Ludlum Measurements 177-84-2 Operator's Manual
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Ludlum Measurements 177-84-2 Operator's Manual

Alpha/beta ratemeter
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LUDLUM MODEL 177-84-2
ALPHA/BETA RATEMETER
September 2020
Serial No. 330935 and Succeeding
Serial Numbers

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Summary of Contents for Ludlum Measurements 177-84-2

  • Page 1 LUDLUM MODEL 177-84-2 ALPHA/BETA RATEMETER September 2020 Serial No. 330935 and Succeeding Serial Numbers...
  • Page 2 LUDLUM MODEL 177-84-2 ALPHA/BETA RATEMETER September 2020 Serial No. 330935 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.

  • Page 5: Table Of Contents

    PC Interface ..............................15 Recycling ..............................21 Parts List ..............................22 Appendix ..............................28 Appendix 1: Checkout Procedure .......................... 28 Appendix 2: Model 177-84-2 Mode Switch Addition .................... 30 Appendix 3: Model 4902 Specifications ........................ 31 Revisions ..............................32 ..............................32 IRMWARE Version 34702N04 ..............................

  • Page 7: Introduction

    Model 177-84-2 Alpha/Beta Ratemeter Section Introduction The Model 177-84-2 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 8 Model 177-84-2 Alpha/Beta Ratemeter alarm audio acknowledge, and meter reset. All calibration controls are located internally or require the PC Interface to prevent tampering. The only user-accessible controls include the ACK/RESET and BKG UPDATE push-buttons located on the front and an ON/OFF switch located on the back.

  • Page 9: Specifications

    Model 177-84-2 Alpha/Beta Ratemeter Section Specifications HIGH VOLTAGE: variable from 0 to 1500 volts ALPHA THRESHOLD: adjustable from -4 to -180 mV ALPHA METER SCALE: 0-500 cpm, 4-8 Vdc ALPHA RANGE: X1, X10, X100, X1K BETA THRESHOLD: adjustable from -1 through -4 mV BETA WINDOW: adjustable from 4 to 70 mV BETA METER SCALE: 0-500 cpm;...
  • Page 10 Model 177-84-2 Alpha/Beta Ratemeter FINISH: powder coat paint POWER: 12 Vdc 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 15.2 cm (7.5 x 9 x 6 in.) (H x W x L), excluding handle WEIGHT: 2.2 kg (4.9 lb)

  • Page 11: Description Of Controls And Functions

    Model 177-84-2 Alpha/Beta Ratemeter Section Description of Controls and Functions Front Panel METERS: The left meter is a 0 to 500 cpm linear scale that shows the number of alpha counts. The right meter is a 0 to 500 cpm linear scale that shows the number of beta counts.

  • Page 12: Rear Panel

    Model 177-84-2 Alpha/Beta Ratemeter BETA ALARM: This LED will come on when the beta radiation level has exceeded the beta alarm point. ACK/RESET: This pushbutton has three functions. If the instrument is in an alarm condition, the first push of the button will turn the audio off. The second push will reset the meters to zero.
  • Page 13 Model 177-84-2 Alpha/Beta Ratemeter HRead: This trimmer potentiometer is used calibrate the read-back voltage applied to the micro-controller ADC. HCal: This trimmer potentiometer is used to calibrate the actual HV output as measured at the detector connector on the front panel. Use a pulser with high-voltage readout capability or the Ludlum T1016 or something comparable to measure the HV output at the detector connection.

  • Page 14: Safety Considerations And Maintenance

    Cleaning Instructions and Precautions The Model 177-84-2 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 15: 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 16: Battery Replacement

    Model 177-84-2 Alpha/Beta Ratemeter “Repair and Calibration” from the drop-down menu. Then choose the appropriate Repair and Calibration division where you will find a link to the form. Battery Replacement The battery should be replaced at least every four years. To replace the battery, remove the two screws holding the battery access door on the rear of the instrument and remove the door.

  • Page 17: Operating Procedures

    Model 177-84-2 Alpha/Beta Ratemeter Section Operating Procedures • Remove the cover of the Model 177-84-2 and set audio volume. Replace the cover. • Use the PC Interface to set the alarm points, beta audio divide, time constants, ranges, and other parameters as desired.

  • Page 18: Theory Of Operation

    Model 177-84-2 Alpha/Beta Ratemeter • Slowly increase the HV to observe the beta meter for an increase, then a decrease, and then an 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 19 Model 177-84-2 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 20 Model 177-84-2 Alpha/Beta Ratemeter Meter Drive Pulses are coupled to the gate of Q201 and Q301. R403 and C401 provides integration. Integrated meter drive voltage is coupled via the METER MODE switch to U212. The meter is driven by the emitter of Q211 and Q311, coupled as a voltage follower in conjunction with U212.

  • Page 21: Pc Interface

    The PC Interface is a Windows application that is used to set the alarm set points, range multiplier for the meters, ratemeter time constants, and voltages. Connect the 177-84-2 to the computer using the supplied USB cable and install the drivers, which are located on the installation disk under the FTDI folder.
  • Page 22 Model 177-84-2 Alpha/Beta Ratemeter The parameters will be downloaded from the 177-84-2 and displayed on the main screen. Alpha Default Range: Sets the default starting range for the alpha channel. If the count rate exceeds this range, the next higher range will be selected if auto- range is enabled.
  • Page 23 Default is OFF. Enable Click Audio: Temporarily disable the audible clicks to indicate counts. This setting only applies until the model 177-84-2 is turned off. After power on, the click audio is enabled. Default is ON.
  • Page 24 Model 177-84-2 Alpha/Beta Ratemeter High Voltage: Set the detector high voltage. Voltage is adjustable from 0 to 2000 volts. The default is 750 volts. Check with applicable detector manual for correct high voltage. Alpha LLD: Set the Alpha Lower Level Discriminator in millivolts. Adjustable from 0 to 3300 millivolts.
  • Page 25 The PC Interface can also log the ratemeter reading at user-defined intervals. This data is stored in a comma separated (csv) file that can be loaded into Excel for further processing. The default location is a folder called Model 177-84-2 Data, which is in the user’s Documents folder.
  • Page 26 Model 177-84-2 Alpha/Beta Ratemeter To print the current parameters, select the File/Print menu. Ludlum Measurements, Inc. Page 20 September 2020...

  • Page 27: 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 28: Parts List

    Model 177-84-2 Alpha/Beta Ratemeter Section Parts List Reference Description Part Number Model 177-84-2 UNIT Completely Assembled Alpha/Beta Model 177-84-2 Alpha/Beta Ratemeter 48-4260 Ratemeter BOARD Assembled Board 5347-563 Main Board, Drawing 347 x 563 CAPACITORS 10 µF, 100V 04-6011 C2-C3 0.1 µF, 25V...
  • Page 29 Model 177-84-2 Alpha/Beta Ratemeter Reference Description Part Number 0.001µF, 3kV 04-5727 100 pF, 3kV 04-5735 0.001µF, 3kV 04-5727 0.01 µF, 3kV 04-5525 68 µF, 10V 04-5654 0.01 µF, 3kV 04-5525 0.1 µF, 50V 04-5663 1 µF, 35V 04-5656 0.01 µF, 50V 04-5664 0.1 µF, 25V...
  • Page 30 Model 177-84-2 Alpha/Beta Ratemeter Reference Description Part Number 75K, 100mW 12-8027 249 Ohm, 100mW 12-7191 100K, 100mW 12-7082 16.9K, 100mW 12-7199 5K, 3269W1-104 09-6918 475K, 100mW 12-7088 46.4K, 100mW 12-8294 100 Ohm, 100mW 12-7142 49.9K, 100mW 12-7200 2K, 100mW 12-7144 22.1K, 100mW...
  • Page 31 Model 177-84-2 Alpha/Beta Ratemeter Reference Description Part Number 130K, 250mW 12-8302 169K, 250mW 12-8008 0 Ohm, 100mW 12-8013 2K, 100mW 12-7144 49.9K, 100mW 12-7200 2K, 100mW 12-7144 0 Ohm, 100mW 12-8013 49.9K, 100mW 12-7200 SWITCHES SW1-SW2 KSLOV411 08-6798 DF62J12S2AHQA ON/OFF...
  • Page 32 Model 177-84-2 Alpha/Beta Ratemeter Reference Description Part Number CRYSTALS 32.768KHz 01-5740 MISCELLANEOUS HSMJ-A401-U40M1 LED Red-Orange 07-6520 F1-F2 MF-MSMF030-2 300mA, 30V 1812 Fuses 21-8294 FERRITE BEAD-220 Ohm 0805 21-9986 Mech1 RLP1-200-500 LPR1-LIGHTPIPE 07-6657 W1-W3 73412-0110 Ucoax Jack 13-9376 534-1284 Screw Terminal 6/32...
  • Page 33 13-8088 640456-2 MTA 100X2 13-8073 MISCELLANEOUS METER ASSY Model 177 4173-166 MAIN BOARD MODEL 177-84-2 5347-563 DISPLAY BOARD Model 177-84-2 5347-564 2 EA. PROTECTION BOARD 5347-576 MAIN HARNESS Model 177-84-2 8347-576 PORTABLE CAN HARNESS 8363-462 UNIMORPH HARNESS Model 215 8110-153...

  • Page 34: Appendix

    Model 177-84-2 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 35 Model 177-84-2 Alpha/Beta Ratemeter 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.

  • Page 36: Appendix 2: Model 177-84-2 Mode Switch Addition

    This addition was originally put on the Model 177-84-2 so that it would work better with the Model 4902 Hand & Foot Detector Stand. The user can put the Model 177- 84-2 into Frisk Mode and then remove the hand detector from its cradle and use it as a frisker.

  • Page 37: 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 177-84-2. Other instruments can be used.

  • Page 38: Revisions

    Model 177-84-2 Alpha/Beta Ratemeter Section Revisions Firmware Version 34702N04 Added Clear Alarm on Overload. Fixed where voltages were not changed immediately when setting default values but would be correct after a power-cycle. Updated default values. Version 34702N03 Fixed issue where background subtract was disabled after pressing the ACK/Mode button.

  • Page 39: Diagrams And Drawings

    Model 177-84-2 Alpha/Beta Ratemeter Section Diagrams and Drawings Main Board, Drawing 347 x 563 (4 sheets) Main Board Component Layout, Drawing 347 x 564 (2 sheets) Display Board, Drawing 347 x 569 Display Board Component Layout, Drawing 347 x 570 (2 sheets)

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