Model 79 Portable Stretch Scope

Model 79 portable stretch scope Model 79 portable stretch scope Model 79 with user


The Model 79 Stretch Scope provides the operator with the ability to investigate areas of suspected gamma contamination while remaining at a greater distance from potentially high fields of radioactivity. The 4.5 m carbon fiber telescoping pole allows the attached detector to reach areas difficult to access with other types of instruments, and its significantly reduced weight mitigates fatigue for the operator.

A large, easy-to-read LCD display rotates to maximize ease of viewing. Padded shoulder strap (included), audio warning tone, and easy, intuitive design are also featured. The unit’s body is made of durable, high-impact plastic with a separate battery compartment. 

This versatile instrument has three modes of operation – RATE, MAX, and COUNT. Measurements can be collected in two sets of units (primary and secondary) for RATE and MAX modes in cps, cpm, Sv/h, mrem/hr, and R/hr units. The user can choose between two sets of units by simply pressing the Units button. An internal switch is used to enable or disable the front-panel setup feature to protect desired settings from inadvertent modification. Setup is also available via software from Ludlum Measurements.

Detector Energy-compensated GM tube
Detection Range 10 µSv/h to 10 Sv/h (1 mR/hr to 1000 R/hr)
Energy Response Within 25% of true value from 60 keV to 3 MeV
Linearity Reading within 10% of true value
LCD Display 3-digit LCD with large 13.4 mm (0.53 in.) digits, low-battery indicator, MAX, ALARM, MUTE
Units: (k)cps, (k)cpm, (k)Bq, (k)dpm, (μ)(m)R(/h), (μ)(m)Sv(/h), (μ)(m)rem(/h)
Display Range
0.0 cps to 99.9 kcps
0.00 cpm to 999 kcpm
0.00 Bq to 99.9 kBq
0.00 dpm to 999 kdpm
0.00 μR/h to 999 R/h
0.00 μSv/h to 999 Sv/h
0.00 µrem/h to 999 rem/h
Can be set to limit display to calibrated range.
Backlight Built-in ambient light sensor automatically activates low-power LED backlight, unless internal dipswitch is set to continuous-On (will reduce battery life)
User Controls
ON/OFF/ACK: Press to turn ON; Tap to acknowledge alarms and silence alarm tone; Press to reset Sigma Audio alarm, turn "click" audio On/Off, turn Sigma Audio beep On/Off; Hold for OFF
Units: Changes the units between primary and secondary units
Mode: Alternates between NORMAL (count rate), MAX (captures peak rate), and COUNT (user-selectable preset count time from 0 to 10 min.). Number of modes can be reduced in setup.
Response Time User-selectable from 1 to 60 s, or Auto-Response Rate FAST or SLOW
Warm-Up Time Less than 2 minutes
Alarms Count rate, exposure/dose, and scaler alarm setpoints adjustable over the display range
Overload High count rate saturation protection to prevent the false display of lower count rates
Zero Protection After a user-settable time interval (default 60 seconds) of no pulses from the detector, the instrument will flash zero reading and the alarm audio will be triggered
Dead Time Correction Employs first and second order corrections for extended performance
Audio Greater than 75 dB at 0.6 (2 ft), approximately 4 kHz
Power Two alkaline or two rechargeable “AAA” batteries (instrument does not support in-device charging)
Battery Life Approximately 100 hours of operation, 24-hour low battery warning and battery level indicator at start up
Meter: High-impact plastic with separate battery compartment
Pole: Carbon fiber, telescoping
Temperature Range
-20 to 50 °C (-5 to 122 °F)
May be certified for operation from -40 to 65 °C (-40 to 150 °F)
Environmental Rating IP rating of 52 on the electronics
Size (H x W x L) 20.3 x 8.1 x 114 cm (8 x 3.2 x 45 in.) retracted, 4.5 m (177 in.) fully extended
Weight 1.4 kg (3 lb), including batteries and shoulder strap