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Ludlum Measurements 2224-1 Manual

Scaler / ratemeter
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LUDLUM MODEL 2224-1
SCALER / RATEMETER
January 2012
Serial Number 125559 and Succeeding
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Summary of Contents for Ludlum Measurements 2224-1

  • Page 1 LUDLUM MODEL 2224-1 SCALER / RATEMETER January 2012 Serial Number 125559 and Succeeding Serial Numbers...
  • Page 2 LUDLUM MODEL 2224-1 SCALER / RATEMETER January 2012 Serial Number 125559 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

    Safety Considerations Environmental Conditions for Normal Use Cleaning Instructions and Precautions Warning Markings and Symbols Calibration and Maintenance Calibration Establishing an Operating Point Meter Calibration Detector Overload Calibration Maintenance Recalibration Batteries Technical Principle of Operation January 2012 Ludlum Measurements, Inc.
  • Page 6 MODEL 2224-1 Technical Manual Troubleshooting Recycling Parts List Model 2224-1 Scaler / Ratemeter 10-1 Amplifier / Power Supply Board, Drawing 390 × 104 10-1 Processor Board, Drawing 390 × 107 10-4 Calibration Board, Drawing 390 × 112 10-4 Display Board, Drawing 390 × 127 10-5 Interconnect Board, Drawing 390 ×...

  • Page 7: Introduction

    Technical Manual Section 1 Section Introduction he Model 2224-1 is a portable 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 data is displayed by an analog ratemeter and a six-digit liquid crystal display (LCD) counter.

  • Page 8: Getting Started

    The Model 2224-1 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 9: Battery Installation

    A mild electric shock may occur if you make contact with the center pin of the input connector. Switch the Model 2224-1 to the ˝ ˝ position before connecting or disconnecting the cable or detector.

  • Page 10: Operating The Instrument

    ) and proceed with use. Principle of Operation The Model 2224-1 is to be used in combination with alpha/beta scintillation or proportional detectors. The instrument uses pulse heights discrimination to distinguish between alpha and beta pulses from the radiation detector.

  • Page 11: Specifications

    MODEL 2224-1 Technical Manual Section 3 Section Specifications : four linear range multiples of ×1, ×10, ×100 and ×1000; used in Ranges combination with the 0-500 meter dial, providing an overall range of 0-500 kcpm : beta threshold ( ) is adjustable from -2 to -10 millivolts Thresholds (mV);...
  • Page 12 MODEL 2224-1 Technical Manual Section 3 : two standard ˝D˝ cell batteries Power : instrument calibration change less than 3% to Battery Dependence battery endpoint : exceeds 350 hours with a fresh set of alkaline ˝D˝ cell Battery Life batteries : -20 to 50 °C (-4 to 122 °F)

  • Page 13: Description Of Controls And Functions

    MODEL 2224-1 Technical Manual Section 4 Section Description of Controls and Functions Operator Controls (or Range Selector Switch): a six- OFF/BAT/X1000/X100/X10/X1 Switch position rotary switch to select the analog meter range multipliers and check the battery status. When switched to the...

  • Page 14: Internal Controls

    MODEL 2224-1 Technical Manual Section 4 regardless of the switch position and will continue to function when the channel is not selected for display. This allows the operator to view each channel separately or together by simply selecting the appropriate switch position.
  • Page 15 MODEL 2224-1 Technical Manual Section 4 The ratio is selected from the following table. (O is open and C is closed) SWITCH DIVIDE BY RATIO 1000 Not used Dipswitch 3 & 4 (SPARE) : a one-pole DIP switch used to select tone Dipswitch 5 (TONE) discrimination between alpha and beta count channels.
  • Page 16 MODEL 2224-1 Technical Manual Section 4 : a multi-turn potentiometer that provides a means to vary the detector current overload set point. : a multi-turn potentiometer used to set the maximum limit to 2000 Vdc. : a multi-turn potentiometer used to adjust the high-voltage test reading to correspond with the actual high-voltage output.

  • Page 17: Safety Considerations

    This is typical of industrial or construction sites.) Cleaning Instructions and Precautions The Model 2224-1 Scaler/Ratemeter 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: 1.

  • Page 18: Warning Markings And Symbols

    Ludlum Measurements, Inc. The Model 2224-1 Scaler / Ratemeter is marked with the following symbols: CAUTION (per ISO 3864, No. B.3.1) – designates hazardous live voltage and risk of electric shock.

  • Page 19: Calibration And Maintenance

    1. Connect a Ludlum Model 500 Pulser or equivalent to the Model 2224-1. 2. Switch the Model 2224-1 channel selector to the β position. Adjust the beta threshold ( ) for 3.5 mV and the window ) for 30 mV.

  • Page 20: Meter Calibration

    The adjustment is on the front of the meter bezel. It must be adjusted to zero with the range selector switch in position. 2. Connect the Model 500 Pulser to the Model 2224-1 with the appropriate cable. Rotate the Model 2224-1 range selector switch to the ×100 position.
  • Page 21 1.0 kV on the meter dial. Adjust the output from 500 to 1500 Vdc and confirm that the Model 2224-1 meter corresponds to the external voltmeter within  1 0% of each reading.

  • Page 22: Detector Overload Calibration

    MODEL 2224-1 Technical Manual Section 6 11. Replace the Model 2224-1 cover (can) and proceed with use. ETECTOR VERLOAD ALIBRATION Note: The detector operating voltage ( ) must be determined and set before the (overload) adjustment is performed. If the detector operating voltage is re-adjusted, the overload adjustment must be re-adjusted.

  • Page 23: Maintenance

    Maintenance Instrument maintenance consists of keeping the instrument clean and periodically checking the batteries and the calibration. The Model 2224-1 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 24 MODEL 2224-1 Technical Manual Section 6 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 25: Technical Principle Of Operation

    MODEL 2224-1 Technical Manual Section 7 Section Technical Principle of Operation Refer to the Amplifier/Power Supply Board Schematic, Drawing 390 × 104, for the following: Detector Input/ Amplifier Negative-going detector pulses are coupled from the detector through C021 to amplifier U021. R023 and CR021 protects the input of U021 from inadvertent shorts.
  • Page 26 MODEL 2224-1 Technical Manual Section 7 U111 to provide a time delay for the μP clock cycle to complete before the next alpha pulse can be recognized by the μP. Beta pulses from pin 1 of U011 are coupled to univibrator U101. Pulses are coupled to the μP from pin 7 of U101 as long as pins 3 and 13 of U011...
  • Page 27 MODEL 2224-1 Technical Manual Section 7 Detector Overload A voltage drop is developed across R121 and sensed by comparator U012 as detector current increases. When the voltage at pin 3 of U012 goes below pin 2, pin 1 goes low, illuminating the...
  • Page 28 MODEL 2224-1 Technical Manual Section 7 period. At full meter deflection, the low pulse period, leading edge to leading edge, will be 166 μs, 500 cpm = 130 μs, 400 cpm = 104 μs, 200 cpm = 52 μs, 100 cpm = 26 μs, and 0 = no pulse or +5 V. The pulses are inverted by Q302 on the amplifier/power Supply board and then integrated by R403, C401.

  • Page 29: Troubleshooting

    MODEL 2224-1 Technical Manual Section 8 Section Troubleshooting ccasionally you may encounter problems with your LMI instrument or detector that may be repaired or resolved in the field, saving turn-around time and expense in returning the instrument to us for repair. Toward that end, LMI electronics technicians offer the following tips for troubleshooting the most common problems.
  • Page 30 MODEL 2224-1 Technical Manual Section 8 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) Check for loose or broken wires, especially between the main board and the calibration board.
  • Page 31 MODEL 2224-1 Technical Manual Section 8 SYMPTOM POSSIBLE SOLUTION Meter goes full-scale Open the instrument “can” and or “pegs out” check for loose wires. (continued) Ensure that the instrument’s “can” is properly attached. When attached properly, the speaker will be located on the left side of the instrument.

  • Page 32: 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. With many different agencies –...

  • Page 33: Parts List

    Technical Manual Section 10 Section Parts List Reference Description Part Number Model 2224-1 UNIT Completely Assembled Scaler / Ratemeter Model 2224-1 Scaler / Ratemeter 48-2679 BOARD Completely Assembled Amplifier/Power Amplifier/Power Supply Board 5390-099 Supply Board, C001 100PF, 100V 04-5661 Drawing 390 × 104...
  • Page 34 MODEL 2224-1 Technical Manual Section 10 Reference Description Part Number Q111 2N7002L 05-5840 TRANSISTORS Q301 MMBT4403LT 05-5842 Q302 2N7002L 05-5840 Q311-C312 MMBT3904T 05-5841 Q421 MJD210 05-5843 U001 LM285M-2.5 06-6291 INTEGRATED CIRCUITS U011-U012 TLC372ID 06-6290 U021 CA3096M 06-6288 U101 CD74HC4538M 06-6297...
  • Page 35 MODEL 2224-1 Technical Manual Section 10 Reference Description Part Number R021 392K, 1%, 125mW 12-7841 R022-R023 10.0K, 1%, 125mW 12-7839 R024 33.2K, 1%, 125mW 12-7842 R025 22.1K, 1%, 125mW 12-7843 R026 10-7028 R101 100K, 1%, 125mW 12-7834 R103 4.75K, 1%, 125mW...
  • Page 36 MODEL 2224-1 Technical Manual Section 10 Reference Description Part Number BOARD Completely Assembled Processor Board, Processor Board 5390-100 Drawing 390 × 107 Y211 6.144 MHZ 01-5262 CRYSTAL CAPACITORS C101 0.15µF, 50V 04-5665 C201 47µF, 10V 04-5666 C211-C212 27PF, 100V 04-5658 C221 68µF, 6.3V...
  • Page 37 MODEL 2224-1 Technical Manual Section 10 Reference Description Part Number HLMP4700, OVERLOAD 07-6356 LED-SPACER 457-570 07-6357 250K, HV SET 09-6819 POTENTIOMETER CONN-640456-5 MTA100 13-8057 MISCELLANEOUS Display Board, BOARD Completely Assembled Drawing 390 x 127 Display Board 5390-118 DSP1 LCD 7728-365-481...

  • Page 38: Amplifier / Power Supply Board, Drawing 390 × 104

    MODEL 2224-1 Technical Manual Section 11 Section Drawings and Diagrams AMPLIFIER / POWER SUPPLY BOARD, Drawing 390 × 104 AMPLIFIER / POWER SUPPLY LAYOUT, Drawing 390 × 105 PROCESSOR BOARD, Drawing 390 × 107 PROCESSOR BOARD, LAYOUT, Drawing 390 × 108 CALIBRATION BOARD, Drawing 390 ×...

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