1. Manuals
  2. Brands
  3. LUDLUM Manuals
  4. Measuring Instruments
  5. 2241-2i
  6. Technical manual

LUDLUM 2241-2i Technical Manual

Survey meter. serial number 170658 and succeeding serial numbers
Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
LUDLUM MODEL 2241-2i AND -2i/2
SURVEY METER
January 2018
Serial Number 170658 and Succeeding
Serial Numbers

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the 2241-2i and is the answer not in the manual?

Questions and answers

Related Manuals for LUDLUM 2241-2i

Summary of Contents for LUDLUM 2241-2i

  • Page 1 LUDLUM MODEL 2241-2i AND -2i/2 SURVEY METER January 2018 Serial Number 170658 and Succeeding Serial Numbers...
  • Page 2 LUDLUM MODEL 2241-2i AND -2i/2 SURVEY METER January 2018 Serial Number 170658 and Succeeding Serial Numbers...
  • Page 3 Ludlum Measurements, Inc. January 2018...

  • 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

    Front-Panel Calibration Controls Main Board Controls Switch Board Controls Safety Considerations Environmental Conditions for Normal Use Detector Connector Warning Markings and Symbols Maintenance Recalibration Batteries Technical Theory of Operation Main Board Switch Board Display Board Ludlum Measurements, Inc. January 2018...
  • Page 7 Detector Overload (OVL) Calibration 8-19 Software License Agreement 8-21 Recycling Parts List Model 2241-2i and 2241-2i/2 Survey Meter 10-1 Main Circuit Board, Drawing 408 × 223 10-1 Calibration Board, Drawing 408 × 120 10-3 Display Board, Drawing 408 × 259 10-4 Switch Board, Drawing 408 ×...

  • Page 8: Introduction

    The internal detector is an energy compensated GM tube capable of measuring fields up to 4 R/hr (0.04 Sv/h) for the Model 2241-2i and up to 1 R/hr (0.01 Sv/h) for the Model 2241-2i/2. Programmable display units (...
  • Page 9 Model 2241-2i & -2i/2 Technical Manual Section 1 alarm, indicating that the counting circuitry is nearing the maximum counting capability. All of the features described above may be programmed manually using the internal switch board or by computer through the RS-232 port. Two different detector operating parameters may be stored in non-volatile memory.

  • Page 10: Getting Started

    The survey meter 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 11: Operational Check

    If using a Ludlum Model 44-9 detector, a typical reading would be 25-50 cpm or 8-15 uR/hr. If using a Ludlum Model 44-2 detector, a typical reading would be 1.4-2.6 kcpm or 8-15 uR/hr. Expose the detector to a check source and verify that the instrument indicates within 20% of the check source reading obtained during the last Ludlum Measurements, Inc.
  • Page 12 Model 2241-2i & -2i/2 Technical Manual Section 2 calibration. Alternatively, expose the detector to a source of known value and verify that the detector detects greater than or equal to the efficiency listed in the detector manuals’ specification section. Failure to meet these criteria may indicate a detector malfunction.

  • Page 13: Specifications

    Model 2241-2i & -2i/2 Technical Manual Section 3 Section Specifications : two each, ˝D˝ cell batteries housed in an externally accessible Power Instrument: sealed compartment. Current draw is approximately 35 mA with the backlight . Minimum battery voltage is 2.2 ± 0.1 Vdc.

  • Page 14: Removable Switchboard Adjustable Parameters

    Model 2241-2i & -2i/2 Technical Manual Section 3 : accessible from the front of the instrument Calibration Controls (protective cover provided). These controls are preset at the factory or calibration lab and should not be adjusted by field personnel. : adjustable from 2 to 100 Discriminator / Input Sensitivity mV;...
  • Page 15 Model 2241-2i & -2i/2 Technical Manual Section 3 : allows for input of detector parameters RS-232 Detector Setup Mode via the RS-232 port : selects either 150, 300, 600, 1200, 2400, 4800, 9600, or Baud Rate 19200 bps : adjustable from 0 to 9999...

  • Page 16: Identification Of Controls And Functions

    Section Identification of Controls and Functions Display The Model 2241-2i and 2241-2i/2 utilize a four-digit liquid crystal display (LCD) with two-digit overflow ( mode) and moving decimal point. SCALER The two smaller digits located in the lower right corner of the display...

  • Page 17: Front-Panel Controls

    Model 2241-2i & -2i/2 Technical Manual Section 4 mode when the six-digit display (four digits display and two overflow digits in right corner) reaches ˝999999˝ and starts to roll over again. : Indicates that the detector is being exposed to radiation OVERLOAD intensities greater than the detector maximum operating limit.

  • Page 18: Front-Panel Calibration Controls

    : a multi-turn potentiometer (approximately 20 DISC (Discriminator) revolutions), used to vary the detector pulse-counting threshold from 2 to 100 millivolts. A Ludlum Model 500 Pulser or equivalent should be used in checking or adjusting the pulse discrimination parameter. Ludlum Measurements, Inc.

  • Page 19: Main Board Controls

    Note: When making adjustments to the potentiometers, make note of the following precautions: Use a Ludlum Model 500 Pulser or high-impedance voltmeter with a high-voltage probe to measure the high voltage at the detector connector. If a Ludlum Model 500 Pulser is not available, ensure that the impedance of voltmeter used is 1000 megohms or greater.

  • Page 20: Switch Board Controls

    Model 2241-2i & -2i/2 Technical Manual Section 4 position, the clicks-per-event or the audible alarm(s) will not be audible when active. Switch Board Controls The switch board utilizes a 16-position rotary switch ( ) to select FUNCTION the 16 setup parameters. (Refer to schematics and component layout drawing near the end of the manual.) All of the setup parameters are stored...

  • Page 21: Safety Considerations

    Warning Markings and Symbols Caution! 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. Ludlum Measurements, Inc. Page 5-1...
  • Page 22 Model 2241-2i & -2i/2 Technical Manual Section 5 The Model 2241-2i and -2i/2 Survey Meter is marked with the following symbols: CAUTION, RISK OF ELECTRIC SHOCK (per ISO 3864, No. B.3.6): designates a terminal (connector) that allows connection to a voltage exceeding 1 kV.

  • Page 23: Maintenance

    Check the appropriate regulations to determine required recalibration intervals. Ludlum Measurements offers a full-service repair and calibration department. We not only repair and calibrate our own instruments, but most other manufacturers’ instruments as well.

  • Page 24: Batteries

    Model 2241-2i & -2i/2 Technical Manual Section 6 Batteries The batteries should be removed and the battery contacts cleaned of any corrosion at least every three months. If the instrument has been exposed to a very dusty or corrosive atmosphere, more frequent battery servicing should be used.

  • Page 25: Technical Theory Of Operation

    Model 2241-2i & -2i/2 Technical Manual Section 7 Section Technical Theory of Operation Refer to the Main Detector Input/Amplifier Board schematic for the following: Negative-going detector pulses are coupled from the detector through C021 to amplifier U021. R024 and CR021 protect the input of U021 from inadvertent shorts.
  • Page 26 Model 2241-2i & -2i/2 Technical Manual Section 7 High-Voltage Supply High voltage is developed by blocking oscillator Q241, T141, and C244 and rectified by voltage multiplier CR041-CR043, C041-C043, and C141. High voltage increases as current through R241 increases, with maximum output voltage with Q241 saturated.

  • Page 27: Switch Board

    Model 2241-2i & -2i/2 Technical Manual Section 7 S1 (FUNCTION) Refer to the Switch Board schematic for the following: S1 is a 16-position binary rotary switch, which selects the programmable parameters for the survey meter. The switch selects the parameters using the...

  • Page 28: Instrument Setup

    Model 2241-2i & -2i/2 Technical Manual Section 8 Section Instrument Setup Entering or Changing Switch Board Parameters On the switch board, select the desired parameter to enter or change by using the corresponding switch position. Depress the FUNCTION ENTER button and a character on the LCD will start to flash. The flashing character indicates that the program is in the parameter change mode.

  • Page 29: Function Switch Position Descriptions And Variables

    Model 2241-2i & -2i/2 Technical Manual Section 8 UNCTION WITCH OSITION ESCRIPTIONS AND ARIABLES places the survey meter in the POSITION 0 NORMAL OPERATION normal (counting) operating mode. Unplugging the switch board from the survey meter main board defaults to normal operating mode.
  • Page 30 Entering the appropriate Calibration Constant (position 2) and Dead Time correction (position 1) may calibrate the Model 2241-2i or Model 2241-2i/2 and detector in either exposure rate (R/hr or Sv/h). The survey meter will automatically convert to the correct reading when switching between R and Sv.
  • Page 31 Model 2241-2i & -2i/2 Technical Manual Section 8 selects the audible clicks-per-event POSITION 5 AUDIO DIVIDE division rate for the current detector setup. If the switch is AUD ON in the position, no audible clicks-per-event will be heard. This parameter ranges from: 0 ...
  • Page 32 Model 2241-2i & -2i/2 Technical Manual Section 8 POSITION A NOT USED : LCD Backlight is the amount of time that the LCD POSITION B ON TIME backlight will stay on after pressing the front-panel switch labeled LIGHT This value is stored in EEPROM.

  • Page 33: Loading Default Parameters

    DATA IN HANDSHAKING IN HANDSHAKING OUT Note: Ludlum Measurements, Inc. offers a PC compatible software program that incorporates the read/write commands necessary to communicate between the PC and the survey meter. The program also incorporates an algorithm to calculate the detector Calibration Constant and Dead Time Constant.

  • Page 34: Calibration

    9600 LCD Time Off 5 secs Detector Calibration The Model 2241-2i and 2241-2i/2 calibration routine consists of entering detector parameters into memory by way of the switch board and adjusting controls ( ) for the specific detector operating DISC requirements.

  • Page 35: General Detector Setup Information

    Model 2241-2i & -2i/2 Technical Manual Section 8 The last subsection of calibration deals with the Detector Overload ( ENERAL ETECTOR ETUP NFORMATION The operating point for the instrument and probes is established by setting the probe voltage and instrument sensitivity ( ).

  • Page 36: Counts Per Minute (C/M) Calibration

    OUNTS PER MINUTE ALIBRATION This procedure will setup the Model 2241-2i or 2241-2i/2 for the counts per minute (C/m) mode of operation. Refer to section 8, (Page 8-2 and following) for more information on setup parameter variables.
  • Page 37 Model 2241-2i & -2i/2 Technical Manual Section 8 Position 7 selects the desired ratemeter trip points. ALERT ALARM If the parameters are undetermined, arbitrarily choose “0050 kC/m” for the alarm and “0045 kC/m” for the alert to confirm operation of the alert/alarm function.

  • Page 38: R/Hr Calibration

    Model 2241-2i & -2i/2 Technical Manual Section 8  Confirm that the scaler readout is within 2% of the pulser input rate.  Ensure that the s function by inputting the preset ALERT ALARM alarm levels as to initiate the alert and alarm conditions.
  • Page 39 This procedure contains the algorithm (hi-lo method) for determining the CC (Calibration Constant) and the DTC (Dead Time Correction). An example of the Ludlum Model 44-9 GM detector calibration is used in conjunction with the algorithm calculations to aid in solving the equations.
  • Page 40 Model 2241-2i & -2i/2 Technical Manual Section 8 Preliminary CPS Setup Refer to Section 8, Subsection “Function Switch Position Descriptions and Variables,” for cps readout variables. Select position 1 on the toggle switch located on the front panel (Model 2241-2). Starting with...
  • Page 41 Model 2241-2i & -2i/2 Technical Manual Section 8 Reference the table at the end of this section to determine the cps/exposure rate (cps/ER). The conversion can be determined by placing the detector in a radiation field that produces from 50 to 200 cps.
  • Page 42 Model 2241-2i & -2i/2 Technical Manual Section 8 CC and DTC Algorithm Equations (5) and (6) convert units per time (R/hr Display Units) to units per second: units units  time second Insert the cps lo data point (8 mR/hr for the Model 44-9 example)
  • Page 43 Model 2241-2i & -2i/2 Technical Manual Section 8 As an example, assume a 60-second count sample in a low field of 8 mR/hr: Example 26,427 CORR Place detector in the high field and enter the counts per second: Equation 8...
  • Page 44 Model 2241-2i & -2i/2 Technical Manual Section 8 Enter the results of equations (9) and (10) into equation (11) to solve for Equation 11 count Example  seconds  84 x 10  count Solve for f Equation 12 units...
  • Page 45 The data represented in the table above is typical. Actual values may vary among detector and instrument combinations. This table represents some of the common detectors operated with the Model 2241-2i and 2241-2i/2. Consult the LMI sales department for information concerning detectors not listed in the table above.

  • Page 46: Detector Overload (Ovl) Calibration

    OVERLOAD control accordingly. Example: Ludlum Model 44-9 is calibrated with Model 2241-2i in the R/hr units display, utilizing DT. The upper linear operating point is 400 mR/hr for the Model 44-9. Place the detector at the 1000 mR/hr point and adjust the control to initiate alarm.
  • Page 47 Model 2241-2i & -2i/2 Technical Manual Section 8 The detector overload or saturation point for alpha and/or beta scintillation detectors is when the detector face (Mylar) has been punctured, allowing light to saturate the photomultiplier tube (PMT). The pulse output will decrease or even appear non-responsive to any radiation activity, depending upon the size of the puncture and the light intensity to the PMT.
  • Page 48 Model 2241-2i & -2i/2 Technical Manual Section 8 Ludlum Measurements, Inc. Page 8-21 January 2018...
  • Page 49 Model 2241-2i & -2i/2 Technical Manual Section 8 Ludlum Measurements, Inc. Page 8-22 January 2018...
  • Page 50 Model 2241-2i & -2i/2 Technical Manual Section 8 Ludlum Measurements, Inc. Page 8-23 January 2018...

  • Page 51: 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 52: Parts List

    Model 2241-2i & -2i/2 Technical Manual Section 10 Section Parts List Reference Description Part Number Model 2241-2i and UNIT Completely Assembled 2241-2i/2 Survey Meter Model 2241-2i Survey Meter 48-2960 UNIT Completely Assembled Model 2241-2i/2 Survey Meter 48-3100 BOARD Completely Assembled...
  • Page 53 Model 2241-2i & -2i/2 Technical Manual Section 10 Reference Description Part Number C241 1µF, 35V 04-5656 C242 68µF, 10V 04-5654 C243 0.1µF, 50V 04-5663 C251 68µF, 10V 04-5654 TRANSISTORS Q101 2N7002L 05-5840 Q141 MMBT3904LT1 05-5841 Q211 2N7002L 05-5840 Q212 MMBT4403LT1...

  • Page 54: Calibration Board, Drawing 408 × 120

    Model 2241-2i & -2i/2 Technical Manual Section 10 Reference Description Part Number R031 1M, 1/4W, 5% 10-7030 R032 1M, 1/4W, 5% 10-7028 R033-R034 1G, FHV-1, 2% 12-7686 R111-R113 22.1K, 1/4W, 1% 12-7843 R121 100 Ohm, 1/4W, 1% 12-7840 R122 6.81K, 1/4W, 1%...

  • Page 55: Switch Board, Drawing 408

    Model 2241-2i & -2i/2 Technical Manual Section 10 Reference Description Part Number 10K, 1/3W 12-7748 1K, 1/3W 12-7750 CONNECTOR CONN-640456-7, MTA100 13-8115 LED Backlite BOARD Completely Assembled Display Board, Display Board 5408-259 Drawing 408 × 259 CAPACITORS 27PF, 100V 04-5658...

  • Page 56: Chassis Wiring Diagram, Drawing 408 × 123

    "D" Duracell Battery 21-9313 MISCELLANEOUS Model 2241 Switch Board Add On 4408-053 Model 2240 Digital Bezel Assembly 4408-020 Model 2241-2i Internal Det. Bd. 5408-160 Model 241-2i/2 Internal Det. Bd. 5408-162 Bezel Back 7408-025 Bezel Back Gasket 7408-026 Portable Battery Contact Set...
  • Page 57 Model 2241-2i & -2i/2 Technical Manual Section 10 Reference Description Part Number Model 2241-2i Can Assy. 4363-441 Model 2241-2i/2 Can Assy. 4363-868 Assembled Battery Lid 9408-136 Model 2241 Handle Assy. w/o clip 4408-075 2 ea Can Gasket 22-9773 Portable Knob...
  • Page 58 Model 2241-2i & -2i/2 Technical Manual Section 11 Section Drawings Optional Source Holder Assembly, Drawings 62 × 166 & 62 × 166B Main Circuit Board, Drawings 408 × 223 (3 sheets) Main Circuit Board Component Layout, Drawing 408 × 224 Calibration Board, Drawing 408 ×...

  • Page 74: Binary Output Format

    Appendix A Appendix RS-232 Output Formats The Ludlum Model 2241 series of instruments has an RS-232 serial communications port that can be used to log readings and read or set instrument parameters. There are two formats available. Most Model 2241...
  • Page 75 Model 2241-2i & -2i/2 Technical Manual Appendix A RS-232 Commands E – auto dump off A – auto dump on C – start scaler F – set scaler count time R – send parameters from instrument to computer S – read parameters from computer to instrument O –...
  • Page 76 Model 2241-2i & -2i/2 Technical Manual Appendix A BYTE34 CheckSource+3 BYTE35 CheckSource+4 BYTE36 PercentCS+0 BYTE37 MinDisplay+0 BYTE38 Carriage Return (0DH) BYTE39 Line Feed (0AH) Input of “S” Command – Send Parameters BYTE1 DeadCosntant+0 BYTE2 DeadConstant+1 BYTE3 CalConstant+0 BYTE4 CalConstant+1 BYTE5...

  • Page 77: Ascii Output Format

    Model 2241-2i & -2i/2 Technical Manual Appendix A Input of “F” Command – Set Count Time BYTE1 CountTime+0 BYTE2 CountTime+1 Units 0 = R 1 = Sv 2 = cpm Timebase 0 = min 1 = seconds AudioDivide 0 = Auto...
  • Page 78 Model 2241-2i & -2i/2 Technical Manual Appendix A byte 8 Line Feed (0AH) The ratemeter is displayed as 5 ASCII digits with a decimal, if necessary, and matches the LCD display on the 2241-2. The display mode is a value from 0 to 9 representing the display units.

This manual is also suitable for:

2241-2i/2

Table of Contents