DISASSEMBLY FOR REPAIR
Special care and attention required for assembly
1. Gluing to the key top (MIC element section)
You must also glue on the speaker storage area and heap
the glue up until wealthy glued on the speaker storage area
and the key top for waterproofing the MIC element side of
the key top. (Fig. 1)
Heap the glue up until wealthy glued on the speaker
storage area and the key top (MIC element section).
Fig. 1
2.
Bending the LCD hardware fixture (J21-8456-03) tabs
(1)Insert the tabs of the LCD hardware fixture into four holes
in the LCD installing position of the TX-RX PCB (TX-RX unit
A/3). (Fig. 2)
Fig. 2
(2)By pressing the LCD hardware fixture from the component
side of the TX-RX PCB, you must bent all 4 tabs of the LCD
hardware fixture being visible from the foil side until the
bases of each tabs are folded at least 45 degrees (Fig. 3). If
the bending angle of the tabs of the LCD hardware fixture
is less than 45 degrees, a display error may occur.
Min 45
degrees
Bending position
NG
NG
Fig. 3
3. PTT PCB (TX-RX unit C/3) installation procedure
Installing the PTT PCB on the TX-RX PCB and chassis are
as follows:
(1)Insert the PTT PCB connector (CN7) into the TX-RX PCB
connector (CN6) lightly.
(2)Push three parts of the PTT PCB to contact tightly with the
chassis. There may be a small gap between the connectors.
(Fig. 4)
Note: A double-side adhesive tape (J99-0376-04) is used
behind the PTT switch. When reassembling the PTT
PCB to the chassis, press the PTT PCB (under the PTT
switch) so that the tape hold the PCB and chassis
securely.
Chassis
OK
PTT switch
Push three parts of the PTT PCB
to contact tightly with the chassis.
(1)Before installing the numeric key PCB (TX-RX unit B/3) on
the chassis, push three parts of the packing to contact tightly
with the chassis as shown in Fig. 6. If the packing is not in
contact with the chassis, there may be a gap between the
transceiver bottom case assembly and the battery, and
water may enter through the gap.
OKNG
Push three parts of the packing to
contact tightly with the chassis.
Clearance NG
Fig. 6
Do not fix this part of the
key top to the rib of the
case assembly.
Fig. 8
7.
Cautions for installing the key top on the case assembly
(1)Install the key top keypad section and the power switch
section on the rib of the case assembly.
(2)Do not fix the part between the key top keypad section and
the power switch section to the rib of the case assembly,
but install it as shown in Fig. 8.
5
TH-K4AT/K4E
CIRCUIT DESCRIPTION
Frequency Configuration
The frequency configuration is shown in Figure 1 and
Table 1.
TX/RX :
ANT
ANT
SW
FINAL
DRIVE
400.000~469.995MHz(M2)
430.000~439.995MHz(E)
1st MIX
RF
AMP
361.150~431.145MHz(M2)
PRE
DRIVE
391.150~401.145MHz(E)
400.000~469.995MHz(M2)
430.000~439.995MHz(E)
MCF
38.85MHz
450kHz
CF
MIX, IF,
DET
Tripler
x 3
PLL
VCO
38.4MHz
AF
AMP
TCXO
MIC
AMP
SP
12.8MHz
MIC
Fig. 1 Frequency configuration
Double super heterodyne
Reception method1st IF Frequency 38.85MHz (Lower)
2nd IF Frequency 450kHz (Lower)
Transmission method
VCO direct oscillation amplification
ModulationVariable reactance phase modulation
Table 1 Basic configuration
Receiver System
■ Front End
The received signal from the antenna passes through a lowpass filter and then through a transmission/reception switching
circuit (antenna switch) and enters the band-pass filter (L40,
L41, L38).
The signal passing through the band-pass filter (L40, L41,
L38) is amplified by with an RF amplifier (Q17), passes through
a band-pass filter (L32, L34) and enters the first mixer (Q16).
These band-pass filters are tuned to a desired frequency
by varicaps (D21, D20, D19, D18).
A tuning voltage corresponding to the desired signal is
applied to each varicap through the BPF/APC terminal (pin 6)
of the MPU (IC8) to tune to the receive frequency.
■ First Mixer
The received signal passing through the band-pass filter
(L32, L34) is mixed with the first local signal generated by the
VCO by the first mixer (Q16) to produce a first IF signal (38.85
MHz) (Lower heterodyne).
The first IF signal passes through a MCF (Monolithic crystal
filter: XF1) to remove unwanted components.
The first IF signal passing through the MCF (XF1) is amplified
by an IF amplifier (Q24) and the resulting signal enters the FM
IC (IC3).
ItemRating
Nominal center frequency (fo)38.85MHz
Pass bandwidth±6.0kHz or more at 3dB
Attenuation bandwidth±25kHz or less at 35dB
Ultimate attenuation70dB or more (fo –910 kHz)
Spurious response40dB or more (fo +1MHz)
Ripple1dB or less
Insertion loss4dB or less
Terminating impedance610Ω ±5% // 3pF ±0.5pF
Table 2 MCF (L71-0619-05) characteristics (TX-RX unit XF1)
ItemRating
Nominal center frequency (fo)450kHz
3dB bandwidth±6.5kHz or more
50dB bandwidth±15.5kHz or less
Ripple2dB or less (fo ±6.5kHz)
Guaranteed attenuation55dB or more
(fo ±18kHz to ±33kHz)
50dB or more (fo ±100kHz)
Insertion loss4dB or less
I/O matching impedance1.5kΩ
Table 3 Ceramic filter (L72-0968-05) characteristics (TX-RX unit CF1)
ANT
BPF
L41,L40,L38
ANT
SW
Tuning voltage
PLL
LV
LPF
VCO
6
RF AMP
Q17
D20D21
6
BPF/APC
MPU
IC8
Fig. 2 Receiver section configuration
BPF
L32,L34
MIXER
D18D19
Q16
MCF
XF1
38.85MHz
1st Local OSC
(PLL)
IF AMP
Q24
5R5R
FM IC
IC3
IF AMP,
DET
2nd Local OSC
Tripler
x 3
TCXO
12.8MHz
AF AMP
IC6
Q23
X1
SP
TH-K4AT/K4E
CIRCUIT DESCRIPTION
■ IF Circuit
The first IF signal (38.85 MHz) amplified by the IF amplifier (Q24)
and the second IF signal (38.4 MHz) generated by tripling the 12.8
MHz reference oscillator frequency of the TCXO (X1) by Q23, are
mixed in the FM IC to produce a second IF signal (450 kHz) (Lower
heterodyne).
The second IF signal passes through a ceramic filter (CF1)
to remove unwanted components.
The second IF signal passing through the ceramic filter (CF1)
passes through the IF amplifier in the FM IC again and is
detected to produced an audio signal.
■ Squelch and Mute Circuit
A noise component is obtained by passing FM detection
output (FM IC pin 9) through an operational amplifier in the
9
AFM
49
IC8
MPU
1st IF input
(38.85MHz)
SM
SQ
IC3
FM IC
2nd local OSC
(38.4MHz)
SMV
48
SQV
161514131211109
MIX
Noise
comp
Rectifier
Buffer
Local
OSC
12345678
CF1
450kHz
RSSI
IF AMP
5R
CD1
Quadrature
detector
C173C174
Inverter
R135
R125
AF OUT
Noise
AMP
AMP
FM IC and band-pass filter consisting of R125, R126, R135,
C173, C174. The noise component is rectified in the FM IC to
produce a DC voltage, which is output from the N-REC terminal
(pin 14) of the FM IC as squelch voltage.
The squelch voltage enters the SQ terminal (pin 48) of the
MPU (IC8) and is compared with the reference voltage preset
in the MPU to control audio signal ON/OFF.
When "L" is output from the AFM terminal (pin 9) of the MPU,
the AF mute switch (Q20) is activated to mute the audio signal.
■ S Meter Circuit
The S meter voltage is output from the RSSI terminal (pin
12) of the FM IC (IC3) and input to the SM terminal (pin 49) of
the MPU. Then the voltage is converted from analog to digital
in the MPU to control the S meter display on the LCD.
VOL IN
Q20
AF MUTE
SWITCH
Q21
AF FILTER
LPF
R126
5R
Fig. 3 IF, Squelch, Mute and S meter circuit
■ AF Amplifier
The detected audio signal passes through an AF filter (Q21)
and enters an AF mute switch (Q20).
After passing through the AF mute switch (Q20), the signal
passes through an AF volume (VR201) and is amplified to a
specified output level with an AF amplifier (IC6).
The audio signal amplified with the AF amplifier (IC6) is
output through an internal speaker or an external speaker
jack (J4).
The beep tone and the DTMF signal are output from the
DTMF/BEEP terminal (pin 40) of the MPU (IC8), enters the AF
amplifier (IC6) and is output as a monitor tone.
IC3
FM IC
9
AF OUT
VR201
AF VOLUME
40
DTMF/BEEP
IC8
MPU
Q21
AF
FILTER
IC6
AF AMP
REM
46
Q20
AF MUTE
SWITCH
SPG
REM/TXD
SPK
AFO
Fig. 4 AF amplifier
J4
SP JACK
SP
7
TH-K4AT/K4E
CIRCUIT DESCRIPTION
Transmitter System
■ Microphone Amplifier Circuit
The audio signal from the microphone passes through a
high-pass filter (IC5) and enters a microphone amplifier (IC16).
The signal passes through a pre-emphasis circuit, limiter
amplifier and splatter filter inside the microphone amplifier.
The splatter filter will remove distortion outside the audio band.
IC16
MIC AMP
MICIC5
61
HPF
emphasis
Fig. 5 Microphone amplifier circuit
■ Modulation Circuit
The audio signal amplified by the microphone amplifier
(IC16) passes through a semi-fixed volume (VR5) for
modulation adjustment, and goes to the VCO modulation
varicap (D6) for variable reactance phase modulation.
■ Drive and Final Circuit
The output signal from VCO (Q1) passes through an RF
amplifier (Q2, Q5, Q9) and drive amplifier (Q10, Q11), and is
amplified by a power amplifier (Q12).
■ Transmission/Reception Switching Circuit
The signal amplified by the power amplifier (Q12) passes
through a transmission/reception switching circuit and a lowpass filter, and is fed to the antenna.
Q11
Q10
Pre-
Limiter
Splatter
filter
VCO
Q12
The transmission/reception switching circuit consists of
D10, D11, L19, D12 and D13. These diodes are turned ON in
transmit mode and OFF in receive mode to switch signals.
MIC
IC5
HPF
AMP
DRIVE AMP
Q10
DRIVE AMP
IC16
MIC
Q11
VR5
MAX DEV
Q12
POWER AMP
Q1
RF AMP
VCO
D10,D11,L19
D12,D13
ANT
SW
Q2
RF AMP
LPF
Q5
ANT
Q9
RF AMP
Fig. 6 Modulation, Drive, Final and
Transmission/reception switching circuit
■ APC Circuit
The APC (Automatic Power Control) circuit is used to obtain
a stable transmission power and controls transmission output
by detecting the drain current of Q11 and Q12.
The transmission output can be changed in three levels:
High, Mid, and Low.
The reference voltage is output from the BPF/APC terminal
(pin 6) of the MPU (IC8) and the detection voltage generated by
R70, R71 and R72 are fed to the APC differential amplifier (IC2).
The voltage in proportion to the difference between
reference voltage and detection voltage is output from the
BOUT terminal (pin 7) of IC2 as an APC voltage.
ANT
D10
D11
LPF
L19
D13
RX
Q55
–t
TH1
+
51
THERM
7
KAPC
6
BPF/APC
IC8
MPU
FINAL
16
Q58
D12
VGG
Q15
5T
R72
R71
R70
B
Q13
B
8
Fig. 7 APC and Temperature protection circuit
1
2
3
4
VDD
APC AMP
AOUT
A–IN
A+IN
GND
IC2
BOUT
B–IN
B+IN
8
V+
7
6
5
Q14
TH-K4AT/K4E
Fo/LD
PLL LD
IC8
MPU
IC1
PLL IC
R32
D16
C40
R35
14
102
5C
CIRCUIT DESCRIPTION
The APC voltage controls the gate voltage of Q11 and Q12,
and keeps transmission output stable.
The MPU detects power supply voltage and controls Q58
by transmission power supply voltage and transmission power.
For example, if the power supply voltage during transmission,
is equal to or higher than approx. 10.5 V and if power is at Mid
or Low level, the APC voltage level applied to Q12 is reduced
by Q58.
■ Temperature Protection Circuit
To prevent thermal destruction of the power amplifier (Q12),
this circuit reduces APC voltage when Q12 temperature rises.
The MPU (IC8) detects temperature with a thermistor (TH1)
and controls reference voltage to the APC circuit.
PLL System
■ PLL Circuit
A reference frequency of 5 kHz or 6.25 kHz is produced by
dividing the 12.8 MHz reference frequency of the TCXO (X1)
with PLL IC (IC1). Comparison frequency is produced by
TO
5C
5/0V
5MS
5/0V
TCXO
VR1
VC
X1
TCXO
12.8MHz
12.8MHz
IF
5C
5/0V
CLOCK
DATA
LE
Fo/LD
PLL
IC1
Rectifier
PLL IC
LOOP
FILTER
LPF Q6
RF
Amp
amplifying VCO output with an RF amplifier (Q6) and dividing
it with the PLL IC.
The PLL synthesizer with 5 kHz and 6.25 kHz step is
configured by comparing phases of the reference frequency
and comparison frequency.
The phase difference between reference frequency and
comparison frequency passes through a charge pump in the
PLL IC, then ripples are removed with a loop filter with lowrange passing characteristics to produce VCO control voltage
(lock voltage).
■ VCO Circuit
The VCO produces a desired frequency directly with a
Colpits oscillation circuit containing an oscillation transistor (Q1)
used for both transmission and reception.
The VCO control voltage is applied to varicap (D1, D2, D3,
D4) to produce a desired frequency.
The SHIFT terminal (pin 113) of the MPU (IC8) goes "H"
during transmission, and the shift control switch (Q3) is turned
ON to change oscillation frequency.
VCO
Q4
Ripple
Filter
D1-D4
Q3
SHIFT
SW
Q1
OSC
MOD
Q2
Amp
Buff
Q5
RF
Amp
D8,D9
SW
TX
RX
5T 5/0V
5R 5/0V
LV
1~5V
5C
5/0V
SHIFT
H/L
Fig. 8 PLL and VCO circuit
■ Unlock Detection Circuit
When the PLL is unlocked, the waveform of the pulse
output from the Fo/LD terminal (pin 14) of the PLL IC (IC1) is
rectified with R32, D16, R35 and C40, and the Fo/LD terminal
is made "L" level. The voltage at the Fo/LD terminal is detected
by the MPU to control transmission/reception switching timing.
MOD
Fig. 9 Unlock detection circuit
9
TH-K4AT/K4E
CIRCUIT DESCRIPTION
Power Supply Circuit
■ Charging Circuit
When an external power supply is connected to the DC IN
terminal, the constant-current circuit consisting of Q33 and
D31 provides a constant current of approx. 110 mA to the NiMH battery.
If no external power supply is connected to the DC IN
terminal, the constant-current circuit does not function.
IC8
MPU
BTEMP
DCDET
VR1
ENC
IC1
TCXO
Q4,5,6
D40,41
IC5
Q30
IC3,17
D9,14
Q16,17
Q22,23,24
Q9,10,13
D8,10
TH1
IC16
Q47
5MS
5MV
5C
5R
5T
Q41
RN2105
5MS SW
Q57
RN2105
5C SW
Q53
RN2701
5R SW
5MV SW
Q55
CPH3317
5T SW
5M
CUCB
IC9
TK11250
CM
AVR
5.0V
IC12
TK11250
AVR
5.0V
D35
RB521S-30
PROTECT
D36
RB521S-30
PROTECT
IC6
D48,49
D42,43,46
D47,44
AF AMP
Q36
2SJ347
THERM
DET
BTDET
Q35
2SK1830
DC-IN
DET
Q37, Q38
2SB1184
(Q,R)
2SC4617(R)
AF/LAMP
AVR
IC4
XC6202PB
52FR
AVR
11.5V
■ Power Supply Switching Circuit
The voltage supplied through the battery terminal or DC IN
terminal is branched in the power supply switching circuit as
shown in Fig.10 and then supplied to the required components.
■ Battery Type Recognition Circuit
When the battery pack is attached to the transceiver, the
battery type is recognized with the T terminal on the
transceiver. This battery type recognition activates charging
for the Ni-MH battery pack and displaying the battery meter.
-
T
+
BATT TERMINAL
7.5V Norminal
(6.0 - 9.0V)
Q33
2SB1184
(Q,R)
BATT
D31
DA221
CONSTANT
CURRENT
B
CHARGE
Q34
2SK1830
CHARGE
SW
D30
RB521S-30
PROTECT
CHARGE
D81
RB521S-30
PROTECT
D33
RB051L-40
PROTECT
B
D32
RB051L-40
PROTECT
DC IN
13.8V Norminal
(12.0 - 16.0V)
B
J2
Fig. 10 Charging and Power supply switching circuit
Control System
■ Reset and Backup Circuit
When power is supplied to the transceiver, the 5M voltage
goes "H" as C303 is charged.
A rising edge of the 5M voltage is detected by the voltage
detection IC (IC11) and when its output (RESET) goes "H", the
reset status of the MPU is released.
5C
IC11
INOUT
IC10
INOUTINT
BATT
D35
IC9
INOUT
5V
AVR
R244
C303
5M
+
If the supplied voltage to the transceiver is reduced and
the 5M voltage falls below the detection voltage of the voltage
detection IC (IC10), the MPU detects it by an interrupt
processing, backs up data in EEPROM (IC15) and turns the
power off.
Timing chart
Power
ON
5V5M
0
5VRESET
0
5VINT
Power
OFF
R243
C307
L63
IC15
EEPROM
IC8
MPU
RESET
10
Fig. 11 Reset and Backup circuit
0
TH-K4AT/K4E
CIRCUIT DESCRIPTION
■ Voltage Detection Circuit
Various voltages are input to the A/D port of the MPU (IC8)
for processing.
Battery voltage is divided with resistors (R240, R241) and
enters the BATT terminal (pin 52) of the MPU.
Battery voltage is used for battery meter indication during
transmission or for alert tone processing when an abnormal
power supply voltage (approx. 16.5 V or higher) is applied.
Squelch voltage becomes DC voltage by detecting changes
in noise voltage in the FM IC (IC3), and the signal is used for
squelch control.
The S meter voltage is output from the RSSI pin of the FM
IC to control S meter display.
Detection of thermistor voltage (temperature) in the Ni-MH
battery during charging, detection of remote microphone key
pressing and VOX voltage monitoring are performed through
each A/D port of the MPU.
■ Battery Save Circuit
If there is no signal (squelch off, scan off or no key operation)
for longer than 10 seconds, the transceiver will enter the
battery save mode.
Battery save operation is performed by controlling Q57 with
an output signal from the 5C (SAVE) terminal (pin 15) of the
MPU.
The 5C ON/OFF cycle ratio during battery saving can be set
from a transceiver menu.
■ LED Drive Circuit
The LCD and key illumination LEDs are lighted by controlling
Q51 for the LCD and Q50 for keys according to the output
voltage from the AF/LAMP AVR (Q37).
The BUSY and TX illumination LEDs are lighted by controlling
Q47.
Q47
D46
Q51
56
99
LAMP
RX LED
5T
AF AMP
D33
Q38
Q37
5C
D48
D49
D41
BUSY LED
D40
TX LED
D42
D42
D42
D43
D43
D43
R227
R226
D44
D47
Q50
B
Fig. 13 LED drive circuit
IC8
MPU
5MS
Q41
37
5MS
5C (SAVE)
IC8
MPU
5C
Q57
15
Fig. 12 Battery save circuit
5M
11
TH-K4AT/K4E
CIRCUIT DESCRIPTION
■ Key and Encoder Input Circuit
The POWER key is assigned to the interrupt port (pin 95) of
the MPU.
The PTT key is assigned to the dedicated port (pins 13, 14)
of the MPU.
16 key (M2 type)
KIN1 KIN2 KIN3 KIN4
KIN0KOUT0 KOUT1 KOUT2 KOUT3
F321
VFO654
MR987
CALL
∗
#0
MENU
LAMP
MONI
SET
Other keys composes a matrix and key presses are detected
by scanning them by software.
The encoder reads data using the interrupt port (pins 35
and 36) of the MPU.
IC8
MPU
PWRSW
SW
PTTI14PTTE13ENCB36ENCA
95
S7POWER
35
ROTARY
ENCODER
4 key (E type)
IC8
KIN0KOUT0 KOUT1 KOUT2 KOUT3
KIN1 KIN2 KIN3 KIN4
MRVFOF
MENUCALL
LAMP
MONI
SET
MPU
Fig. 14 Key and Encoder input circuit
PWRSW
POWER
SW
J3
PTTI14PTTE13ENCB36ENCA
95
S7
J3
35
ROTARY
ENCODER
12
TH-K4AT/K4E
CIRCUIT DESCRIPTION
■ CTCSS/DCS
The encode signal is generated by the MPU (IC8) and output
from the TONE terminal (pin 41) of the MPU.
The unwanted high-frequency components of the encode
signal output from the MPU are removed with a low-pass filter,
and applied to VCO modulation input (MOD) and TCXO VC
terminal for modulation.
The VCO and TCXO modulation levels are adjusted by VR6
to produce flat modulation characteristics in low and high
ranges.
The decode signal is input to the SIGIN pin (pin 47) of the
MPU after the waveform of the audio signal from the FM IC is
rectified with a CTCSS/DCS filter (IC17). Then the set CTCSS
tone frequency and DCS code are detected by digital signal
processing in the MPU to control muting.
X1
TCXO
VC
VCO
VR6
MOD
VR5
1
MIC
AMP
6
LPF
AMP
IC16
■ DTMF
The DTMF signal is generated by the MPU (IC8) and is
output from the DTMF/BEEP terminal (pin 40) of the MPU.
The DTMF signal is mixed with an audio signal at the input
side of the AF amplifier (IC6), and is output as a monitor tone.
The DTMF signal is mixed with a modulation signal at the
input side of pre-emphasis in the microphone amplifier (IC16)
and used as a transmit signal.
■ VOX
The IC5 and Q30 amplify the audio signal captured in the
microphone, and then the signal is converted into the DC
Voltage D24 rectifies.
The DC voltage activates the MPU (IC8), and the VOX starts.
41
50
TONE
SIG INVOX IN
IC8
MPU
DTMF/BEEP
40
47
CTCSS/DCS
IC17D24Q30IC3
9
FILTER
FM
IC
MIC
IC5
HPF
IC6
AF AMP
Vin
VOL OUT
Fig. 15 CTCSS/DCS and DTMF, VOX
■ Serial Control
Serial control must be enabled from a transceiver menu so
that the REM/TXD pin of the speaker jack (J4) and the PTT
(RXD) pin of the microphone jack (J3) function as TXD and
RXD, respectively, when communicating with a personal
computer.
MIC JACK
J3
J4
SP JACK
PTT
MIC
IM
REM/TXD
SP
5MS
SPG
SPK
AFO
IC5
HPF
5MC
10
+
–
POUT
IC6
AF AMP
MIC
46
REM
IC8
MPU
13
PTTE
TXD
RXD
12
11
Fig. 16 Serial control
13
TH-K4AT/K4E
SEMICONDUCTOR DATA
MPU : 90522BPFFG139 (IC8)
■ Pin function
PinPin
No.Name
1CLOCKOCommon serial clock output
2DATAOCommon serial data output
3EEPDIIData input from EEPROM
4EEPCSOChip select output to EEPROM
5VOXOVOX power supply switchL:ON
6BPF/APC O
7KAPCOAPC ON/OFF switchL:APC ON
8VCC-Positive power supply
9AFMOAF mute switchL:Mute
10 SPMOSpeaker mute switchH:Mute
11 RXDIUART data input line from PC (9600bps)
12 TXDOUART data output line to PC (9600bps)
13 PTTEIExternal [PTT] key inputL:ON
14 PTTII[PTT] key inputL:ON
15
36 ENCBIEncoder B side input
37 5MSO5MS main power supply switch L:ON
38 DVCC-Reference voltage input for DAC
39 DVSS-Ground for DAC
DTMF/
40
BEEP1750Hz (D/A)
41 TONEO
42 AVCC-Positive power supply for ADC
43 AVRH-Reference voltage input for ADC
44 AVRL-Ground reference voltage input for ADC
45 AVSS-Ground for ADC
46 REMI
47 SIGINI
14
I/OFunction
BPF tuning voltage output, APC voltage
output (PWM)
OSave power supply switchL:ON
Gate bias control of TX final amplifier
Power supply stabilization (Connected to
VSS through 0.1uF)
Encode waveform output of DTMF/BEEP/
O
Encode waveform output of CTCSS/DCS
(D/A)
Remote control microphone key voltage
input (A/D)
Decode waveform input of CTCSS/DCS
(A/D)
L:Bias ON
PinPin
No.Name
48 SQINoise voltage input for squelch (A/D)
49 SMIRSSI voltage input for S-meter (A/D)
50 VOXINIMicrophone voltage input for VOX (A/D)
51 THERMITX temperature compensation input(A/D)
52 BATTIBattery voltage input (A/D)
On when charging
H: DC IN detection
On when temperature detection is activated
On when the speaker outputs the audio
or lamp lights
On when the key LED lights
On when the LCD LED lights
On when 5R or 5MV is applied
Off when High power is selected
On TX
APC reference voltage
Charge current
Constant-current charge
DC IN
Battery
16
Use/Function
AVR
D34
constant-voltage
Reverse current
D35
prevention
Reverse current
D36
prevention
D40TX LEDLights on TX
D41BUSY LEDLights on RX
D42-44
D46,47
D48,49
D62-65
D69-72
D79,80 Limiter
Key illumination
LED
LCD illumination
LED
Key type
D60
detection
UHF type
D61
detection
market code
detection
Reverse current
prevention
D73Voltage drop
Over input
D74
protection
Reverse current
D81
prevention
Operation/Condition/Compatibility
Battery
DC IN
Key backlight illumination
LCD backlight illumination
Key matrix
PARTS LIST
New Parts. indicates safety critical components.
∗
Parts without Parts No. are not supplied.
Les articles non mentionnes dans le Parts No. ne sont pas fournis.
Teile ohne Parts No. werden nicht geliefert.
TH-K4AT/K4E (Y50-581X-XX)
TX-RX UNIT (X57-675X-XX)
C37CK73HB1H471KCHIP C470PF K
C38CK73HB1C103KCHIP C0.010UF K
C40CK73HB1A104KCHIP C0.10UF K
C41C92-0507-05CHIP-TAN4.7UF6.3WV
C42CK73HB1H471KCHIP C470PF K
C165CC73HCH1H030BCHIP C3.0PFB
C166CK73HB1C103KCHIP C0.010UF K
C167,168CK73HB1A104KCHIP C0.10UF K
C169,170CK73HB1A683KCHIP C0.068UF K
C171CK73HB1H471KCHIP C470PF K
C172CK73HB1H182KCHIP C1800PF K
C173,174∗ CC73HCH1H181JCHIP C180PF J
C175CC73HCH1H220JCHIP C22PFJ
C176CK73HB1A104KCHIP C0.10UF K
C177C92-0628-05CHIP-TAN10UF10WV
C178CK73HB1C103KCHIP C0.010UF K
C179CK73HB1A104KCHIP C0.10UF K
C180CC73HCH1H121JCHIP C120PF J
C182,183CK73HB1A104KCHIP C0.10UF K
C186CC73HCH1H240JCHIP C24PFJ
C187CC73HCH1H020CCHIP C2.0PFC
C188CC73HCH1H240JCHIP C24PFJ
C189CK73HB1H471KCHIP C470PF K
C190-192CK73HB1C103KCHIP C0.010UF K
C193C92-0507-05CHIP-TAN4.7UF 6.3WV
C194CK73HB1A104KCHIP C0.10UF K
C195C92-0628-05CHIP-TAN10UF10WV
C196,197CK73GB1C273KCHIP C0.027UF K
C198CK73EF1C105ZCHIP C1.0UFZ
C200CK73HB1C103KCHIP C0.010UF K
C201CK73HB1H122KCHIP C1200PF K
C202CK73HB1H271KCHIP C270PF K
C203CC73HCH1H121JCHIP C120PF J
C204CK73HB1A333KCHIP C0.033UF K
C205CK73HB1A473KCHIP C0.047UF K
C108CC73HCH1H101JCHIP C100PF J
C109-115CK73HB1H471KCHIP C470PF K
C116C92-0544-05CHIP-TAN10UF4WV
C117,118CK73HB1H471KCHIP C470PF K
C124CK73HF1C104ZCERAMIC C 0.1UFZ
C125CC73HCH1H1R5CCHIP C1.5PFC
C126CC73HCH1H100DCHIP C10PFD
C128CK73HB1C103KCHIP C0.010UF K
C129CC73HCH1H110JCHIP C11PFJ
C130CK73HB1H471KCHIP C470PF K
C131-133CK73HB1C103KCHIP C0.010UF K
C134CK73HB1H471KCHIP C470PF K
C135,136CC73HCH1H050CCHIP C5.0PFC
C137CC73HCH1H070DCHIP C7.0PFD
C139CK73HB1H471KCHIP C470PF K
C147CK73HB1H471KCHIP C470PF K
C148CC73HCH1H060BCHIP C6.0PFB
C152,153CK73HB1H471KCHIP C470PF K
C156CK73HB1H471KCHIP C470PF K
C157∗ CC73HCH1H180GCHIP C18PFG
E : TH-K4EM2 : TH-K4AT
18
C206∗ CK73HB1C183KCHIP C0.018UF K
C207CK73HB1C223KCHIP C0.022UF K
C208CC73HCH1H820JCHIP C82PFJ
C209CK73HB1H471KCHIP C470PF K
C210CK73HB1C103KCHIP C0.010UF K
C211CK73HB1H222KCHIP C2200PF K
C212CK73HB1C123KCHIP C0.012UF K
C213C92-0714-05TANTALUM C 4.7UF 6.3WV
C219CK73HB1A473KCHIP C0.047UF K
C220CK73HB1E472KCHIP C4700PF K
C221,222CK73HB1C103KCHIP C0.010UF K
C223CK73HB1H471KCHIP C470PF K
C224CK73HB1A104KCHIP C0.10UF K
C225CK73GB0J105KCHIP C1.0UF K
C226CK73HB1A104KCHIP C0.10UF K
C227C92-0587-05CHIP-TAN2.2UF 4WV
C228,229CK73HB1A104KCHIP C0.10UF K
C230CK73FB1C105KCHIP C1.0UFK
C231CK73HB1H471KCHIP C470PF K
C235,236CK73HB1C103KCHIP C0.010UF K
C237C92-0628-05CHIP-TAN10UF10WV
C238-241CK73HB1H471KCHIP C470PF K
C242CK73HB1C103KCHIP C0.010UF K
C243CK73HB1H471KCHIP C470PF K
C246C92-1327-05CHIP-TAN100UF 10WV
PARTS LIST
New
Ref. No.
C247,248CK73HB1A104KCHIP C0.10UF K
C249CK73HB1H471KCHIP C470PF K
C250CK73EF1C105ZCHIP C1.0UFZ
C252CC73HCH1H101JCHIP C100PF J
C253C92-0628-05CHIP-TAN10UF10WV
C255C92-0628-05CHIP-TAN10UF10WV
C256,257CK73HB1H102KCHIP C1000PF K
C258CK73HB1A104KCHIP C0.10UF K
C270-272CK73HB1H471KCHIP C470PF K
C276CK73HB1H471KCHIP C470PF K
C279-285CK73HB1H471KCHIP C470PF K
C286CK73FB1C105KCHIP C1.0UFK
C290,291CK73HB1H471KCHIP C470PF K
C293CC73HCH1H470JCHIP C47PFJ
C294,295CC73HCH1H050CCHIP C5.0PFC
C297CK73HB1A104KCHIP C0.10UF K
C298CK73HB1H471KCHIP C470PF K
C299CK73FB1C105KCHIP C1.0UFK
C300CK73HB1H471KCHIP C470PF K
C302CK73HB1H471KCHIP C470PF K
C303C92-0605-05TANTALUM C 150UF 6.3WV
C304-306CK73HB1H471KCHIP C470PF K
C307CK73HB1A104KCHIP C0.10UF K
C308CK73HB1H471KCHIP C470PF K
C309CK73FB1C105KCHIP C1.0UFK
C310CK73EF1C105ZCHIP C1.0UFZ
C311CK73GB1C104KCHIP C0.10UF K
C312,313CK73HB1A393KCHIP C0.039UF K
C314CK73HB1H471KCHIP C470PF K
C316CK73GB1C104KCHIP C0.10UF K
C317,318CK73HB1H471KCHIP C470PF K
C319C92-0628-05CHIP-TAN10UF10WV
C323,324CK73HB1H471KCHIP C470PF K
C326CK73HB1H471KCHIP C470PF K
C327CK73HB1A104KCHIP C0.10UF K
C328CK73GB0J105KCHIP C1.0UF K
C329CC73FCH1H120JCHIP C12PFJ
C330,331CK73HB1H471KCHIP C470PF K
C332CK73HB1A104KCHIP C0.10UF K
C335,336CK73HB1A104KCHIP C0.10UF K
C338CK73FB1C105KCHIP C1.0UFK
C339CK73HB1A473KCHIP C0.047UF K
C344-348CK73HB1H471KCHIP C470PF K
C349CK73HB1A104KCHIP C0.10UF K
C351CK73HB1C103KCHIP C0.010UF K
C352-354CK73HB1H471KCHIP C470PF K
C355,356CK73HB1C103KCHIP C0.010UF K
C357CK73EF1C105ZCHIP C1.0UFZ
C358CK73HB1A473KCHIP C0.047UF K
C359,360CK73HB1A104KCHIP C0.10UF K
C361CK73HB1H471KCHIP C470PF K
C363CC73HCH1H100CCHIP C10PFC
C364CC73FCH1H180JCHIP C18PFJ
C365-367CK73HB1H471KCHIP C470PF K
C368CK73GB1H471KCHIP C470PF K
C369-371CK73HB1H471KCHIP C470PF K
C372CK73GB1H471KCHIP C470PF K
C374CC73HCH1H101JCHIP C100PF JE
C510CK73HB1A473KCHIP C0.047UF K
C511CK73HB1H471KCHIP C470PF K