Originally Posted on Linuxslate.com May 2019
Introduction:
Ever since I was very young, I have been interested in electronics. I started with one of those basic electricity learning kits when I was less than 10 years of age. I was soon obsessed with almost any sort of electronic gadget that I could build, take a part, or repair. If it was portable, that was even better. After all, OCD is not something you can leave at home.
A little further along my path of electronics learning, someone gave me one of these:

Radiation Meter.
This (as well as a few other cool gadgets) brought rise to a parallel addiction — Fascination with the unseen world. That vintage Geiger Counter is portable, but not very. It’s not something I am likely to carry with me on – for example – a trip to the supermarket.
As smaller, digital devices became available, I bought a couple of radiation meters (Links still point to Linuxslate.com) that were much more portable than that vintage Geiger Counter, but again, an addiction is not easily overcome. I needed more. I craved the lasting high of features and functionality, but in this strange obsession, I also needed smaller, more portable.
My next “hit” of “rad” meter had to meet the following “requirements”:
- Small – almost pen sized. I wanted something not much larger than a Civil Defense Pen dosimeter.
- It had to have a clear and readable LCD display.
- It should have a large Geiger-Muller (GM) tube for sensitivity and fast readings.
- It should allow the GM tube to be exposed so that it is sensitive to beta (β) particles.
- It should run on commonly available dry cell batteries.
The reasoning behind each of these can be found in my Radiation Detector Buyer’s Guide, and will not be repeated here.
Other Devices:
There are other devices that “fit the bill”. So why did I buy the “Rodnik 3”?
The Radex One is readily available (ships from the USA if you use the provided link), it’s actually cheaper and it has PC connectivity. It also looks and works more like a pen. But the meter reviewed here is actually slightly smaller in every dimension, and has a much bigger display. The Radex One, at least as far as I know, does not allow you to expose the tube. The website does not mention any ability to detect α or β particles.
There are also a few different small (and again, less expensive) older Russian devices. But again, they are bigger in at least one dimension, often have a smaller tube, and the ones I know of have very small LCD displays, if they have a display at all.
The EcoTest VIP is nice, very “pen-like”, and definitely represents a “hit of the good stuff” for anyone fascinated with radioactivity, or radiation testing. But again, I don’t see a way to expose the tube (at least without removing a cover that could get lost or broken), and the EcoTest VIP is quite expensive.
There are also small devices that plug into a mobile phone’s headset jack, and with a special app, they allow you to measure, and even track radiation. Most of these are actually semiconductor devices. They are not true Geiger counters, and not sensitive to α or β particles.
There are also wand like radiation detectors that connect to a mobile phone with a short cable. Some of these do contain actual GM tubes, but these are more expensive, and by the time you connect 2 devices together with a wire, you actually end up with something less convenient, and less likely to be actually used, than a single compact device with an integrated display.
Since the tragedy at the power plant in Fukushima, a Japanese company has begun marketing several very compact radiation meters, including one that is very compact, and “pen-like”. Again, however, these use a semiconductor device as a sensor, and thus detect gamma (γ) radiation only.
Let’s get Physical:
IdealRatio.ru (Russian Language – Link Removed due to current sanctions.) seems to distribute a number of the Soeks, Radex, and other portable radiation detection devices (as well as devices for detection of nitrates and RF radiation). But according to a translation of their web page, they apparently realized the same deficiency of the other products as I mentioned above. They decided to “go it on their own”.
Please see the actual unboxing video of this device on the CarCynic.com YouTube Channel.
It’s not my intent to copy the “IdealRatio” instruction book or web advertising here, but I will point out that it meets most of the criteria mentioned above and in the Radiation Detector Buyer’s Guide.
Here are the basic physical specifications:
- It is one of the smallest true Geiger Counters that I have seen (112mm х 32mm х 19 mm)
- It has a full length SBM 20-1 true Geiger-Muller Tube.
- The back is slotted to allow detection of α and β particles
- It uses standard AAA Batteries.
- It has a side mounted LCD display.

Radiation Detector in this screen shot from the Unboxing Video.
The Rodnik 3 is smaller, more sensitive, and has more features.
Other Features and Pluses:
In addition to the basic features mentioned above, I would also like to point out some of the specific things I like about this particular meter now that I actually have used it.
- The front facing display is large and easy to read. It has very good contrast in all lighting conditions (except darkness). Making it front facing (as opposed to on the top like the Radex One) was a good choice. No one is going to make the funny face needed to see a display in your shirt pocket.
- It has an LED that blinks for both particle counts, and flashes for alarm conditions.
- Having a slotted area over the GM tube is desirable over a flimsy or easily lost cover. As the owner’s manual states, if you are checking liquids, or using the unit in an environment where it could get wet or become contaminated, the unit can be put in a small plastic bag.
- As many of these devices, it also has a basic alarm clock, and could serve as a travel alarm.
- When displaying the time, it won’t click or flash for incoming particles, but it will alarm if the radiation threshold is reached. It can remain in this mode for years on a single set of batteries.
- Single button operation, and the feel of the button is a good compromise between ease of use and preventing accidental operation when in a pocket.
- It has 2 magnets built into the back panel so that the unit can be held by any ferrous metal surface for convenient storage or continuous background radiation monitoring.
- Mine was supplied with an English language owner’s manual.

make the Rodnik 3 able to quickly identify these
candlestick holders as genuine Vaseline glass
even though they are only very mildly radioactive.
The display is showing 0.35µSv/h, or about 5 times
the normal background radiation in my area.
The Minuses:
A perfect portable device would cure my addiction. But as I mentioned, finding the right drug to cure an addiction is not easy. This device definitely has some misses:
- I’d still like something more pen-like. A well constructed pocket clip would help a lot, but there is none included with this device.
- The items in the settings are labeled with “English” language characters, but they are 3 character abbreviations on a numeric LCD display. If I am not going to memorize what each one means, no one else is either. While you don’t need to change settings often (really ever), if you do, you will need the manual (in your language) in hand.
- Single button operation makes it awkward to set the clock and change the settings. Again, not a big deal, since most users will not need to change the settings more than perhaps once.
- One of the settings is to adjust the accuracy of the time function. In today’s world of network synced time, and highly accurate crystal controlled devices, the consumer should not be asked to perform a task like adjusting the accuracy of clock.
- If the Rodnik 3 is in clock mode, and alarms due to increased radiation, you get the flashing red LED, and the alarm tones, but the display continues to show the time. It does not show the radiation level until you push the button.
- The LCD display is not visible in darkness. Again, this should never really be a problem. In an actual civil emergency, a flashlight is even more important than a radiation meter, and for more casual use, I think it is safe to assume that few go antique shopping or grocery shopping in total darkness. Given the necessary choice of a backlight, or great battery life, I think they made the right choice by omitting a backlight.
The above are minor gripes, or at worst, things I would change if I were designing one (which I did start to do at one point). Unfortunately, there are 2 bigger problems with this unit:
- The beeper (sound) is very low. There is no way to set the volume (although you can set the duration of both key clicks and particle beeps). This unit is never going to wake a heavy sleeper if there is a nuclear accident. Unless your surroundings are fairly quiet, you may not even hear the alarm if the unit is in your pocket or purse.
- Lastly, folks, is the big one: This unit has no accumulated dose function. Despite saying “Radiation Dosimeter” across the top, it does not/cannot show daily dose or dose over any other time period except acute dose. This also means you cannot set an alarm for total accumulated dose. Notice that I do not call it a dosimeter in this article. I only emphasize this since the size and portability of the Rodnik 3 may cause buyers to think of it as a digital replacement for a dosimeter pen. It is, in fact, the opposite, since classic dosimeter pens show only accumulated dose, and do not show acute radiation levels. Of course lack of an accumulated dose function does not affect using the Rodnik 3 to find radioactive antiques, check your food, or alerting you to entering a dangerous area.
Conclusion:
Overall, this is an excellent and very discreetly portable radiation meter. It is at the very least a good choice as compared to the other small units mentioned above. Under the conditions that (1) You understand that it does not do accumulated dose, and (2) Conveniently carrying it is of prime importance, I do recommend buying the “IdealRatio” “Rodnik 3” Portable Radiation Detector. It’s size, cost, build quality, sensitivity overall, and sensitivity to alpha particles make it excellent for finding either radioactive substances you want (like antique shopping) or radioactive substances you want to avoid. For more serious life – or – cancer circumstances, however, I would recommend that the buyer look for a larger unit with more features.
Extra: Did I Find Anything Radioactive?
Obviously, a good test of a Radiation Detector is to find something radioactive. Did I find anything radioactive with my Rodnik 3? Well, I recently went on a family vacation, and I took my Rodnik 3 with me. — This Content will be moved here from Linuxslate.com shortly.
Disclaimer:
THIS DOCUMENT IS PROVIDED BY THE AUTHOR “AS IS”. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES, INJURY, OR ILLNESS ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENT, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE, INJURY, OR ILLNESS.
IF YOU HAVE SOMETHING THAT YOU THINK IS RADIOACTIVE, OR OTHERWISE HAZARDOUS, OR IF YOU SUSPECT OTHERS OF HAVING SUCH, CONTACT YOUR LOCAL EMERGENCY SERVICES. THIS GUIDE IS A TECHNICAL DESCRIPTION OF CONSUMER ELECTRONIC DEVICES ONLY. IT DOES NOT, NOR DOES IT PURPORT TO, GIVE MEDICAL OR ANY FORM OF HEALTH ADVICE. IF YOU SUSPECT THAT YOU HAVE BEEN EXPOSED TO A HAZARDOUS SUBSTANCE, OR ARE HAVING HEALTH PROBLEMS, CONTACT A PHYSICIAN OR YOUR LOCAL EMERGENCY SERVICES.
UPDATES: A few additional comments on the Ideal Ratio Rodnik -3: First, battery life seems to be someplace between fantastic and amazing. In addition, mine has gone through the laundry *twice*. There is no damage or discoloration of the LCD display. After each time, I open it, blotted out any visible moisture, sprayed it with AMSOIL MP, changed the batteries, and re-assembled it. The unit still looks and operates fine. There is no damage to or discoloration of the LCD display.
Originally Posted: Wed Dec 30 2020 11:04:43 GMT-0500 (Eastern Standard Time)
Here’s another “Have I Found Anything Radioactive?”
I did:
In this picture, my IdealRatio Rodnik 3 is showing approximately 50x background a few centimeters from a rather unremarkable looking rock.
Based on a (very) little research I did while writing this post, I believe this may be a specimen of coffinite.
Before you ask why I would own something that is highly radioactive, and with a name that has a close association with death, I should mention that coffinite is named after American geologist Reuben Clare Coffin. The name of the mineral is just a coincidence of a rather unfortunate last name. While coffinite does contain Uranium, the name was not meant to portray this mineral as any more or less dangerous than any other naturally occurring mineral that contains toxic metals or radioactive elements.
The assumption that the stone in the picture is coffinite is based on pictures from a Google Images search that seem to show similar grayish rocks with traces of yellow crystals. In addition, coffinite is the 2nd most prevalent uranium-containing mineral, so simple statistics show good odds that it is in fact coffinite.
So how did I come to posses this bit of hyperactive nature?
I would have never found this stone without my IdealRatio Rodnik 3. I was at my local flea market. There are 2 vendors there that specifically sell crystals, stones and minerals, but this rock didn’t come from them. I did buy a piece of tumbled green apatite from the larger vendor. I learned that green apatite seems to generally be more radioactive than blue apatite.
I also purchased a tumbled malachite stone – not for it’s radioactivity (it isn’t radioactive), but for the name association with a project covered on Linuxslate.com.
Having passed the crystal/stone vendors, and in fact reached the very end of the market, I came across a man with several full tables of random rocks, as well as quite a lot of abalone shells.
I don’t remember if it was something the seller said, a sign or label, or just the general look of the various rocks, but I got the impression that the rocks were from the Western United States.
I waved my Rodnik 3 over the boxes, and it gave a flew clicks over a specific corner of one box. Of course random events of cosmic or local nature can cause a momentary jump in counts, so I waived the counter over the same area again, and again it reacted. I picked up some rocks in that part of the box, but when I tested those rocks while holding them away from the box, my Rodnik 3 began to decrease back toward a normal background reading. With some of the rocks moved away, I again held the Rodnik 3 over the box. It began a steady stream of beeps followed almost immediately by the alarm mode.
Something in the box was "hot", and the other rocks had basically been shielding it. So you basically know the full story. The source of the radioactivity was the small stone pictured above. I paid the man $3 and took my rock home with me (but not in my pocket.)