| T O P I C    R E V I E W | 
               
              
                | atomic.dave | 
                Posted - 01/14/2012 : 22:27:04  How do you calibrate the GMC280? | 
               
              
                | 1   L A T E S T    R E P L I E S    (Newest First) | 
               
              
                | ZLM | 
                Posted - 01/15/2012 : 01:37:37  GMC-080, GMC-280 CPM reading does not need a special calibration, as long as the tube voltage is set correctly. The on board hardwae take care the accuracy of CPM.
  If you want uSv/h  or  mR/h  reading correctly, the factory default value is for M4011 tube or similar tube such as SBM-20. You do not need to do calibration on those those two tubes. Unless you found the value is offset too much.
  Other tubes need a reference source with a known uSv/h.  Then place the source with GMC-280 to get CPM, and input this CPM and the known uSv/h in calibration menu.   It accepts up to three reference values.
 
  The first calibration data CPM should be always background CPM, then the uSv/h value normally is 0.05 uSv/h.  This 0.05 uSv/h value is the typical background radiation dosage value. If you location is near rocky mont, then the value may be higher.
 
 
 
  | 
               
             
           | 
         
       
       
     |