SmartTrunk Systems ST-2112D, Service Manual, Page: 2 / 55

ST-2112D SM R 1.2 SMARTRUNK SYSTEMS, INC. 2
Table of Contents
1. Specifications: ............................................................................................................................... 5
2. ST-2112 EXPLODED VIEW .............................................................................................................. 6
3. ST-2112 SIMPLIFIED DIAGRAM ..................................................................................................... 7
4. - ST-2112 RF DESCRIPTION ................................................................................................................ 8
4.1. Circuit Configuration ................................................................................................................. 9
4.2. Receiver System ........................................................................................................................ 9
4.2.1. Front-end RF Receiver ........................................................................................................... 9
4.2.2. ANALOG Audio Processing .................................................................................................... 9
4.2.3. Virtual Squelch Circuit ........................................................................................................... 9
4.2.4. Virtual VOLUME CONTROL .................................................................................................. 10
4.2.5. Sub audio signaling ............................................................................................................. 10
4.2.6. ANALOG AUDIBLE SIGNALING ............................................................................................. 10
4.2.7. DIGITAL AUDIO PROCESSING .............................................................................................. 10
4.3. Transmitter System ................................................................................................................. 11
4.3.1. ANALOG TX SIGNAL ............................................................................................................. 11
4.3.2. DIGITAL TX AUDIO: .............................................................................................................. 11
4.3.3. Drive and Final Amplifier Stages ......................................................................................... 11
4.3.4.
Automatic Transmit Power Control .................................................................................... 12
5.
RC-2112 ALIGNMENT .................................................................................................................. 13
5.1. Introduction ............................................................................................................................ 13
5.2. ALIGNMENT:............................................................................................................................ 13
5.3.
Alignment Procedure .............................................................................................................. 14
5.3.1. GENERAL ALIGNMENT CONSIDERATIONS: .......................................................................... 14
5.4. MAIN RADIO ALIGNMENT ....................................................................................................... 15
5.5. TRANSMITTER ALIGNMENT: ................................................................................................... 15
5.5.1. Main Clock alignment: ........................................................................................................ 16
5.5.2. Transmit Power alignment: ................................................................................................. 17