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Ludlum Measurements 2221 Manual

Portable scaler ratemeter
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LUDLUM MODEL 2221
PORTABLE SCALER RATEMETER
Revised January 2025
Serial Number 343649 and Succeeding
Serial Numbers

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Summary of Contents for Ludlum Measurements 2221

  • Page 1 LUDLUM MODEL 2221 PORTABLE SCALER RATEMETER Revised January 2025 Serial Number 343649 and Succeeding Serial Numbers...
  • Page 2 LUDLUM MODEL 2221 PORTABLE SCALER RATEMETER Revised January 2025 Serial Number 343649 and Succeeding Serial Numbers...

  • Page 4: Statement Of Warranty

    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 6: Table Of Contents

    Model 2221 Portable Scaler Ratemeter January 2025 TABLE OF CONTENTS 1. GENERAL ..........................1 2. SPECIFICATIONS ........................1 3. DESCRIPTION OF CONTROLS AND FUNCTIONS ............2 4. OPERATING PROCEDURES ....................4 4.1 Initial Preparation.........................4 4.2 Operating Point ........................4 4.3 Limitation of Controls......................4 5. DETERMINING INSTRUMENT PLATEAU AND SELECTING OPERATING POINT ..5 6.

  • Page 7: General

    Model 2221 Portable Scaler Ratemeter January 2025 1. GENERAL The Ludlum Model 2221 Portable Scaler A single channel analyzer is also featured in Ratemeter is a self-contained counting this unit for use in gamma spectrum analysis. instrument designed for operation with The analyzer may be switched on or off, scintillation, proportional, or GM detectors.

  • Page 8: Description Of Controls And Functions

    Model 2221 Portable Scaler Ratemeter January 2025 3. DESCRIPTION OF CONTROLS AND FUNCTIONS • POWER: two-position ON-OFF switch • SCALER/DIG RATE Toggle Switch: Two-position toggle switch • DETECTOR: Series "C" connector for selecting scaler or digital ratemeter detector SCALER Position: The display shows the counter contents.

  • Page 9: Status Indicators

    Model 2221 Portable Scaler Ratemeter January 2025 • HV: 20-turn potentiometer used to 1 Position: provides 1 click per event 10 Position: provides 1 click per 10 adjust detector voltage events • O.L.: 20-turn potentiometer used to 100 Position: provides 1 click per 100...

  • Page 10: Operating Procedures

    Model 2221 Portable Scaler Ratemeter January 2025 4. OPERATING PROCEDURES 4.1 Initial Preparation marked difference apparent contribution of these three sources of count. 1. Unscrew battery door latch. In the singular case of the GM detector, a 2. Install 4 "D" size batteries in the battery minimum operating voltage is required to holder.

  • Page 11: Determining Instrument Plateau And Selecting Operating Point

    Model 2221 Portable Scaler Ratemeter January 2025 5. DETERMINING INSTRUMENT PLATEAU AND SELECTING OPERATING POINT 1. Set WIN ON/OFF to OFF. 5. Expose the detector to a source and again make a plot of voltage versus count. 2. Set MINUTES switch to 0.1 minutes.

  • Page 12: Overload Detection Calibration

    = 200 mR/hr (2 mSv/h). Set the field intensity until a decrease in count Model 2221 to overload at 500 mR/hr rate is noticed. For alpha scintillators, (5 mSv/h) field, then position detector the detector photomultiplier tube (PMT)

  • Page 13: Calibration

    Model 2221 Portable Scaler Ratemeter January 2025 8. CALIBRATION Refer to schematic and component layout for corresponds to the voltmeter reading at the following calibration: pin 7 of U3. 8.1 Ratemeter Calibration 8.3 High Voltage Calibration 1. Set THR control to 100 and Window 1.
  • Page 14 Model 2221 Portable Scaler Ratemeter January 2025 20, 30, 40, and 50 mV window cut-off points. 6. Set WIN back to 100 and OUT position. 7. Check the rest of the front-panel functions for proper operation. page 8...

  • Page 15: Overhaul Procedure

    Model 2221 Portable Scaler Ratemeter January 2025 9. OVERHAUL PROCEDURE The checkout below can be performed with boards in instrument. An extender board (LMI 10. Adjust the HV front panel control to the part # 5261-098) is available if better access to fully clockwise position.

  • Page 16: Processor Board Checkout

    Model 2221 Portable Scaler Ratemeter January 2025 19. Press BAT test pushbutton and confirm 29. Adjust R173 T Pulse (labeled "T") for a pin 7 is approximately 0.5 with supply 2.5 microsecond positive pulse width at voltage at +5 Vdc.

  • Page 17: Functional/Chassis Checkout

    Model 2221 Portable Scaler Ratemeter January 2025 16. Change the multiplier range on the 6. Adjust the Frequency Symmetry, signal generator to correspond to each Amplitude and D.C. Offset controls to decade on the rate multiplier to confirm achieve a 5 volt negative pulse with a range switch operation.
  • Page 18 Model 2221 Portable Scaler Ratemeter January 2025 2. Connect one lead of an ohmmeter to 9. Connect positive voltmeter lead to pin 7 chassis ground. (TLC27M7IP) amplifier/power supply board. Connect 3. Connect other lead of ohmmeter to the negative lead to ground near U3.
  • Page 19 Model 2221 Portable Scaler Ratemeter January 2025 function is defeated. Then adjust to fully clockwise position. 30. With the THR control adjusted for 100, adjust R174 Gain (labeled G) for 1.5 19. Set THR control to 100 and Window millivolt input sensitivity. Ensure IN/OUT switch to the OUT position.
  • Page 20 Model 2221 Portable Scaler Ratemeter January 2025 and confirm BAT test and actual supply 42. Increase count rate enough to overflow input is 5 ±0.05 Vdc. counter. An "H" should be observed in the MSD flashing every count interval. 41. Switch SCALER/DIG. RATE switch to the SCALER position, Count Time 43.

  • Page 21: Parts List

    Model 2221 Portable Scaler Ratemeter January 2025 10. PARTS LIST Ref. No. Description Part No. Ref. No. Description Part No. Model 2221 Portable Scaler Ratemeter TRANSISTORS Q130 2N3904G 05-5755 UNIT Completely Assembled Model 2221 Q173 MPS-W51AG 05-5765 Portable Scaler Ratemeter...

  • Page 22: Processor Board, Drawing 261 X 91

    Model 2221 Portable Scaler Ratemeter January 2025 Ref. No. Description Part No. Ref. No. Description Part No. R120 220 OHM 12-7753 R258 100k 09-6823 R131 470k 12-7757 R259 09-6822 R132 12-7748 R260 100k 09-6823 R134 100k 12-7747 R268 09-6828 R135...

  • Page 23: Calibration Board, Drawing 261 X 59

    Model 2221 Portable Scaler Ratemeter January 2025 DIODE Ref. No. Description Part No. MMBD914 07-6353 CONNECTOR P6/1-7 640457-7 MTA100 13-8183 Ref. No. Description Part No. Ref. No. Description Part No. RESISTORS LCD Display Board, Drawing 261 X 58 1M, RCDRCAL...

  • Page 24: Rs-232 Port Kit, Board Drawing 261 X 179

    Model 2221 Portable Scaler Ratemeter January 2025 Ref. No. Description Part No. PHONE JACK TINI #42A 21-9333 J6-J7 (ON CAL HARNESS) 8261-088 (ON MAIN HARNESS) 8261-087 (ON BATTERY HARNESS) 8261-089 NOT USED (ON MAIN HARNESS) 8261-087 Ref. No. Description Part No.

  • Page 25: Rs-232 Port Addition

    The Model 2221 RS-232 port addition allows available. the Model 2221 data to be read as output to a computer or serial printer, by dumping either The Model 2221 will dump the data, no matter the ratemeter or scaler reading as desired.

  • Page 26: Drawings And Diagrams

    Model 2221 Portable Scaler Ratemeter January 2025 12. DRAWINGS AND DIAGRAMS Amplifier/Power Supply Board Schematic, Drawing 261 x 216 Amplifier/Power Supply Board Component Layout, Drawing 261 x 219 (2 sheets) Processor Board Schematic, Drawing 261 x 91 Processor Board Component Layout, Drawing 261 x 103 (2 sheets)

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