Monitor 200 Geiger Counter


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2.00 LBS
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The Monitor 200 measures alpha, beta, gamma, and x-rays. Its digital display shows readings in your choice of CPM, CPS, μSv/hr, mR/hr, or in accumulated counts. It has a digital display, a red count light, and a beeper that sounds with each count detected. Other features include an adjustable timer, and selectable alert. With the free Observer USB Software Family, you can set computer alarms, calibrate your instrument, and download your collected data from the internal memory for easy reporting!



Halogen-quenched GM tube with thin mica end window. Mica window density 1.5-2.0 mg/cm2. Effective window diameter is .360 inch. Side wall is .012 inch thick.

Operating Range

mR/hr - .001 (1µR) to 200 mR/hr µSv/hr - .01 to 2000 CPM - 0 to 235,400 CPS - 0 to 3923 Total Counts - 1 to 9,999,000 counts


Typically ±15% from factory, ±10% (NIST)

Energy Sensitivity

1070 CPM/mR/hr referenced to Cs137 Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is greater than 80%. Detects beta at 50 keV with typical 35% detection efficiency. Detects beta at 150 keV with typical 75% detection efficiency. Detects gamma and x-rays down to 10 keV typical through the window, 40 keV minimum through the case.


Readout will OVERRANGE in radiation fields as high as 100 times the maximum reading.

Selectable Alert Set Range

mR/hr .001 - 100 and CPM 1 - 350,000. Pulsating beeper sounds the alert. Adjustable alert levels are used for mR/hr / CPM, and µSv/hr / CPS. 70db @ 1m. Alarm will sound when in Timer Mode when set alarm threshold is reached. Energy Response Curve


Graphic LCD with Backlight.

Count Light

Red LED flashes with each count.

Audio Indicator

    Internally mounted beeper (can be switched off for silent operation)

Data Logging Capacity

     5,452 data points, which at 1 minute intervals as an example, equates to 3.7 days


USB for use with Observer USB Software Family

Bluetooth for use with the Free Observer BLE App for Android.

Power Requirements

Two AA alkaline batteries (included). Approx. 800 hrs @ background.


140 X 68 X 33 mm (5.5 X 2.7 X 1.3 in.)


6.4 oz (0.4 lbs.)


Carrying Case, Xtreme Boot, Lanyard, Stand, Batteries, Mini-USB Cable, Observer USB Software Download, Certificate of Conformance


NIST Calibration

Limited Warranty

1 year limited warranty  

The Monitor 200 typically ships within 1 business day.

Monitor 200 Operating Manual

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  • 5
    Monitor 200

    Posted by IVAN VERDEZOTO on Sep 5th 2023

    Excelente producto