Ludlum Measurements 2241-3 User manual

LUDLUM MODEL 2241-3 & 2241-3i
SURVEY METER
January 2016
Serial Number 299171 and Succeeding
Serial Numbers

LUDLUM MODEL 2241-3 & 2241-3i
SURVEY METER
January 2016
Serial Number 299171 and Succeeding
Serial Numbers

STATEMENT OF WARRANTY
Ludlum Measurements, Inc. warrants the products covered in this manual to be free of
defects due to workmanship, material, and design for a period of twelve months from the
date of delivery. The calibration of a product is warranted to be within its specified
accuracy limits at the time of shipment. In the event of instrument failure, notify Ludlum
Measurements to determine if repair, recalibration, or replacement is required.
This warranty excludes the replacement of photomultiplier tubes, G-M and proportional
tubes, and scintillation crystals which are broken due to excessive physical abuse or used
for purposes other than intended.
There are no warranties, express or implied, including without limitation any implied
warranty of merchantability or fitness, which extend beyond the description of the face
there of. If the product does not perform as warranted herein, purchaser’s sole remedy
shall be repair or replacement, at the option of Ludlum Measurements. In no event will
Ludlum Measurements be liable for damages, lost revenue, lost wages, or any other
incidental or consequential damages, arising from the purchase, use, or inability to use
product.
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.
Your cooperation will expedite the return of your equipment.
LUDLUM MEASUREMENTS, INC.
ATTN: REPAIR DEPARTMENT
501 OAK STREET
SWEETWATER, TX 79556
800-622-0828 325-235-5494
FAX [phone]

Ludlum Measurements, Inc. January 2016
Table of Contents
Introduction 1
Information on Model 2241-3i 1-2
Getting Started 2
Unpacking and Repacking 2-1
Battery Installation 2-1
Connecting a Detector 2-2
Operational Check 2-2
Specifications 3
Removable Switchboard Adjustable Parameters 3-2
Internal Detector Specifications for Model 2241-3i 3-4
Identification of Controls and Functions 4
Display 4-1
Display Status Definitions 4-1
Front Panel Controls 4-2
Front Panel Calibration Controls 4-3
Main Board Controls 4-4
Switch Board Controls 4-5
Safety Considerations 5
Environmental Conditions for Normal Use 5-1
Detector Connector 5-1
Warning Markings and Symbols 5-1
Maintenance 6
Operational Check 6-1
Recalibration 6-1
Batteries 6-3
Technical Principle of Operation 7
Main Board 7-1
Switch Board 7-2
Display Board 7-3

Model2241-3&3i TechnicalManual
Ludlum Measurements, Inc. January 2016
Instrument Setup & Calibration 8
Entering or Changing Switch Board Parameters 8-1
Loading Default Parameters 8-1
The Function Switch 8-2
Function Switch Position Descriptions and Variables 8-2
Calibration 8-7
General Detector Setup Information 8-8
Counts per minute (C/m) Calibration 8-9
R/hr Calibration 8-11
Determining CC and DTC 8-12
Software License Agreement 8-19
Recycling 9
Parts List 10
Model 2241-3 Survey Meter 10-1
Main Circuit Board, Drawing 408 × 285 10-1
Calibration Board, Drawing 408 × 98 10-3
Display Board, Drawing 408 × 259 10-4
Switch Board, Drawing 408 × 45 10-5
Chassis Wiring Diagram, Drawing 408 × 101 10-5
Drawings and Diagrams 11
RS-232 Output Formats - Appendix A A
Binary Output Format A-1
ASCII Output Format A-4

Model2241-3 & 3i TechnicalManual Section1
Ludlum Measurements, Inc. Page 1-1 January 2016
Introduction
he Model 2241-3 is a portable microprocessor-based digital Scaler/
Ratemeter designed for use with scintillation, Geiger-Mueller (GM),
and proportional-type detectors for measurement of ionizing
radiation. Data is presented on a four-digit (six digits in the scaler
mode) Liquid Crystal Display (LCD) with moving decimal point. A toggle
switch labeled SCA/RATE selects the desired operating mode for the
instrument. A five-position switch labeled ˝OFF/DET 1/DET 2/DET 3/DET
4˝allows for a quick change of operating parameters when changing out
detectors.
Programmable display units (RATEMETER mode only) can be represented in
R/hr, Sv/h, cpm, or cps with multipliers of micro (µ) or milli (m) for R/hr
and Sv/h and kilo (k) for cpm or cps. The display units are auto-ranging,
enabling the readout to display a broad range of radiation levels. The display
also offers lower limit capability. For example, the display can be set to show
only values that are greater than or equal to1 µR/hr.
This instrument incorporates independent adjustable alarms for RATEMETER
and SCALER operating modes. The RATEMETER mode has two alarm
indicators. The first-level alarm is indicated by display of the word ˝ALERT˝
on the LCD. The second-level alarm is indicated by display of the word
˝ALARM˝and by the emitting of a continuous audible tone. The SCALER
alarm condition will also display the word ˝ALARM˝and produce the same
audible tone. Both audible alarms may be silenced (acknowledged) by
depressing the RESET switch. All alarms are concurrent.
Other features include: 1) Dead Time Correction (DTC) to compensate for
detector dead time; 2) audible click-per-event with programmable 1, 10, 100,
and 1000 divide-by; 3) LCD backlight with programmable ON time; 4)
programmable fixed or variable response time; and 5) count overflow visual
alarm, indicative of the counting circuitry nearing the maximum counting
capability.
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Model2241-3 & 3i TechnicalManual Section1
Ludlum Measurements, Inc. Page 1-2 January 2016
All of the features described above may be programmed manually using the
internal switch board or by computer through the RS-232 port. Four
different detector operating parameters may be stored in non-volatile
memory. The switch board can be removed after entering or changing
parameters to prevent tampering with setup parameters.
A regulated high-voltage power supply, four independent set-point controls
adjustable from 400 to 2500 volts, and adjustable discrimination levels, add
versatility to the instrument. This supports operation for a broad range of
detectors and connecting cable lengths. All of the calibration controls are
covered to prevent any inadvertent adjustment to the detector operating
parameters.
The instrument is powered by two standard ˝D˝cell batteries. The unit body
is made of cast-and-drawn aluminum with beige powder coating, which aids
in the decontamination of surfaces.
The Model 2241-3i is identical to the Model 2241-3 except for the
following:
The five-position selector switch located on the front panel has been
modified to provide for selection of an internal detector. When selected, the
INT position (formerly DET4) switches detector operation to an internal,
energy-compensated Geiger-Mueller detector. Appropriate wiring changes
to accommodate the internal detector have been made; however, physical
dimensions are the same as for a Model 2241-3.
A drawing of the front-panel of the 2241-3i is included at the beginning of
this manual. A wiring diagram for the instrument is included in the back of
the manual with the other drawings. The internal detector specifications can
be found at the end of Section 3 of this manual.

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Ludlum Measurements, Inc. Page 2-1 January 2016
Getting Started
Unpacking and Repacking
Remove the calibration certificates and place them in a secure location.
Remove the instrument, detectors, and accessories (batteries, cable, etc.), and
ensure that all of the items listed on the packing list are in the carton. Check
individual item serial numbers and ensure calibration certificates match. The
Model 2241-3 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.
Important!
If multiple shipments are received, ensure that the detectors
and instruments are not interchanged. Each instrument is
calibrated to specific detectors, and are therefore, not
interchangeable.
To return an instrument for repair or calibration, provide sufficient packing
material to prevent damage during shipment. Also provide appropriate
warning labels to ensure careful handling. Include detector(s) and related
cable(s) for calibration.
Every returned instrument must be accompanied by an Instrument Return
Form, which can be downloaded from the Ludlum website at
www.ludlums.com. Find the form by clicking the “Support” tab and
selecting “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 Installation
Ensure the OFF/DET 1/DET 2/DET 3/DET 4 switch is in the OFF position.
Open the battery lid by turning the quarter-turn thumb screw counter-
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