Icom IC-A23 Service Manual page 5

SECTION 2
• RF UNIT
BOTTOM VIEW
ALC CTRL
(Q1: UMS1)
VOR switching
(Q19: UN9210)
[IC-A23] only
1st mixer
(Q12: 3SK151
30.05 MHz)
ALC amplifier
(Q5: 2SC4211)
Lo switching diode
(D6, D17: MA77)
• LOGIC UNIT
INSIDE VIEWS
Q15
Q16
Q13
EEPROM
(IC7: HN58X2432)
RESET
(IC2: S-80945ALMP)
VOR circuit
(IC-A23 only)
AF amplifier
(IC6: TA7368F)
Electric volume
(IC505: M52429FP)
IF amplifier
(Q13, Q15, Q16,
Q17: 2SC4215)
2nd mixer,
IF amplifier,
Noise detector
(IC1: TA31136FN)
PLL IC
(IC3: TB31207FN)
BOTTOM VIEW
2 - 1
TOP VIEW
Clock oscillator
(X1: CR-534,
5.039 MHz)
CPU
(IC1: M38267M6L)
PTT detector
(Q10: 2SB1462)
Microphone
amplifier
(IC9: BA3308F)
Microphone
mute
(Q12: UN9211)
AF amplifier/
Low-pass filter
(IC510: TC75W51F)
ALC detector
(D2, D3: MA728)
Antenna switching
circuit
RF amplifier
(Q11: 3SK230)
Power amplifier
(Q2: 2SK2994)
YGR amplifier
(Q3: 2SK2973)
IF discreminator
crystal
(X1: CDBCA450CX24
450 kHz)
VCO circuit
Reference
oscillator
(X2: CR-683,
29.600 MHz)