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Ludlum Measurements 18, Manual

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Ludlum Measurements 18 Manual Download Page 6

Model 18 Analyzer  

Technical Manual   

 

 

Ludlum Measurements, Inc. 

 

March 2012 

 

    Batteries 

6-7 

Troubleshooting 

  7 

Troubleshooting Electronics which utilize a  
    GM, Scintillator, or Proportional Detector 

7-1 

Troubleshooting GM Detectors 

7-3 

Troubleshooting Scintillators 

7-4 

Troubleshooting Proportional Detectors 

7-4 

Recycling 

 8 

Parts List 

 9 

Model 18 Analyzer 

9-1 

Main Board, Drawing 363 × 509  

9-1 

Calibration Board, Drawing 363 × 513 

9-3 

Wiring Diagram, Drawing 363 × 515 

9-4 

Drawings and Diagrams 

10 

Summary of Contents for 18

Page 1: ...LUDLUM MODEL 18 ANALYZER March 2012 Serial Number 217996 and Succeeding Serial Numbers ...

Page 2: ...LUDLUM MODEL 18 ANALYZER March 2012 Serial Number 217996 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...

Page 4: ......

Page 5: ...ns 4 Safety Considerations 5 Environmental Conditions for Normal Use 5 1 Warning Markings and Symbols 5 1 Cleaning and Maintenance Precautions 5 2 Calibration and Maintenance 6 Establishing an Operating Point 6 1 Calibration 6 1 GM Detectors 6 2 Proportional Detectors 6 2 Scintillation Detectors 6 3 Window Calibration 6 3 HV Calibration 6 4 Ratemeter Calibration 6 5 Detector Overload Option Calibr...

Page 6: ...lize a GM Scintillator or Proportional Detector 7 1 Troubleshooting GM Detectors 7 3 Troubleshooting Scintillators 7 4 Troubleshooting Proportional Detectors 7 4 Recycling 8 Parts List 9 Model 18 Analyzer 9 1 Main Board Drawing 363 509 9 1 Calibration Board Drawing 363 513 9 3 Wiring Diagram Drawing 363 515 9 4 Drawings and Diagrams 10 ...

Page 7: ...h voltage HV test buttons The instrument includes a unimorph speaker and is complete with connector cable and batteries Three gamma thresholds may be detected by utilizing the three preset high voltage settings For example the gamma threshold can be set for above 10 keV above 30 keV and above 100 keV In the presence of mixed radiation including plutonium americium and uranium 235 a quantitative es...

Page 8: ...rtant If multiple shipments are received ensure that the detectors and instruments are not interchanged Each instrument is calibrated to specific detectors and 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 ...

Page 9: ...connector Switch the Model 18 range selector switch to the OFF position before connecting or disconnecting the cable or detector Connect one end of a detector cable to the detector by firmly pushing the connectors together while twisting clockwise a quarter of a turn Repeat the process in the same manner with the other end of the cable and the instrument Battery Test The batteries should be checke...

Page 10: ...ng low numbers which require a more stable meter movement The fast response position is used at high rate levels Check the meter reset function by depressing the RES pushbutton and ensuring the meter needle drops to 0 When the RES pushbutton is released the meter needle recovers to the original reading Depress the HV pushbutton and note that the meter indicates the high voltage set point Note HV p...

Page 11: ...check source should be obtained at the time of initial calibration or as soon as possible for use in confirming proper instrument operation In each case ensure a proper reading on each scale If the instrument fails to read within 20 of a proper reading it should be sent to a calibration facility for recalibration ...

Page 12: ...an be turned ON or OFF Overload optional senses detector saturation indicated by red lamp on meter face and or full scale meter deflection adjustable depending on the detector selected Meter 6 4 cm 2 5 in arc 1 mA analog type Meter Dial 0 500 cpm 0 2 5 kV BAT TEST others available Range typically 0 500 000 counts minute CPM Linearity reading within 10 of true value with detector connected Battery ...

Page 13: ...eading Connector Series C other available Reset pushbutton to zero the meter Operating Temperature 20 to 50 C 4 to 122 F Power two D cell batteries housed in a sealed externally accessible compartment Battery Life typically 600 hours with alkaline batteries battery condition may be checked on the meter Size 16 5 x 8 9 x 21 6 cm 6 5 x 3 5 x 8 5 in H x W x L Weight 1 6 kg 3 5 lb including batteries ...

Page 14: ... depressed this switch provides a rapid means of driving the meter needle to zero AUD ON OFF Toggle Switch In the ON position operates the unimorph speaker located on the left side of the instrument The frequency of the clicks is relative to the rate of the incoming pulses The higher the rate the higher the audio frequency The audio should be turned OFF when not required to reduce battery drain HV...

Page 15: ...ment Recessed potentiometers located under the calibration cover These controls allow for individual calibration of each range multiplier THR Recessed potentiometer located under the calibration cover which allows the input sensitivity threshold to be adjusted from 2 to 60 millivolts The threshold is normally set at the factory for 10 millivolts WIN Recessed potentiometer located under the calibra...

Page 16: ...ductive due to condensation This is typical of industrial or construction sites Warning Markings and Symbols Caution The operator or responsible body is cautioned that the protection provided by the equipment may be impaired if the equipment is used in a manner not specified by Ludlum Measurements Inc The Model 18 Analyzer is marked with the following symbols CAUTION RISK OF ELECTRIC SHOCK per ISO...

Page 17: ...it for one minute before accessing internal components The CE mark is used to identify this instrument as being acceptable for use within the European Union The crossed out wheelie bin symbol notifies the consumer that the product is not to be mixed with unsorted municipal waste when discarding each material must be separated The symbol is placed on the battery compartment lid See section 8 Recycl...

Page 18: ... are above the discrimination level and the unwanted pulses from noise are below the discrimination level and are therefore not counted Total system gain is controlled by adjusting either the instrument threshold or high voltage Voltage affects control in the probe THR threshold controls the amplifier gain The operating point for each detector is set at a compromise point of sensitivity stability ...

Page 19: ...5 Connect GM detector and confirm proper operation with a radiation source PROPORTIONAL DETECTORS 1 Set THR for 2 millivolts 2 Set WIN IN OUT to OUT 3 Expose detector to a radiation source and the observe count rate with and without the source as voltage is increased in 50 volt increments Make a plot of Data vs High Voltage 4 Select an operating high voltage point with minimum change in count rate...

Page 20: ...ould be taken with the WIN IN OUT switch in the OUT position and plotted for both background and a reference source such as 137 Cs for high energy or 241 Am for low energy Window calibration will be valid only with the specific detector to be used with the Model 18 A check source will be required A Model 500 Pulser will be required if the WIN calibration is shifted to another energy Using the puls...

Page 21: ...et THR to 21 millivolts and WIN to 26 millivolts Cs This gives 53 KeV per millivolt Ten millivolts is equivalent to 53 KeV and the 5 millivolt wide window window setting minus threshold setting is equivalent to 265 KeV or the window is between 530 KeV and 795 KeV HV CALIBRATION High voltage may be adjusted by the HV control Select the desired position on the HV selector switch and press the HV pus...

Page 22: ...unter clockwise position With Scintillation Detectors 1 For alpha or beta scintillators expose the detector photomultiplier tube PMT to a small light leak by loosening the detector window The meter should start to decrease toward zero as light saturates the scintillation material 2 Expose just enough light to where the meter starts to decrease Adjust the OL control until the overload LED just begi...

Page 23: ... reading 200 mR hr Adjust the OL control until the LED flickers at 1000 mR hr and then place the detector at 500 mR hr to ensure the LED is disabled Note When a GM and scintillation detector is used the overload set point must be adjusted for the GM detector due to the greater current drain from the GM detector Maintenance Instrument maintenance consists of keeping the instrument clean and periodi...

Page 24: ...s but most other manufacturers instruments as well Calibration procedures are available upon request for customers who choose to calibrate their own instruments BATTERIES The batteries should be removed any time the instrument is placed into storage Battery leakage may cause corrosion on the battery contacts which must be scraped off and or washed using a paste solution made from baking soda and w...

Page 25: ...s 2 sticky meters and 3 battery contacts Note that the first troubleshooting tip is for determining whether the problem is with the electronics or with the detector A Ludlum Model 500 Pulser is invaluable at this point because of its ability to simultaneously check high voltage input sensitivity or threshold and the electronics for proper counting We hope these tips will prove to be helpful As alw...

Page 26: ...ed to check the HV ensure that one with high impedance is used as a standard multimeter could be damaged in this process 2 Check for noise in the detector cable by disconnecting the detector placing the instrument on the lowest range setting and wiggling the cable while observing the meter face for significant changes in readings 3 Check for sticky meter movement Does the reading change when you t...

Page 27: ...d detector and or cable 2 Has the correct operating voltage been set Refer to the calibration certificate or detector instruction manual for correct operating voltage If the instrument uses multiple detectors confirm that the high voltage is matched to the current detector being used 1 Ensure that the AUD ON OFF switch is in the ON position 2 Remove the instrument housing and check the connection ...

Page 28: ...operate from 10 to 35 mV High voltage varies with the photomultiplier tubes PMT from as low as 600 Vdc to as high as 1400 Vdc 3 On a gamma scintillator visually inspect the crystal for breakage or humidity leakage Water inside the crystal will turn it yellow and gradually degrade performance 4 Check the PMT to see if the photocathode still exists If the end of the PMT is clear not brownish this in...

Page 29: ... 1750 Vdc and 30 mV threshold 3 Gas proportional detectors need P 10 gas so check the window for tears or leaks and ensure an adequate supply of gas 4 If the window is torn the anode wires are likely to be broken as well shorting against the detector Replace broken wires clean the lacquer thinner then bake at 200 F 5 Humidity can also be a problem for proportional detectors Dry and or check the de...

Page 30: ...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 electronics products and should be recycled separately The list is not all inclusive nor does it suggest that all materials are present...

Page 31: ...1μF 35V 04 5656 C113 C114 0 01μF 50V 04 5664 C121 C122 68μF 6 3V 04 5654 C201 0 0047μF 3kV 04 5547 C202 100pF 3kV 04 5532 C203 C204 0 0047μF 3kV 04 5547 C211 0 01μF 50V 04 5664 C212 0 022μF 50V 04 5667 C221 47μF 04 5666 C222 470pF 100V 04 5668 C301 10μF 20V 04 5655 C302 100pF 3kV 04 5532 C303 0 001μF 100V 04 5659 C311 313 47pF 100V 04 5660 C401 10μF 20V 04 5655 C402 0 01μF 50V 04 5664 C403 47pF 10...

Page 32: ...6290 U411 CA3096M 06 6288 CR001 MR250 2 07 6266 CR111 MMBD914L 07 6353 CR211 CR214 MR250 2 07 6266 R211 250 07 6366 R421 1M HV LIMIT LIM 09 6906 R423 500K HV HV READOUT 09 6913 R111 200 OHM 1 12 7846 R112 2 21k 1 12 7835 R113 22 1k 1 12 7843 R114 1 M 1 12 7844 R121 2 21k 1 12 7835 R122 2 37k 1 12 7861 R201 1 G 12 7686 R212 301 OHM 12 7863 R213 10k 1 12 7839 R214 22 1k 1 12 7843 R215 1 M 1 12 7844 ...

Page 33: ... 10k 1 12 7839 R414 100k 1 12 7834 R415 200 OHM 1 12 7846 R416 22 1k 1 12 7843 R422 475k 1 12 7859 R424 182k 1 12 7860 R511 22 1k 1 12 7843 R2110 100k 1 12 7834 R2111 1 G 12 7686 R2112 1 M 1 12 7844 P1 CONN 1 640456 1 MTA100 13 8059 P2 CONN 1 640456 2 MTA100 13 8061 P4 CONN 640456 2 MTA100 13 8073 L021 470 UHY 21 9699 T011 L8050 40 0902 BOARD Completely Assembled Calibration Board 5363 657 C1 0 00...

Page 34: ...6518 S4 PA 600 210 08 6501 S5 7101 SYZ QE 08 6511 S6 30 1 PB GRAYHILL 08 6517 S7 MRS 2 5 08 6514 J1 CONN 1 640442 1 MTA100 13 8137 J2 CONN 1 640442 2 MTA100 13 8407 J3 CONN 640442 9 MTA100 13 8169 J4 CONN 640442 2 MTA100 13 8178 J5 CONN 640442 4 MTA100 13 8170 DS1 UNIMORPH 21 9251 B1 B2 D CELL BATTERY 21 9313 M1 PORT BEZEL W OL MVMNT ASSY 4363 720 BATTERY BOX LID Model 18 9363 998 BATTERY CONTACT ...

Page 35: ...T MTR BEZEL W MVMNT ASSY 4363 188 PORT MTR BEZEL W GLASS SCREWS 4363 352 PORT CAL COVER W SCREWS 9363 200 01 UNIMORPH W WIRES O RING 40 0034 PORT HANDLE GRIP W SCREWS 7363 139 PORT HANDLE FOR CLIP W SCREWS 7363 203 Model 44 3 TYPE CLIP W SCREWS 7002 026 01 Model 44 7 TYPE CLIP W SCREWS 7010 007 01 Model 44 6 44 9 TYPE CLIP W SCREWS 7010 008 01 ...

Page 36: ...rements Inc Page 10 1 March 2012 Drawings MAIN CIRCUIT BOARD SCHEMATIC Drawing 363 509 MAIN CIRCUIT BOARD LAYOUT Drawing 363 510 CALIBRATION BOARD SCHEMATIC Drawing 363 513 CALIBRATION BOARD LAYOUT Drawing 363 514 WIRING DIAGRAM Drawing 363 516 Section 10 ...

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