Samyung STR-6000A, Руководство по обслуживанию

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APC APC APC APC (AUTOMATIC POWER CONTROL) CIRCUIT (AUTOMATIC POWER CONTROL) CIRCUIT (AUTOMATIC POWER CONTROL) CIRCUIT (AUTOMATIC POWER CONTROL) CIRCUIT
APC CIRCUIT STABILIZES Tx OUTPUT POWER. RF OUTPUT SIGNAL FROM POWER
AMPLIFIER (U8) IS DETECTED TO OUTPUT DETECTING CIRCUIT (D13, D14). THEN, IT IS
APPLIED TO ONE OF DIFFEENTIAL MOTION AMPLIFIER (Q22) INPUTS VIA High/Low
CONTROL CIRCUIT (VR2, Q23). APPLIED POWER CONTROLS DIFFEENTIAL MOTION
AMPLIFIER (Q22) OUTPUT & BIAS VOLTAGE CONTROL (Q17). LIKE THIS, APC CIRCUITS
KEEPS CERTAIN OUTPUT POWER.
PLL
PLL PLL
PLL (PHASE LOCKED LOOP) CIRCUIT
(PHASE LOCKED LOOP) CIRCUIT (PHASE LOCKED LOOP) CIRCUIT
(PHASE LOCKED LOOP) CIRCUIT
OUTLINE OUTLINE OUTLINE OUTLINE
PLL CIRCUIT PROVIDES STABLE OSCILLATING OF Tx FREQUENCY & Rx THE 1-LO
FREQUENCY. PLL CIRCUIT COMPARES PHASES OF VCO FREQUENCIES, DIVIDED TO
STANDARD FREQUENCIES. PLL OUTPUT FREQUENCIES ARE CONTROLLED BY
DIVIDING RATE OF MODIFYING OSCILLATOR & PROGRAM POSSIBLE DIVIDER. U5 IS
PLL IC, WHICH INCLUDES VCO CIRCUIT CONTROL & FREE SCALER FOR Tx, Rx,
PROGRAM POSSIBLE COUNTER, PROGRAM POSSIBLE DIVIDER, PHASE DETECTER,
CHARGE PUMP, ETC. PLL CIRCUIT DIRECTLY CREATES TX FREQUENCIES & Rx 1-1F
FREQUENCIES ON ONE CHIP PLL IC (U5) TOGETHER WITH VCO. IT SETS DIVIDING
RATE, ACCORDING TO SERIES DATA FROM PLL CPU, AND COMPARES PHASES OF
VCO SIGNALS, TOGETHER WITH STANDARD OSCILLATING FREQUENCIES. RESULTS,
PHANSE DETECTED FROM PLL IC, ARE SUPPLIED FROM PIN2 AGAINST EACH Tx & Rx.
STANDARD FREQUENCY (21.25 MHz) IS OSCILLATED AT X2.
PLL PLL PLL PLL LOOP LOOP LOOP LOOP
SIGNALS, CREATED FROM VCO (Q15, D11, D17) ARE INPUT TO PLL IC (U5, PIN 6). THEN,
IT IS APPLIED TO PHASE DETECTER, AFTER BEING DIVIDED FROM PROGRAM
POSSIBLE DIVIDER. PHASE DETECTER COMPARES INPUT SIGNALS WITH STANDARD
FREQUENCY, THEN, IT OUTPUTS SIGNALS (PULSE-FORM-SIGNAL) OF PHANSE
DISCREPANCIES AT PIN 2. SIGNAL OF PULSE-FORM IS CHANGED TO DIRECT VOLTAGE
(LOCK VOLTAGE) AT LOOP FILTER (C132, C143, C140, R73, R72). THEN IT IS APPLIED IN
ORDER TO STABILIZE OSCILLATING FREQUENCIES OF VARACTOR DIODES (D11, D17)
OF VCO.