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APC Circuit
The automatic transmission power control (APC) circuit
detects part of a power module output with a diode (D34,
D36) and applies a voltage to IC12. IC12 compares the APC
control voltage (PC) generated by the D/A converter (IC3)
and DC amplifier (IC4) with the detection output voltage to
control Q27 and Q28, generates DB voltage from B voltage,
and stabilizes transmission output.
The APC circuit is configured to protect over current of
the power module due to fluctuations of the load at the an-
tenna end and to stabilize transmission output at voltage
and temperature variations.
Q23
Q25
IC101
RF
RF
POWER
D19
AMP
AMP
MODULE
DB
DRIVER
Q27
DRIVER
IC4
IC12
PC
DC
IC3
AMP
CONTROL
3pin
Fig. 9 APC circuit
Control Circuit
The CPU carries out the following tasks:
1) Controls the WIDE, NARROW, TX/RX outputs.
2) Adjusts the AF signal level of the AF filter (IC10) and turns
the filter select compounder on or off.
3) Controls the DTMF decoder (IC9).
4) Controls the display unit.
5) Controls the PLL (IC1).
6) Controls the D/A converter (IC3) and adjusts the volume,
modulation and transmission power.
DTMDAT
IC9
DTMCLK
IC6
DTMF
CPU
DTMSTD
DECO.
Fig. 10 Control circuit
Memory Circuit
The transceiver has an 8k-bit EEPROM (IC7). The
EEPROM contains adjustment data. The CPU (IC6) controls
the EEPROM through three serial data lines.
EEPCK
EEPDT
IC6
CPU
EEPWP
Fig. 11 Memory circuit
CIRCUIT DESCRIPTION
ANT
D30,31
ANT
LPF
SW
Q28
D34,36
APC
POWER
+B
DET
PRI
APC
CNTCK
IC3
CNTDT
D/A
DAST
converter
PLLE
DT
IC1
PLL
CK
IC7
EEPROM
Display Circuit
The CPU (IC6) controls the display LEDs. When the trans-
ceiver is busy, the LEDG line goes high, Q4 turns on and the
green LED (D11) lights. In transmit mode, the LEDR line
goes high, Q8 turns on and the red LED (D12) lights. Backlit
LEDs (D1~D4) are provided.
When a function key (MON, PF, C1, C2, C3 or C4) is se-
lected, its respective line goes high (LED MON, LED PF,
LED C1, LED C2, LED C3 or LED C4), the switch connected
to that line turns on and the amber LED lights.
LEDMON
Q1
SW
LEDPF
Q5
SW
LEDC1
Q2
SW
LEDC2
Q6
SW
LEDC3
Q3
SW
LEDC4
Q7
SW
LEDG
Q4
SW
LEDR
Q8
SW
MICBL
Q10
SW
Fig. 12 Display circuit
Key Matrix Circuit
The TK-7102 front panel has function keys. Each of them
is connected to a cross point of a matrix of the KMI1 to
KMO2 ports of the microprocessor. The KMO1 to KMO2
ports are always high, while the KMI1 to KMI4 ports are al-
ways low.
The microprocessor monitors the status of the KMI1 to
KMO2 ports. If the state of one of the ports changes, the
microprocessor assumes that the key at the matrix point
corresponding to that port has been pressed.
KMI1
KMI2
KMI3
IC6
KMI4
CPU
KMO2
KMO1
Fig. 13 Key matrix circuit
TK-7102
D5
D6
D7
D8
D9
D10
D11
D12
Q9
SW
D1~4
13
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