AIR TEST versus IN GROUND

[ToddB64]

I've read that doing air tests (to learn how your metal detector works) isn't as good as in-ground testing.

If my Ace250 metal detector is "ground balanced", to ignore the masking effect that iron ground minerals have over metal targets, then what makes an "in ground" test any different than an "air test" ?

I realize that ground and air are two separate environments, but if the ground balancing circuit feature is neutralizing the unwanted return signals from ferrous minerals, then what's left to make an in-ground test any different than an air test ?

My purpose for asking this question is that I would like to do air tests knowing that the results are, for all intents and purposes, as good as in-ground tests with a ground balanced metal detector.

Thanks in advance to all who reply.

Todd

 

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[eagle77]

From what I have noticed the VDI reading from an air test give 'deeper' results than that in the ground. Also I've noticed the ID is not as accurate, but still within range if properly ground balanced. This is why many have test gardens. The air test will give you a basic reference point, but I don't feel that it will be as accurate from my own experiences.

I had read somewhere that the 'standard' is a dime and companies use the dime in air tests to do a check on machines. Dunno if it's true or not.

 

[BioProfessor]

Eagle77 is right. The air test gives "incorrect" depth reading. Most of the testing done like this is to check for depth sensitivity between machines. Here accuracy is not so important as the ranking. Easy to test a group of different type detectors with things in the air. It's just not accurate and really may not give reliable information from each machine. In my opinion, it is good only to test your machine to see if it will pick up or reject certain items. It is just easy to do. All the other information you get, VDI, depth, etc is all crap (not crape). Also, if you bury a coin, the readings you get will not be the same as the ones you get in undisturbed ground. "Halo effect" is one thing that is missing. Also, freshly plowed or dug earth is a mixture of soil and air that is different that what the detector is designed to "assume" and it just doesn't read correctly. If you want to bury a coin to test, push it in the side of the hole you dig so it is under undisturbed soil. The readings and depth sensitivity is much better then.

Daryl

 

[Gen. Breckinridge]

I had a Garrett CX-Plus and it would air test on a miniball about 12 inches. Put that mini in the ground and forget it! Even at 5 inches the CX-Plus didn't know it was there... Even with a 12.5" coil! That's why I'm hunting with a Whites MXT now. The Garrett Ace 250 is a good little machine for the $$$.

 

[luvsdux]

It's been my experience and I've seen it mentioned on other forums that as a rule of thumb, you can figure a measured test in air will be 30 - 40% greater than the same target in the ground. However, this can vary by a fair amount depending on the ground dampness, mineralization, length of time the target as been buried, etc. Also, I have an idea that target depths are like gas mileage and fish stories, some detectorists are prone to fudge a bit. LOL
However, as mentioned in one of the previous posts, air test are a good way to compare different machines or the response on one machine with different coils and/or settings.
My two bits.
HH
luvsdux