4. THEORY OF OPERATION page 15
Model PRM-470B
4. THEORY OF OPERATION
The PRM-470B is designed to locate radioactive sources and measure intensity in the field. It
uses low power CMOS electronics to provide over 60 hours of operation from the NiCad
batteries. For emergency response or other applications where rechargeable batteries are not
suitable, the PRM-470B features a self test during power-up, automatic background count and
user determined alarm settings.
For wiring, and signal flow information, refer to "PRM-470B Internal, 3D View" Drawing 2 and
"PRM-470B Wiring Diagram" Drawing 3 (Appendix F).
4.1. COMPONENTS AND SUBASSEMBLIES
4.1.1. Main Circuit Board, PRCB-001:
Refer to "PCRB-001 Control Board Schematic Diagram" Drawing 4 and "PCRB-001 Control
Board Component Designator" Drawing 5 (Appendix F.).
The PRCB-001 microprocessor control board is the computer board for the system. Its program
runs the PRM and processes the incoming signal from the detector assembly. The signal is
analyzed with the resultant count rate output to the display. The board also accepts input from
the various switches and outputs to the display and beeper.
4.1.2. High Voltage Power Supply, HHV-454:
Refer to "HHV-454 High Voltage Power Supply Schematic Diagram" Drawing 6 and "HHV-454
High Voltage Power Supply Component Designator" Drawing 7 (Appendix F.).
The HHV-454 high voltage power supply supplies regulated high voltage to the voltage divider
assembly to power the PMT (photo-multiplier tube). This assembly is shielded to reduce RFI.
