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3.4 Control Head ........................................................................................................... 17
3.4.1 Block Diagram ............................................................................................... 17
3.4.2 Working Principle .......................................................................................... 17
3.4.3 MCU Reset .................................................................................................... 17
3.4.4 Key and Display Management ...................................................................... 17
3.5 Rear Board .............................................................................................................. 18
3.5.1 Block Diagram ............................................................................................... 18
3.5.2 Working Principle .......................................................................................... 18
3.6 Troubleshooting Flow Chart ..................................................................................... 19
4. Tuning Description ............................................................................................................ 20
5. Interface Description ......................................................................................................... 21
5.1 Internal Interface ..................................................................................................... 21
5.2 External Interface .................................................................................................... 27
6. UHF1 (400–470 MHz) Information .................................................................................... 29
6.1 Transmitter Circuit ................................................................................................... 29
6.1.1 RF Power Amplifier Circuit ............................................................................ 29
6.1.2 Low-Pass Filter Circuit .................................................................................. 30
6.1.3 Auto Power Control Circuit ............................................................................ 30
6.2 Receiver Circuit ....................................................................................................... 31
6.2.1 Receiver Front-End ....................................................................................... 31
6.2.2 Receiver Back-End ........................................................................................ 32
6.3 FGU ......................................................................................................................... 33
6.3.1 Working Principle of PLL ............................................................................... 33
6.3.2 Working Principle of VCO .............................................................................. 34
6.3.3 Two-Point Modulation .................................................................................... 34
6.4 PCB View ................................................................................................................ 35
6.5 Block Diagram ......................................................................................................... 40
6.6 Schematic Diagram ................................................................................................. 45
6.7 Parts List ................................................................................................................. 68
6.8 Troubleshooting Flow Chart ................................................................................... 124
6.8.1 Receiver Circuit ........................................................................................... 124
RDR9000 Service Manual
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General