Description Of Components - Kenwood TK-280 Service Manual

DISPLAY UNIT (X54-3180-XX)
Ref. No. Use/Function
IC300 IC Audio power amplifier
IC301 IC Counter
Q300 FET DC switch
Q301 FET DC switch
Q302 Transistor DC switch
Q303 Transistor DC switch
Q304 Transistor DC switch
Q305 Transistor Current driver
Q306 Transistor DC switch
Q307 Transistor Current driver
Q308 FET DC switch
Q309 Transistor Temperature compensation
Q310 FET Mute switch
D300 Zener diode Surge absorption
D301 LED LED
D302 Diode Quick discharge /AF mute
D303 Zener diode Voltage reference
D304 Diode Voltage reference
D305~310 LED LCD back light
D315~318 Diode Reverse current prevention
D319~321 Zener diode Surge absorption
TX-RX UNIT (X57-5740-XX)
Ref. No. Use/Function
IC1,2 IC Buffer amplifier
IC3 IC Voltage detector / Reset
IC4 IC Buffer amplifier
IC5 IC Voltage regulator / 5M
IC6 IC Voltage regulator / 5V
IC7 IC Buffer amplifier
IC8 IC D/A converter (Adjustment)
IC9 IC Voltage regulator / 5C
IC10 IC Active filter / For HSDout
IC11 IC Active filter / For LSDin
IC12 IC FM IF system
IC13 IC Audio processor
IC14 IC PLL system
IC16 IC DTMF decoder
IC17 IC Flash memory
IC18 IC Active DBM
IC19 IC Microprocessor
IC20 IC EEPROM
IC21,22 IC Shift register / Output expander
IC23 IC Comparator (APC)
IC24 IC Analog switch
Q1 Transistor Switch
Q2 FET DC switch / 5R
Q3 Transistor DC switch / 5T
Q4 Transistor Noise amplifier / Squelch
Q5 FET DC switch / Save
nd
Q6 Transistor 2 IF W/N switch sets to on when Narrow
nd
Q7 Transistor 2 IF W/N switch sets to on when Wide

DESCRIPTION OF COMPONENTS

Operation/Condition
/Key scan
/ INT MIC on/off
/ LED (Red) driver
/ LED (Green) driver
/ Audio amp AVR
/ LCD back light LED AVR
/ SP INT/EXT
/ Red, Green
Operation/Condition
Ref. No. Use/Function
Q8 Transistor Ripple filter
Q9 Transistor DC switch / W/N audio amplitude adjust
Q10 Transistor AF mute switch
Q11 FET Mute switch
Q12 Transistor IF amplifier
Q13 FET Mute switch / MIC line mute
Q14 FET DC switch
Q15 FET DET mute
Q16 Transistor PLL IC fin amplifier
Q17 FET Mute switch / MIC line mute
Q18 Transistor Buffer amplifier
Q19 Transistor Clock frequency shift
Q20 Transistor RF amplifier / TX driver
Q21 FET DC switch
Q22 Transistor DC switch
Q23 FET DC switch
Q24 FET RF amplifier
Q25 Transistor DC switch
D1 Diode Reverse protection
D2 Diode Overload protection
D3 Diode Reverse current protection
D4 Diode Noise detection
D5 Diode RF switch (2
D6 Diode Current steering
D7 Diode RF switch (2
D8 Diode Voltage clamp
D9 Diode TX/RX switch
D10 Diode Overload protection
D12,14 Diode ANT switch
D15 Diode Overload protection
D16,17 Diode Varactor tuning
D18,19 Diode Surge absorption
D20,21 Diode Varactor tuning
D22 Diode ANT switch
D23 Diode TX/RX switch
D24 Diode Voltage drop
SUB UNIT (X58-4580-XX)
Ref. No. Use/Function
Q1 FET DC switch
Q2,3 FET VCO oscillation
Q4 Transistor DC switch
Q5 Transistor RF Buffer amplifier
D1-D8 Diode Frequency control
D9 Diode TX modulation
TK-280
Operation/Condition
nd
IF wide/narrow)
nd
IF wide/narrow)
Operation/Condition
27