MONITOR4 Analog-Based Ionizing Radiation Detector

I recently purchased the Monitor 4 geiger counter due to the ongoing nuclear crisis in Japan. I have been very pleased so far. It is very sensitive, accurate, durable and easy to use. Plus, the price is fair. I strongly recommend anyone who purchases this geiger to also purchase the Observer geiger software Radiation Alert OBSERVER Software For Collecting Counts From Radiation Detectors . When used together with the software, it turns the Monitor 4 into a very capable instrument. I have been using both together to check for low-levels of food and drink contamination. It has been very useful so far. I have also owned the Inspector+ geiger counter. That geiger counter has a super-sensitive pancake sensor. Only a 10-minute count is required for that instrument to get a fairly accurate reading of low-level contamination. BUT the same thing can be accomplished with the Monitor 4 when used with the Observer software. This can be done by taking a longer timed count of at least 20 minutes (but 30 minutes to 1 hour is even better). The reason the longer timed count is necessary is because the Monitor 4 has a much smaller sensor compared to the Inspector+. But in the end the same thing can be accomplished when used with the software. Plus the Monitor 4 is in stock NOW. The Inspector+ is back ordered everywhere by at least 6-12 months. You really can't go wrong with the Monitor 4 when used with the Observer software. It is a reliable, accurate, and durable instrument that will last many years. Just ask the owners of the older design Monitor 4.

The product is described as registering 5 to 20 CPM (counts per minute) "normal background radiation". This is how many clicks or beeps you'll get when you use the meter without any radioactive sample nearby, for instance if you are trying to detect food contamination. However, the analog needle display will not distinguish between these values. The most sensitive setting has the display read between 0 and 500 CPM, but at 5 CPM the needle will jump up a tiny bit and slowly drop back to zero after each particle is detected. You would need to connect the device to a computer in order to get such a sensitive reading. Such a reading would be made using software to count events over several minutes or an hour. It's nice that the meter has a headphone jack, which is a bit easier to interface a computer to than USB. It's also nice that the product specifications for the GM tube are more complete than other Geiger counters I've seen on Amazon. Just be aware that the needle display is not useful unless you happen to be around something that's really radioactive. Also, Geiger counters cannot be returned to Amazon, so you might be stuck with it. I wish that Amazon gave information about the sensitivity of the GM tubes in each of their Geiger counter products. I would like to find a counter which registers, say, 50 CPM for normal background radiation, using a larger tube window.

Purchased this at about the time that North Korea was saber rattling. We live in Seattle, which is more or less directly downwind from there, so it's worth having supplies on hand when things "get hot". The unit is obviously industrial quality, and several random tests of various sources indicated that it was detecting radiation at low levels. Compared to the "consumer grade" devices this instrument rocks. Finally, if you need precise calibration they provide instructions on how to do that. Of course it was already calibrated at the factory, so I did not worry about this aspect. Hopefully I never need to press this into action; however having it on hand sure beats guessing at the moment that you need it!

I looked at a number of radiation monitoring devices and this seemed to be a good choice for the price. I have a rather old geiger counter that is not as sensitive as this one. My only complaint is that the directions for use comes on a CD and I didn't think was greatly helpful. It is possible that someone with more experience than I have would find the directions more helpful. I am satisfied with this purchase but feel written directions for less experienced users would be helpful.

Pro: cheaper than its brother (Inspector). Con: analog meter - have to count the "beeps" to measure CPM/accumulated readings. It seems the detector works (I'm not a radiation expert). I get background radiation 25-30 'beeps' a minute(CPM) here in SW US, and no significantly higher level was detected in the food that I've tested so far (wild salmon, squid, etc. from the pacific). I was cleaning up a closet today and found an old (20+Y.O.) gas lantern and remembered that some old filaments for those lanterns include radioactive material. The detector proved itself by showing 300+ CPM level (lower mR/hr for beta & gamma measures) on the filament. Obviously, the detector works!

A broken, non-functional device has been sent to me.

I am not sure if it is really accurated, I have not a ny instrument to make a quantitative comparison

I purchased this device because I am working on radioactive isotope 32P (strong beta) extensively, and I want a personal device that measures me to ensure there is no contamination on me after work. First of all, it does count. However, it is not sensitive enough compare to a traditional Geiger counter with a pancake detector. I have compared side by side that when the traditional one used in the lab gives about 1.5k cpm, this Monitor4 does not show any difference compare to background, even when the detector is about 1-inch to the source. I am not sure about other application, for serious beta ray detection it does not work well.