Hytera MD78X Service Manual page 6

Service Manual
9.1.11 Pressure Pad Switch ........................................................................................................ 103
9.2 Receiver Circuit ............................................................................................................................ 103
9.2.1 Receiver Front-end ............................................................................................................. 104
9.2.2 Receiver Back-end ............................................................................................................. 105
9.3 Frequency Generation Unit (FGU) ............................................................................................... 105
9.3.1 PLL Synthesizer ................................................................................................................. 105
9.3.2 Reference Oscillator ........................................................................................................... 106
9.3.3 PLL IC ................................................................................................................................. 106
9.3.4 VCO .................................................................................................................................... 107
9.4 PCB View ...................................................................................................................................... 108
9.5 Block Diagram .............................................................................................................................. 112
9.6 Schematic Diagram ...................................................................................................................... 115
9.7 Parts List ....................................................................................................................................... 129
9.8 Troubleshooting Flow Chart ......................................................................................................... 167
10. UHF2 (450-520MHz 25W) Information .......................................................................................... 173
10.1 Transmitter Circuit ...................................................................................................................... 173
10.1.1 Power Amplifier ................................................................................................................ 173
10.1.2 TX Buffer Amplifier ........................................................................................................... 173
10.1.3 Pre-driver Power Amplifier ............................................................................................... 174
10.1.4 Driver Power Amplifier ...................................................................................................... 174
10.1.5 Final Power Amplifier ....................................................................................................... 174
10.1.6 Antenna Switch ................................................................................................................. 174
10.1.7 Low-pass Filter ................................................................................................................. 174
10.1.8 Directional Coupler ........................................................................................................... 175
10.1.9 Output Power Control ....................................................................................................... 175
10.1.10 Thermal and Over-voltage Protections .......................................................................... 175
10.1.11 Pressure Pad Switch ...................................................................................................... 175
10.2 Receiver Circuit .......................................................................................................................... 175
10.2.1 Receiver Front-end........................................................................................................... 176
10.2.2 Receiver Back-end ........................................................................................................... 177
10.3 Frequency Generation Unit (FGU) ............................................................................................. 177
10.3.1 PLL Synthesizer ............................................................................................................... 177
10.3.2 Reference Oscillator ......................................................................................................... 178
10.3.3 PLL IC ............................................................................................................................... 178
10.3.4 VCO .................................................................................................................................. 178
10.4 PCB View .................................................................................................................................... 180
10.5 Block Diagram ............................................................................................................................ 184
10.6 Schematic Diagram .................................................................................................................... 187
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