Power Supplycircuits - Icom IC-7400 Service Manual

(1) CPU and EEPROM (CTRL unit)
The antenna tuner CPU (IC5) controls the tuning motors via
the motor driver circuit (Q211–Q218) and tuning relays di-
rectly, and memorizes the best preset position in 100 kHz
steps. The memory contents are stored in the EEPROM
(IC6) without a backup battery.
(2) Tuning motors (CTRL unit)
The motor driver circuit (Q211–Q218) rotates the tuning mo-
tors (MF1, MF2) to obtain a low SWR.
(3) Tuning relays (TUNER unit)
According to the operating frequency band and antenna con-
dition, tuning relays select the capacitors (C34–C43) and
coils ( L3–L9, L11, L12).
4-4-4 ANTENNA TUNER CPU PORT ALLOCATION
(CTRL unit; IC5)
Pin Port
number name
Input port for the resistance com-
1 AN2
ponents detection voltage.
Input port for the reflected RF
2 AN1
power voltage.
Inpout port for the forward RF
3 AN0
power voltage.
Input port for the transceiver power
4 PWRS
OFF.
Input port for the reference voltage
7 SETI
setting.
13 CIKY Outputs tuner data signal.
15 CIST Input port for the serial signal.
Outputs the [TUNER] ON/OFF sig-
17 THRU
nal.
19 CDRS Input port for reset signal.
Input port for the TX/RX switching
TRC
21
signal.
Input ports for the antenna tunner
22, 23 XIN, XOUT
CPU system clock.
25, NVHF, CO3,
Output the capacitor selection sig-
34–36 CO2, CO1,
nals.
38–40 CI3, CI2, CI1
VHF, 24M,
26–32 18M, 14M, Output the coil selection signals.
10M, 7M, 4M
Output ports for the tuning motor
41–44 P07–P04
(MF2) drive signals.
Output ports for the tuning motor
45–48 P03–P00
(MF1) drive signals.
Input port for the reactance compo-
64 AN3
nents detection voltage.
Description
4 - 8
4-5 POWER SUPPLY CIRCUITS
4-5-1 PA UNIT
Line
The voltage from an external power supply via
H14V
the common filter circuit (FILTER board, L1).
The same voltage as the H14V line passed
HV
through a fuse.
The same voltage as the HV line passed through
14VS
the switching relay (RL1).
The same voltage as the 14VS line passed
14V
through coils (L22, L23).
Common 8 V converted from the 14V line and
8V
regulated by the +8 regulator circuit (IC3).
Common 5 V converted from the 14V line and
5V
regulated by the +5 regulator circuit (IC2).
Common 5 V converted from the HV line and
H5V
regulated by the +5 regulator circuit (IC1).
4-5-2 S-LOGIC BOARD
Line
Common –8 V converted from the 14V line and
–8 V
regulated by the –8 V DC-DC converter (IC401).
4-5-3 MAIN UNIT
Line
Receive 8 V converted from the 14V line and
R8V regulated by the R8V regulator circuit (Q451,
Q453).
Transmit 8 V converted from the 14V line and
T8V regulated by the T8V regulator circuit (Q450,
Q452).
4-5-4 PLL UNIT
Line
Common 5 V converted from the 8V line and
5VPLL
regulated by the 5 V regulator circuit (IC1051).
Description
Description
Description
Description