Nautel VS300, Operation And Maintenance Manual

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VS300 Operations and Maintenance Manual Description
Issue 8.0 2016-03-01 Page 1-3
Exciter/control stage
See also electrical schematic Figure
SD-1
and Audio Path Block Diagram Figure 1.2 on page 1-8 .
Detailed schematics are not included in the Troubleshooting Manual .
The exciter/control stage performs many critical functions for the transmitter. The primary
component of this stage is the exciter/control PWB (A1).
The exciter portion of the exciter/control PWB performs the following functions:
• accepts the audio inputs and generates the RF drive signal required to modulate the audio
signal at the desired carrier frequency.
• measures the audio input level.
• provides the status of any exciter fault conditions.
The control portion of the exciter/control PWB performs the following functions:
• contains monitoring and protection circuits to prevent transmitter damage under adverse or
fault conditions, including high speed SWR protection and interlock/muting.
• monitors the current value of various parameters including cooling fan tachometer outputs,
transmitter output forward and reflected power, PA temperature, PA current levels, and PA
power supply status signals.
• measures and monitors the the output voltage from the power supply module as well as the
low voltage supplies (+15 V and +5 V) and +48 V power supply.
• generates the dc bias signals for the pre-amp and PA PWBs.
• generates the signals that enable the power supply module and control its output voltage.
• provides the status of any controller fault conditions.
• an integral DSP performs all audio processing including filtering and FM baseband
modulation.
• interfaces with the RF and power supply sections of the transmitter to perform control and
monitoring functions.