Samyung STR-6000A, Service Manual

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AMPLIFIES & FILTERS NOISE COMPONENT. FILTERED SIGNAL IS APPLIED TO NOISE
DETECTER & "NREC" SIGNAL IS OUTPUT FROM PIN 14. "NREC" SIGNAL IS AMPLIFIED
BY DC AMPLIFIER (U10/B) OF CPU BOARD & APPLIED AS "SQL0" BY CPU (U8, PIN 80).
CPU ANALYZE NOISE STATUS AND OUTPUT "RMUTM", "RMUTS" SIGNALS TO CHANGE
AF MUTE SWITCH(U12/A, U12/B).
TRANSMITTER
TRANSMITTER TRANSMITTER
TRANSMITTER
MICROPHONE AMPLYFYING CIRCUIT MICROPHONE AMPLYFYING CIRCUIT MICROPHONE AMPLYFYING CIRCUIT MICROPHONE AMPLYFYING CIRCUIT
MICROPHONE AMPLYFYING CIRCUIT AMPLIFIES VOICE SIGNAL TOGETHER WITH
+6dB/OCTAVE PRE-EMPHASIS FROM MICROPHONE TO THE LEVEL, MODULATING
CIRCUIT NEEDS.AF SIGNAL FROM MICROPHONE IS AMPLIFIED BY MICROPHONE
AMPLIFIER(U7/A) VIA ANALOGUE SWITCH(U10/B). CONDENSER (C162) & RESISTER
(R101) ARE LINKED TO GAIN PRE-EMPHASIS AGAINST AMPLIFIER. AMPLIFIED SIGNAL
PASSES BY IDC AMPLIFIER (U15/A) & ANALOGUE SWITCH (U9/B). AND IT IS DELIVERED
THROUGH CROSSTALK FILTER (U15/B) TO REMOVE UNNECESSARY SIGNALS OVER 3
kHz. THEN, FILTERED SIGNAL IS APPLIED TO MODULATING CIRCUIT.
MODULATING CIRCUIT MODULATING CIRCUIT MODULATING CIRCUIT MODULATING CIRCUIT
MODULATING CIRCUIT MODULATES VCO OSCILLATING SIGNAL (RF SIGNAL), USING
MICROPHONE VOICE SIGNAL. VOICE SIGNAL FROM CROSSTALK FILTER (IC13b) IS
APPLIED TO MODULATE SIGNAL, OSCILLATED AT TXVCO (Q7), AFTER
PASSING FREQUENCY ADJUSTING PORT (R172) & CHANGING REACTANCE OF D8 AT
MODULATING CIRCUIT (D8).
DRIVE AMPLIFYING CIRCUIT DRIVE AMPLIFYING CIRCUIT DRIVE AMPLIFYING CIRCUIT DRIVE AMPLIFYING CIRCUIT
DRIVE AMPLIFYING CIRCUIT AMPLIFIES VCO OSCILLATING SIGNAL TO THE LEVEL,
POWER AMPLIFIER NEEDS. VCO OUTPUT IS APPLIED TO Tx/Rx SWITCH (D8). Tx SIGNAL
FROM Tx/Rx SWITCH AMPLIFIES PRE-DRIVE (Q19) & DRIVE (Q18) AMPLIFIER, IN ORDER
TO GAIN SIGNAL LEVEL ABOUT 200mW. THEN AMPLIFIED SIGNAL IS APPLIED TO RF
POWER AMPLIFIER (U8).
POWER AMPLIFIER CIRCUIT POWER AMPLIFIER CIRCUIT POWER AMPLIFIER CIRCUIT POWER AMPLIFIER CIRCUIT
POWER AMPLIFIER CIRCUIT AMPLIFIES DRIVER SIGNAL TO THE OUTPUT POWER
LEVEL. U8 IS POWER MODULE, WHICH HAS ABOUT 35W AMPLIFYING OUTPUT
FUNCTION AGAINST 300mW INPUT. OUTPUT FROM U8 (PIN 4) IS DELIVERED BY
ANTENNA CHANGING CIRCUIT (D9). THEN, IT IS APPLIED TO ANTENNA CONNECTOR
VIA LOW PASS FILTER.