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Ludlum Measurements 2241-3, Manual

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Model 2241-3 & 3i 

Technical Manual   

 

Section 8

 

Ludlum Measurements, Inc. 

Page 8-21 

January 2016 

 

 

 

Summary of Contents for 2241-3

Page 1: ...LUDLUM MODEL 2241 3 2241 3i SURVEY METER January 2016 Serial Number 299171 and Succeeding Serial Numbers ...

Page 2: ...LUDLUM MODEL 2241 3 2241 3i SURVEY METER January 2016 Serial Number 299171 and Succeeding Serial Numbers ...

Page 3: ...anty of merchantability or fitness which extend beyond the description of the face there of If the product does not perform as warranted herein purchaser s sole remedy shall be repair or replacement at the option of Ludlum Measurements In no event will Ludlum Measurements be liable for damages lost revenue lost wages or any other incidental or consequential damages arising from the purchase use or...

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Page 6: ...ecifications for Model 2241 3i 3 4 Identification of Controls and Functions 4 Display 4 1 Display Status Definitions 4 1 Front Panel Controls 4 2 Front Panel Calibration Controls 4 3 Main Board Controls 4 4 Switch Board Controls 4 5 Safety Considerations 5 Environmental Conditions for Normal Use 5 1 Detector Connector 5 1 Warning Markings and Symbols 5 1 Maintenance 6 Operational Check 6 1 Recalib...

Page 7: ...tup Information 8 8 Counts per minute C m Calibration 8 9 R hr Calibration 8 11 Determining CC and DTC 8 12 Software License Agreement 8 19 Recycling 9 Parts List 10 Model 2241 3 Survey Meter 10 1 Main Circuit Board Drawing 408 285 10 1 Calibration Board Drawing 408 98 10 3 Display Board Drawing 408 259 10 4 Switch Board Drawing 408 45 10 5 Chassis Wiring Diagram Drawing 408 101 10 5 Drawings and ...

Page 8: ... a broad range of radiation levels The display also offers lower limit capability For example the display can be set to show only values that are greater than or equal to1 µR hr This instrument incorporates independent adjustable alarms for RATEMETER and SCALER operating modes The RATEMETER mode has two alarm indicators The first level alarm is indicated by display of the word ALERT on the LCD The...

Page 9: ...the detector operating parameters The instrument is powered by two standard D cell batteries The unit body is made of cast and drawn aluminum with beige powder coating which aids in the decontamination of surfaces The Model 2241 3i is identical to the Model 2241 3 except for the following The five position selector switch located on the front panel has been modified to provide for selection of an ...

Page 10: ...hat the detectors and instruments are not interchanged Each instrument is calibrated to specific detectors and are therefore not interchangeable To return an instrument for repair or calibration provide sufficient packing material to prevent damage during shipment Also provide appropriate warning labels to ensure careful handling Include detector s and related cable s for calibration Every returne...

Page 11: ...y using the cable provided firmly pushing the connectors together while twisting clockwise until the connector latches 1 4 turn The diagram to the left illustrates how this is done Next place the detector selector switch in the appropriate position Operational Check Place the SCA RATE scaler ratemeter switch in the RATE position Notice that the display goes through an initialization sequence The d...

Page 12: ... or repair If desired multiple readings may be taken at different distances and or with different sources so that other ranges or scales are checked Switch the AUD ON OFF switch to the ON position and confirm that the external unimorph speaker produces an audible click for each event detected audio divide by 1 parameter The AUD ON OFF switch will silence the clicks if in the OFF position however a...

Page 13: ...on Depress the COUNT switch located in the end of the carrying handle in order to initiate a count cycle The word COUNTING should be flashing on the LCD during the count cycle and should disappear at the end of the predetermined count time If a scaler ALARM condition occurs the RESET switch can be depressed to acknowledge the alarm however the COUNT switch must be depressed to clear the visual ALA...

Page 14: ...ER Depending upon how the instrument was calibrated the RATEMETER can display in either R hr Sv h cpm or cps when the control switch is in the RATEMETER position SCALER activated by pushbutton in handle when the three position switch is in the SCALER position Count time is adjustable Calibration Controls accessible from the front of the instrument protective cover provided These controls are prese...

Page 15: ...w is approximately 35 mA with the backlight OFF Minimum battery voltage is 2 2 0 1 Vdc Battery Dependence Meter readings vary by less than 3 from fully charged batteries until the battery symbol appears indicating the need for recharge or replacement Battery Life typically 200 hours with alkaline batteries display indicates low battery condition Instrument will operate for approximately 24 hours a...

Page 16: ...10 100 or 1000 events per click Response Time variable or fixed ratemeter response All stated times correspond to a range of 10 to 90 of the final reading Factory default is variable so that the instrument will automatically adjust the response time to the best setting for the current count rate Variable Response dependent on the number of counts present typically 4 to 25 seconds for FAST and 4 to...

Page 17: ...Detector Specifications for Model 2241 3i Operating Voltage recommended 550 volts Input Sensitivity 30 mV 10 mV Dead Time typically 80 microseconds Energy Reponse within 15 Tube 30 mg cm2 stainless steel Halogen quench GM Size 2 3 x 10 2 0 9 x 4 in Dia x L Temperature Range 20 to 50 C 4 to 122 F ...

Page 18: ...tone will accompany the latching ALARM condition Depressing RESET will acknowledge the audible ratemeter and or scaler alarm Depressing RESET a second time will reset the ratemeter reading and ratemeter alarm To reset the scaler ALARM depress the COUNT switch located in the carrying handle to re initiate the scaler count cycle ALERT Ratemeter count has increased above the preset alert threshold To...

Page 19: ...itch The click per event audio may be silenced or enabled via this front panel toggle switch The audible alarm is independent of the AUD ON OFF switch and will override the audible click per event An audible alarm can only be silenced by depressing the RESET button F S Fast Slow Response Switch a two position toggle switch that selects fast or slow counting response time Variable Response The F po...

Page 20: ... the end of the Model 2241 3 carrying handle which when depressed initializes the start of the scaler count accumulation for the preset scaling time The SCA RATE switch must be in the SCA position to initiate the counting cycle The scaler display uses the two digits in the lower right hand corner for the two most significant digits of the six digit readout Scaling time can be set from 1 to 9999 se...

Page 21: ...ote To access the internal circuit boards unlatch the latches at each end of the Model 2241 3 Carefully separate the top chassis from the bottom cover referred to as a can The can has the audio speaker unimorph with a two conductor cable attached to the main board The audio plug may be disconnected during the internal control adjustments HV LIMIT R027 A multi turn potentiometer approximately 20 re...

Page 22: ...yout drawing near the end of the manual All of the setup parameters are stored in the non volatile EEPROM which will retain data even after the Model 2241 3 batteries are removed After the parameters are entered the switch board can be removed and the Model 2241 3 will continue to operate from the previously programmed information Changing parameters and information on switchboard controls are cov...

Page 23: ...ue to condensation This is typical of industrial or construction sites Detector Connector Caution The detector operating voltage HV is supplied to the detector by way of the input connector A mild electric shock may occur if contact is made with the center pin of the input connector Switch the Model 2241 3 to the OFF position before connecting or disconnecting the cable or detector Warning Marking...

Page 24: ...lectric shock During normal use internal components are hazardous live This instrument must be isolated or disconnected from the hazardous live voltage before accessing the internal components This symbol appears on the front panel Warning The operator is strongly cautioned to take the following precautions to avoid contact with internal hazardous live parts that are accessible using a tool 1 Turn...

Page 25: ...essing internal components for maintenance Operational Check An instrument operational check should be performed prior to each use by exposing the detector to the supplied check source confirming the proper reading on each scale See Section 2 Subsection Operational Check for further details Recalibration Recalibration should be accomplished after any maintenance or adjustment of any kind has been ...

Page 26: ...ed and the battery contacts cleaned of any corrosion at least every three months If the instrument has been exposed to a very dusty or corrosive atmosphere more frequent battery servicing should be used Use a spanner wrench to unscrew the battery contact insulators exposing the internal contacts and battery springs Removing the handle will facilitate access to these contacts Note Never store the i...

Page 27: ...r Positive pulses from amplifier U021 are coupled to pin 2 of U011 comparator The discrimination level is set by the DISC control connected to pin 3 of U011 As the positive pulses at pin 2 of U011 increase above DISC reference at pin 3 pin 1 goes low producing a low pulse Pin 1 of U011 is normally held high 5 volts by R014 The low pulse from pin 1 of U021 is coupled to univibrator U001 U001 shapes...

Page 28: ...f stability Microprocessor µP U111 controls all of the data control inputs and display information The clock frequency is crystal controlled by Y221 and related components at 6 144 MHz The µP incorporates internal memory ROM storing the program information U1 resets the µP at power up to initiate the start of the program routine During the program loop the µP looks at all the input switches for in...

Page 29: ...LCD drivers The backplane BP signal from U211 provides the reference signal approximately 125 Hz at 5 Vdc to the LCD DSP1 BP connection When a segment is illuminated the signal to that segment will be out of phase with the BP signal If the segment is OFF the signal will be in phase with the BP signal Backlight Drive Depressing the LIGHT button instructs the µP to set the BACKLIGHT line pin 31 on µ...

Page 30: ...to another character increment the LEFT pushbutton until the desired character is reached The LEFT pushbutton switch enables the operator to sequence through all the characters on the LCD associated with a particular parameter Once the desired data is entered depress the ENTER button The LCD characters should stop flashing and the new parameter data should display Note The DETECTOR SELECT switch a...

Page 31: ...r 0 The Function Switch FUNCTION Switch a 16 position rotary switch labeled 0 9 and A F This switch selects a parameter setup mode for the Model 2241 3 If the board is not installed the normal operation mode counting mode is selected If the switch board is installed the selector switch must be set to the 0 position for normal instrument operation The following may be changed using the switch board...

Page 32: ... the calibration constant for the current detector setup The calibration constant CC adjusts from 0 001 to 280 109 The calibration constant converts counts time base to units time base The CC must be set to 1 to readout in cps counts per second or cpm counts per minute CC CONVERSION TABLE Conversion Rate Multiply by to get CC cps µR hr 3 6 x 109 cps mR hr 3 6 x 106 cps R hr 3 6 x 103 cpm µR hr 6 0...

Page 33: ...v h Sieverts per hour C time base Counts per time The display is auto ranging with the appropriate multiplier symbol appearing in front of the R Sv or C indicating the range µR hr mR hr R hr µSv h mSv h Sv h C s kC s C m kC m POSITION 4 TIME BASE CPS or CPM selects the display time base for the current detector setup This time base only applies if the units are set to C Counts time The time base f...

Page 34: ...me constant TC for the variable mode The fast position varies the TC from 4 25 seconds and the slow position varies from 4 60 seconds Fixed Response The Fast F response position is programmable from 2 50 seconds and the slow response is 5 times slower than the fast TC For MDA type measurements the fixed response time mode is recommended POSITION 7 RATEMETER ALARM ALERT allows changing the ratemete...

Page 35: ...es are 00 0 µ 000 µ 0 00 m 00 0 m 000 m 0 00 00 0 000 R hr 000 µ 000 µ 00 0 m 000 m 0 00 00 0 000 Sv h 0 00 00 0 000 0 00 k 00 0 k 000 kcpm or cps POSITION D RS 232 DATA DUMP MODE allows the RS 232 port to dump ratemeter data every two seconds The Model 2241 3 is fully functional during RS 232 data dump with the exception of the audio function The LCD will alternate between display of the ratemete...

Page 36: ...te the detector Calibration Constant and Dead Time Constant The software is offered in a DOS version part number 1370 025 or a WINDOWS version part number 1370 024 Read the Software License Agreement at the end of this section before installing any LMI software Calibration The Model 2241 3 calibration routine consists of entering detector parameters into memory by way of the switch board and adjus...

Page 37: ...oise are fixed by the physical makeup of the given detector and rarely vary from unit to unit However the selection of the operating point makes a marked difference in the apparent contribution of these three sources of count In setting the operating point the final result of the adjustment is to establish the system gain so that the desirable signal pulses including background radiation are above...

Page 38: ...out a source present Measure the HV output then decrease the HV setting to operate 100 volts below breakdown Proportional Detectors For proportional detectors set the DISC control for 2 millivolt discrimination near maximum clockwise Expose the detector to a check source and plot count rate versus HV similar to the one in the figure below Refine the HV adjustment for optimum source efficiency with...

Page 39: ...trip points If the parameters are undetermined arbitrarily choose 0050 kC m for the alarm and 0045 kC m for the alert to confirm operation of the alert alarm function Position 8 selects the scaler alarm parameter and the scaler count time If the values are unknown set the scaler alarm to 4500ALARM00 and the count time to 0060 60 second count time Position 9 is not used and position A is not used S...

Page 40: ... and ALARMs function by inputting the preset alarm levels as to initiate the alert and alarm conditions R hr CALIBRATION The following calibration procedure assumes that detector Calibration Constant CC and Dead Time Constant DTC are already known If these constants must be determined reference the following subsection Determining CC and DTC Switch the toggle switch to DET2 Detector setup number 1...

Page 41: ...License Agreement at the close of this section prior to installing any LMI software Hi Lo Method The hi lo method refers to the placement of the detector in a radiation field using a two point CC and DT calibration to make linear the detector response even in the non linear operating regions of the detector The low radiation field CC should be a field that yields from 2 to 5 count loss The high ra...

Page 42: ...temeter Alm Alert 8 0060 s ScalerAlm Count Time 9 Not Used A Not Used B N A LCD Backlight C 000 C s Set Minimum Display D F N A RS 232 Parameters Equation 2 DT x 19 1 CPSLO5 The equations to the left Equations 1 4 determine the hi and lo radiation fields used to acquire counts for the CC and DTC algorithm These calculations require an unknown variable DT Dead Time Typical dead times for some of th...

Page 43: ...d be between 240 and 619 cps and the hi field is between 5040 17 650 cps Dividing the cps values by the 55 cps mR hr conversion equates to between 4 11 mR hr for the lo field and 91 320 mR hr for the hi field Select a calibrated field between the lo and hi data points determined above lo CALlo 8 mR hr hi CALhi 200 mR hr The following procedure outlines the hi lo method units Sv R counts CALlo lo f...

Page 44: ...d from equations 1 and 2 Insert the cps hi data point 200 mR hr for the Model 44 9 example determined from equations 3 and 4 Place the detector in the low field and enter the counts per second Note The low field count sample should be 3000 counts Use the scaler and adjust the count time to accumulate count 3000 Equation 5 s 10 x 2 22 s 60 m 1 x m 60 h 1 x h R 0 008 CAL 6 lo Equation 6 s 10 x 55 6 ...

Page 45: ...tion 8 s counts time count SAMPL CORR hi hi Counts second sample in high field of 200 mR hr Example C s 5830 1 5830 CORR hi Insert the values calculated in equations 5 6 7 and 8 and solve for fd Equation 9 s units CORR CAL x CORR CAL f lo lo hi hi d Example s R 10 x 26 2 440 10 x 2 22 x 5830 10 x 55 6 f d 6 6 6 Solve for ad Equation 10 s count units CORR x CAL CORR x CAL a 2 hi lo hi hi d Example ...

Page 46: ...s DT x CORR x CAL CAL f lo lo lo cal Example s R 10 x 2 14 10 x 84 x 440 x 10 x 2 22 10 x 2 22 f cal 6 6 6 6 Enter the result of equation 12 into Equation 13 units count f CORR CC cal lo and solve for CC Example R counts 10 x 206 10 x 2 14 440 CC 6 6 Enter the CC and DT values positions 1 and 2 of the FUNCTION switch derived from the equations above Perform an R hr calibration as described in the ...

Page 47: ... 55 µs 44 2 Gamma Scint 2800 cps mR hr 8 12 µs 44 10 Gamma Scint 15 000 cps mR hr 18 20 µs 44 3 Low Energy Gamma Scint N A operated in Counts units mode 8 12 µs 44 21 Beta Gamma Scint N A operated in Counts units mode 8 12 µs 43 5 Alpha Scint N A operated in Counts units mode 20 28 µs Note The data represented in the table above is typical Actual values may vary among detector and instrument combi...

Page 48: ...Model2241 3 3i TechnicalManual Section8 Ludlum Measurements Inc Page 8 19 January 2016 ...

Page 49: ...Model2241 3 3i TechnicalManual Section8 Ludlum Measurements Inc Page 8 20 January 2016 ...

Page 50: ...Model2241 3 3i TechnicalManual Section8 Ludlum Measurements Inc Page 8 21 January 2016 ...

Page 51: ...ut simply desires to inform its consumers of the range of recyclable materials present in its products so that the user will have flexibility in following all local and federal laws The following types of recyclable materials are present in Ludlum Measurements Inc electronic products and should be recycled separately The list is not all inclusive nor does it suggest that all materials are present ...

Page 52: ... 04 5659 C012 0 1µF 50V 04 5663 C021 100pF 3KV 04 5532 C031 0 0047µF 3KV 04 5547 C032 100pF 3KV 04 5532 C033 0 0047µF 3KV 04 5547 C041 C043 0 0047µF 3KV 04 5547 C101 47uF 10V 04 5666 C121 47uF 10V 04 5666 C122 C123 27pF 100V 04 5658 C131 0 0047µF 3KV 04 5547 C132 C133 0 1µF 50V 04 5663 C134 0 01µF 50V 04 5664 C135 47µF 10V 04 5666 C136 0 01µF 50V 04 5664 C137 47µF 10V 04 5666 C138 100pF 100V 04 56...

Page 53: ...51FC 06 6303 U121 LM285MX 2 5 06 6291 U122 X24C02S8T5 06 6299 U131 LM358D 06 6312 U231 LT1073CS8 5 05 5852 CR021 MMBD7000LT1 07 6355 CR031 GI250 2 07 6266 CR041 CR044 GI250 2 07 6266 CR231 CXSH 4 EB33 07 6358 CR241 MMBD914LT1 07 6353 CR242 CXSH 4 EB33 07 6358 R002 10K 3269X1 103 VOLUME 09 6921 R027 1M 3269X1 105 HV LIMIT 09 6906 R001 100K 1 4W 1 12 7834 R011 R012 10K 1 4 W 1 12 7839 R013 1K 1 4W 1...

Page 54: ...W 1 12 7839 R141 22 1K 1 4W 1 12 7843 R211 2 21K 1 4W 1 12 7835 R231 100Ohm 1 4W 1 12 7840 R241 2 21K 1 4W 1 12 7835 R242 200Ohm 1 8W 1 12 7846 Y221 6 144 MHZ 2 GND 3 GND 01 5262 L231 100uH CTX100 2 21 9740 T101 4275 083 AUDIO 4275 083 T141 L8050 40 0902 P1 P2 1 640456 3 MTA100X13 13 8100 P3 640456 6 MTA100X6 13 8095 P4 640456 2 MTA100X2 13 8073 P5 1 640456 2 MTA100X12 13 8061 BOARD Completely Ass...

Page 55: ...1 3W 12 7751 P7 CONN 640456 7 MTA100 13 8115 BOARD Completely Assembled Display Board 5408 259 C1 27PF 100V 04 5658 U1 AY0438 I L 06 6358 U2 AY0438 I L 06 6358 R001 R004 10 0K 1 125mW 12 7839 R005 392 Ohm 1 1 8 W 12 7054 J1 CONN 640456 8 MTA100 13 8039 DS1 EL BACKLIGHT LED 07 6527 DSP1 MAIN DISPLAY LCD 8246 365 4E1 A W REV1 07 6383 RESISTORS CONNECTOR Display Board Drawing 408 259 CAPACITORS INTEG...

Page 56: ...AYHILL 08 6517 S2 PA 1012 08 6540 S3 S4 7101 SYZ QE C K 08 6511 S5 30 1 PB GRAYHILL 08 6517 S6 7201KZQE Toggle 08 6749 S7 MPS 103F 08 6699 Switch Cap 08 6871 R1 10 M 1 4W 5 10 7031 J1 J2 CONN 1 640442 3 MTA100 13 8138 J3 CONN 640442 6 MTA100 13 8171 J4 CONN 640442 2 MTA100 13 8178 J5 CONN 1 640442 2 MTA100 13 8407 J6 CONN 1 640442 3 MTA100 13 8138 J7 CONN 640442 7 MTA100 13 8172 J8 CONN 640442 8 M...

Page 57: ...e Battery Contact Set 2001 042 Model 2241 3 Main Harness 8408 121 Portable Harness Can Wires 8363 462 Switch Board Harness 8408 027 Portable Can Assembly MTA 4363 441 Can Gasket 22 9773 Portable Knob 08 6613 Assembled Battery Lid 2363 191 Portable Battery Gasket 7363 183 Portable Calibration Cover with Screws 9363 200 Model 2241 3 Flat Handle Assembly without Clip 4408 179 Cable C 1 meter 39 in on...

Page 58: ...nt Layout Drawing 408 286A Calibration Board Drawing 408 98 Calibration Board Component Layout Drawings 408 99 2 sheets Display Board Drawing 408 259 Display Board Component Layout Drawings 408 260 2 sheets Switch Board Drawing 408 45 Switch Board Component Layout Drawing 408 46 Wiring Diagram Drawing 408 101 Wiring Diagram for Model 2241 3i Drawing 408 263 Section 11 ...

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Page 73: ...ity and 1 stop bit 9600 8 N 1 Ludlum Measurements can supply a Windows based software that can be used to help calibrate the instruments but note that it will not communicate with the newer ASCII output Model 2241 2 units Binary Output Format 15 Bytes BYTE01 RatemeterCPS 0 MSB BYTE02 RatemeterCPS 1 BYTE03 RatemeterCPS 2 BYTE04 RatemeterCPE 3 LSB BYTE05 Scaler 0 MSB BYTE06 Sclaer 1 BYTE07 Scaler 2 ...

Page 74: ...TE04 CaConstant 0 MSB BYTE05 CalConstant 1 BYTE06 CalConstant 2 BYTE07 CalConstant 3 BYTE08 CalConstant 4 BYTE09 CalConstant 5 LSB BYTE10 RateAlarm 0 MSB BYTE11 RateAlarm 1 BYTE12 RateAlarm 2 BYTE13 RateAlarm 3 BYTE14 RateAlarm 4 LSB BYTE15 ScalerAlarm 0 MSB BYTE16 ScalerAlarm 1 BYTE17 ScalerAlarm 2 BYTE18 ScalerAlarm 3 BYTE19 ScalerAlarm 4 LSB BYTE20 CountTime 0 MSB BYTE21 CountTime 1 LSB BYTE22 ...

Page 75: ...YTE8 CalConstant 5 LSB BYTE9 RateAlarm 0 MSB BYTE10 RateAlarm 1 BYTE11 RateAlarm 2 BYTE12 RateAlarm 3 BYTE13 RateAlarm 4 LSB BYTE14 ScalerAlarm 0 MSB BYTE15 ScalerAlarm 1 BYTE16 ScalerAlarm 2 BYTE17 ScalerAlarm 3 BYTE18 ScalerAlarm 4 LSB BYTE19 CountTime 0 MSB BYTE20 CountTime 1 LSB BYTE21 Units 0 BYTE22 TimeBase 0 BYTE23 AudioDivdeBy 0 BYTE24 Response 0 BYTE25 RateAlert 0 MSB BYTE26 RateAlert 1 B...

Page 76: ... 08 06 2003 2241 2 Special Firmware 40806n13 04 04 2003 2241 3 Special Firmware 40806n16 07 07 2004 The old format was binary Byte 1 Ratemeter CPS 0 Byte 2 Ratemeter CPS 1 Byte 3 Ratemeter CPS 2 Byte 4 Ratemeter CPS 3 Byte 5 Scaler 0 Byte 6 Scaler 1 Byte 7 Scaler 2 Byte 8 Scaler 3 Byte 9 Scaler 4 Byte 10 Count Time 0 Byte 11 Count Time 1 Byte 12 Count Time Left 0 Byte 13 Count Time Left 1 Byte 14 ...

Page 77: ...ary and matches the LCD display on the 2241 2 The display mode is a value from 0 to 9 representing the display units CPS 0 KCPS 1 CPM 2 KCPM 3 µR 4 mR 5 R 6 µSv 7 mSv 8 Sv 9 Note The LMI Model 2241 calibration software is not compatible with this firmware version Example output 02 991 2 99 kcps 01 801 1 80 kcps 01 221 1 22 kcps 00 831 0 83 kcps 00 581 0 58 kcps 004160 416 cps ...

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