July 22, 2024

GQ GMC-300 Digital Geiger Muller Counter

If you’ve ever wanted to know if it’s safe to go outside after the nuclear apocalypse then you need a GQ GMC-300. It  is an amazing device for the price that does everything I would need. I put it through a number of tests and it performed beautifully. I know they have a newer model out but I got this one a couple of years ago and it is still a good device.

I tried placing my smoke detector (containing americium 241) a few inches above it and it climbed to .68 μSv/h and set off the beeping alarm. The alarm was set at .50 μSv/h by default but can be user configured. When I put the smoke detector back on the ceiling where it belongs the meter went back down to .15 to .25 μSv/hr which appears to be the background level for my room.

I have a natural uranium ore sample to use for calibration and testing. This detector reported 27.89 μSv/h which is about what I would expect for the type of ore I have.
The units can be changed from μSv/hr, CPM, or mR/h.

The detector tube can be replaced when it’s useful life has ended which is nice. I’ve read that the tubes can last 6-8 years, some people reporting longer. It can be re-calibrated if necessary. It’s almost prefect until I installed the computer application.

First impressions of the GQ GMC Data Viewer application on Windows 7… Looks like a dated and hastily thrown together MFC application with few features and plain aesthetics. On the plus side… Installation was easy. My PC connected to the GMC-300 painlessly and without problems. The application collects data stored on the GMC-300 and also has a real-time display feature. The graph is scalable and even has auto scaling. You can save the data as a .csv for graphing or visualization. That’s about all it does. However, If you have some programming knowledge, the manual claims this to be an “open protocol” device and they do provide some information on utilizing the GMC-300 USB-serial connection.

Drawbacks to the application… I select the COMM port for its USB to serial interface every time I launch the program, even though Windows Device Manager is able to detect and display the correct COMM. I’d be very surprised if the USB to serial API for Windows doesn’t have a way to detect COMM port. Even if the API didn’t have an easier way, they could still check each Comm port until the unit responds through one of them. Disappointing. Even though the GMC-300 unit itself has an alarm for high level radiological events, the software does not. The application seems to be pretty dumb… take the data from the GMC-300 and put it over there in that file and then do nothing more with it.

I installed the demo version of the GQ Geiger Counter Data Logger pro-application which they want an additional $9.99 USD to activate. It is supposed to be a more feature rich version of the GQ GMC Data Viewer application. Honestly… why companies still do the “9.99” thing, I’ll never know. It’s 10 dollars, just say 10 dollars… seriously are we all four years old? Ok, so I could get a one penny discount for their $10 program; what do I get for that?

Still looks like the same dated UI as the application that comes with the GMC-300. There are a few more options on how to display units over time. The graph displayed in real-time mode seems like it might be a little more useful, showing an average over time instead of just counted hits over time which is an improvement over the included app. I don’t know what the averaging window is; it doesn’t say. I would assume not over a few seconds because it seems to go up and down with a curve that is pretty close to the second per second hit count. I still have to set my COMM port each time I launch. It does give a few more ways of viewing data. It has some options that are grey’ed out I assume because I’m running the demo version. There is an OCOC Wizard that is grey’ed out; don’t know what that does. Also, a grey’ed FTP menu; that sounds interesting… and a grey’ed out “other” menu. It would have been really nice to at least give me a 30 day period of full access to the app so I could try it and decide if I want to buy it.

I really wanted to give the GMC-300 five stars. The device itself deserves five stars but since looking at the whole product and the ability to interface with your computer with the software included, I can not. I would like to see a little more effort on the application side of things.

I want to look into the newer version of this device. I have to save up the greenbacks for a little bit first. Still, overall a great product.


Chris is a creative and experienced website and web application developer with over 6 years of experience creating UI excellence and fluid User Experiences, bringing modern responsive web environments that engage users. Chris also has an additional 8 years of graphic design and publishing expertise that was perfected in the years prior to entering the web development world. Since modern website environments are necessarily and universally graphic and visual, both skill sets blend together perfectly. Chris’ focus on teamwork, coordination, and communication makes him a valuable asset to any team; creating interactive websites and spectacular graphics, in addition to demonstration videos for trade shows and training.

View all posts by C S H →

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.