Icom IC-4008MKII Port Allocations, Power Supply Circuits Voltage Line, CPU Main unit IC1

4-4 POWER SUPPLY CIRCUITS VOLTAGE LINE

LINE	DESCRIPTION
BATT	The voltage from the connected battery pack.
	Common 3 V converted from the BATT line at
3V	the 3V regulator circuit (IC6). The circuit outputs
	the voltage regardless of the power ON/OFF
	condition.
+3V	Common 3 V converted from the BATT line at
	the +3V regulator circuit (Q25, D4).
R+3	Receive 3 V cotrolled by the R+3 regulator circuit
	(Q18) using the “RXV” signal from CPU (IC1).
	Transmit 3 V converted from the BATT line at the
T+3	T+3 regulator circuit (Q27, Q28, D5, etc.) using
	the “TXV” signal coming from CPU (IC1).

4-5 PORT ALLOCATIONS

4-5-1 CPU (MAIN unit; IC1)

Pin	Port	Description
number	name
		Input port for the PTT switch from the
31	PTT2	external mic jack (MAIN unit; J1).
		Low : External PTT switch is ON.
34	PTT1	Input port for the internal PTT switch.
		Low : While PTT switch is pushed.
35	DOWN	Input port for the [DOWN] switch.
36	UP	Input port for the [UP] switch.
37	MODE	Input port for the [MODE] switch.
		Input port for the POWER switch.
38	POWSW	Low : While POWER switch is
		pushed.
		Input port for PLL unlock signal from
45	UNLK	the PLL IC (RF unit; IC1).
		Low : During unlock.
46	BEEP	Outputs beep audio signal.
		Outputs volume mute switch (Q23)
48	RMUTE	control signal.
		High : While squelched
		Outputs control signal for the AF ampli-
49	AFON	fier regulator circuit (Q5, Q10, Q11).
		High: When squelch is open.
50	PLLCK	Outputs clock signal to the PLL IC (RF
		unit; IC1).

Pin	Port	Description
number	name
51	PLLDA	Outputs data signals to the PLL IC (RF
		unit; IC1).
52	PLLST	Outputs strobe signals for the PLL IC
		(RF unit; IC1).
53	POWER	Outputs control signal for the +3V reg-
		ulator circuit (MAIN unit; Q25, D4).
54–56	CTCO0–	Output port for the CTCSS signals.
	CTCO2
		Outputs control signal for the MIC
57	TXMOD	amplifier (IC2).
		Low : While microphone amplifier is
		ON.
58	CTCIN	Input port for the CTCSS decode sig-
		nals.
59	SQLIN	Input port for squelch level signal.
60	REMIN	Input ports for the control signal from
		the external remote microphone.
61	BATIN	Input port form the connected battery
		pack for low battery indication.
		Input port for the RSSI signal from the
62	SENIN	FM IF IC (RF unit; IC2) to detect receiv-
		ing signal strength level.
73	EEPCK	Outputs clock signal to the EEPROM
		(IC3).
74	EEPDA	Outputs data signals to the EEPROM
		(IC3).
		Output port for power save function,
75	PSC	applied to VCO regurator circuit (RF
		unit; Q13, Q14, D8, D9).
76	RXV	Outputs the R+3 regulator control sig-
		nal (Q18).
77	TXV	Outputs the T+3 regulator control sig-
		nal (Q27, Q28, D5, etc.).
		Outputs control signal for LCD back-
78	LAMPC	light.
		Low : While LCD backlight is ON.
		Outputs internal microphone control
79	MICSW	signal.
		High : While internal PTT switch is
		pushed.
		Outputs MIC mute signal for RING
80	MMUTE	function.
		High : While RING signals are out-
		put, etc.

4 - 3