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Pin
Port
Description
number
name
Pin
Port
Description
number
name
4 - 5
4-5 PORT ALLOCATIONS
4-5-1 CPU (LOGIC UNIT; IC1)
2
3
4
5
6
7
8
9
10
12
17
21
22
23
24
28–31
32
33
39
40
41
REMOTE
SD
CTCIN
PCON
PLST
PLCK/ECK
PDA/UL
CTCSS
DTMF
NOISE
LOCK
DIUD
DICK
POWER
CONT
KR3–KR0
PTT
RESET
CFC
ESIO
BLED
Input port for remote control signal
from an optional HM-75A microphone
via the [EXT MIC] jack.
Input port for detected S-meter signals
from the IC101 (pin 12) on the 2F unit.
Input port for received CTCSS tone
signals.
Output port for +3C regulator circuit
control signals.
“HIGH” : Power ON.
Output PLL strobe signals.
Output port for clock signals to PLL
and EEPROM ICs.
DATA bus line for PLL.
• Outputs PLL DATA when PLL is
locked.
• When PLL is unlocked, PLL IC
releases the port being pulled up,
therefore, the CPU receives “HIGH”
level signal.
Output port for CTCSS tone signals.
Output port for:
• Beep audio signals while receiving.
• DTMF signals or 1,750 Hz tone sig-
nal while transmitting.
(According to versions)
Input pulse signals for noise squelch
from the IC101 (pin 13) on the 2F unit.
Input port for the [LOCK] switch.
“LOW” : [LOCK] switch is ON.
Inputs up/down signals from the
[DIAL] control.
Input port for dial clock signals.
Input port for the [POWER] switch.
“Low” : [POWER] switch is pushed.
Outputs LCD contrast control signals.
Input port for key matrix.
Input port for the PTT control circuit.
“HIGH” : When transmitting.
Input port for reset circuit (LOGIC unit;
IC3, pin 1).
Outputs control signals to the power
supply of the CTCSS band-pass filter
(LOGIC unit; Q45).
“LOW” : Activates the BPF.
DATA bus line for the EEPROM
(LOGIC unit; IC15) data signals.
Outputs [BUSY] LED control signals.
“HIGH” : The [BUSY] LED lights.
42
43
44
46
47
48
49
55
56
Outputs LCD backlight control signals.
“High” : The backlight lights.
Output port for the microphone ampli-
fier (LOGIC unit; IC12).
“LOW” : Activates the mic. amplifier.
Output a mute signal.
[MM]
: Microphone mute for DTMF
or 1,750 Hz tone while
transmitting.
[RM]
: Audio mute for squelch cir-
cuit while receiving.
“HIGH” : To mute one of above.
Outputs transmit frequency band con-
trol signals.
“HIGH” : UHF band.
“LOW” : VHF band.
Output port for the UHF band VCO
(DUAL-VCO board; Q301, Q302 and
D301) control signals.
“HIGH” : Activates the UHF-VCO.
Output port for the VHF band VCO
(DUAL-VCO board; Q304, Q305 and
D303) control signals.
“HIGH” : Activates the VHF-VCO.
Output port for SHIFT signals to the
shift switches (1F unit; Q354, Q854).
“HIGH” : Transmit on VHF.
“LOW” : Transmit on UHF.
Outputs control signals to the AF reg-
ulator circuit (2F unit; Q151,Q152).
“HIGH” : Activates the AF amplifier.
Output port for the TX output power
(HIGH or LOW) select signals.
“LOW” : HIGH power is selected.
LIGHT
MICC
MM/RM
TXSEL
HVCO
LVCO
SHIFT
AFON
H/L