Related Manuals for Ludlum Measurements 177-84
Summary of Contents for Ludlum Measurements 177-84
- Page 1 LUDLUM MODEL 177-84 ALPHA/BETA RATEMETER September 2023 Serial No. 128600 and Succeeding Serial Numbers...
- Page 2 LUDLUM MODEL 177-84 ALPHA/BETA RATEMETER September 2023 Serial No. 128600 and Succeeding Serial Numbers...
- Page 3 RETURN OF GOODS TO MANUFACTURER If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please send to the address below. All shipments should include documentation containing return shipping address, customer name, telephone number, description of service requested, and all other necessary information.
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Page 7: Table Of Contents
243) ................. 21 HASSIS IRING IAGRAM RAWING 8. APPENDIX ............................. 23 1 – C ....................23 PPENDIX HECKOUT ROCEDURE 2 – M 177-84 M ................ 25 PPENDIX ODEL WITCH DDITION 3 – M 4902 S ..................26 PPENDIX ODEL PECIFICATIONS... -
Page 9: Introduction
Model 177-84 Alpha/Beta Ratemeter Section Introduction The Model 177-84 is a microprocessor-based radiation survey instrument used to measure and discriminate low-level alpha/beta radiation when used with an alpha/beta scintillation or proportional detector. The instrument has beta automatic background subtract and beta automatic background update. - Page 10 Model 177-84 Alpha/Beta Ratemeter adjustable volume, low-battery LED, high-voltage readout, alarm audio acknowledge, and meter reset. All calibration controls are located internally to prevent tampering. The only user accessible controls include the Acknowledge/Reset push-button switch, a rotary switch to switch the meters between ratemeter readout, alarm setpoint readout, high voltage readout, and the ON/OFF switch located on the rear of the instrument.
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Page 11: Specifications
Model 177-84 Alpha/Beta Ratemeter Section Specifications HIGH VOLTAGE: variable from 200 to 2500 volts ALPHA THRESHOLD: adjustable from -4 to -180 mV ALPHA METER SCALE: 0-1000 cpm BETA THRESHOLD: adjustable from -1 through -4 mV BETA WINDOW: adjustable from 4 to 70 mV BETA METER SCALE: 0-100,000 CPM;... - Page 12 Model 177-84 Alpha/Beta Ratemeter FUSE: 1 amp, 5 x 20 mm 250 V fuse POWER: 117 VAC 60 Hz line power and internal rechargeable 6 V (sealed lead-acid) battery; battery life approximately 50 hours BATTERY DEPENDANCE: instrument calibration change less than 3% until Low Battery LED comes on SIZE: 19.1 x 22.9 x 15.3 cm (7.5 x 9 x 6 in.) (H x W x L), excluding handle...
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Page 13: Description Of Controls And Functions
Model 177-84 Alpha/Beta Ratemeter Section Description of Controls and Functions Front Panel METERS: The left meter is a three-decade log scale that shows the number of alpha counts. The right meter is a three-decade log scale that shows the number of beta counts. -
Page 14: Rear Panel
Model 177-84 Alpha/Beta Ratemeter ALPHA ALARM: This LED will come on when the alpha radiation level has exceeded the alpha alarm point. BETA ALARM: This LED will come on when the beta radiation level has exceeded the beta alarm point. - Page 15 Model 177-84 Alpha/Beta Ratemeter BT - Beta Threshold: This control sets the threshold level for the Beta channel. It is adjustable from -1 to -4 mV. BAP - Beta Alarm Point: This control sets the Beta alarm point. Turn the METER MODE switch to READ ALARM to view and set the alarm point.
- Page 16 Model 177-84 Alpha/Beta Ratemeter divide-by selection. Position 3: This position puts the instrument into meter calibration mode. When the third switch is turned on, the meters will be driven to full scale. You can then use the meter cal controls (AMC and BMC) to adjust the meters to read full scale.
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Page 17: Safety Considerations And Maintenance
Cleaning Instructions and Precautions The Model 177-84 may be cleaned externally with a damp cloth, using only water as the wetting agent. Do not immerse the instrument in any liquid. In addition, the operator is strongly cautioned to avoid contact with internal hazardous live parts that are accessible using a tool. -
Page 18: Replacement Of Fuses
Re-calibration should be accomplished after any maintenance or adjustment of any kind has been performed on the instrument. Ludlum Measurements recommends recalibration at intervals no greater than one year. Check the appropriate regulatory agencies’ regulations to determine required recalibration intervals. -
Page 19: Battery Replacement
Model 177-84 Alpha/Beta Ratemeter Form, which can be downloaded from the Ludlum website at www.ludlums.com. Find the form by clicking the “Support” tab and selecting “Service Department” from the drop-down menu. Then choose the appropriate Service Department division where you will find a link to the form. -
Page 20: Operating Procedures
Model 177-84 Alpha/Beta Ratemeter Section Operating Procedures • Remove the cover of the Model 177-84 and set the alarm points, audio volume, beta audio divide, and the count time as desired. Replace the cover. • Connect a detector to the Model 177-84. -
Page 21: Theory Of Operation
Model 177-84 Alpha/Beta Ratemeter • Slowly increase the HVS potentiometer to observe the beta meter for an increase, then decrease, and increase again in count as the HV is increased. Decrease the HV until the ratemeter is in the "dip" of the observed count rate-versus-HV plot just performed. -
Page 22: Alpha/Beta Discriminator Logic Circuit
Model 177-84 Alpha/Beta Ratemeter Alpha/Beta Discriminator Logic Circuit Alpha pulses from U022 are coupled to univibrator U121. Pulses at pin 6 of U121 are inverted by Q121 for connection to reset (R) pins 3, 13 of U111. Pin 9 of U121 provides the pulses to be counted by the microprocessor (µP). -
Page 23: Meter Drive
Model 177-84 Alpha/Beta Ratemeter pin 2, pin 1 goes low, illuminating the OVERLOAD LED and driving the meter to full scale. R305, OL, provide adjustment for the overload set point. Meter Drive Pulses are coupled to the gate of Q201 and Q301. R403 and C401 provides integration. -
Page 24: Recycling
To this end, Ludlum Measurements, Inc. strives to supply the consumer of its goods with information regarding reuse and recycling of the many different types of materials used in its products. -
Page 25: Parts List
Model 177-84 Alpha/Beta Ratemeter Section Parts List Reference Description Part Number Model 177-84 UNIT Completely Assembled Alpha/Beta Ratemeter Model 177-84 Alpha/Beta Ratemeter 48-2727 BOARD Assembled Board 5347-314 Main Board, Drawing 347 x 600 C011 100pF, 100V 04-5661 CAPACITORS C012 47pF, 100V... - Page 26 Model 177-84 Alpha/Beta Ratemeter Reference Description Part Number C432 2700MF, 35V 04-5621 C511 47MF, 10V 04-5666 DIODES CR031 MMBD7000LT1 07-6355 CR121-CR122 MMBD914L 07-6353 CR231-CR235 GI250-2 07-6266 CR421 MMBD914L 07-6353 CR521 CXSH-4 07-6358 CR531-CR532 CXSH-4 07-6358 Q121 2N7002L 05-5840 TRANSISTORS Q201...
- Page 27 Model 177-84 Alpha/Beta Ratemeter Reference Description Part Number R123 22.1K 1/8W 1% 12-7843 R124 100K 1/8W 1% 12-7834 R131 4.7 MEG 1/4W 5% 10-7030 R132 1 GIG-OHM FHV-1 2% 12-7686 R133 1 MEG 1/4W 5% CR25 10-7028 R134 1 GIG-OHM FHV-1 2%...
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Page 28: Front Panel Board, Drawing 347 X 244
Model 177-84 Alpha/Beta Ratemeter NETWORK RN401 220K 12-7923 TRANSFORMERS T331 XFMR-L8050 40-0902 T501 XFMR-Model 177 AUDIO 4275-083 SWITCHES S401 90HBW04S 08-6709 S501 NC3KR16B 08-6757 CONNECTORS 640456-4 MTA100 WHITE 13-8088 1-640456-1 MTA100 WHITE 13-8059 640456-7 MTA100 WHITE 13-8115 640456-2 MTA100 WHITE... -
Page 29: Chassis Wiring Diagram, Drawing 347 X 243
Model 177-84 Alpha/Beta Ratemeter Reference Description Part Number LEDS DS113 LED-E112 07-6390 DS114 LED-E112 07-6390 DS115 LED-E112 07-6390 DS116 LED-E116 07-6393 DS117 LED-E116 07-6393 DS118 LED-E116 07-6393 DS119 LED-E176 RED 07-6362 DS120 LED-E176 RED 07-6362 RESISTORS R123 150 OHM 1/4W 5%... - Page 30 Model 177-84 Alpha/Beta Ratemeter Reference Description Part Number FRONT CHASSIS HARNESS Model 177-84 8347-327 REAR CHASSIS HARNESS MODEL 177-84 8347-323 BATTERY NP1-6 YUASA 21-9385 FUSE 1 AMP 5X20mm 21-9704 TRANSFORMER 22-9908 Ludlum Measurements, Inc. Page 22 September 2023...
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Page 31: Appendix
Model 177-84 Alpha/Beta Ratemeter Section Appendix Appendix 1: Checkout Procedure 1. Check all connections. Install the microprocessor chip 87C51FC with program firmware #34700N00 (or greater), and turn instrument ON with battery disconnected and the red positive lead to the battery attached to a +6 Vdc power supply. - Page 32 Model 177-84 Alpha/Beta Ratemeter there are no shorts present in the HV section or in the coax connection to the detector connector. Set the high voltage to 1750 Vdc. Turn the METER MODE switch to READ HV. Adjust the HVR (High Voltage Read) until the beta meter reads 1.75 kV.
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Page 33: Appendix 2: Model 177-84 Mode Switch Addition
This addition was originally put on the Model 177-84 so that it would work better with the Model 4902 Hand & Foot Detector Stand. The user can put the Model 177- 84 into Frisk Mode and then remove the hand detector from its cradle and use it as a frisker. -
Page 34: Appendix 3: Model 4902 Specifications
Model 4902. If a count timer is required, the instrument used with the Model 4902 must have that capability. An instrument typically used with the Model 4902 is a Ludlum Model 177-84. Other instruments can be used. -
Page 35: Drawings And Diagrams
Model 177-84 Alpha/Beta Ratemeter Section Diagrams and Drawings Main Board, Drawing 347 x 600 (3 sheets) Main Board Component Layout, Drawing 347 x 243A (2 sheets) Front Panel Board, Drawing 347 x 244 Front Panel Board Component Layout, Drawing 347 x 258A (2 sheets) Wiring Diagram, Drawing 347 x 243 Ludlum Measurements, Inc.
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