Power Supply Circuits - Icom IC-2200H Service Manual

4-3-3 REFERENCE OSCILLATOR CONTROL
CIRCUIT (LOGIC AND MAIN UNITS)
The reference oscillator control circuit changes the refer-
ence frequency when using digital voice function.
When digital voice signals output from the optional digital
voice unit, the "REFMOD" signal outputs from it via the J4
(pin 4) at the same time. The "REFMOD" signal is applied to
the amplifier (IC521, pin 3), and passes through the CTCSS
switch (IC524, pins 6 and 1). The signal is applied to the D/A
convertor (MAIN unit; IC5, pin 13) via the "CTCSS" line. The
output signal from the D/A convertor (MAIN unit; IC5, pin 14)
is applied to the reference oscillator (MAIN unit; X1) to con-
trol the reference frequency while transmitting digital signals
as "DTC" line.

4-4 POWER SUPPLY CIRCUITS

VOLTAGE LINES
Line
The 13.8 V voltage from the connected DC
HV
power supply.
The same voltage as the HV line which is con-
trolled by the HVSW circuit (Q28, Q30, Q31).
When the [POWER] switch (LOGIC unit; S1) is
SWHV
pushed, the CPU (LOGIC unit; IC1, pin 40) out-
puts the "PWRON" control signal to the power
switching circuit to turn the circuit ON.
Common 5 V for the CPU (LOGIC unit; IC1)
converted from the HV line by the C5V regulator
C5V
circuit (IC8). The circuit outputs the voltage
regardless of the power ON/OFF condition.
Common 8 V converted from the SWHV line by
+8V
the +8V regulator circuit (IC7).
Common 5 V converted from the +8V line by the
+5V
+5V regulator circuit (Q21, Q22).
Transmit 8 V controlled by the T8 regulator cir-
cuit (Q14, Q15) using the "TXC" signal from the
T8
I/O expander IC (IC2, pin 6). The voltage is con-
verted from the +8V line at the regulator circuit.
Receive 5 V controlled by the R5 regulator cir-
cuit (Q25) using the "RXC" signal from the I/O
R5V
expander IC (IC2, pin 5). The voltage is con-
verted from the +5 V line at the regulator circuit.
Description
4-5 PORT ALLOCATIONS
4-5-1 D/A CONVERTER IC (MAIN UNIT; IC5)
Pin Port
number name
Outputs RF tracking voltage while
2 T3
receiving.
3 SQLATT
10 FC
Outputs squelch control signal to
11 SQLIN
adjust threshold level.
14 DTC Outputs DTCS slope correction signal.
Outputs transmitting deviation control
15 MOD
signal.
Outputs RF tracking voltage while
22 T2
receiving.
• Outputs RF tracking voltage while
23 T1
• Outputs transmitting power control
4-5-2 EXPANDER IC (MAIN UNIT; IC2)
Pin Port
number name
Outputs AF mute control signal.
4 AFMUTE
5 RXC
6 TXC
Outputs 2nd IF filter select signal
([W/N] version ONLY).
11 W/N
Outputs VCO regualtor (Q1, Q3, Q5,
Q8, D1) control signal.
14 SHIFT
4 - 5
Description
Outputs attenuator control signal.
Outputs reference frequency control
voltage.
receiving.
signal while transmitting.
Description
High: While muting.
Outputs R5 regulator (Q25) control
signal.
Low: While receiving.
Outputs T8 regulator (Q14 and Q15)
control signal.
High: While transmitting.
High: While wide passband width
(±5.0 kHz) is selected (FI1 is
selected).
Low: While narrow passband width
(±2.5 kHz) is selected (FI2 is
selected).
Low: While transmitting.
High: While receiving.