Kenwood TK-3130 - ProTalk XLS UHF, Руководство по обслуживанию

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7
TK-3130/3131
Control System
■
Reset Circuit
When a battery voltage is dropped, IC201 is detected low
voltage, and this detected signal input to IC204 for stop the
CPU function. IC200 is detected the reset voltage.
■
Battery Voltage Detection Circuit
The unit detects a low battery voltage and display the
BATT indicator on the LCD. The battery voltage is divided
and applied to the analog value input pin (BATT) of the CPU,
and converted to a digital signal.
■
Power Supply Circuit
The power supply voltage is maintained to 3.0V by the
series regulator (IC213). It is used as CPU power 3M. The
3C, 3R and 3T voltages are regulated by the IC209.
The B (battery voltage) is supplied to the RF final transis-
tor Q10.
The transmission power 3T is supplied to the transmis-
sion output circuit when the CPU turns Q219 on only in
transmit mode. 3T is junction to VR2 to generate PA gate
(Q10) for power alignment.
The reception power 3R is provided to the receive and IF
circuits when the CPU turns Q220 on only in receive mode.
The transmission/reception power 3C is supplied to the
VCO and PLL circuits when the CPU turns Q218 on in trans-
mit and receive modes.
If no signal is received for 10 seconds, the CPU enters
the power save mode, and turns common power 3C and
reception power 3R on for one cycle and off for three cycles
according to the signals from the CPU to save the battery
power.
CIRCUIT DESCRIPTION
Fig. 9 Reset, battery voltage detection and
power supply circuits
Fig. 10 QT/DQT circuit
IC213
AVR
IC209 Q218
Q220
Q219
AVR SW
SW
SW
3C
3M
SB
3R
3T
Power
SW
B
IC204
CPU
BATT
IC204
CPU
TO
IC206 IC2
TI
40
20
LPF
TCXO
IF IC
VCO
TX AF
VR200
LPF
RX AF
Fig. 11 AK2368 (IC205) block diagram
HPF
+VR1
Com-
pressor
Pre-
emphasis
Scrambler
Limiter
Splatter
filter
+VR2
HPF
BPF
OSC
LPF
+VR3
–
–
+
+
Control register
and data buffer
MSK
MODEM
Expander
+VR4
De-
emphasis
De-
scrambler
–
+
23
22
14
15
Reception
signal
input
Transmission
signal output
6
3.6864MHz
17 18 19
3
4
11
20
21
Microphone
input
Frame
detection
Receiver
Reception output
TX data/
RX data
Control data
■
QT/DQT
• Encode (Transmit)
QT/DQT signal is generated by CPU (IC204). Output sig-
nal (IC204 pin 40 (TO)) goes to TCXO modulation and VCO
modulation (Through the VR200).
• Decode (Receive)
Detected AF signal go to IC206. Function of IC206 is LPF
for sub-audible frequency. This signal goes to IC204 pin 20
(TI). IC204 is detected the QT or DQT.