Samyung STR-6000A, Руководство по обслуживанию

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11.
11. 11.
11. CIRCUIT EXPLANATION
CIRCUIT EXPLANATION CIRCUIT EXPLANATION
CIRCUIT EXPLANATION
RX RX RX RX
ANTENNA CHANGEOVER CIRCUIT
ANTENNA CHANGEOVER CIRCUIT ANTENNA CHANGEOVER CIRCUIT
ANTENNA CHANGEOVER CIRCUIT
ANTENNA CHANGEOVER CIRCUIT'S FUNCTION IS A LOW-PASS FILTER IN RECEIVING,
TUNING CIRCUIT IN TRANSMITTING. CIRCUIT PROTECTS TRANSMITTING SIGNALS
FROM BEING INPUT TO RECEIVING CIRCUIT. RECEIVING SIGNAL IS INPUT TO MAIN
UNIT THROUGH ANTENNA CONNECTOR & LOW-PASS FILTER (L12, L13, C102-C104,
C97). INPUT SIGNAL IS APPLIED TO RF CIRCUIT VIA THE NEXT ANTENNA
CHANGEOVER CIRCUIT. (D7, L9, C72. C105)
RF
RF RF
RF CIRCUIT
CIRCUIT CIRCUIT
CIRCUIT
RF CIRCUIT AMPLIFIES SIGNALS WITHIN DESIRED FREQUENCY RANGE, REMOVE
SIGNALS OUF OF BAND. RECEIVING SIGNAL VIA ANTENNA CHANGEOVER CIRCUIT IS
APPLIED TO RF AMPLIFIED CIRCUIT (Q4) THROUGH 2 STEP COMMUTATOR TYPE BAND
PASS FILTER (D2-D3-L3-L4-C40-C42-C41-C44). THE SIGNAL, AMPLIFIED BY Q4, IS
APPLIED TO 2 STEP COMMUTATOR TYPE BAND PASS FILTER (D4-D5-L5-L6-C45-C47-
C46-C52) IN ORDER TO REMOVE UNNECESSARY SIGNAL & IMPROVE THE SELECTION.
THEN, THE SIGNAL IS APPLIED TO THE 1ST MIXER CIRCUIT. D2-D5 ARE CONTROLLED
BY TRANSISTOR, ACCORDING TO THE CALCULATION FROM CPU, IN ORDER TO
ORGANIZE THE ROUTE OF BAND PASS FILTER.
THE 1ST MIXER CIRCUIT & THE 1ST MIDDLE FREQUENCY CIRCUIT
THE 1ST MIXER CIRCUIT & THE 1ST MIDDLE FREQUENCY CIRCUIT THE 1ST MIXER CIRCUIT & THE 1ST MIDDLE FREQUENCY CIRCUIT
THE 1ST MIXER CIRCUIT & THE 1ST MIDDLE FREQUENCY CIRCUIT
THE 1ST MIXER CIRCUIT CHANGES RECEIVED SIGNAL TO THE FIXED FREQUENCY OF
THE 1-1F SIGNAL, TOGETHER WITH THE 1ST LO (VCO OUTPUT) FREQUENCY. DESIRED
FREQUENCY, DERIVED FROM CHANGING THE 1ST LO FREQUENCY, WILL BE
DELIVERED TO THE CRYSTAL FILTER, ORGANIZED AS A PAIR AT THE NEXT STEP OF
THE MIXER.
SIGNAL, DELIVERED FROM RF CIRCUIT, IS MIXED WITH VOC SIGNAL AT THE 1ST
MIXED CIRCUIT(Q5) IN ORDER TO CREATE THE 1-1F SIGNAL OF 21.7MHz.1-IF SIGNAL IS
APPLIED TO THE CRYSTAL FILTER(FL1, FL 2), ORGANIZED AS A PAIR, WHICH REMOVE
SIGNALS OUT OF BAND. THEN, IT IS AMPLIFIED AT IF AMP (Q6). AMPLIFIED SIGNAL IS
APPLIED TO THE 2ND MIXED CIRCUIT (U2).