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Ludlum Measurements 12, Technical Manual

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Page 1: ...LUDLUM MODEL 12 SURVEY METER July 2017 Serial Number 218039 and Succeeding Serial Numbers ...

Page 2: ...LUDLUM MODEL 12 SURVEY METER July 2017 Serial Number 218039 and Succeeding Serial Numbers ...

Page 3: ... any implied warranty 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 th...

Page 4: ...f Controls and Functions 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 Calibration 6 1 True Reading Calibration 6 1 Internal Calibration after overhaul 6 2 Establishing an Operating Point 6 3 Maintenance 6 4 Recalibration 6 5 Batteries 6 5 Troubleshooting 7 Troubleshootin...

Page 5: ...riminator 8 1 Audio 8 1 Scale Ranging 8 2 Digital Analog Converter 8 2 Ratemeter Drive Circuit 8 2 HV Meter Drive 8 2 Battery Test 8 2 HV Power Supply Board Drawing 464 243 8 3 Switching Convertor 8 3 Feedback 8 3 Voltage Control 8 3 Filtering 8 3 Recycling 9 Parts List 10 Model 12 Survey Meter 10 1 Main Board Drawing 464 275 10 1 HV Power Supply Board Drawing 464 243 10 4 Wiring Diagram Drawing 4...

Page 6: ...cast aluminum and the can is 0 23 cm 0 09 in thick aluminum The audio provides a brief click for every radiation event detected It also provides a steady tone to warn the user of a low battery condition This low battery warning overrides the position of the AUD ON OFF switch With an adjustable detector voltage of 400 2500 volts and adjustable discriminator of 1 100 millivolts this unit can be oper...

Page 7: ...tors 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 related cable s for calibration Every returned instrument must...

Page 8: ...he 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 Check the batteries daily or prior to use whichever is less frequent to assure proper operation of the instrument Move the range multiplie...

Page 9: ...mportant for consistent measurements There are in general three types of meter faces 1 count rate typically cpm counts per minute 2 exposure rate typically mR hr and 3 combo typically cpm and mR hr The following examples are intended to help the user interpret the correct reading The normal procedure is to turn the range selector switch to the highest range and if no readings are seen on the meter...

Page 10: ...s 0 2 mR hr The bottom scale also reads 0 2 mR hr and is for 100 scale only The 100 ONLY scale will work correctly when the multiplier switch is in the 100 range The meter face also has a BAT TEST position on the dial If the needle is pointing as indicated below and the range selection switch is on the 0 1 scale then the reading is 0 1 mR hr The same needle indications on successive ranges would b...

Page 11: ... to as a combo meter face since it has both count rate cpm and exposure rate mR hr arcs Simpler meter faces may only have a count rate or an exposure rate arc s like the previous meter faces shown A combo meter face is specifically designed for a particular detector In the example above the 1 0 mR hr mark on the middle arc lines up with 3 3 kcpm on the upper arc The meter face in this example work...

Page 12: ...or s between calibrations an instrument operational check including battery test and instrument test as described above should be performed at least daily or prior to use whichever is less frequent A reference reading s with a check source should be obtained with the detector s in a constant and reproducible manner at the time of calibration or at the time the instrument is received in the field I...

Page 13: ...gohm 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 Calibration Controls individual potentiometers for each range accessible from the front cover while in operational status Response toggle switch for FAST 4 seconds or SLOW 22 seconds from ...

Page 14: ...with alkaline batteries battery condition may be checked on the meter End of Battery Life Warning At 2 1 Vdc the meter needle will drop to the edge of the BAT TEST or BAT OK area when the meter selector switch is moved to the BAT position At 2 0 Vdc a steady audible tone will be emitted to warn the user of the low battery condition Size 16 5 x 8 9 x 21 6 cm 6 5 x 3 5 x 8 5 inch H x W x L Weight 1 ...

Page 15: ...F to BAT provides the operator with a battery check of the instrument A BAT check scale on the meter provides a visual means of checking the battery charge status Moving the range selector switch to one of the range multiplier positions 1000 100 10 1 provides the operator with four decades of an overall range Multiply the scale reading by the multiplier to determine the actual scale reading D Disc...

Page 16: ... S Toggle Switch Provides meter response Selecting the fast F position of the toggle switch provides 90 of full scale meter deflection in four seconds In the slow S position 90 of full scale meter deflection takes 22 seconds In the F position there is fast response and large meter deviation The S position should be used for slow response and damped meter deviation Note The slow response position i...

Page 17: ...ed for operation from 40 to 65 C 40 to 150 F Maximum relative humidity of less then 95 non condensing Pollution Degree 3 as defined by IEC 664 Occurs when conductive pollution or dry nonconductive pollution becomes conductive 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...

Page 18: ...ntact with internal hazardous live parts that are accessible using a tool 1 Turn the instrument power OFF and remove the batteries 2 Allow the instrument to sit for one minute before accessing internal components 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 pl...

Page 19: ...d Both methods are described below Unless otherwise specified the instrument is calibrated to true reading at the factory Note Measure high voltage with a Model 500 Pulser or a high impedance voltmeter with a high meg probe If one of these instruments is not available use a voltmeter with a minimum of 1000 megohm input resistance True Reading Calibration Connect the input of the instrument to a ne...

Page 20: ...r efficiency for many sources Geometry calibration is often used when the instrument is utilized to measure radiation with a limited spectrum for example a single isotope calibration To calibrate the instrument using this technique obtain calibration sources with a spectrum similar to the target radiation Expose the probe to the source and adjust the calibration control until the meter reading cor...

Page 21: ... amplifier gain In the special case of GM detectors a minimum voltage must be applied to establish the Geiger Mueller GM characteristic Further changes in gain will not affect this type of probe The operating point for each detector is set at a compromise point of sensitivity stability and background contribution These operating points are best for general monitoring In application these arbitrari...

Page 22: ...e without a source present Measure the HV output then decrease the HV setting to operate 100 volts below breakdown Scintillators Set the DIS for 10 millivolts Carefully increase the HV until the instrument plateaus on the background count This provides the most stable operating point for the detector Check the calibration and proceed to use the instrument Maintenance Instrument maintenance consist...

Page 23: ...ut 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 wate...

Page 24: ...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 always ...

Page 25: ...o 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 tap t...

Page 26: ...etector 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 bet...

Page 27: ...rate from 10 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 indicate...

Page 28: ...dc 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 93 C 200 F 5 Humidity can also be a problem for proportional detectors Dry and or check the desi...

Page 29: ... Positive pulses from Q1 are coupled to the discriminator U8 Amplifier gain is controlled by R47 Discriminator Comparator U8 has a fixed discrimination of 15 millivolts Any pulse above 15 millivolts causes the output of U8 to go low This negative pulse is coupled to pin 5 of U9A for meter drive and pin 12 of U9B for audio drive The pulse is also available at pin 3 of P2 for special applications Au...

Page 30: ...off by R25 The voltage across C9 is proportional to the incoming count rate RateMeter Drive Circuit Voltage across C9 is measured by voltage follower U10 and Q2 Q2 converts voltage input to a constant current output at Q2 collector Current flow is controlled by R19 For slow time constant C17 is switched from the output to parallel C9 at the input Reset SW2 shorts the input capacitor R44 stabilizes...

Page 31: ... through R8 to the switcher feedback input pin 8 of U2 Voltage Control The switching convertor U2 and T1 will develop an output voltage at C3 and R4 such that the voltage at pin 8 of U2 stays at 1 24 volts If voltage at pin 2 is zero voltage at pin 1 of U1 must be 2 541 volts to maintain 1 24 volts at pin 8 of U2 To obtain 2 541 volts at pin 1 of U2 the output voltage must be 2 541 volts In like m...

Page 32: ...mply 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 in e...

Page 33: ...C4 NOT USED C5 0 1 F 35V T 04 5755 C6 2 2 F 20V 04 5790 C7 0 022 F 50V 04 5667 C8 1 F 16V 04 5701 C9 10 F 10V DT 04 5766 C10 100pF 100V 04 5661 C11 C12 68 F 10V 04 5654 C13 2 2 F 20V 04 5790 C14 470pF 100V 04 5668 C15 0 1 F 25V 04 5744 C16 100pF 3KV 04 5532 C17 47 F 10V 04 5666 C18 470pF 100V 04 5668 C19 0 001 F 3KV 04 5632 C20 10 F 10V 04 5766 C21 0 01 F 50V 04 5664 C30 10 F 10V 04 5766 C31 1 F 1...

Page 34: ...5X 06 6410 U11 LT1304CS8 06 6394 U12 MIC1557BM5 06 6457 U13 LMC7111BIM5X 06 6410 U14 TPS76050 05 5913 U15 CMXT3906 05 5890 U16 MAX4541ESA 06 6452 CR2 CMSH1 40M 07 6411 CR3 CMPD2005S 07 6468 SW1 CENTRAL 2P6P 08 6761 SW2 TP11LTCQE 7464 186 SW3 SW4 7101SDCQE 08 6781 SW5 TP11LTCQE 7464 186 R33 250K 64W254 100 09 6819 R34 250K 64W254 10 09 6819 R35 500K 64W504 1 09 6850 R36 250K 64W254 0 1 09 6819 R38 ...

Page 35: ...8W 1 12 7834 R21 249K 1 4W 1 12 7862 R22 1M 1 8W 1 12 7844 R23 124K 1 4W 1 12 7032 R24 14 7K 1 8W 1 12 7068 R25 200K 1 4W 1 12 7992 R26 100K 1 4W 1 12 7834 R27 68 1K 1 8W 1 12 7881 R28 100K 1 8W 1 12 7834 R29 1K 1 8W 1 12 7832 R30 100K 1 8W 1 12 7834 R31 475K 1 8W 1 12 7859 R32 100K 1 8W 1 12 7834 R37 200K 1 4W 1 12 7992 R39 1M 1 4W 1 12 7844 R40 10K 1 4W 1 12 7839 R41 R42 100K 1 4W 1 12 7834 R43 ...

Page 36: ... 5663 C24 68 F 10V 04 5654 C25 NOT USED U1 LMC7111BIM5X 06 6410 U2 LT1304CS8 06 6394 CR1 CR10 CMPD2005S 07 6468 CR11 CMSH1 40M 07 6411 R2 R3 750K 1 4W 1 12 7882 R4 R5 500M 3KV 2 12 7031 R6 1M 1 4W 1 12 7844 R7 10K 1 4W 1 12 7839 R8 1M 1 4W 1 12 7844 R9 953K 1 8W 1 12 7950 R10 10 Ohm 1W 1 12 7952 R11 R12 150K 1 4W 1 12 7833 R13 100K 1 4W 1 12 7834 P1 640456 4 MTA100 4 13 8088 P2 CON 1 18 9238 T1 31...

Page 37: ... 13 8088 J5 MAIN BOARD 5464 275 J6 MAIN BOARD 5464 275 DETECTOR CONNECTOR RECPT C SOLDERLESS 4478 049 DS1 UNIMORPH TEC 3526 PU 21 9251 B1 B2 D CELL BATTERY 21 9313 M1 PORT BEZEL W MVMNT ASSY 4363 188 RANGE KNOB 08 6613 PORTABLE BATTERY NEGATIVE CONTACT ASSY 2001 065 PORTABLE BATTERY POSTIVE CONTACT ASSY 2001 066 PORTABLE BATTERY LID WITH STAINLESS CONTACT 2009 036 CAN GASKET 22 9773 Wiring Diagram...

Page 38: ...s Inc Page 11 1 July 2017 Drawings MAIN CIRCUIT BOARD Drawing 464 275 3 sheets MAIN CIRCUIT BOARD LAYOUT Drawing 464 276 2 sheets HV POWER SUPPLY BOARD Drawing 464 243 HV POWER SUPPLY BOARD LAYOUT Drawing 464 244 WIRING DIAGRAM Drawing 464 309 Section 11 ...

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