Kenwood TK-90, Service Manual

Page: 35 / 142

TK-90
35
Ref. No. Use / Function Operation / Condition
IC857 Reset IC Back up indicate signal
IC859 5V AVR 5V for CPU
IC861 5V AVR 5V for option board
IC863 OP amplifier Buffer for Selcall/option
IC864 OP amplifier Selcall function
IC865 FSK tone decoder For selcall function
Q1 Switching Receiving RATB power supply
control (ON during reception)
Q2 Switching ON during TX
Q3 Amplifier Transmission drive output amplifier
Q4 Mute switch Mute reception path during
transmission (ON during reception)
Q5~12 Switching BPF selection (ON when selected)
Q13 Switching ATT changeover relay control
(OFF when ATT is ON)
Q101 Switching ON when preamplifier is ON
Q102 Switching OFF when preamplifier is OFF
Q103 Amplifier Preamplifier
Q104 Switching Preamplifier power supply control
(ON when preamplifier ON)
Q105,106 Mixer Receiving first mixer
Q107 Amplifier RX LO1 amplifier
Q108,109 Mixer Receiving first mixer
Q110 Switching Preamplifier
Q181 Switching Transmission IF mute control
(Mute when ON)
Q182 Amplifier Transmission IF amplifier
Q183 Amplifier Receiving IF amplifier
(Controlled by AGC)
Q184 Amplifier LO2 amplifier
Q185 Amplifier 2nd IF amplifier (Controlled by AGC)
Q186 Amplifier ALC amplifier for TX
Q187 Buffer ALC buffer for TX
Q251 Amplifier 2nd IF amplifier for receiving
Q252 Switching Correction IF filter loss
Q253 Amplifier Amplifier for TX
Q254 Buffer CAR input buffer
Q255 Buffer MOD input buffer
Q311 Switching RXB power supply generation switch
Q312 Switching TXB power supply generation switch
Q313 Switching RXB power supply generation switch
Q321 Buffer NB input buffer
COMPONENTS DESCRIPTION /
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