Kenwood TK-90 Service Manual page 34

TK-90
Ref. No. Use / Function
IC423 OP amplifier
IC451 Mixer IC
IC452 Multiplexer
IC453 OP amplifier
IC454 5V AVR
IC521 AF amplifier
IC551~553 Analog switch
IC554 A/D
IC555 A/D
IC601 NOR
IC602 OP amplifier
IC603 OP amplifier
IC604 DI amplifier
IC605 MIC amplifier
IC606 Buffer
IC701 DDS
IC702 DDS
IC703 PLL
IC704 5V AVR
IC851 Analog switch
IC852 OP amplifier
IC853 5V AVR
IC854 EEPROM
IC855 MCU
IC856 Reset IC
34
COMPONENTS DESCRIPTION /
Operation / Condition
Buffer for S-meter voltage
Demodulator
Detect signal select
Detect signal buffer
Ref voltage
For analogue circuit
Audio amplifier
Audio signal select
Electrical volume
1: DEO output
2: No use
3: MOD signal
4: AM AGC
5: Anti VOX level
6: DI level
7: MIC sense
8: VOX sense
Electrical volume
1: Audio output level
2: Beep level
3: Side tone level
4: Emergency tone level
5: VGS-1 monitor level
6: VGS-1 signal for DEO
7: Reserved
8: No use
VOX control
AGC amplifier for MOD
For VOX function
Amplifier for DI/VOX
Amplifier for MIC/ANTI VOX
Buffer for UART signal
LO1-PLL reference signal is generated
CAR signal generation
LO1 control
For PLL circuit
RTK control switch
Buffer for DEO signal
5V for VGS-1
EEPROM
Main microcomputer
CPU reset signal
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