13
TK-7102
■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.
■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.
Control CircuitThe 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.
Fig. 9 APC circuit
Fig. 10 Control circuit
CIRCUIT DESCRIPTION
RF
AMP
Q23
RF
AMP
Q25
POWER
MODULE
IC101
APC
DRIVER
Q28
DB
+B
Q27
PRI
DRIVER
DC
AMP
IC4
ANT
SW
D30,31
LPF
ANT
POWER
DET
D34,36
IC12
APC
CONTROL
D19
PC
IC3
3pin
IC3
D/A
converter
IC1
PLL
IC9
DTMF
DECO.
IC6
CPU
DTMDAT
DTMCLK
DTMSTD
DAST
CNTDT
CNTCK
PLLE
DT
CK
■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.
Fig. 11 Memory circuit
EEPCK
IC6
CPU
IC7
EEPROM
EEPDT
EEPWP
Q1
SW
LEDMON
IC6 CPU
D5
Q5
SW
LEDPF
D6
Q2
SW
LEDC1
D7
Q6
SW
LEDC2
D8
Q3
SW
LEDC3
D9
Q7
SW
LEDC4
D10
Q4
SW
LEDG
D11
Q8
SW
LEDR
D12
Q10
SW
Q9
SW
MICBL
D1~4
■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.
IC6
CPU
KMI1
KMI2
KMI3
KMI4
KMO2
KMO1
C1 C2 C3 C4
VOL
UD
VOL
DN PF MON