Fluke 35040 manual Basic Measurement Techniques, General Considerations

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35040

Operators Manual

WARNING

Mating and unmating to this connector (or to the other end of a cable already connected to it) should be done only when the bias is set to 0 volts, or when the instrument power is turned off. The central pin and inner shield shell of the triaxial connector are operated at the bias voltage above the outer shell and instrument case. Although the bias potential is energy and current limited, care should be taken to avoid unnecessary and possibly hazardous shocks.

The connector is a triaxial female with dust cap and chain. It connects to any low-noise triaxial male cables. The NE 2571A 0.6 cc Farmer Ion Chamber and other ion chambers may be operated with the Model 35040 Therapy Dosimeter.

The connector is mounted to avoid contaminating spills and dust. Putting its dust cap in place whenever a cable is not connected will help assure long service with minimum leakage problems.

3.7 Basic Measurement Techniques

3.7.1 General Considerations

The dosimeter must be placed on a solid, non-vibrating surface. Both the dosimeter and the operator must be outside the radiation field. Any cable movement will induce a current that may interfere with proper measurements. You should wait ten seconds or more after moving the ion chamber, triaxial cable, or disturbing another part of the high impedance circuit before taking a measurement.

3.7.2 Making Non-Timed Exposure Measurements

With Automatic Leakage Compensation Disabled

The instrument must be manually reset before each exposure when automatic leakage compensation is disabled.

Procedure

•Hold RESET/MEASURE for one second just before making the exposure to reset the instrument. Note that the instrument displays the “Rst” annunciator while the hardware is being reset.

•Wait for the reset to complete.

•Make the exposure.

The exposure measurements will be displayed but may drift due to leakage. Repeat this sequence for every exposure.

With Automatic Leakage Compensation Enabled

In addition to compensating measurements for leakage, the instrument holds the exposure measurements and automatically resets after each exposure when automatic leakage compensation is enabled.

3-4

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Contents 35040 Therapy DosimeterFluke Biomedical Table of Contents Addendum Features of Firmware Version 27JAN00 or Later Troubleshooting and ServiceSample Customization Reports Iii Blank Introduction FeaturesIntroduction Safety Symbols And Terms Before You Start Safety PrecautionsOperators Manual Specifications Factory Calibration Error Source ± %rdgMaximum Error Manual AddendaFull Scale Range Display Resolution Noise ± counts Full Scale Range Display ResolutionTimed Charge Measurements Current MeasurementsEffective Exposure Time Measurements SpecificationsGeneral Measurements High Performance Power Supply and Battery Charger Unpacking and Inspection 35040 Hardware Block Diagram of the Model 35040 Therapy Dosimeter Functional DescriptionPower Supply Front PanelMicroController Serial Communications PortBasic Operating Equations ElectrometerBias Supply Multiplexer and A/D ConverterQuantity Description Units Comments QExposureQAccum QAccumpreviousLeakage Measurements Charge and Current Measurements= time of electrometer conversion s Exposure Charge and Dose Timed Charge and DoseSetting Thresholds Predicted Timed Charge and DoseAccumulated Charge and Dose Exposure Current and RateExposure Time DoseRate = I a × Iccf Units/C × Adcf × RateMultiplier s⎝ P Air Density Correction FactorMm Hg = inch Hg x Standard Resolution Error Units Display Minimum MaximumSetup SetupFront Panel Familiarization IntroductionPowering The System Rear Panel FamiliarizationPower-Up Self-Test and Display Messages Ion Chamber ConnectorGeneral Considerations Basic Measurement TechniquesMaking Non-Timed Exposure Measurements Timer Use Timer Setup3Making Timed Exposure Measurements Battery Care Using Other Ion ChambersPower Battery CareOperation Instructions Front Panel ControlsPowering Up the Model 35040 Therapy Dosimeter Using the Test Function Button Powering Down the Model 35040 Therapy DosimeterOperation Instructions QScaleFactor=1.0000 IScaleFactor=1.0000 12. The Test Function Screen Showing the Timer Settings 5Automatic Leakage CompensationCalibrated by Keithley RMD Nov 15 6Timer Setup 17. The Test Function Screen Showing the Timer SettingsUsing the Detector Select Button Using the AIR Density ButtonUsing the Units Select Button Using the Bias Select ButtonSet 300.0 V 100% Central Electrde Pos IC Bias 300.0 V CEP Using the RESET/MEASURE Button Overranging ConditionsOverrange Conditions Reset ErrorCondition Values Overranged Reset Error With Automatic Leakage Compensation Enabled AnnunciatorsAnnunciators Annunciator ConditionMeasurement Indicators and Conditions Indicator Measurement Condition? left of value Condition Overranged MeasurementInstalling/Uninstalling Customization Software CustomizationConnection to the Computer Starting the Customization SoftwareMenu Items and Controls DownloadingCOM Port Drop Down List Close or File Close Ion ChambersFile Save AS and File Print Edit OK and Cancel Special ItemsDownload and Cancel 36. The Special Items Menu Calibration Temperature has focusMeasurement Displays Operators Manual Available Display Lines Display LineUsing the APPEND, DELETE, and Insert Buttons Display Line Group SelectionSelecting an Item and Placing It Changing a Line on a DisplayTimer Intervals 38. The Timer Intervals FormBias Settings 39. The Bias Settings FormExamples Changing the Pressure Units Customizing a Measurement DisplayAppending a Display Deleting a DisplayErrors Troubleshooting and Service TroubleshootingSymptom Display does not light up when Power is pressed Symptom ??Bias annunciator displayedSymptom HiBias annunciator displayed Symptom LoBias annunciator displayedSymptom Internal Reset Error displayed Symptom Configuration Error displayedBit Description Action Do not makeSymptom Current Overrange Displayed Symptom Dashes displayed instead of digitsSymptom Bias voltage measurement changes by one digit Measurements. ReturnExample 299.9 to Display Will Not Light Low Battery Hours? Is the battery voltage greater than 5.9 volts?Go to Bias ErrorLine Line Fuse Replacement Model 35040 Therapy Dosimeter Fuse ReplacementCleaning The Instrument Interface Connector CleaningReplaceable Parts Information Warranty Information Replaceable Parts ListRecalibration, Repair Information & Technical Assistance Replaceable Parts InformationBlank Sample Customization Reports Sample Documents35040 Appendix Sample Customization Reports 35040 Appendix Sample Customization Reports Blank Overview Introduction New FeaturesTimed Measurements Specifications Update Setup New Features BTimer Use Procedure Timer Setup ProcedureMaking Timed Exposure Measurements RESET/MEASURE Setup BADC ALC Automatic Leakage CompensationStart NA pA Stop Thres Current Operation Instructions BTimer Setup Decimal PlacesTable B-2. Measurement Indicators and Conditions Annunciators, Indicators, and Overrange ConditionsTable B-1. Annunciators Table B-3. Overrange Conditions Condition Overranged Measurement1Theory Of Operation Theory of OperationConfiguration Error Service Required Error Number Measurement Menu Main MenuMeasurement Displays Figure B-9 shows the Measurement Displays dialog box Table B-4. Available Display Lines Figure B-10. The Timer Intervals dialog box Page Fluke Biomedical