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LUDLUM MODEL 19 Manual

Micro r meter
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LUDLUM MODEL 19
MICRO R METER
February 2012
Serial Number 207422 and Succeeding
Serial Numbers

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Summary of Contents for LUDLUM MODEL 19

  • Page 1 LUDLUM MODEL 19 MICRO R METER February 2012 Serial Number 207422 and Succeeding Serial Numbers...
  • Page 2 LUDLUM MODEL 19 MICRO R METER February 2012 Serial Number 207422 and Succeeding Serial Numbers...

  • Page 4: Table Of Contents

    Troubleshooting Electronics which utilize a Scintillation Detector Technical Theory of Operation Detector Input Amplifier Discriminator Audio Scale Ranging Digital Analog Converter Meter Drive Fast/Slow Time Constant Low Voltage Supply High Voltage Test High Voltage Supply February 2012 Ludlum Measurements, Inc.
  • Page 5 Model 19 MICRO R METER Technical Manual Recycling Parts List Model 19 Micro R Meter Main Board, Drawing 367 × 166 Wiring Diagram, Drawing 367 × 174 Drawings and Diagrams February 2012 Ludlum Measurements, Inc.

  • Page 6: Introduction

    " cell batteries are located in an isolated compartment, easily accessible from the front panel. The Model 19 NaI scintillator is energy sensitive. An energy response curve is included in section 10 of this manual for further reference. Page 1-1 February 2012 Ludlum Measurements, Inc.

  • Page 7: Getting Started

    The Model 19 serial number is located on the front panel below the battery compartment. Most Ludlum Measurements, Inc. detectors have a label on the base or body of the detector for model and serial number identification.

  • Page 8: Operational Check

    Model 19 MICRO R METER Technical Manual Section 2 Note the (+) and (-) marks inside the battery door. Match the battery polarity to these marks. Close the battery box lid, push down and turn the quarter-turn thumb screw clockwise a quarter of a turn.

  • Page 9: Maintenance

    Maintenance Instrument maintenance consists of keeping the instrument clean and periodically checking the batteries and the calibration. The Model 19 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.
  • Page 10 Model 19 MICRO R METER Technical Manual Section 2 insulators, exposing the internal contacts and battery springs. Removal of the handle will facilitate access to these contacts. Note: Never store the instrument over 30 days without removing the batteries. Although this instrument will operate at very high ambient temperatures, battery seal failure may occur at temperatures as low as 37 °C (100 °F).

  • Page 11: Specifications

    Model 19 MICRO R METER Technical Manual Section 3 Section Specifications reading within 10% of true value Linearity: variable from 400 to 1500 Vdc; electronically regulated to High Voltage: within 1% instrument calibration change less than 3% Battery Dependence: within the meter battery check limits two standard alkaline "...

  • Page 12: Identification Of Controls And Functions

    Model 19 MICRO R METER Technical Manual Section 4 Section Identification of Controls and Functions a six-position switch marked , 5000, 500, Range Selector Switch: 250, 50, and 25. Moving the range selector switch to one of the range positions (5000, 500, 250, 50, 25) provides the operator with an overall range of 0-5000 µR/hr.
  • Page 13 Model 19 MICRO R METER Technical Manual Section 4 provides a means to vary the high voltage from 400 to HV Adjustment: 1500 V. recessed potentiometers located under Range Calibration Adjustments: the calibration cover on the right side of the front panel. These adjustment controls allow individual calibration for each range multiplier.

  • Page 14: Safety Considerations

    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 19 Micro R Meter is marked with the following symbols: CAUTION (per ISO 3864, No.

  • Page 15: Cleaning And Maintenance Precautions

    European Union. Cleaning and Maintenance Precautions The Model 19 may be cleaned externally with a damp cloth, using only water as the wetting agent. Do not immerse the instrument in any liquid. Observe the following precautions when cleaning or performing maintenance on the instrument: 1.

  • Page 16: Troubleshooting

    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.
  • Page 17 Model 19 MICRO R METER Technical Manual Section 6 SYMPTOM POSSIBLE SOLUTION No power (or meter Check battery contacts. Clean them does not reach with rough sandpaper or use an engraver to clean the tips. TEST BAT OK mark) (continued)

  • Page 18: Technical Theory Of Operation

    Model 19 MICRO R METER Technical Manual Section 7 Section Technical Theory of Operation Detector The detector consists of a crystal of sodium iodide with Thallium activation (NaI Tl) that gives off light pulses when penetrated by radiation photons. The light pulses are converted to electrical pulses by the photo cathode of the photomultiplier tube.

  • Page 19: Audio

    Model 19 MICRO R METER Technical Manual Section 7 Audio Discriminator pulses are coupled to univibrator pin 12 of U9B. Front-panel audio selector controls the reset at pin 13 of U9B. When , pulses from pin 10 of U9B turn on oscillator U12, which drives the can-mounted unimorph.

  • Page 20: High Voltage Supply

    Model 19 MICRO R METER Technical Manual Section 7 through analog switch logic circuit U15, U14, and U3. High Voltage Supply High voltage is developed by switching regulator U13 and T1. Voltage multiplier CR3 thru CR7, and associated components, develop the detector voltage.
  • Page 21 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. With many different agencies –...
  • Page 22 Model 19 MICRO R METER Technical Manual Section 9 Section Parts List Reference Description Part Number Model 19 UNIT Completely Assembled Micro R Meter Model 19 Micro R Meter 48-1615 Main Board, BOARD Completely Assembled Drawing 367 × 166 Circuit Board...
  • Page 23 Model 19 MICRO R METER Technical Manual Section 9 Reference Description Part Number TRANSISTORS MMBT3904LT1 05-5841 MMBT4403LT1 05-5842 MMBT3904LT1 05-5841 VOLTAGE REGULATOR LT1460KCS3-2.5TR 05-5867 INTEGRATED CIRCUITS U1-U3 MAX4542ESA 06-6453 U4-U5 CMXT3904 05-5888 CMXT3906 05-5890 MAX4541ESA 06-6452 MAX985EUK-T 06-6459 CD74HC4538M 06-6297...
  • Page 24 Model 19 MICRO R METER Technical Manual Section 9 Reference Description Part Number 100K, 64W104 HV ADJ 09-6813 10K, 3266X1-103 NAME 09-6822 RESISTORS R1-R5 200K, 1/8W, 1% 12-7992 8.25K, 1/8W, 1% 12-7838 10K, 1/8W, 1% 12-7839 2.37K, 1/8W, 1% 12-7861...
  • Page 25 Model 19 MICRO R METER Technical Manual Section 9 Reference Description Part Number CONN-640456-3 MTA100x3 NAME 13-8081 CONN-640456-2 MTA100x2 NAME 13-8073 CONTACT #1434 NAME 18-9124 INDUCTOR 22µH, CD43-220 21-9808 TRANSFORMER 31032R 21-9925 Wiring Diagram, Drawing 367 × 174 Model 19 LAMP BOARD 5367-113...
  • Page 26 Model 19 MICRO R METER Technical Manual Section 9 Reference Description Part Number PORTABLE KNOB 08-6613 SWITCH SEAL (P/B) 08-6611 UNIMORPH W/WIRES, O'RING 40-0034 CAL COVER W/SCREWS 4363-200 HANDLE- PORTABLE (GRIP) 7363-139 Page 9-5 February 2012 Ludlum Measurements, Inc.
  • Page 27 Section Drawings Model Board Circuit, Drawing 367 × 166 (4 sheets) Model Board Component Layouts, Drawings 367 × 167 (2 sheets) Wiring Diagram, Drawing 367 × 174 Energy Response for Ludlum Model 19 Page 10-1 February 2012 Ludlum Measurements, Inc.

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