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UHF (7640) CIRCUIT DESCRIPTION
5B-12
November 1998
Part No. 001-7600-001
5.7.5 UHF I/O EXPANDER IC12 (MAIN UNIT)
5.7.6 UHF PORT EXPANDER IC13 (MAIN UNIT)
51 BM Outputs control signal for beep mute cir-
cuit Q10. High = Beep muted.
52-
54
CTDA0-
CTDA2
Output port for CTCSS/DTCS signals.
55 HANG Input port for the microphone hanger
detection signal. Low = Microphone on
hook.
90 MTONE Output port for beep audio while receiving
and 2/5 tone signals while transmitting.
91 TONED Outputs DTMF signals.
94-
96
OPV3-
OPV1
Input port for option connector J4 state
(main unit).
97 CTCIN Input port for the CTCSS/DTCS IN
decode signals.
98 SD Input port for S-meter signal.
99 LVIN Input port for PLL lock voltage.
100 TEMP Input port for the transceiver’s internal
temperature.
Pin
No.
Port
Name
Description
2, 3,
10
T1-T3 Output tunable bandpass filter control
signals.
11 T4 Output port for tunable bandpass filter
control signal while receiving and power
control signal while transmitting.
14 REF Output port for reference frequency
control voltage.
Pin
No.
Port
Name
Description
Pin
No.
Port
Name
Description
4 TXC Outputs control signal for R8 regulator
Q10/Q11 (main unit). High = Transmit
mode.
5 TMUT Outputs control signal for T8 regulator
Q8/Q9 (main unit). High = Transmitter
off.
6 RM Outputs AF mute switch IC11(main unit)
control signal for the receiver circuit. High
= No receive audio is emitted.
7 MM Outputs MIC mute control signal. High =
DTMF signals are output, etc.
11 HORNO Outputs external device control signal.
High = Matched 2/5-tone signals are
received.
12 AFON Outputs control signal for the AF amplifier
regulator circuit. High = Squelch is open,
etc.
13 AFHPF Outputs AF filter control signal. High =
Filter out CTCSS or DTCS frequency.
14 NWC Outputs receive/transmit passband width
control signal. High = Narrow bandwidth
is selected.