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The Model 5085 Meridian is a highly evolved neutron REM meter of classic design. It is an ideal portable instrument for measuring neutrons in reactors, laboratories and hospitals. The Meridian has a wide energy response and closely conforms to the ICRU REM response curve.

The autoranging display has both a digital readout and a bargraph that simulates a moving pointer. The display is mounted on top of the moderator which makes it easy to see when it is being carried. The display also rotates in 2 axes and can be placed at either end of the moderator; it can be separated for a remote readout. No matter where you place the moderator, you can usually move the display so you can read it.

The moderator is a classic boron loaded Anderson Braun design. One end of the moderator is rounded to give better directional response. In the moderator, the detector cable passes through a labyrinth to eliminate streaming. The standard Meridian has a Bf3 detector; a He3 detector is also available which offers more sensitivity. The instrument may be carried with the rounded end or the flat end toward the front with the display moved accordingly.


Size overall: 8.5 in. (22 cm) W x 9.5 in. (24 cm) L x 17.5 in. (45 cm) H. Gasketed splashproof aluminum enclosure. Top panel is milled and anodized with non-eraseable nomenclature. Bottom painted. LCD window is acrylic. Handle is acrylic.
Weight: 20.5 lbs (9.3 kg) with batteries.
External controls: 4 pushbuttons, Power, Mode, Speaker and light. Power button when held down for 5 seconds resets the microprocessor.
Internal construction: Circuit board hinges for easy access. Batteries are mounted on an aluminum panel in nylon holders. ICs are socketed. All components are standard types.

Detectors: Bf3 Standard, He3 available.
Detector Sensitivity: Bf3: ~12kc/mrem,
He3:~50Kc/mrem, both with Cf252
Display: 2 line x 20 character alphanumeric supertwist LCD with backlight. Contrast adjustable from front panel.
Audio: Built in piezo beeper at 2.4 kHz
Adjustments: Threshold, HV and contrast digitally set.
High voltage: Adjustable from 300 to 1800 Volts.
Batteries: 6 AA cells for 100 hour life. Battery condition displayed at turn on and turn off. Low battery warning during operation. Instrument will automatically turn off when batteries are too low for proper operation. May be set for auto turn off.
Calibration and parameter storage: Data stored in permanent memory for minimum of 40 years. Batteries not required for storage.

Modes: 2 modes available, Rate, and Integrate, others programmable. Calibration, Setup, and Maintenance mode also available.
Units: Conventional and SI units
Menu selection: Only one menu.
Rate mode: Shows numeric value of rate. Updated every second. Limited to 3 significant digits. Autoranging.
Integrate mode: Shows Integrated dose and integration time. Count-down and count-up for time.
Bargraph: Moving digital pointer on background of scale markings. Updated 10 times every second. Bargraph width is 3 in (7.6 cm). Full scale markings are actively shown on the display.
Calibration: Calibration accessed through front panel or through battery compartment.

Range: 0.01 to 10,000 mrem/h.
Accuracy: Within 1% or 2 digits for Count rates independent of detector. Within 15% for detector. Timebase is crystal controlled.
Time constant: Dynamically set depending on count rate but has additional settings of short, med and long.
Dead time correction: Corrects up to 4 times actual rate.
Gamma Response: No response up to 500 R/h Cs137.

Temperature range: -20°C to 50°C
Humidity range: 0 to 95% non condensing

Options: Repair manual, He3 detector, extended range 2GeV moderator , many different setup configurations, scales and units.
Equipment: Supplied w/ manual, batteries,

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Specifications subject to change without notice.
Far West Technology, Inc. © 2003 Fax: +1.805.964.3162 Tel: +1.805.964.3615 Email: info@fwt.com