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4-5-3 D/A CONVERTOR IC (MAIN UNIT; IC251)
Pin
number
2
3
10
11
14
15
22
23
Port
name
SQCON
MOCON
DTCON
FRCON
T1CON
T2CON
T3CON
T4CON
Description
Outputs squelch level control signal.
Outputs modulatin level control signal.
Outputs DTCS modulation balance
control signal.
Outputs reference frequency level
control signal.
Outputs bandpass filter1 tuned and
transmitting power control signals.
Outputs bandpass filter2 tuned signal.
Outputs bandpass filter3 tuned signal.
Outputs bandpass filter4 tuned signal.
Pin
number
111
112
113
114
115
119
Description
Input port for the [DOWN] key.
Low : While [DOWN] key is pushed.
Input port for the [CH/WX] key.
Low : While [CH/WX] key is pushed.
Input port for the [16/9] key.
Low : While [16/9] key is pushed.
Input port for the [SCAN] key.
Low : While [SCAN] key is pushed.
Input port for the [H/L] key.
Low : While [H/L] key is pushed.
Input port for the PLL unlock signal.
High : PLL lock voltage is unlocked.
Pin
number
5
6
7
11
12
13
Port
name
SRXMS
DETMS
CKSIS
ATTS
TXMS
VCOS
Description
Outputs the AF mute switch (IC281,
pin 3) control signal.
Low : While the scrambler decording
signal is muted.
Outputs the AF mute swtich (IC281,
pin 7) control signal.signal.
Low : While AF signal is muted.
Outputs the scrambler IC’s clock shift
control signal.
High : While the clock is shifted.
Outputs the RF attenuator control
signal.
High : While attenuator is ON.
Outputs the TX mute swtich (Q141)
control signal.
Low : While receiving.
Outputs the TX/RX VCO control
signal.
4-5-2 EXPANDER IC (MAIN UNIT; IC341)
DOWN
CH/WX
16/9
SCAN
H/L
UNLK
Port
name
CPU–Continued