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Radalert 100 Radiation Detector


Item Code: SS-RA-100

Radalert 100 Radiation Detector
Radalert 100 Radiation Detector
Radalert 100 Radiation Detector
  • Radalert 100 Radiation Detector
  • Radalert 100 Radiation Detector
  • Radalert 100 Radiation Detector
  • Radalert 100 Radiation Detector
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Detail Description


The successor to the proven and popular Radalert 50, the Radalert 100 (or its identical sister instrument, the Digilert 100) is a digital pocket Geiger counter designed for general purpose monitoring of radioactivity.

It detects Alpha, Beta, Gamma and X-radiation, visually shown on a highly accurate digital display with readings in your choice of both CPM (to 110,000 counts per minute) and mR/hr (up to 110 mR/hr), or switchable to the international standard of µSv/hr (up to 1,100 uSv/hr). 

A red LED blinks and a beeper chirps with each radiation count.  The audio chirp can be turned off.

The Radalert derives its name from an audible alert that sounds when the radiation reaches a user-adjustable level.  

The Radalert 100 also can be set for a Total Count (see closeup of panel), which will accumulate the radiation counts over time.  This is a useful feature especially for establishing your background radiation level.   As an example, you can set the unit to Total, and after say 10 minutes, divide the Total Count value by 10 to arrive at your background radiation in CPM.

This unit also has a Data Output port to record counts on a computer or data logger, as shown in the picture at right. Select the navigation button above or click on this link for more on the on data output, and the optional Software accessories.  Also note the Audio Output port for external sound.

The Radalert 100 runs on a single 9 volt alkaline battery (included) which will last up to three months on continuous use at background levels.

The Radalert also comes with a padded vinyl carrying case with belt loop, shown at left. The Radalert 100 is a very popular unit.  If you want an all-around excellent Pocket Geiger Counter with a digital readout versus an analog meter, along with a user adjusted audible alert, and/or desire a data port, we recommend this unit.

Download Radalert 100 Instruction Manual


Halogen-quenched, long thin cylindrical Geiger-Mueller tube (LND712) with side wall of .012" #446 stainless steel, and  with thin mica end window

Window Size

1.5 to 2.0 mg/cm²  thick;

Radiation Detected Alpha, Beta, Gamma, X-ray
Sensitivity Detects alpha down to 2.5 MeV; efficiency at 3.6 MeV > 80%
  Detects beta at 50 keV w/35% efficiency, at 150 keV w/75%
  Detects gamma and X rays down to 10 keV thru window, 40 keV minimum through case; gamma sensitivity is 1,000 CPM/mR/hr referenced to Cs-137
  Normal background is approximately 10 to 20 CPM


± 10% typical; ± 15% max.

Operating Ranges

.001 to 110 mR/hr; .01 to 1,100 µSv/hr; 0 to 350,000 CPM; 0 to 3,500 CPS; Total from 1 to 9,999,000 counts; Timer: up to 40 hours

Anti-Saturation "Jam" protection allows readout out to hold at full scale in high radiation fields
Indicators LED display, red LED count light, audible beeper for count rate, and audible alert
Display 4-digit liquid crystal display with mode indicators; updates every 3 seconds
Count Light Red LED flashes with each count
Beeper Chirps for each count (can be muted)
Alert User-adjustable alert level  to 50 mR/hr & 160,000 CPM, set using three buttons - default is 100 CPM


At factory to NBS standard Cesium 137 gamma source

Temperatur Range -10 deg. to +50 deg. C, 14 deg. to 122 deg. F

Power Required

One 9-volt alkaline battery (included in price of the unit)

Battery Life

About  2,160 hours at nomal background radiation; about  625 hours at 1 mR/hr with beeper off


225 grams (8 oz.) including battery


150 x 80 x 30 mm (5.9 x 3.2 x 1.2 in.)

Output Port Stereo 3.5 mm jack on side sends counts to computers, data loggers, other CMOS-compatible devices, and headphones
Input Port Mono 2.5 mm jack provides electronic calibration input
Options Computer cable and software (See Software)
Warranty One year limited on instrument, 90 days on Geiger-Mueller tube; includes CE mark

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