Ludlum Measurements 2200 Owner's manual

LUDLUM MODEL 2200

SCALER RATEMETER

November 2020

Serial No. 185785 and Succeeding

Serial Numbers

LUDLUM MODEL 2200

SCALER RATEMETER

November 2020

Serial No. 185785 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 325-235-4672

Table of Contents

1. INTRODUCTION .................................................................................................................................... 1

2. SPECIFICATIONS ................................................................................................................................... 2

3. DESCRIPTION OF CONTROLS AND FUNCTIONS ........................................................................... 4

FRONT PANEL ............................................................................................................................................ 4

REAR PANEL ............................................................................................................................................. 5

INTERNAL CONTROLS ............................................................................................................................... 5

4. SAFETY CONSIDERATIONS AND WARNING MARKINGS ............................................................ 6

ENVIRONTMENTAL CONDITIONS FOR NORMAL USE ................................................................................. 6

CLEANING INSTRUCTIONS AND PRECAUTIONS .......................................................................................... 6

WARNING MARKINGS AND SYMBOLS ........................................................................................................ 7

REPLACEMENT OF FUSES ........................................................................................................................... 8

RETURN FOR REPAIR AND CALIBRATION ................................................................................................... 8

5. OPERATIONG PROCEDURES .............................................................................................................. 9

POWER ........................................................................................................................................................ 9

DISCR AND THRESHOLD SETTINGS ....................................................................................................... 9

OPERATING POINT .................................................................................................................................... 10

DETERMINING INSTRUMETN PLATEAU .................................................................................................... 11

OPERATING THE INSTRUMENT ................................................................................................................. 11

6. WINDOW OPERATION AND ENERGY CALIBRATION PROCEDURES ...................................... 12

GENERAL .................................................................................................................................................. 12

EQUIPMENT REQUIRED ............................................................................................................................ 12

PROCEDURE TO CALIBRATE THRESHOLD TO 10 KEV/TURN .................................................................... 12

PROCEDURE TO CALIBRATE THRESHOLD TO 100 KEV/TURN .................................................................. 13

7. DATA OUTPUT ..................................................................................................................................... 14

GENERAL .................................................................................................................................................. 14

SOFTWARE ................................................................................................................................................ 14

BUTTON FUNCTIONS ................................................................................................................................ 15

RS-232 PARAMETERS ............................................................................................................................... 16

8. RECYCLING .......................................................................................................................................... 17

9. PARTS LIST ........................................................................................................................................... 18

MAIN BOARD (DRAWING 167 X 413) ....................................................................................................... 18

AMPLIFIER BOARD (DRAWING 167 X 392) ............................................................................................... 20

SWITCH BOARD (DRAWING 167 X 273) ................................................................................................... 22

PUSHWHEEL BOARD (DRAWING 167 X 264) ............................................................................................ 22

DISPLAY BOARD (DRAWING 167 X 276) .................................................................................................. 22

WIRING DIAGRAM (DRAWING 167 X 418) ................................................................................................ 23

APPENDIX A – CALIBRATION PROCEDURE ................................................................................... A-1

APPENDIX B – ELECTRONICS CHECKOUT PROCEDURE ............................................................. B-1

APPENDIX C – SCALER PRINTER OPTION ....................................................................................... C-1

PRINTER SPECIFICATIONS .................................................................................................................... C-1

CONFIGURATION ................................................................................................................................... C-1

APPENDIX D – DRAWINGS AND DIAGRAMS ................................................................................. D-1

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Ludlum Measurements, Inc. Page 1 November 2020

Introduction

The Model 2200 Scaler Ratemeter is a self-contained counting instrument

designed for operation with scintillation, proportional, or GM (Geiger Muller)

detectors. Counting information is displayed both as a scaler count on the LED

(light-emitting diode) display and as an averaged count rate on the analog scaler.

The instrument can be powered by 95-250 Vac, 50-60 Hz, or by four “D” cell

batteries. The unit is complete with a voltage-sensitive preamplifier, linear

amplifier, electronic timer, and detector high-voltage power supply. A single-

channel analyzer is also featured in this unit for use in gamma spectrum analysis.

The analyzer may be switched on or off, allowing gross window counting. Ten-

turn potentiometers are supplied for threshold, window, and high-voltage

controls.

An RS-232 serial port is provided, which can be attached to a computer or

optional printer. A computer interface cable and software is provided to

start/stop and record counts.

Section

1

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Specifications

Meter: 1 mA, 6.4 cm (2.5 in.) scale, self-shielded DC mechanism

Ratemeter: four-decade, linear ratemeter with ranges of 0-500; 0-5000; 0-

50,000; and 0-500,000 cpm (counts per minute); 6.4 cm (2.5 in.) scale panel

meter; separate scales for battery check and high-voltage readout

Ratemeter Accuracy: within 10% of reference value

Scaler: a six-digit, LED readout

Scaler Accuracy: within 2% of reference value

Input Sensitivity: voltage-sensitive for use with all types of detectors –

proportional, GM, scintillator

High Voltage: adjustable with a 10-turn control from 200-2500 V; supports

60 megohm scintillation loads to 1500 V

Time: time base is normally in minutes from 0-999 with multiples of X0.1

and X1. (Optional: Instrument can be switched to a seconds time base by

switching the internal dipswitch SW1 “2” to the ON position. In this case,

the count time may be set to 0-999 seconds with a multiplier switch of X1

and X10.)

Timer Accuracy: time base for the scaler is crystal-controlled and has a timer

accuracy of ±0.2% of the thumbswitch setting

Response Time: in fast position, 4 seconds; in slow position, 22 seconds, for

10-90% of full-scale deflection

Input Connection: series “C” coaxial connector; other connectors are

available upon request

Line Power: 95-250 Vac, 50-60 Hz single phase

Batteries: four “D” cells with typical life of 120 hours; self-contained in the

instrument

Section

2

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Temperature Range: -20 to 50 °C (-4 to 122 °F); may be certified to operate

from -40 to 65 °C (-40 to 150 °F)

Size: 21.6 x 12.7 x 21.6 cm (8.5 x 5 x 8.5 in.) (H x W x L), excluding handle

Weight: 3.4 kg (7.5 lb), including battery

Finish: beige powder coat with sub-surface printed front panel

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Description of

Controls and Functions

Front Panel

COUNT LAMP: a red LED, indicating that the scaler is in the count cycle.

COUNT SWITCH: resets and starts the scaler counting. The scaler turns off at the end

of the preset time.

COUNT TIME: Time base is normally in minutes from 0-999 with multiples of X0.1

and X1. It may be changed to seconds by an internal dipswitch.

MINUTES: a three-decade thumbwheel switch used for presetting count time.

Ratemeter Function Selector: a three-position switch labeled RATE, HV, and BAT.

The function of this switch is to allow the operator to have ratemeter readout on the

meter, HV readout on the meter, or battery check status on the meter.

THRESHOLD: A 10-turn potentiometer is used to set the basic pulse discrimination

point of the scaler. This control is linear in the range of 1.00 through 10.00. If set below

1.00, in addition to non-linearities, the system noise can cause errors.

WINDOW: a 10-turn potentiometer used for adjusting the window width. It is

calibrated with the THRESHOLD control so that one turn of the window control is

equivalent to one turn of the THRESHOLD control.

WINDOW ON-OFF: a toggle switch allowing insertion (ON) or removal (OFF) of the

window.

Detector Input Connection: a series “C” coaxial connector; other connectors are

available upon request.

DISCR: a one-turn potentiometer for setting the range of the threshold potentiometer.

It is a non-indicating control, allowing a wide selection of operating points without

exceeding the linear ranges of the threshold/window circuits or detector voltage rating.

Maximum amplifier sensitivity occurs at maximum clockwise setting.

RANGE Selector Switch: a four-position switch providing range multipliers of X1,

X10, and X1K. With a scale of 0-500 cpm, the full range of the instrument is 0-500,00

cpm.

Section

3

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ZERO Switch: When depressed, this switch discharges the integrating capacitor, driving

the meter to zero.

F-S Response: a two-position toggle switch indicating fast or slow response. In “F”

position, the meter will deflect from 10 to 90% of full scale in 4 seconds. In “S” potion,

the meter will deflect from 10 to 90% of full scale in 22 seconds.

HV: a 10-turn potentiometer control for adjusting HV from 200 V to 2500 V. It

provides a linear adjustment of the detector voltage supply. Changing the detector voltage

will cause the detector gain to change. A linear change in voltage will cause an exponential

change in detector gain. The instrument will support 100 megohm scintillation loads to

1500 V.

RATEMETER: a four-decade linear meter with ranges of 0-500, 0-5000, 0-50,000, and

0-500,000 cpm. Readout is on a 6.4 cm (2.5 in.) scale panel meter. Separate scales are for

battery check and high-voltage readout in conjunction with the Rate, HV, and Bat Switch.

Count Readout: a six-decade, LED readout indicating the count.

Rear Panel

RS-232 Connector: a 9-pin “D” connector, allowing computer or printer output.

RS-232 Data Dipswitch: two-pole dipswitch located on the rear chassis

underneath the calibration cover; controls the RS-232 data. The top switch,

labeled “PC” and “PRNTR,” controls the type of data. In PC mode, data is bi-

directional, allowing the computer to start/stop counting. If the dipswitch is set

to PC, and the pushwheels are set to all zeroes, the instrument count time can

also be changed by the computer through the RS-232 port. In the PRNTR mode,

the scaler count is output at the end of each count only. If the dipswitch is set to

PRNTR, setting the pushwheels to 000 sets the count time to infinity, allowing

for very long count times. The bottom dipswitch, marked “RECYCLE” and

“OFF,” allows counting to recycle instead of requiring a manual count for each

cycle.

Input Power: a receptacle for 95-250 Vac, 50-60 Hz line cord.

Battery Compartment: holds four “D” cell batteries.

Internal Controls

Ratemeter Calibration Controls: four potentiometers used to calibrate the

ratemeter. Each range control is labeled respectively to the ratemeter range switch

on the front panel.

Time base Dipswitch: two-pole dipswitch located on the main circuit board. It

allows for selection of a seconds time base, variable from 0 to 999 seconds, with a

multiplier switch of X1 and X10.

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Safety Considerations and

Warning Markings

Environmental Conditions for Normal Use

Indoor use only

No maximum altitude

Temperature range of -20 to 50 °C (-4 to 122 °F)

Maximum relative humidity of less than 95% (non-condensing)

Mains supply voltage range 95-250 Vac

Maximum transient voltage of 1500 Vac

Installation Category (Overvoltage Category) II (as defined by IEC 1010-1)

Pollution Degree 2 (as defined by IEC 644)

Cleaning Instructions and Precautions

The Model 2200 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. Turn the instrument OFF and disconnect the instrument power cord.

2. Allow the instrument to sit for one minute before cleaning.

Section

4

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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.

Caution!

Verify instrument voltage input rating before connecting to a power

converter. If the wrong power converter is used, the instrument

and/or power converter could be damaged.

The Model 2200 is marked with the following symbols:

DIRECT CURRENT (DC) (IEC 417, No. 5032) - designates an input

receptacle that accommodates a power cord intended for connection to DC

voltages. This symbol appears on the front panel.

PROTECTIVE CONDUCTOR TERMINAL (per IEC 417, No. 5019) –

designates the central grounding point for the safety ground. This symbol is

visible inside the chassis.

ALTERNATING CURRENT (AC) (IEC 417, No. 5032) - designates an

input receptacle that accommodates a power cord intended for connection to

AC voltages. This symbol appears on the back panel.

CAUTION (per ISO 3864, No. B.3.1) – designates hazardous live voltage

and risk of electric shock. During normal use, internal components are

hazardous live. This instrument must be isolated or disconnected from the

hazardous live voltage before accessing the internal components. This

symbol appears on the front panel. Note the following precautions:

Warning!

The operator is strongly cautioned to take the following precautions to

avoid contact with internal hazardous live parts that are accessible using

a tool:

1. Turn the instrument power OFF and disconnect the power cord.

2. Allow the instrument to sit for one minute before accessing internal

components.

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The “crossed-out wheelie bin” symbol notifies the consumer that the product

is not to be mixed with unsorted municipal waste when discarding; each material

must be separated. See section 8, “Recycling” for further information. Also

displayed on the side panel.

The “CE” mark is used to identify this instrument as being acceptable for use

within the European Union.

Replacement of Fuses

Warning!

For continued protection against risk of fire, replace only with fuses of

the specified type and current rating!

Return for Repair or Calibration

To return an instrument for repair or calibration, provide sufficient packing

material to prevent damage during shipment.

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.

Note:

Ludlum Measurements, Inc. recommends recalibration at intervals

no greater than one year, assuming that regular operational checks

are performed. Check the appropriate local, state, and federal

regulations to determine required recalibration intervals.

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Operating Procedures

Power

Select either line or battery operation with the power switch.

Line Operation: Connect the instrument to line power of 95-250 Vac, 50-60

Hz. Turn the power switch to LINE and proceed to use the instrument.

Battery Operation: The battery lids are located at the rear of the instrument.

Use a coin or screwdriver to open the lids. Place 4 “D” cells in the instrument

with the terminal “buttons” (positive ends) facing out. Turn the power switch to

BAT to operate. Check the battery condition by placing the RATE-HV-BAT

selector to BAT. (A downscale reading indicates battery reversal.)

Operational Check: Determine that the instrument is operational by pressing

COUNT. The count lamp should illuminate. (This action starts the scaler

count.)

DISCR and THRESHOLD Settings

The instrument DISCR control is calibrated at the factory so that 1.00 on the

threshold dial is equal to a 10 mV input sensitivity. The DISCR control should

not be changed unless a pulser is available to determine the threshold-versus-

millivolt relationship.

The threshold control should not be set below 1.00. Excessive counting may

occur at lower threshold settings.

Set DISCR and THRESHOLD for appropriate detector.

For scintillation detectors:

 Set THRESHOLD on 1.00.

 Connect scaler to pulser.

 Set pulser pulse height at 10 mV.

Section

5

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 Adjust DISCR until scaler meter reaches 75% of generated, incoming

count rate. The input sensitivity is now set for 10 mV with

THRESHOLD set for 1.00.

 Proceed to use instrument with THRESHOLD setting at 1.00 or

more.

For Geiger Mueller (GM) detectors:

 Set the THRESHOLD and the pulser as in the first three steps for

scintillation detectors.

 Disconnect pulser and set the THRESHOLD on 3.00 and proceed

to use the instrument. The input sensitivity is approximately 30 mV.

At settings less than this, double-pulsing may occur. Some GM tubes

may require even higher settings of 7.00 or 8.00.

For proportional detectors:

 Set the THRESHOLD on 1.00.

 Connect the scaler to the pulser.

 Set the pulser pulse height at 2 mV.

 Adjust the DISCR until the scaler meter reaches 75% of the

generated incoming count rate. The input sensitivity is now set for 2

mV with the THRESHOLD SET ON 1.00.

 Proceed to use instrument with THRESHOLD setting at 1.00 or

more.

Operating Point

The instrument and detector operating point is established by setting the

probe voltage (HV) and instrument sensitivity (DISCR and THRESHOLD).

Efficiency, background, and noise for a given detector system are fixed by

the physical makeup of the detector and rarely vary from unit to unit.

However, the selection of the operating point makes a marked difference in

the apparent contribution of these three sources of count.

In the singular case of the GM detector, a minimum operating voltage is

required to establish the GM operating region. (At lower voltages, the

detector operates as a very insensitive proportional counter.) This detector is

not capable of energy discrimination (pulse-height discrimination).

For gain sensitive detectors (proportional or scintillation), the most

straightforward method of selecting the operating point is to develop a

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graph, relating count rate to system gain. This relationship is commonly

referred to as a plateau or instrument plateau curve. System gain may be

changed by adjusting detector high voltage (HV), THRESHOLD control or

DISCR (amplifier gain).

Determining Instrument Plateau

 Set window ON-OFF at OFF.

 Set the time multiplier toggle switch to X0.1 and the MINUTES

thumbwheel switch to 001. This gives a 0.1 minute count.

 Set THRESHOLD control at 1.0.

 With the detector shielded from the source, adjust the high-voltage control

by 100-volt increments and take a plot of HV-versus-background coutn rate

until the detector voltage rating is reached. Return the HV control to zero.

Note: If the detector voltage is reached before any background counts are

detected, turn the DISCR clockwise to increase the sensitivity.

 Expose the detector to a source and again make a plot of count-versus-

voltage.

 Plot both sets of data and select the operating point to correspond with the

maximum source count and minimum background count. Avoid areas of

very fast count rate changes with small changes in detector voltage. The

optimum operating point for low background detectors is just above the

inflection point (or break-over point) of the plateau curve. If the background

count is irrelevant, shift the operating point to the plateau center for greater

stability.

Operating the Instrument

Ensure that all settings and adjustments have been properly made. Proceed

to use the instrument.

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Window Operation and Energy

Calibration Procedures

General

The Model 2200 is calibrated at the factory so that one turn on the

THRESHOLD controls is equal to one turn on the window dial.

Equipment Required

 Detectors capable of energy discrimination. Examples used are the

Ludlum Models 44-3 and 44-2.

 Known gamma radiation sources. Typical sources are 137Cs (662 keV)

and 241Am (60 keV).

Procedures to Calibrate

Threshold to 10 keV/Turn

Initial Model 2200 control settings

 Window ON-OFF switch at OFF

 Ratemeter RANGE selector switch at X10

 THRESHOLD dial at 5.50

 WINDOW dial at 1.00

 HV dial at 0.00

Turn-on

 Connect the Model 44-3 detector to the instrument.

 Turn the power switch to the appropriate power supply.

Operation and Calibration

 Expose 241Am to the detector.

 Increase the HV setting until the count from the source just starts to

count.

Section

6

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Ludlum Measurements 2200 Owner's manual

Ludlum Measurements 2200 Owner's manual

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