LUDLUM 177-84-2 User manual

LUDLUM MODEL 177-84-2
ALPHA/BETA RATEMETER
April 2022
Serial No. 330935 and Succeeding
Serial Numbers

LUDLUM MODEL 177-84-2
ALPHA/BETA RATEMETER
April 2022
Serial No. 330935 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]

Table of Contents
Introduction...................................................................................................................................................1
Specifications................................................................................................................................................3
Description of Controls and Functions .........................................................................................................5
FRONT PANEL ..............................................................................................................................................................5
REAR PANEL.................................................................................................................................................................6
INTERNAL CONTROLS....................................................................................................................................................7
Safety Considerations and Maintenance .......................................................................................................8
ENVIRONMENTAL CONDITIONS FOR NORMAL USE ....................................................................................8
CLEANING INSTRUCTIONS AND PRECAUTIONS ..........................................................................................8
REPLACEMENT OF FUSES ...........................................................................................................................9
MAINTENANCE ...........................................................................................................................................9
INSTRUMENT RETURN FOR REPAIR/CALIBRATION .....................................................................................9
BATTERY REPLACEMENT..........................................................................................................................10
ELECTRICAL SAFETY PRECAUTIONS ........................................................................................................10
Operating Procedures..................................................................................................................................11
THEORY OF OPERATION..............................................................................................................................................11
PC Interface ................................................................................................................................................14
Recycling ....................................................................................................................................................20
Parts List .....................................................................................................................................................21
MAIN BOARD, DRAWING 347 X 563.............................................................................................................................21
DISPLAY BOARD, DRAWING 347 X 569.........................................................................................................................25
PROTECTION BOARD, DRAWING 347 X 578..................................................................................................................26
WIRING DIAGRAM, DRAWING 347 X 375......................................................................................................................26
Revisions.....................................................................................................................................................27
FIRMWARE ................................................................................................................................................27
SOFTWARE ................................................................................................................................................27
Diagrams and Drawings..............................................................................................................................28

Model 177-84-2 Alpha/Beta Ratemeter
Ludlum Measurements, Inc. Page 1 April 2022
Introduction
The Model 177-84-2 is a 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 instrument has
beta automatic background subtract and beta automatic background update.
The radiation level is displayed on two analog meters. The Alpha meter dial
indicates 0-500 cpm with range multipliers of X1, X10, X100, and X1000.
The Beta meter dial indicates 0-500 cpm with range multipliers of X1, X10,
X100, and X1000. The meter range may be fixed or auto-ranging, depending
on PC Interface software settings. Each channel has its own distinguishable
click-per-event audible tone. Beta events are a low pitch and alpha events are
a high pitch.
Each channel has its own alarm point, which is adjustable from 0 to 500,000
cpm (full scale). Alarms are indicated by an audible tone and LEDs (Light
Emitting Diodes) located underneath the meters.
Section
1

Model 177-84-2 Alpha/Beta Ratemeter
Ludlum Measurements, Inc. Page 2 April 2022
A regulated high-voltage power supply adjustable from 0 to 1500 volts with
detector overload detection is utilized to operate a wide range of scintillation
detectors. Other operating features of the instrument include adjustable
volume, low-battery LED, high-voltage readout, battery voltage readout,
alarm audio acknowledge, and meter reset.
All calibration controls are located internally or require the PC Interface to
prevent tampering. The only user-accessible controls include the
ACK/RESET and BKG UPDATE push-buttons located on the front and an
ON/OFF switch located on the back. The ACK/RESET button functions
as a mode button when not alarming to switch between displaying the alarm
set point and the battery and high voltage.
The unit operates on line power or an internal rechargeable battery. It is
useable in temperatures ranging from -15 to approximately 50 °C (5 to 122
oF).

Model 177-84-2 Alpha/Beta Ratemeter
Ludlum Measurements, Inc. Page 3 April 2022
Specifications
HIGH VOLTAGE: variable from 0 to 1500 volts
ALPHA THRESHOLD: Adjustable from -4 to -180 mV, typically -125 mV
(measured by pulser)
ALPHA METER SCALE: 0-500 cpm, 4-8 Vdc
ALPHA RANGE: X1, X10, X100, X1K
BETA THRESHOLD: Adjustable from -1 to -4 mV, typically -3.5 mV
(measured by pulser)
BETA WINDOW: Adjustable from -4 to -70 mV, typically -60 mV
(measured by pulser)
BETA METER SCALE: 0-500 cpm; 0-1500 V
BETA RANGE: X1, X10, X100, X1K
CROSSTALK: no more than 1% of gross Beta counts in alpha channel and
no more than 10% of gross Alpha counts in Beta channel
LINEARITY: within 10% of true value, typically ± 2% of true value when
measured with an electronic pulser
RESPONSE TIME: The micro-controller calculates the response time
based on the number of incoming counts. Both the minimum and maximum
values are user adjustable from 1 to 99 seconds in software. The default Beta
response times are typically set to 2 seconds minimum and 5 seconds
maximum. The Alpha response times are set to 5 seconds minimum and 10
seconds maximum.
METERS: 1 mA, 2.5 in., DC movement.
CONNECTOR: Series "C" (BNC, MHV, and SHV connectors available)
REAR PANEL TEST OUTPUTS: two MHV type connectors for
Section
2

Model 177-84-2 Alpha/Beta Ratemeter
Ludlum Measurements, Inc. Page 4 April 2022
attaching directly to a scaler input. These are low-level (5-10 mV) negative-
going pulses used for timed counting during test. Set the scaler around 5 mV
and preferably adjust the HV on the scaler to 900 V or less, though these
outputs can survive up to 1500 Vdc.
AUDIO: dual tone click-per-event through a built-in unimorph with an
internal volume control.
ALARM RANGE: adjustable from 0 through full scale
FINISH: powder coat paint
POWER: 12 Vdc (9.5-16 Vdc “electronically qualified input”, internal
rechargeable 6 V (sealed lead-acid) battery; battery life approximately 50
hours
BATTERY DEPENDANCE: instrument calibration change less than 3%
until Low Battery LED comes on
SIZE: 19.1 x 22.9 x 15.2 cm (7.5 x 9 x 6 in.) (H x W x L), excluding handle
WEIGHT: 2.2 kg (4.9 lb)