Air and Ground Testing your Metal Detector

Air testing your machine is great for many reasons. One, it teaches you what the machine will sound like for various types of targets. So take a few coins, pieces of gold/silver/platinum and see how your machine reacts. This is very beneficial when you first get your machine. You can see what things sound like. You can see what iron and gold each sound like.

Additionally, air testing is a great way to see how deep your machine will get with various settings. Air testing can provide a glimpse into your machines depth however some machines, like Minelab which have automatic ground balance can be off in air tests. However machines like the CZ21 will show your max depth with an air test. 

Some words of caution about air tests. First, interference can really mess up an air test. So you cannot air test in a house. There is too much metal around which will definitely prevent you from getting accurate results. This also goes for the outside of your house. I recommend testing the ground and trying to find an area with no signals to perform the air test. Additionally, you want to ensure there are not strong EMI/RF signals around to interfere with your detector. These signals can come from home Wi-Fi, cell phones towers, and power lines. You can buy EMI detectors to be sure of this but in general the further away from houses you are the better.

Here is an example EMF detector: https://www.amazon.com/Cornet-ED78S-Meter-ElectroMagnetic-Detector/dp/B00P67QLA0/ref=sr_1_14?ie=UTF8&qid=1467210910&sr=8-14&keywords=rf+detector

Ground tests are good tests as well because it will show how your detector acts with various types of soil. Usually I do this out in the field but you can do this at home by digging holes to various depths and putting coins/targets in. In the example below I am going to show some air and ground tests I did with my machines.

Ground test

For the ground test I used a quarter and taped it to a ruler. The ground at my house is a mixture of sand and soil. It was also damp from rain. It is a bit salty too. I live about 1 mile from the coast and about 300 yards from the intercoastal waterway.

Whites DF

12 inches - Nothing
10 inches - Nothing
8 inches - Break in threshold. I may of stopped but it would of been easy to miss.
6 inches - Yes

Excal II - 10 inch stock machine (I was new to this machine when doing this test so results may be different now that I have more hours on it)

12 inches - Nothing
10 inches - Nothing
8 inches - Maybe a very faint tone. Not sure I would of stopped but sometimes I pick these up. In Disc it would null and then ring but then I couldn't repeat the ring very easily.
6 inches - Yes

CZ21 - 10 inch stock machine

12 inches - Nothing
10 inches - Nothing
8 inches - Maybe a very faint tone. Not sure I would of stopped but sometimes I pick these up. It rang as iron in disc 0.
6 inches - Yes

Air Tests

Whites DF

Nickel - 10-11
Quarter - 9-10

Excal II (More recent air tests of this I have gotten closer to 13'' with a quarter - I was new to the machine when I originally did this test)

Nickel - 10-11
Quarter - 11-12

CZ21

Nickel - 10
Quarter - 10-11

What did I learn? Overall all 3 detectors are about the same depth in air/low mineralized soil. Now, how they handle mineralized soil/water is a different story. My beaches have very little mineralization so I dont expect different measures at my beaches. In the water, I expect the CZ/Excal to begin to drop off but the DF should stay the same.