Codan 8525B Series - Page 6

iv Table of Contents 8525B/8528 Technical Service Manual
Issue 6 Publication No: 15-02036
4.9 PA and Filters (04-02452)................................................................................4-24
4.9.1 Introduction ...................................................................................4-24
4.9.2 PTT Control...................................................................................4-24
4.9.3 Gain Control Stage........................................................................4-24
4.9.4 Pre-Driver Stages ..........................................................................4-24
4.9.5 Driver Stage...................................................................................4-25
4.9.6 Output Stage and Bias Regulator ..................................................4-25
4.9.7 Output Filters and Control.............................................................4-25
4.9.8 ALC Control..................................................................................4-26
4.9.9 Transmit Indicator.........................................................................4-27
4.10 PA Exciter Interface.........................................................................................4-27
4.10.1 Introduction ...................................................................................4-27
4.10.2 Control Lines.................................................................................4-27
4.10.3 Power On/Off................................................................................4-27
4.10.4 PTT Circuit....................................................................................4-27
4.10.5 Transmit Amplifier........................................................................4-28
4.10.6 Receive Circuit..............................................................................4-28
4.10.7 Antenna Control............................................................................4-28
4.10.8 PA Unit..........................................................................................4-28
4.11 Selective Calling (04-02250)............................................................................4-29
4.11.1 Selective Calling ...........................................................................4-29
4.11.2 Selective Call Detection (04-02250).............................................4-30
4.12 Two-Tone Calling ............................................................................................4-31
4.12.1 Two-Tone Calling .........................................................................4-31
4.12.2 Two-Tone Detection......................................................................4-31
4.13 Option PS—External Signalling Interface .......................................................4-33
4.13.1 External Selective Calling.............................................................4-33
4.13.2 Selective Call Scanning.................................................................4-34
4.13.3 RTTY—ARQ mode......................................................................4-34