REXON LIS 2013 FuG 13b, Руководство по обслуживанию

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control audio power amplifier ( U301 ). The mute control switch is achieved with U202 pin 12
to control transistor ( Q301 ) to mute demodulator signal. The U202 control by MCU(U101).
• TX AUDIO
The audio signal is passed to high pass filter from microphone jack and scr sw, the high pass
filter contains
C402, C403, C404, R413, R414 & U401(A) , and then the signal gets into C405,
R403, U401 (2/4) amplifier to an adjustment VR401 to limit modulation deviation,
The U401(C) is limiter & combiner.
The U401(D) is low pass filter.
Q401 & Q402 control deviation channel spacing. Q403 controls
microphone mute circuit.
Q404 that is control modulation level.
MICRO-CONTROLLER UNIT
LCD Display
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DIGITAL CONTROL
MCU (U101) is an 8-bit micro-processor with 64KB ROM & 2KB RAM memory.
Micro-processor functions as following:
• LCD driver.
• EPROM programming read/write.
• TX / RX mode control.
• Keypad I/O control.
• PTT (Push To Talk) control.
• RSSI Indicator of radio signal-strength.
• Squelch control.
• MCU clock shift control.
• Series clock and data control.
• Hi / Lo power & power enable control.
• Indicator of battery capacity.
• POWER SUPPLY CIRCUIT
The Power energy is from 7.5VDC NI-MH or li-ion battery pack which offer to audio power
amplifier & TX PA unit supplies to regulator (U201) for obtain converted 5VDC (VCCS) supply
for digital, Q201 (T5V), Q202 (R5V), Q203 (S5V) and TX5.
4