Hytera HD785 - 3.1 Power Section Details

Service Manual Contents
iii
9.2.1 Receiver Front-end
...........................................................................................................213
9.2.2 Receiver Back-end
...........................................................................................................214
9.3 Frequency Generation Unit (FGU)
..............................................................................................214
9.3.1 Working Principle of PLL...................................................................................................215
9.3.2 Working Principle of VCO
.................................................................................................215
9.3.3 Two-point Modulation
........................................................................................................216
9.4 PCB View....................................................................................................................................217
9.5 Block Diagram
............................................................................................................................225
9.6 Schematic Diagram
.....................................................................................................................228
9.7 Parts Lis
t.....................................................................................................................................244
9.8 Troubleshooting Flow Chart
........................................................................................................295
10. UHF5 (806-941MHz) Information
..................................................................................................301
10.1 Transmitter Circuit
.....................................................................................................................301
10.1.1 RF Power Amplifier Circuit..............................................................................................301
10.1.2 Low-pass Fil
ter Circuit ....................................................................................................302
10.1.3 Auto Power Control Circuit
..............................................................................................302
10.2 Receiver Circuit.........................................................................................................................302
10.2.1 Receiver Front-end
.........................................................................................................303
10.2.2 Receiver Back-end
.........................................................................................................304
10.3 Frequency Generation Unit (FGU) ............................................................................................304
10.3.1 Working Principle of PLL
.................................................................................................305
10.3.2 Working Principle of VCO
...............................................................................................305
10.3.3 Two-point Modulation
......................................................................................................306
10.4 PCB Vi
ew..................................................................................................................................307
10.5 Block D
iagram ..........................................................................................................................315
10.6 Schematic Diagram
...................................................................................................................318
10.7 Parts List...................................................................................................................................334
10.8 Troubleshooting Flow Chart
......................................................................................................388
11. VHF (136-174MHz) Information
....................................................................................................396
11.1 Transmitter Circuit
.....................................................................................................................396
11.1.1 RF Power Amplifier Circuit
..............................................................................................396
11.1.2 Low-pass Fil
ter Circuit.....................................................................................................397
11.1.3 Auto Power Control Circuit
..............................................................................................397
11.2 Receiver Circuit.........................................................................................................................397
11.2.1 Receiver Front-end
.........................................................................................................398
11.2.2 Receiver Back-end
..........................................................................................................399
11.3 Frequency Generation Unit (FGU)
............................................................................................399
11.3.1 Working Principle of PLL
.................................................................................................400