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PM 1703 Scintillator picture

For measuring Gamma when surveying granite countertop slabs or existing countertops, we use a PM 1703 Scintillator. When a Gamma ray hits the crystal inside the meter, it causes a flash of light, which is measured by a photodiode, then counted by the electronics. We will cover basic operation of the meter in this article.

In the picture, there are two grey buttons, top and botom. The top button is the mode button. If the meter is reading “off” when you get it, just hold the top button down for a few seconds and it will start up. If you have recieved a brand new meter, just insert the battery. Look for the large honking screw on the side of the case.

Once it comes on, the unit will test itself, then it will calibrate itself to background radiation. Takes a minute for both to happen. If the meter doesn’t pass the test, it won’t start the callibration process.

At this point, you are ready to go to work. Just hold the meter in contact with what you want to test. If you move the meter slowly, you can scan an item. Move too fast, and it won’t read accurately. One foot of travel per three or four seconds will do for a rough survey.

The lower button turns on a light for the screen, allows you to turn the unit on and off, and allows the unit to communicate with a computer to download info or upload info.

The beeper can be turned off, so can the vibrate alert. I recomend turning off the beeper if you are surveying in a slab yard or stone showroom, annoying as hell, and you will scare people.

To turn the beeper and vibrate on and off, hold down the top button, the mode button, for a few seconds, maybe six seconds. At first it will say “cal” for calibration, keep the buttom pressed down. After five or six seconds, it will display a “n 5.5″ or something close. That is the alarm level, set at 5.5 ratio (why the meter re callibrates each time you turn it on). punching the lower button will cause the “n5.5″ to flash on and off.

When it does that, punching the bottom or top button will make the “5.5″ go up or down. play with it, set it where you wish, then do nothing. The meter will reset itself with the new level of alarm.

It is recomended to leave it at 5.5, set it on one and the meter will beep a lot. Set it at 9.9, and it will read fine, but the alarm won’t warn you when the radiation level shoots up high.

Now do that again, but this time when the “n5.5″ is displayed, punch the top button. Now the meter shoud read “1-on”. Punching the lower button toggles the on and off function. #1 is the beeper, #2 is the vibrator.

If you do nothing after that, the meter will reset.

After setting the “1″ to on or off, punch the top button and it should display “2-on”. Same procedure if you want to turn that function on or off. Pretty simple.

The meter reads in micro Roentgens per hour. You now have the data to make a decision, what normal background radiation is, and how hot the granite is.

Now we enter unknown territory. Two camps, but the overwhelming consensus is that ALARA, As Low As Readily Attainable, is the standard. Sure there is a camp that believes in Hormesis, a fringe theory that says radiation is good for you….. We will stick to facts here.

To turn the meter off, hold down the lower button (the light button) for a second, then while still holding the light button down, depress and hold the top button for a few seconds till “off” appears on the screen.

Please don’t drop the meter. It has a crystal inside that can be broken.

This meter retails for over $1.200, but they can be found one place cheaper, for $383.28 with shipping. The SSA has arranged a group rate if we buy in multiple units, you would save shipping, and the SSA gets a small percentage. Any money raised will be earmarked for technical equipment for testing. Units will be shipped in lots to us, the meters will be tested, then reshipped to the owner. You are saving $13.00, and someone knowlegable and neutral has made sure it is working fine. We will pay the shipping going out.