LUDLUM MODEL 3 Technical Manual Download Page 1

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LUDLUM MODEL 3

SURVEY METER

April 2016

Serial Number 294605 and Succeeding

Serial Numbers

Summary of Contents for MODEL 3

Page 1: ...LUDLUM MODEL 3 SURVEY METER April 2016 Serial Number 294605 and Succeeding Serial Numbers ...

Page 2: ...LUDLUM MODEL 3 SURVEY METER April 2016 Serial Number 294605 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 5: ...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 Exposure Rate Calibration 6 2 CPM Calibration 6 3 Establishing an Operating Point 6 4 Maintenance 6 5 Recalibration 6 5 Batteries 6 6 Troubleshooting 7 Troubleshooting Electronics which...

Page 6: ...8 1 High Voltage Supply 8 1 Detector Input 8 1 Amplifier 8 1 Discriminator 8 2 Audio 8 2 Scale Ranging 8 2 Meter Drive 8 2 Meter Reset 8 2 Fast Slow Time Constant 8 2 Recycling 9 Parts List 10 Model 3 Survey Meter 10 1 Main Board Drawing 464 204 10 1 Wiring Diagram Drawing 464 212 10 3 Drawings and Diagrams 11 ...

Page 7: ...d meter housing are made of cast aluminum and the can is 0 23 cm 0 090 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 Any Geiger Mueller GM detector offered by Ludlum Measurements will operate with this unit as we...

Page 8: ...s and instruments are not interchanged Each instrument is calibrated to specific detector s 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 b...

Page 9: ...y 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 multiplier switch to the BAT position Ensure that the meter needle deflects to the ...

Page 10: ... count rate typically cpm counts per minute 2 exposure rate typically mR hr 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 turn the selector switch down to the lower scales until a reading is seen The ranges on t...

Page 11: ...ds 0 2 mR hr The bottom scale also reads 0 2 mR hr and is for 100 only scale 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 ...

Page 12: ... 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 13: ...librations an instrument operational check including battery test and instrument test as described on pages 2 2 and 2 3 should be performed at least daily or prior to use whichever is less frequent A reference reading or readings 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 t...

Page 14: ...ent protective cover provided 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 Battery Dependence less than 3 change in readings to battery failure indication Reset pushbutton to zero t...

Page 15: ...Section3 Ludlum Measurements Inc Page 3 2 April 2016 Size 16 5 x 8 9 x 21 6 cm 6 5 x 3 5 x 8 5 in H x W x L including handle Weight 1 6 kg 3 5 lb including batteries Construction cast and drawn aluminum with beige powder coat ...

Page 16: ...e 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 100 10 1 0 1 provides the operator with an overall range of 0 to 500 000 cpm Multiply the scale reading by the multiplier to determine the actual scale reading Calibration Controls Recessed potentiometers that are used t...

Page 17: ... 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 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 is normally used when the inst...

Page 18: ...e due to condensation This is typical of industrial or construction sites Water resistance is achieved by the use of rubber seals on all front panel switches and gaskets on the battery lid meter bezel and between the instrument can and front panel Warning Markings and Symbols Caution The operator or responsible body is cautioned that the protection provided by the equipment may be impaired if the ...

Page 19: ...ions to avoid contact 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 ...

Page 20: ...ed below Unless otherwise specified the instrument is calibrated to exposure rate 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 megаohm input resistance Calibration shall include response evaluations and adjustment for two points of each scale o...

Page 21: ...he 100 calibration control for the proper reading Reposition the detector so the field corresponds to approximately 20 of full scale meter deflection Confirm that the meter reading is within 10 of the field Repeat this process for the 10 1 and 0 1 ranges If your gamma exposure range cannot calibrate two positions on each scale the pulser may be used to electronically calibrate the remaining points...

Page 22: ...ale on the 100 range Adjust the 100 calibration control for the proper reading Check the 20 scale indication of the Model 3 by reducing the pulser count rate by a factor of 4 The Model 3 should read within 10 of the actual pulse rate Decrease the pulse rate of the Model 500 by one decade and turn the Model 3 range selector to the next lower range Repeat the above procedure for the remaining lower ...

Page 23: ... least 1000 megohm input resistance to measure the high voltage GM Detectors In the special case of GM detectors a minimum voltage must be applied to establish the Geiger Mueller characteristic The output pulse height of the G M detector is not proportional to the energy of the detected radiation Most GM detectors operate at 900 volts although some miniature detectors operate at 400 500 volts Refe...

Page 24: ...n and periodically checking the batteries and the calibration The Model 3 instrument may be cleaned with a damp cloth using only water as the wetting agent Do not immerse instrument in any liquid Observe the following precautions when cleaning 1 Turn the instrument OFF and remove the batteries 2 Allow the instrument to sit for one minute before accessing internal components Recalibration Recalibra...

Page 25: ...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 water Use a spanner wrench to unscrew the battery contact insulators exposing the internal contacts and battery spri...

Page 26: ...bles 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 ...

Page 27: ... 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 the meter Does ...

Page 28: ...able 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 between the circuit...

Page 29: ... assembly will usually fix the problem Note When replacing the window make sure to use a window made with the same thickness Mylar and the same number of layers as the original window 2 Verify that the HV and input sensitivity are correct Alpha and gamma scintillators typically operate from 10 35 mV High voltage varies with the photomultiplier tubes PMT from as low as 600 Vdc to as high as 1400 Vd...

Page 30: ...is coupled back through R39 to pin 8 of U13 High voltage output is set by front panel potentiometer R42 which sets the voltage feedback of 1 31 Vdc to pin 8 of U13 R38 and C28 provide filtering Detector Input Detector pulses are coupled from the detector through C6 to amplifier input pin 2 of U4 CR1 protects U4 from input shorts R37 couples the detector to the high voltage supply Amplifier A self ...

Page 31: ... and C7 Scale Ranging Detector pulses from the discriminator are coupled to univibrator pin 5 of U9 For each scale the pulse width of pin 6 of U9 is changed by a factor of 10 with the actual pulse width being controlled by the front panel switch the analog switches U1 and U2 and the related potentiometers This arrangement allows the same current to be delivered to C9 by 1 count on the 0 1 range as...

Page 32: ...imply 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 in e...

Page 33: ... 5669 C4 10pF 100V 04 5673 C5 0 01 F 50V 04 5664 C6 100pF 3KV 04 5735 C7 0 022 F 50V 04 5667 C8 1 F 16V 04 5701 C9 10 F 25V 04 5655 C10 100pF 100V 04 5661 C11 68 F 10V 04 5654 C12 10 F 25V 04 5728 C14 470pF 100V 04 5668 C15 220pF 100V 04 5674 C16 68 F 10V 04 5654 C17 47 F 10V 04 5666 C18 C27 0 01 F 500V 04 5696 C28 0 001 F 2KV 04 5703 or 100pF 3KV 04 5735 C29 10 F 25V 04 5655 C30 C31 1 F 16V 04 57...

Page 34: ...MPD2005S 07 6468 CR2 RECTIFIER CMSH1 40M 07 6411 CR3 CR7 CMPD2005S 07 6468 CR9 RECTIFIER CMSH1 40M 07 6411 SW1 D5G0206S 9802 08 6761 SW2 TP11LTCQE 08 6770 SW3 SW4 7101SDCQE 08 6781 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 R42 1 2M 3296W HV 09 6814 R1 R5 200K 1 8W 1 12 7992 R6 8 25K 1 8W 1 12 7838 R7 10K 1 8W 1 12 7839 R8 2 37K 1 8...

Page 35: ...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 100K 1 8W 1 12 7834 R38 2 2M 1 8W 1 12 7002 R39 500M 3KV 2 12 7031 R40 402K 1 8W 1 12 7888 R44 1K 1 4W 1 12 7832 P1 640456 5 MTA100 13 8057 P2 640456 6 MTA100 installed as required 13 8095 P3 640456 2 MTA100 13 8073 L1 22 µH 21 9808 T1 31032R 21 9925 J1 MTA100 5 MA...

Page 36: ... PORTABLE KNOB 08 6613 M1 METER ASSEMBLY METER BEZEL W GLASS W O SCREWS 4363 188 METER MOVEMENT 1 mA 15 8030 PORTABLE METER FACE 7363 136 HARNESS PORT CAN WIRES 8363 462 PORTABLE BATTERY LID WITH STAINLESS CNTCT 2009 036 PORTABLE LATCH KIT W O BATTERY LID 4363 349 PORTABLE HANDLE GRIP W SCREWS 4363 139 PORTHANDLE FOR CLIP W SCREWS 4363 203 REPLACEMENT CABLE STD 1 meter 39 in 40 1004 CLIP 44 3 TYPE...

Page 37: ...l Section11 Ludlum Measurements Inc Page 11 1 April 2016 Drawings and Diagrams MAIN CIRCUIT BOARD Drawing 464 204 3 sheets MAIN CIRCUIT BOARD LAYOUT Drawing 464 205 2 sheets CHASSIS WIRING DIAGRAM Drawing 464 212 Section 11 ...

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