QUANTUN QP650U Plus, Service Manual

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QP-650U Plus Circuit Description
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PTT/RXD RSSI
MONI BUSY
QT_IN VOXDET
BATT LD
BEEP APC_SW
DTMFO QT_OUT
APC/TV SAVE
W/N M_Band
SPV_C MIC_EN
CTC/CDC Code
PLL IC
Audio Processor
TXD/RXD
Fig.6 MCU Block Diagram
Circuit in this section is mainly comprised of MCU, EEPROM etc.
MCU control circuit accomplishes the following functions: accomplish the reset initialization
according to the programmed feature of the radio when power on; detect keying signal and monitor
battery voltage; send necessary frequency data to PLL according to encode of the channel; switch and
control transmit/receive according to the signal input from PTT; turn on/off the mute circuit according to
the input signaling decode signal and squelch level signal; output control signal to control the light/off of
LED; control signaling process IC to perform tasks.
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