Technical Manual

Controller Board
Appendix A - UHF Circuit Descriptions
A-12
ATLAS 4500 Multimode Station Technical Manual July 2021
A.4.1 General Description
The Controller PCB contains the following:
• The main microcontroller IC1 containing CPU, flash, RAM, UARTs, ports etc
• Data latches
• Serial Flash
• 3.3-V and 5-V linear regulators
• Power on reset IC
• PA I/F, etc
• Control /noise filter for the fan in the PA
• 10 MHz osc det I/P used for 10 MHz ref switch control in the Exciter
• DSP I/F port
• Exciter I/F port
• Receiver I/F port
• Relay O/P
• LED I/F
• Configuration links
A.4.2 Schematic Description
A.4.2.1 PA Interface
The interface has 14 pins. The PA interface provides 24 V 450 mA and 5 V 10 mA.
It controls the PA by means of the PTT line and the bias line [nominally 4 V at
77°F (25°C)].
The forward power and reverse power detector voltages are transferred to the
controller. The PA copper plate temperature can be read through a single pulse
width modulation line.
During power up, the Controller loads the PA calibration data from the Serial flash
IC on the I2C bus. This bus is also used for initial PA calibration.
A.4.2.2 Exciter Interface
The Exciter interface has 30 pins. The Exciter interface provides
approximately13.8 V at approximately0.6 A. The interface includes:
• Synth – 4 x Lines are provided for 4 VCO controls, 3 x synth frequency setting
lines, lock alarm.