Description Of Components - Kenwood TK-290 Service Manual

TX-RX UNIT (X57-5390-10)
Ref. No. Use / Function
IC2 Level shift
IC3 D/A converter (adjustment)
IC4 DC-DC converter
IC5 Phase locked loop system
IC6 Level shift
IC7 APC comparator
L800 VCO system
IC200 Active DBM
IC300 FM IF system
IC301 Audio mute switch
IC400 Shift register
IC401 Voltage regulator
IC402 Voltage regulator
IC403~405 Shift register
IC406 Microprocessor
IC409 Voltage detector
IC412 EEPROM
IC413 Active filter
IC414 Flash ROM
IC415 Address decode latch
IC600 DTMF decoder
IC601 Buffer amplifier
IC602 Active filter
IC603 D/A converter (Adjustment)
IC604 Summing amplifier/
Buffer amplifier
IC605 Summing amplifier
IC606 Active filter
IC607 Audio processor
Q1 DC switch
Q2 DC convert switch
Q3 RF amplifier
Q4 Ripple filter
Q5 Buffer amplifier
Q6 RF amplifier
Q7 DC switch
Q8 RF amplifier
Q9 DC switch
Q10 DC switch
Q13 DC switch
Q200 RF amplifier
Q301 Noise amplifier

DESCRIPTION OF COMPONENTS

Operation / Condition
Outputs ± twice the
input voltage 5M
2nd mixer, Quadrature
detector, AF output,
Noise amplifier output,
S-meter output
Output expander
5CM
5M
Output expander
16 bit
Reset
For HSD output
NOR gate
LPF for LSD input
AF/TO
MOD : Summing amplifier
LPF for 2-tone
T/R "H" : RX
Buffer for RF input
4C
TX drive
APC circuit power
switch
TX drive
APC voltage control
APC off : Speed up
D/A port protection
RX front
RX on
Ref. No. Use / Function
Q302 IF amplifier
Q303 DC switch
Q304 DC switch
Q305 DC switch
Q400 DC switch
Q401 DC switch
Q402 DC switch
Q403 DC switch
Q404 DC switch
Q405 DC switch
Q406 DC switch
Q407 Clock frequency shift
Q408 DC switch
Q409 DC switch
Q410 DC switch
Q411 Current driver
Q412 DC switch
Q413 DC switch
Q414 DC switch
Q415 DC switch
Q601 Mute switch
Q602 DC switch
D4 Noise rejection
D5 Frequency shift
D6 Current steering
D8 Temperature compensation
D9 Voltage protection
D10,11 ANT switch
D200 Overload protection
D201,202 Varactor tuning
D203,204 Varactor tuning
D205,206 Varactor tuning
D207,208 Varactor tuning
D300 AM detector
D302,303 RF switch
D400 Reverse protection
D401 Overload protection
D402,403 Surge absorption
D404 Reverse current prevention
D408 Reverse current prevention
D409 Voltage reference
D601 Voltage clamp
D602,603 TX/RX switch
TK-290
Operation / Condition
Post amplifier
2nd IF W/N switch sets
to on when Narrow
2nd IF W/N switch sets
to on when Wide
5TC "H" : on
5CC "H" : on,
5TC "H" : on
Regulator 5T, 5C
MIC mute
MIC switch
5CC "H" : on
5R
TX LED (Red) driver
Busy LED (Green) driver
Lamp
Lamp : Backlight
SB
BATT voltage detector
Power supply switch
SB
MIC line mute
2nd local cutoff
frequency
For L201
For L202
For L205
For L206
Noise squelch
2nd IF wide/narrow
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