Power Supply Circuits - Icom IC-F50 Service Manual

4-3-2 VCO CIRCUIT (MAIN UNIT)
The VCO circuit contains a separate RX VCO (Q13, D16)
and TX VCO (Q14, D17). The oscillated signal is amplified
at the buffer amplifiers (Q10, Q11) and is then applied to the
T/R switch (D14, D15). Then the receive 1st LO (Rx) signal
is applied to the 1st mixer (Q3) and the transmit (Tx) signal
to the YGR amplifier circuit (Q9).
A portion of the signal from the buffer amplifier (Q11) is fed
back to the PLL IC (IC4, pin 8) via the buffer amplifier (Q12)
as the comparison signal.
• PLL CIRCUIT
Buffer
"LVIN" signal to the CPU
(FRONT unit; IC401, pin 49)
45.9 MHz 2nd LO
signal to the FM IF IC
(IC1, pin 2)
RX VCO
Q13, D16
Q18
TX VCO
Q14, D17
Loop
filter
Phase
5
detector
Programmable
divider
Tripler
2
3
1
Q34
4-4 POWER SUPPLY CIRCUIT
4-4-1 MAIN UNIT VOLTAGE LINE
LINE
VCC The voltage from the connected battery pack.
Common 5 V converted from the VCC line at the
+5 regulator circuit (IC9). The output voltage is
+5V
supplied to buffer amplifiers (Q18), FRONT unit,
etc.
Common 5 V converted from the VCC line at the
S5 regulator circuit (Q23–Q25). The output volt-
S5V
age is supplied to the ripple filter (Q17), PLL IC
(IC4), FRONT unit, etc.
Receive 5 V converted from the S5V line at the
R5 regulator circuit (Q22). The output voltage is
R5V supplied to the tripler (Q34), FM IF IC (IC1), IF
amplifier (Q4), VCO switch (Q15, Q16), 1st
mixer (Q3), etc.
Transmit 5 V converted from the S5V line at the
T5V T5 regulator circuit (Q21). The output voltage is
supplied to the YGR amplifier (Q5, Q9), drive
amplifier (Q8), APC amplifier (IC2), etc..
4-4-2 FRONT UNIT VOLTAGE LINE
LINE
Same voltage as VCC line on the MAIN unit is
applied to the FRONT unit via the J401, pins 1,
VCC
2 (FRONT unit). The voltage is supplied to the
[PWR] switch controller (Q401, Q402).
Same voltage as +5V line on the MAIN unit is
applied to the FRONT unit via the J401, pin 4
CPU5
(FRONT unit). The voltage is supplied to the
CPU (IC401), reset IC (IC408), etc.
Same voltage as S5V line on the MAIN unit is
applied to the FRONT unit via the J401, pin 5
S5V
(FRONT unit). The voltage is supplied to the mic
mute circuit (IC406), AF mute circuit (Q403-
Q406, IC406), etc.
Buffer
Q11
IC4 MB15A02
Programmable
Prescaler
counter
Shift register
X2
15.3 MHz
4 - 4
DESCRIPTION
DESCRIPTION
D15
Buffer
to 1st mixer circuit
Q10
D14
to transmitter circuit
Buffer
Q12
LPF
8
9
SCK
10
SO
11
PLST