GQGMC-300S Geiger Counter Nuclear Radiation Detector Dosimeter for Beta, Gamma, X-Ray Portable Radiation Monitor Geiger Counter (Silicone case)

I bought it to check for radioactivity in granite counter tops (to avoid any radon gas). So far I have found nothing but this would be great when armageddon arrives.

I recieved the GQ GMC-300S counter, a setup guide, USB to USB-C cable, USB to USB-C adapter, and a "Nuclear Radiation Safety Guide" card. Note: this type of detector only measures beta, x-ray, and gamma radiation. If you want to measure alpha radiation you need a different kind of detector.The counter has a backlit LCD display and 4 simple buttons, Power, up/down, and display mode. If you set it to the text mode display, it will display the CPM and rate (uSv/hr or mR/hr) and one of the following: Total counts, Elapsed time, Average CPM, Max CPM, CPS, or Cumulative dose. On graphic mode, it can display line and bar graphs with the added function of both at the same time and you can scale the axis manually or automatically. The counter has a headphone jack and USB-C port. The buttons are a little finicky but they work. If you press them too quickly they might not register. There is a website where you can download software, but I did not download it.The "Nuclear Radiation Safety Guide" is a bit misleading and sites 1.3mR/hr (13uSv/hr) as "Extremely high. Evacuate immediately, report to government". While I will admit, if you find this radiation level while on an evening stroll it would be abnormally high but it is not a dangerously high level of radiation. For reference, a radiation area is defined in the federal code of regulations to be, "any area, accessible to individuals, in which radiation levels could result in an individual receiving an equivalent dose to the whole body in excess of 0.005 rem (0.05 mSv) in 1 hour at 30 centimeters from the source or from any surface that the radiation penetrates." - All I am saying is that the card makes this number seem woefully larger than it is (25% of the federally defined minimum for a radiation area).This geiger counter would be sufficient for demonstrations or rough approximations in a pinch (there is no evidence of a calibration standard).Overall, it is good enough for anyone that would be buying a geiger counter on Amazon - look elsewhere if you need new radiacs at your nuclear power plant.

This Geiger counter is not a toy. It really works. For whatever it is worth, I think it is a real shame that it actually makes sense to buy your own personal Geiger counter in this day and age. I got the GQ Electronics GMC 300S Nuclear Radiation Detector because it appeared on a few websites that provided reviews of high quality Geiger Counter detectors. I also like that it is made by a reputable company (GQ Electronics) in the USA. Lastly, the price is also very good.I do not own the proper equipment to independently calibrate this Geiger counter. However, to be perfectly honest, I really do not care if it is (or isn't) the most accurate Geiger counter sold on Amazon. Even the extensive 24 page GQ Electronics users manual (that you can easily download [for free!] from the corporate GQ website) states: "You do not need to do the calibration if you just want to qualitatively detect radiation." I think that sentence was written for me, because all I want to do is to be able to detect high levels of radiation if the "you know what" ever hits the fan. Side note: Amazon sells several very accurate Geiger counters that have dual Geiger tubes, and they cost significantly more than the GQ GMC 300S. The GMC 300S has one Geiger tube, and that is perfectly fine with me. I do not work in a nuclear power plant or a nuclear submarine. All I want is a device that will give me a fairly accurate outdoor reading if (God forbid) there is ever a nuclear war.The GQ GMC 300S comes with a short color quick start manual, as well as one 3.7V rechargeable 14500, 800mAh lithium ion battery, a handy Nuclear Radiation Safety Guide Card, and a very helpful lanyard. The 24 page detailed users manual that you can download from the GQ website is outstanding (and totally free). You can also download software from GQ Electronics to interface this Geiger detector with your computer. Personally, I am not interested in interfacing the GQ GMC 300S Geiger counter with my computer, but some hobbyist may want to do this.I tested the GQ GMC 300S geiger counter, and I found it easy to set up and use. The short setup guide gives you more than enough info to get started. The 24 page detailed users manual answers every question you will have.So, how did things turn out? Well, the normal background radiation in my home ranged from 10 CPM (Counts Per Minute) to 15 CPM. Those are very low readings, which my wife was very happy with. I do not own a Nuclear Geiger Counter Test Card, which Amazon [amazingly] sells online. However, I knew that home smoke detectors are very, very, very slightly radioactive. Hence, I retrieved an old smoke detector that I recently replaced, and I placed the Geiger tube of the GMC 300S right onto the smoke detector. Within 5 or 10 seconds, the GMC 300S start to register a small amount of radiation, and the CPM reading got up to around 58 CPM. This is extremely low radiation, but it proved to me that the GMC 300S actually works! In one of my attached photos, I pointed out the exact location of the Geiger tube sensor. This is the most sensitive part of the Geiger counter, and I thought you should know where it is located.Summary: The GQ GMC 300S Geiger Counter really works. It is remarkable that we can buy such a well made device for so little money. It is a very good value, and in the event of true nuclear emergency, it will be worth its weight in gold. I rate it 5 stars. Buy it.

This instrument is a convenient method of detecting and measuring local radioactivity, not only for personal safety but also as a way of monitoring radioactivity in the environment. It is also useful as a teaching tool for instructional lessons about radioactivity. I use this tool in my hobby of rockhounding – in the field, this is an excellent way of detecting nearby radioactive rocks and minerals, and in my rock collection, it lets me know if the area around a radioactive specimen has become excessively radioactive. The instrument controls are both simple and intuitive, and the radiation values are both accurate, and easy to read on the screen in whatever form of measurement unit is required. While working in an area of radioactive minerals, I’m protected by the instruments dosimeter function, which lets me know if the radioactive dosage rate becomes unsafe. The battery powers the instrument for at least a day or so in the field before requiring recharging. One feature I greatly appreciate is that the sensor tube is replaceable.