Ludlum Measurements 79 Sreries User manual

Model 79 Series Stretch Scope
Ludlum Measurements
June 2022
Serial Number: 25024424 and Succeeding
Firmware: F.3.1.4549 and Higher

Model 79 Series Stretch Scope
Ludlum Measurements
June 2022
Serial Number: 25024424 and Succeeding
Firmware: F.3.1.4549 and Higher

STATEMENT OF WARRANTY
Ludlum Measurements, Inc. warrants the products covered in this manual to be free of de-
fects 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 lim-
its 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 war-
ranty 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 contain-
ing return shipping address, customer name, telephone number, description of service re-
quested, 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]

CONTENTS
Contents 3
List of Figures 7
List of Tables 9
1 Introduction 11
1.1 Model 79/1, 79/2, and 79/4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Features 13
3 Quick Reference 15
3.1 Instrument Front Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2 Instrument Rear and Sides Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3 Instrument Internal Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4 Getting Started 19
4.1 Unpacking and Repacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Battery Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3 Instrument Use and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.4 Turning the Instrument On and Off . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.5 Instrument Power ON Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5 Normal Operation 23
5.1 Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2 Status Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.3 Display Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.4 Alerts and Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.5 RATE Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.6 MAX Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.7 COUNT Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6 Fault Detection 31
6.1 Instrument Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.1.1 Detector Loss of Counts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.1.2 Detector Over Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.1.3 Detector Overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.1.4 Calibration Expiration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.1.5 Date (Real Time clock) Reset . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.1.6 Defaults Loaded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7 Configuration 35
7.1 Setup Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.2 Setup Menu Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3

4CONTENTS
7.3 Entering Setup Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.4 Entering Setup Menu (Alternative) . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.5 Exit Setup Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.6 Setup Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.7 Setup Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.7.1 Menu Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.7.2 Setup Group (dEt) - Detector . . . . . . . . . . . . . . . . . . . . . . . . . 40
7.7.3 Setup Group (Ch1) Channel 1 . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.7.4 Setup Group (U-1) - Display Unit . . . . . . . . . . . . . . . . . . . . . . 45
7.7.5 Setup Group (U-2) - Display Unit 2 . . . . . . . . . . . . . . . . . . . . . 49
7.7.6 Setup Group (InS) - Instrument . . . . . . . . . . . . . . . . . . . . . . . 50
7.7.7 Setup Group (rtc) - Real Time Clock . . . . . . . . . . . . . . . . . . . . . 53
7.8 DIP Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8 Advanced Features 55
8.1 Dead Time Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.2 Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
8.2.1 R to Sv Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
8.3 Calibration Expiration Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
8.4 Variable LED Brightness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.4.1 Backlight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.4.2 Ambient Light Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.5 Audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.6 Low-Battery Alarm Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
8.7 Software Calibration Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.8 Instrument Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.9 DIP Switch Viewing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.10 Other Device Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.11 Real-time Streaming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
9 Specifications 61
9.1 Instrument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
9.2 Scope Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
10 Safety Considerations 67
10.1 Environmental Conditions for Normal Use . . . . . . . . . . . . . . . . . . . . . 67
10.2 Warning Markings and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
10.3 Cleaning and Maintenance Precautions . . . . . . . . . . . . . . . . . . . . . . . 68
11 Revision History 69
12 Recycling 71
A Typical Values 73
B All Paramters 75
C Errata 83
Ludlum Measurements, Inc.

CONTENTS 5
C.1 Firmware Known Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
D Assembly Parts Lists and Drawings 85
D.1 Overall View and Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
D.2 Overall Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
D.3 Model 79 Detector and Scope Assembly 4272-576 . . . . . . . . . . . . . . . . . 88
D.4 Detector and Scope Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
D.5 Model 79 Clamp Assembly 4498-951 . . . . . . . . . . . . . . . . . . . . . . . . . 90
D.6 Clamp Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
D.7 Model 79 High Range Detector Assembly 4272-557 . . . . . . . . . . . . . . . . . 92
D.8 Detector Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
D.9 Electronics Assembly 4498-383 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
D.10 Electronics Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
D.11 Electronics Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
June 2022

LIST OF FIGURES
4.1 Startup display with all LCD segments shown. . . . . . . . . . . . . . . . . . . . . . . 20
4.2 Firmware version display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.3 Battery voltage display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1 Alert example in rate mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.2 Alarm example in rate mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.3 RATE mode display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.4 MAX mode display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.5 Entering COUNT mode from another mode or changing units within COUNT mode. 28
5.6 COUNT mode ready to start. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.7 COUNT mode results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.1 Fault - Loss of Counts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.2 Fault - Over Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.3 Fault - Overload. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.4 Fault - Calibration Expired. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.5 Fault - Date Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.6 Fault - Defaults Loaded. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.1 Button Press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.2 Menu Short Cut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.3 Setup - DIP switch protection enabled. . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.4 Setup Group - Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
7.5 Setup Group - Channel 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
7.6 Setup Group - Display Unit 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.7 Setup Group - Display Unit 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
7.8 Setup Group - Instrument. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7.9 Setup Group - Real Time Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
7

LIST OF TABLES
2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1 COUNT mode uits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.1 Display Unit RATE/MAX Minimum Values . . . . . . . . . . . . . . . . . . . . . . . . 46
7.2 Display Unit RATE/MAX Maximum Values . . . . . . . . . . . . . . . . . . . . . . . . 46
7.3 Display Unit Count Minimum Values . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.4 Display Unit Count Maximum Values . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8.1 Features That Affect Units in All Modes . . . . . . . . . . . . . . . . . . . . . . . . . . 56
9.1 Instrument Display Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
9.2 Auto Response Times (in seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
9

CHAPTER
1
INTRODUCTION
The Model 79 Stretch Scope allows the user to operate at a safe distance from high-radiation
areas while providing the ability to reach areas that are difficult to access with other probes.
It also has a wide detection range, which is accomplished using an energy-compensated GM
(Geiger-Mueller) detector.
Three modes of operation are available for the Model 79 Series - RATE,MAX rate, and COUNT.
•RATE mode operation will display the current count, exposure, or activity rate.
•MAX rate mode is used to capture the highest count, activity, or exposure rate detected.
MAX mode is useful for finding a peak rate or frisking when the display is not visible.
•COUNT mode allows the user to perform a count for a predetermined time. Depend-
ing on the units chosen, the result can be a scaler count, a time-averaged rate, a time-
averaged exposure or dose, or an integrated exposure or dose.
Two sets of display units can be configured for RATE/MAX mode and COUNT mode. The
user can switch between these by simply pressing the Units button. Available units for each
mode are:
•RATE/MAX: cps, cpm, Bq, dpm, rem/h, R/h, or Sv/h
•COUNT: cps, cpm, c (counts), Bq, dpm, d (disintegration), rem/h, rem, R/h, R, Sv/h, or
Sv
The instrument features a large LCD (liquid crystal display), automatic backlight, audio warn-
ing, and intuitive operation. The instrument housing is made of lightweight but durable
plastic. The instrument has an IP (Ingress Protection) rating of 52 and is splash resistant
when the audio hole seal option is installed (P/N: 4498-913).
The foam grip provides a comfortable ergonomic grip, but may be removed for ease of de-
contamination. Also available to ease decontamination of the telescoping pole is a clear
plastic sleeve (P/N: 2310599).
11

12 CHAPTER 1. INTRODUCTION
An internal switch is used to enable or disable the front-panel setup feature to protect de-
sired settings from inadvertent modification. Setup is also available via Ludlum’s Lumic Cal-
ibration Software.
1.1 Model 79/1, 79/2, and 79/4
There are three additional versions of the Model 79 - the Model 79/1 (part # 48-4241), the
Model 79/2 (part # 48-4203), and the Model 79/4 (part # 48-4325). These versions use differ-
ent detectors than the Model 79 to provide higher sensitivity for measuring in lower ranges.
The Model 79/1 uses an 18 x 18 mm (0.7 x 0.7 in.) Csl (Tl) crystal scintillator to detect the
lowest range of 0.01 µSv/h to 0.5 mSv/h (1 µR/hr to 50 mR/h). The Model 79/2 is designed
for medium range measurement. It uses an internal energy-compensated GM detector to
provide a detection range of 0.001 mSv/h to 0.04 Sv/h (0.1 mR/h to 4 R/h). The Model 79/4
also uses a internal energy-compensated GM detector. It provides a detection range of 0.010
mSv/h to 0.500 Sv/h (1 mR/h to 50 R/h).
Ludlum Measurements, Inc.

CHAPTER
2
FEATURES
Detection Ranges:
Model 79: 10 µSv/h to 10 Sv/h (1 mR/h to 1000 R/h
Model 79/1: 0.01 µSv/h to 0.5 mSv/h (1 µR/h to 50 mR/h)
Model 79/2: 0.001 mSv/h to 0.04 Sv/h (0.1 mR/h to 4 R/h)
Model 79/4: 0.010 mSv/h to 0.500 Sv/h (1 mR/h to 50 R/h)
Extended Length: 4.5 meters (14.75 ft)
Weight: 1.4 kg (3 lb), including batteries and shoulder strap
Fault Detection:
• Overload Protection
• Loss of Count Protection
• Over Range
• Calibration Expiration Lockout
LCD Display: 3-digit with 13.4 mm (0.53 in.) digits
Available Display Range: auto-ranging, maximum and minimum display can be set to limit
display to calibrated range.
Table 2.1
Unit Range Rate Mode Count Mode
R/h 0.00 µ- 999 x x
Sv/h 0.00 µ- 999 x x
R 0.00 µ- 999 x
Sv 0.00 µ- 999 x
cpm 0.00 - 999 k x x
cps 0.00 - 999 k x x
c (counts) 0.00 - 999 k x
(x indicates if the unit is available in a certain Mode)
13

14 CHAPTER 2. FEATURES
Alerts and Alarms: count rate, exposure/dose, and count alarm set points are adjustable
over the display range
On Device Setup: check or configure primary operating parameters without the need of a
computer
Backlight: low-power LED display illumination
Ambient Light Sensor: automatically turns on backlight and varies status LED intensity
Response Time: programmable to fixed fast (4 s), fixed slow (22 s), auto fast, auto slow, or
user defined (0-60 s)
Audio: greater than 75 dB at 0.6 m (2 ft), approximately 4 kHz
Battery Power: two alkaline or rechargeable "AAA" (does not support in-device charging)
Battery Life: approximately 100 hours of operation, 24-hour low-battery warning
Construction: high-impact plastic with water-resistant rubber seals and separate battery
compartment
Environmental Rating: NEMA (National Electrical Manufacturers Association) rating of 3x
or IP (Ingress Protection) rating of 52 with audio hole seal option
Temperature Range: -20 to 50 °C (-4 to 122 °F), may be certified for operation from -40 to 65
°C (-40 to 150 °F)
Ludlum Measurements, Inc.

CHAPTER
3
QUICK REFERENCE
3.1 Instrument Front Diagram
15

16 CHAPTER 3. QUICK REFERENCE
3.2 Instrument Rear and Sides Diagram
Ludlum Measurements, Inc.