Model 78-6

Stretch Scope Survey Meter

Part Number: 48-3411

Features

• Range: 1 to 5000 μR/hr (0.01 μSv/h to 50 μSv/h)
• 1.2 m (4 ft) to 3.7 m (12 ft) Telescoping Stainless Pole
• Dual Analog/Digital Display
• Splashproof Buttons
• 2.5 x 2.5 cm (1 in. x 1 in.) NaI Scintillator Detector 

The Ludlum Model 78-6 Analog Stretch Scope features a 2.5 x 2.5 cm (1 x 1 in.) NaI(Tl) scintillator mounted on a 3.7 m (12 ft) extendable pole to offer an optimum optimum performance in counting low-level gamma radiation. The NaI scintillator is energy sensitive, refer to the energy response curve for the relative response. The detector measures gamma radiation from 1 µR/hr to 5000 µR/hr (0.01 µSv/h to 50 µSv/h).

Five range divisions are provided in the 0 to 5000 µR/hr (0 to 50 μSv/h) spectrum. The meter face is made up of two scales, 0 - 50 and 0 - 25, plus battery test. The 0 - 50 scale corresponds to the 50, 500 and 5000 positions on the range selector switch. The 0 - 25 scale corresponds to the 25 and 250 positions on the range selector switch.

Other instrument features include Dead Time Correction (DTC) to compensate for detector dead time; audible click-per-event with programmable 1, 10, 100, and 1000 divide-by; LCD backlight with programmable "on" time; programmable fixed or variable response time, and a count overflow visual alarm.

• Specifications
• Options
• Documents

• Specifications
• Options
• Documents

Specifications

Indicated Use	High-activity gamma survey with telescoping detector, 3.6 m (12 ft) fully extended
Detector	Photomultiplier coupled to a 2.5 x 2.5 cm (1 x 1 in.) NaI(Tl) crystal mounted inside the instrument housing
Counting Ranges	Two-scale meter face presenting 0 - 50 µR/hr with full-scale range positions of 5000, 500, and 50; and 0 - 25 µR/hr with full-scale positions of 250 and 25
Linearity	Reading within 10% of true value
High Voltage	Variable from 400 to 1500 Vdc, electronically regulated to within 1%
Angular Response	Within 30% as detector is rotated from 0 to 90 degrees (calibration reference is with radiation field parallel to the long axis of the detector)
Geotropism	Referenced to the unit in horizontal position with display up, the indication will not vary more than 2% of the full-scale reading with the unit in any other direction
Alert/Alarm	Visual and audible adjustable alarm points
Detector Dead Time Compensation (DTC)	Adjustable from 0 to 9999 µs (there is a reduced response in pulsed fields due to DTC)
Backlight "On" Time	5, 15, 30, 60, 90, 120, 180, or 240 ± 1 s
Temperature Range	-20 to 50 °C (-4 to 122 °F)
Working Environment	Indoor/Outdoor (splashproof shields for outdoor use), environmental rating IP 52
Power	2 "D" cell batteries (housed in sealed handle)
Battery Life	Approximately 1000 hours with alkaline batteries (low battery indicated on display)
Headphone Jack	Size 0.32 cm (1/8 in.)
Construction	Aluminum housing with beige powder coat and polished stainless steel telescope assembly with brass fittings
Size (H x W x L)	17.7 x 10.2 x 114 cm retracted; 396 cm fully extended (7 x 4 x 45 in. retracted; 156 in. fully extended)
Weight	2.9 kg (6.4 lb), including batteries

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Options

Option	Description	Part Number
Model 78-Series Case	Rugged, watertight, crushproof, and dust proof transport and storage case.	4272-444

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Documents

• Data Sheet
• Product Manual
• CE Certficiate

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