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4 - 5
4-5-2 I/O expander IC
(1) IC12 (MAIN unit)
(2) IC13 (MAIN unit)
Output tunable band pass filter control
signals.
Output port for
tunable band pass filter control signal
while receiving.
output power control signal while
transmitting.
Output port for reference frequency
control voltage.
2, 3, 10
11
14
T1–T3
T4
REF
Pin
Port
Description
number
name
Outputs control signal for the R8 regu-
rator circuits (MAIN unit; Q10, Q11).
High: While transmitting.
Outputs control signal for the T8 regu-
rator circuits (MAIN unit; Q8, Q9).
High: While Tx is muted.
Outputs AF mute switch (MAIN unit;
IC11) control signal for the receiver cir-
cuit.
High: While no receive audio is emit-
ed.
Outputs MIC mute control signal.
High: While DTMF signals are output,
etc.
Outputs external device control signal.
High: When matched 2/5-tone signals
are received.
Outputs control signal for the AF ampli-
fier regulator circuit.
High: When squelch is open, etc.
Outputs AF filter control signal.
High: Filters out CTCSS or DTCS fre-
quency.
Outputs receive/transmit passband
width control signal.
High: While narrow bandwidth is
selected.
4
5
6
7
11
12
13
14
TXC
TMUT
RM
MM
HORNO
AFATT
AFHPF
NWC
Pin
Port
Description
number
name