Ludlum Measurements 2224-1 User manual

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

LUDLUM MODEL 2224-1
SCALER / RATEMETER
January 2012
Serial Number 125559 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 2012
Table of Contents
Introduction 1
Getting Started 2
Unpacking and Repacking 2-1
Internal Switches 2-1
Battery Installation 2-2
Connecting a Detector to the Instrument 2-2
Battery Test 2-2
Operating the Instrument 2-3
Principle of Operation 2-3
Specifications 3
Description of Controls and Functions 4
Operator Controls 4-1
Internal Controls 4-2
Safety Considerations 5
Environmental Conditions for Normal Use 5-1
Cleaning Instructions and Precautions 5-1
Warning Markings and Symbols 5-2
Calibration and Maintenance 6
Calibration 6-1
Establishing an Operating Point 6-1
Meter Calibration 6-2
Detector Overload Calibration 6-4
Maintenance 6-5
Recalibration 6-5
Batteries 6-5
Technical Principle of Operation 7

MODEL 2224-1 Technical Manual
Ludlum Measurements, Inc. January 2012
Troubleshooting 8
Recycling 9
Parts List 10
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 × 124 10-5
Wiring Diagram, Drawing 390 × 110 10-5
Drawings and Diagrams 11

MODEL 2224-1 Technical Manual Section1
Ludlum Measurements, Inc. Page 1-1 January 2012
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. The ratemeter dial indicates 0-500 CPM with four
linear range multipliers of ×1, ×10, ×100, and ×1000, producing an overall
range of 0-500 kCPM. The LCD is used to display the counts accumulated
during the preset count time. Four count times are available for selection
through a front-panel switch. These count times are: 0.5, 1, 2 and, 5 minutes.
The counter is reset and started by pressing the count button located in the
end of the carrying handle.
The ratemeter and LCD can display alpha only, beta only, or alpha and beta
by selecting the corresponding toggle switch selection. Audible click-per-
event tones can also be selected to discriminate beta (low pitch tone) from
alpha (high pitch tone) via the side-mounted speaker. Beta threshold,
window, and alpha threshold are adjustable to optimize alpha/beta efficiency
and count separation.
A regulated high-voltage power supply adjustable from 400 to 2000 volts
with detector overload detection is utilized to operate a wide range of
scintillation detectors. Other operating features of the instrument include
programmable audio divide-by (beta channel only), a two-position switch
(internal) for selecting the audio discrimination mode, audio headphone jack,
adjustable volume, battery test pushbutton, high-voltage display pushbutton,
and a ratemeter reset pushbutton.
The unit body is made of cast aluminum with a drawn aluminum can. The
unit is operated with two ˝D˝cell flashlight batteries for operation from -10
oC to approximately 50 oC (14 to 122 °F). For operation to -10 oC (14 °F),
either very fresh alkaline or rechargeable NiCd batteries may be used.
Section
1
T

MODEL 2224-1 Technical Manual Section2
Ludlum Measurements, Inc. Page 2-1 January 2012
Getting Started
Unpacking and Repacking
Remove the calibration certificate and place it in a secure location. Remove
the instrument 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 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.
Important!
If multiple shipments are received, ensure that the detectors
and instruments are not interchanged. Each instrument is
calibrated to specific detectors, and is 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. Include brief information as to the reason for return,
as well as return shipping instructions:
- Return shipping address
- Customer name or contact
- Telephone number
- Description of service requested and all other necessary
information
Internal Switches
Release the can latches and remove the cover from the instrument, taking
care not to damage the speaker wires. Using a ball-point pen, set the
Section
2

MODEL 2224-1 Technical Manual Section2
Ludlum Measurements, Inc. Page 2-2 January 2012
switches for the desired AUDIO division and TONE as described on Page 4-3.
Replace the cover and fasten the latches.
Battery Installation
Ensure that the range selector switch is in the ˝OFF˝position. Open the
battery lid by pushing down and turning the quarter-turn thumbscrew
counterclockwise one-fourth of a turn. Install two ˝D˝size batteries in the
compartment.
Note the (+) and (-) marks inside the battery door. Match the battery
polarity to these marks. Close the battery box lid, then push down and turn
the quarter-turn thumb screw clockwise one-fourth of a turn.
Note:
The center post of a flashlight battery is positive. The batteries
are placed in the battery compartment in opposite directions.
Connecting a Detector to the Instrument
Caution!
The detector operating voltage (HV) is supplied to the detector
via the detector input connector. 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 ˝OFF˝position
before connecting or disconnecting the cable or detector.
Connect one end of a detector cable to the detector by firmly pushing the
connectors together while twisting clockwise one-fourth of a turn. Repeat
the process in the same manner with the other end of the cable and the
instrument.
Battery Test
The batteries should be checked each time the instrument is turned on.
Move the range selector switch to the BAT position. Verify that the overload
(OL) LED on the front panel turns on briefly. The LCD should go through
an initialization sequence displaying ˝88:8.8:8.8,˝then the current sample
number, and finally ˝0.˝Ensure that the meter needle deflects to the battery
check portion on the meter scale. If the meter does not respond, check to

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Ludlum Measurements, Inc. Page 2-3 January 2012
see if the batteries have been correctly installed. Replace the batteries if
necessary.
Operating the Instrument
Connect a detector to the instrument if you have not already done so.
Obtain a meter reading from a check source or calibrated source, if available.
Verify that the reading falls within the expected range. Remove the source.
If a radiation source is available, increase the meter count to exceed the
counting capability of the instrument, signified by the illumination of OL
LED and full-scale needle deflection.
Depress the RESET pushbutton. The meter needle should drive to zero, and
the alarm circuit should de-energize, shutting off the visual alarm.
Select the desire count channel display (α/α+β/β) and count cycle duration
(MIN) 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.
The detected alpha count is displayed by selecting the αposition on the
three-position α, α+ β, and βtoggle switch. The sum of the alpha and beta
counts are displayed in the α+ βposition, and beta counts are displayed in
the βposition. Multiply the CPM reading on the analog ratemeter by the
range multiplier position. When using the LCD and count cycle selector
switch (MIN), the counts are accumulated in each of the three channels
during the count cycle. The alpha, alpha + beta, and beta counts can be
displayed by selecting the appropriate α, α + β, β channel. The count cycle is
started by depressing the pushbutton switch located in the end of the
carrying handle.
The RESET pushbutton switch resets the meter pointer to zero. The detector
operating voltage is displayed on the meter dial, 0-2 kV (kilovolts), by
depressing the HV switch. The OL (overload) lamp, located in the lower
right-hand corner of the meter dial, is to indicate that the detector is
saturated either by a puncture in the detector face on a scintillation detector
or an exposure to a radiation field above the counting capability of the
instrument. The analog meter will deflect full-scale when the OL lamp is
illuminated.