Fluke 35040 manual Timed Charge Measurements, Average Current Measurements

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35040

Operators Manual

Measurement Accuracy: Charge measurement accuracy is warranted to be better than ± (0.20%rdg + 2 counts) over the operating temperature range of 18°C to 28°C for 1 year.

Field Calibration: Field calibrations may be performed via a restricted distribution MS-DOS Calibration program. This program is available to the AAPM accredited calibration laboratories (or equivalent) and may be used to adjust the current and charge scale factors from their nominal factory setting of 1.000.

Timed Charge Measurements

Range and Resolution: Same as charge measurements.

Measurement Method: The timed charge measurement is derived by monitoring the charge integrated over a time interval that begins with the activation of the timer. The timer automatically stops when the elapsed time is equal to the timer interval setting or the exposure is over. Interpolation is used to determine the charge at an integral number of seconds.

Measurement Accuracy: Same as charge measurements assuming that the rate of charge delivery does not dramatically change within the interpolation window interval.

Current Measurements

Range, Resolution, and Noise:

Full Scale Range

Display Resolution

Noise

(± counts)

 

 

 

 

200.0

pA

0.1

pA

2

 

 

 

 

2.000

nA

0.001 nA

2

 

 

 

 

 

20.00

nA

0.01

nA

1

 

 

 

 

 

200.0

nA

0.1

nA

1

 

 

 

 

1.000

μA

0.001 μA

1

 

 

 

 

 

Measurement Method: The basic current measurement is derived by monitoring the change in the integrated charge level over successive 1-second intervals. Dividing the change in integrated charge by the 1-second integration period interval yields the current value.

Measurement Accuracy: Current measurement accuracy is ± (0.20%rdg + 2 counts) over the operating temperature range of 18°C to 28°C for 1 year. Since the current measurements are based directly upon charge measurements, an independent current calibration is not required.

Measurement Noise: Current measurement noise is typically 1 to 4 counts peak to peak (depending upon the range) when the input is supplied by a quiet DC current source. When using a 0.6 cc Farmer Probe to measure the output of a typical 60Co source, noise in the current measurement may be on the order of 0.4 R/min peak to peak at 100 R/min. Normal variations in the output exposure rate produced by a linear accelerator may result in excessive noise on the current measurement.

Response Speed: The display of current measurement values will begin within 1 second of the start of the exposure and reach 99% of the final level within 2 seconds.

Average Current Measurements

Range and Resolution:

Full Scale Range

Display Resolution

200.00 pA

0.01

pA

 

 

2.0000 nA

0.0001 nA

 

 

 

20.000 nA

0.001

nA

 

 

 

200.00 nA

0.01

nA

 

 

 

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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 Maximum Error SpecificationsFactory Calibration Error Source ± %rdg Manual AddendaTimed Charge Measurements Full Scale Range Display Resolution Noise ± countsFull Scale Range Display Resolution 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 DescriptionMicroController Power SupplyFront Panel Serial Communications PortBias Supply Basic Operating EquationsElectrometer Multiplexer and A/D ConverterQAccum Quantity Description Units CommentsQExposure QAccumpreviousLeakage Measurements Charge and Current Measurements= time of electrometer conversion s Exposure Charge and Dose Timed Charge and DoseAccumulated Charge and Dose Setting ThresholdsPredicted Timed 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 MaximumFront Panel Familiarization SetupSetup 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 ChambersOperation Instructions PowerBattery Care 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 Annunciators Reset Error With Automatic Leakage Compensation EnabledAnnunciators Annunciator Condition? left of value Measurement Indicators and ConditionsIndicator Measurement Condition Condition Overranged MeasurementConnection to the Computer Installing/Uninstalling Customization SoftwareCustomization 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 LineSelecting an Item and Placing It Using the APPEND, DELETE, and Insert ButtonsDisplay Line Group Selection Changing a Line on a DisplayTimer Intervals 38. The Timer Intervals FormBias Settings 39. The Bias Settings FormExamples Appending a Display Changing the Pressure UnitsCustomizing a Measurement Display Deleting a DisplayErrors Troubleshooting and Service TroubleshootingSymptom HiBias annunciator displayed Symptom Display does not light up when Power is pressedSymptom ??Bias annunciator displayed Symptom LoBias annunciator displayedBit Description Action Symptom Internal Reset Error displayedSymptom Configuration Error displayed Do not makeSymptom Bias voltage measurement changes by one digit Symptom Current Overrange DisplayedSymptom Dashes displayed instead of digits 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 Recalibration, Repair Information & Technical Assistance Warranty InformationReplaceable Parts List 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
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