The battery driven measuring system for determining gamma activities in foodstuffs, liquids and bulk materials allows even an untrained user to perform quick and reliable measurements directly in Bq/l. The gamma radiation emitted from the sample is detected with a scintillator using a Marinelli counting geometry.The beaker with volume 0.5 l is placed in a lead shield of 15mm thickness. The total weight of the system is only 12 kg. The statistical accuracy of the result is indicated. The detection limit for Cs-137 is approximately 20 Bq/l.