Specifications

Detector
Monitor 4: Halogen-quenched uncompensated GM tube with thin mica window 1.5-2.0 mg/cm2 thick.
Monitor 4EC: Halogen-quenched GM tube, energy compensated sidewall 2mm tin filter. Thin mica window 1.5-2.0 mg/cm2 thick.
Display
Analog Meter Scale.
Monitor 4 Energy Sensitivity
Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is > 80%.
Detects beta at 50 keV with typical 35% detection efficiency.
Detects beta at 150 keV with 75% typical detection efficiency.
Detects gamma and x-rays down to 10 keV typical through the window, 40 keV minimum through the sidewall of the detector.
Normal background is approximately 10-20 CPM.

Gamma Sensitivity:	Operating Range
1000 CPM/mR/hr (referenced to Cs-137) Energy Sensitivity for the 4EC is the Same as Monitor 4 except the energy response for gamma and x-rays through the detector sidewall is flat within +61% or -26% over the range of 40 keV to 100 keV, and within +35% or -17% over the range of 100 keV to 1.3 MeV.	0-.5, 0-5, 0-50 mR/hr 0-500, 0-5,000, 0-50,000 CPM or 0-500 µSv/hr 0-50 mR/hr. Range Switch X1, X10, X100, Battery Check. Accuracy Typically ±15% of reading (referenced to Cs-137)
Monitor 4	Monitor 4EC

Audio
Internally mounted beeper (can be switched off for silent operation).
Anti-Saturation
Meter will hold at full scale in fields as high as 100 times the maximum reading.

Power Requirements
One 9-volt alkaline battery. Battery life is up to 2,000 hours at normal background radiation levels
Temperature Range
-20° C to 55° C (-4° F to 131° F).
Weight
M4: 178 grams (6.3 oz.) without battery
4EC: 198.1 grams (7 oz.) without battery
Size
145 x 72 x 38 mm (5.7 x 2.8 x 1.5 in.)
Warranty
1 year limited warranty
Monitor 4 Kits
Build your own Monitor 4! Learn about how a geiger counter works!
Includes: All parts required to build a Monitor 4, Assembly and Illustration booklets.

Accessories

Carrying Case	Observer Software

Support

Monitor 4 & 4EC Operation Manual (pdf)| English | Spanish | French | German