Halogen-quenched uncompensated GM tube with thin mica window 1.5-2.0 mg/cm2 thick. Effective diameter of window is 9.1 mm (.36 in.).
Halogen-quenched GM tube, energy compensated sidewall 2mm thin filter. Thin mica window 1.5-2.0 mg/cm2thick. Effective diameter of window is 9.1 mm (.36 in.).
0-.5, 0-5, 0-50 mR/hr 0-500, 0-5,000, 0-50,000 CPM or 0-5, 0-50, 0-500 μSv/hr (SI Scale Meter Option)
1000 CPM/mR/hr (Cs137). M4EC 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. M4 & M4EC meter scales shown below. Both Detect beta at 50 keV with typical 35% detection efficiency and beta at 150 keV with typical 75% detection efficiency.
Typically ±15% of reading (Cs137)
X1, X10, X100, Battery Check.
Analog Meter holds full scale in fields as high as 100X maximum reading. CPM & mR/hr scale. Optional SI Scale Meter Available
Internally mounted beeper (can be turned off for silent operation).
9-volt alkaline battery. Approx. 2,000 hrs. at normal background
-20° to 55°C (-4° to 131°F)
M4: 200 g (7.1 oz) M4EC: 224 g (7.9 oz)
3.5 mm jack with pulse out.
209 x 71 x 50 mm (8.2 x 2.8 x 1.9 in.)
Carrying Case w/ Belt Clip
SI Meter Option, Observer Software, Mini-USB Option w/ USB Observer Software