TM 5-6635-386-12&PWARNINGInsure that the tester handle is placed in the safeposition prior to placing the tester into theapproved carrying case.Upon completion of testing, remove battery pack andstore in storage case separately from tester. There is noON/OFF switch and today’s last readings will still beavailable when the tester is used next.1-5. SOURCE ACTUATIONThe shutter is released by pulling back on the handlelatch pin and pressing down on the handle.The shutter is spring loaded and closes automaticallywhen the handle is raised to the SAFE position.The operator should insure proper latch or handleposition by visually checking the latch pin for full forwardlocation at the desired depth.Lock the source rod when in storage by pushing in thelock button on the end of the rod. Key required to unlockhandle.After repeated tests the shutter mechanism will becomedirty with accumulated soil pulled into the chamber onthe end of the source rod. The shutter will jam orbecome sticky. See Para 3-6 for shutter maintenance.Do not force the source rod to open the shutter.1-6.TO MEASURE OR TAKE A TEST, GENERALThe following operations are required to take a field test:a.Take a Standard Count.b.Prepare the Site.c.Take a Reading on the Site.d.Determine Moisture and Density from theCharts.e.Compute Percent Compaction.WARNINGInsure that the tester handle is placed In thesafe position prior to placing the tester into theapproved carrying case f. Store the TesterAway.1-7. STANDARD COUNTNuclear tester performance is affected by the decay ofthe radioactive source, by aging of the electroniccomponents, and by minor mechanical wear and tear.As with any measurement tool, it is necessary to checkthe tester against a reference standard periodically toinsure continued accurate operation.This is achieved with your tester by the taking of aStandard Count on the reference standard furnished withthe tester. Variations in tester performance will affect theStandard Count in the same proportion as they will affectthe field counts.Should variations in tester performance occur, thesevariations will affect both the field and standard countsproportionately, thus the final ratio remains constant andthe tester remains accurate. The standard count thusbecomes a means of continual calibration correction forthe nuclear tester.A further benefit can be achieved from the standardcount due to the statistically reliable nature of the decayof the radioactive source over short periods of counting.The following paragraphs describe methods ofevaluating tester performance using inspection of aseries of successive counts in a standard count series.1-8. HOW TO TAKE A STANDARD COUNTManual and automatic are two methods of taking astandard count. Both use the same mechanical setup.They differ only in the method of accumulating the finalcount results.1-8
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