4. THEORY OF OPERATION page 16
Model PRM-470B
4.1.3. Detector Assembly:
The detector assembly converts gamma radiation into a voltage pulse. The voltage pulse is
amplified on the PRCB-001 board so it can be counted and analyzed. The detector consists of
organic plastic scintillation material, with a PMT coupled to it using optical adhesive. The
whole assembly is wrapped in light tight materials.
4.1.4. Voltage Divider Assembly:
Refer to "PB-10M Voltage Divider Schematic Diagram" Drawing 8 and "PB-10M Voltage
Divider Component Designator" Drawing 9 (Appendix F.).
The Voltage Divider Assembly is made up of the tube socket and voltage divider (resistors and
capacitors). It divides the incoming high voltage for the dynodes in the PMT, and decouples the
signal from the high voltage.
4.1.5. Batteries and Battery Charger:
The instrument operates on four, AA size, alkaline batteries. When the batteries have discharged
to the point that they will no longer reliably operate the instrument, it will display "LO" and stop
operating. Replace the batteries with a fresh set.
NOTE:
The alkaline batteries are not rechargeable. The charger jack has been disabled.
4.2. SELF TEST (SYSTEM RAM)
When the PRM is turned on it will automatically test the system RAM. Immediately after
turning the instrument on, the display will show "8.8.8.8" and the beeper will sound. The beeper
continues to sound for approximately two seconds while the instrument goes through the RAM
test.
