Roadstar CLT-700 free download

File name CLT-700.pdf

CLT-700 R Service Manual - CLT-700 1. DESCRIPTION OF EQUIPMENT 1. TYPE OF THE CIRCUIT A. BASE UNIT RECEIVER ; Double conversion superheterodyne receiver B. HANDSET RECEIVER ; Double conversion superheterodyne receiver 2. FREQUENCY AND CHANNELS A. BASE UNIT TX RX TX RX CT1 CT1+ 930.0125MHz ­ 931.9875MHz 885.0125MHz ­ 886.9875MHz 959.0125 ­ 959.9875MHz 914.0125 ­ 914.9875MHz B.HANDSET 914.0125 ­ 914.9875MHz 885.0125MHz ­ 886.9875MHz 959.0125 ­ 959.9875MHz 930.0125MHz ­ 931.9875MHz 40 25KHz 80 25KHz C. CHANNELS D. CH SPACING 3. TRANSMIT POWER : 10mW 4. OPERATING VOLTAGE A. BASE UNIT ; B. HANDSET ; AC 230V / 50Hz DC 3.6V 5. OPERATING TEMPERATURE : 0 ~ 55 C 2. CIRCUIT DESCRIPTION A. BASE UNIT 1. Power supply circuit The DC 9V from the AC adaptor is supplied to JP3 (DC modular jack). This input voltage is supplied to the main circuit through D8 (diode) and supplied to the charge circuit. The voltage from D8 is regulated to 5V by regulator U9. This regulated 5V is supplied to main circuit and RF circuit. 2. Charging circuit Charging circuit is composed of U11, Q11, Q12, R99, R100, R102, R103 and R104. This charging circuit supplies constant current to the handset batteries through CHG+1 and CHG-1. When the charge current flows through R100, U11 (photo-coupler) detects the current and send a CHARGE signal to pin 23 of U4 (CPU). Then LD4 (VISION) or LD6 (INNO)1 is lighted by the command from CPU (pin 28) LED_CHG. 3. Receiving audio signal from telephone line The audio signal from JP1 (telephone line modular jack) goes pin 1 of U1 (speech network) through bridge diode composed of D1, D2, D3 and D4, C814 and switching transistor Q3. After being amplified in speech network, it comes out from pin 4 and goes to the pin8 of U10 (compander) through R81 and C62. This signal is amplified and compressed for noise reduction then goes through 3rd order low pass filter composed of op amp in U10, C52, C53, C54 R72, R73 and R74. This signal is sent to the modulation input (MOD_AUDIO) of the RF block through C51, R70 and RV3 and transmitted to the handset. 4. Sending audio signal to telephone line Received RF signal from handset is detected in the RF block and the demodulated audio signal (DEMOD_AUDIO) is filtered by low pass filter composed of U8A, C41, C42, C43, R57, R58 and R59 through C44. This audio signal is filtered again by high pass filter composed of op amp in U10, C37, C38, C39, R53, R54 and R55 then expanded in U10. The expanded signal coming from pin 19 of U10 goes to the pin 6 and 7 of U1 (speech network) through C34 and R52. Speech network adjusts a transmit signal gain and sends it to the telephone line through switching transistor Q3, bridge diode (D1, D2, D3 and D4) and modular jack JP1. 5. Sending and Receiving of data signal The sending MSK data comes out from TX_DATA of CPU (pin 43), and enters into pin 4 of U10 (compander). It is modulated at RF block through the same path as audio signal. The received MSK data which demodulated at RF block