The M4 and M4EC are compact, ergonomic, general purpose survey meters capable of detecting alpha, beta, gamma, and x-rays over 3 selectable ranges. A red count light flashes and a beep sounds with each event detected. The Monitor 4EC offers a more linear reading for gamma and x-rays (above 40 keV).

Detector

Monitor 4:

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.).

Monitor 4EC:

Halogen-quenched GM tube, energy compensated sidewall 2mm thin filter. Thin mica window 1.5-2.0 mg/cm² thick. Effective diameter of window is 9.1 mm (.36 in.).

Operating Range

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)

Energy Sensitivity

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.

Accuracy

Typically ±15% of reading (Cs137)

Monitor 4: Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is greater than 80%. Detects gamma and x-rays down to 10 keV typical through the window, 40 keV minimum through the case.	Monitor 4EC: Detects alpha down to 2.5 MeV; typical detection efficiency at 3.6 MeV is greater than 80%. Detects gamma and x-rays down to 10 keV typical through the window (non-compensated), 40 keV through the sidewall.

Range Switch

X1, X10, X100, Battery Check.

Display

Analog Meter holds full scale in fields as high as 100X maximum reading. CPM & mR/hr scale. Optional SI Scale Meter Available

Audio Indicator

Internally mounted beeper (can be turned off for silent operation).

Power Requirements

9-volt alkaline battery. Approx. 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 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

Options

SI Meter Option, Observer Software

Limited Warranty

1 year limited warranty

Monitor 4 Kits

Build your own Monitor 4! Learn about how a geiger counter works!