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 holds full scale in fields as high as 100X maximum reading. CPM/mR/hr scale default. Optional SI Meter Scale option available upon request.
Energy Sensitivity:
1000 CPM/mR/hr (Cs¹³⁷). 4EC is the same as M4 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.

Observer USB Software	Operating Range
	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 Cs137)
Monitor 4	Monitor 4EC

Mini-USB Port on Side of Unit	Monitor 4 End Window

Audio
Internally mounted beeper (can be turned
off for silent operation).
Power Requirements
9-volt alkaline battery up to 2,000 hrs at
normal background
Temperature Range
-20° to 55°C (-4° to 131°F).
Weight
M4: 200 g (7.1 oz)
M4EC: 224 g (7.9 oz)
Outputs
3.5 mm headphone jack with pulse out.
Size
209 x 71 x 50 mm (8.2 x 2.8 x 1.9 in.)
Includes
Carrying Case w/ Belt Clip, Observer Software, Mini-USB Cable
Accessories
SI Meter Option
Limited Warranty
1 year limited warranty
Monitor 4 Kits
Build your own Monitor 4! Learn about how a geiger counter works!

Included Accessories

Carrying Case	Observer USB Software

Support

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