Like with all measurements, it will be very hard to find two different devices indicating the same readings, especially when we demand increased precision. We now know that there are no such things as absolute time, absolute space, there are no synchronous clocks. It is the same with the absolute measurements, and in some cases it’s becoming more relevant to observe the change: if we see increasing values, we know something is happening with the Radiation levels. But if all we know is a given number, we will know very little.

6 Radiation Dosimeters have been put to a test: the excellent Gamma Scout w/Alert (made in Germany), the new Air Counter_S (made in Japan), a simple clicker named Kvarts DRSB-01 (made in Russia), Radex 1706 (made in Russia), another clicker the Apoc Mini (made in USA), the neat Terra-P MKS-05 (made in Ukraine), all compared against two different radiation sources. The Air Counter_S and the Apoc Mini use a solid state detector (Pin Photodiodes), while the rest are based on one or more Geiger tubes.
It’s worth mentioning the Gamma Scout features a Halogen filled Geiger-Müller tube with mica end window (LND 712 or equivalent) allowing this dosimeter to detect and measure Alpha, Beta, Gamma and X radiation, while the Terra-P MKS-05 featuring a single SBM-20 tube is the only dosimeter in this set with an energy compensated tube (notice the metallic sheet enclosing the tube). These are both excellent choices for those interested in having a good quality radiation dosimeter.
The Radex 1706 has two SBM-20 tubes used in parallel, but they are not energy compensated. The doubled detection volume will offer some increased sensitivity, but this has little relevance to the dosimetry purpose. This unit tends to show unrealistically higher values, so while it does a decent job at sensing radiation, I find it less precise.
The Air Counter_S is a new generation dosimeter featuring a solid state detector in the form of a PIN photodiode. It has a very slow response time, and the values it shows are highly inaccurate.
The Kvarts DRSB-01 and the Apoc mini are simple Clickers, closer to a toy, and have little use other than simple Radiation experiments.

To get back to the tests, first, a Ra226 source in the shape of an old Westclox Pocket Ben with Radium dials has been used.

As you can see, we get very different result on different dosimeters but with the same source. So which result is the correct one? Measuring radiation is not a simple task.

Here’s a new test, using a different Radiation emitter, a spark gap tube containing traces of Cs-137, the EII-43-100:

The decay and the daughter products of Ra226 and Cs137 can be seen in the diagrams below: