air test

[certified male]

by may 1st i should have my prizm 2 and i can start hunting all the places i have researched. had a ? on air tests. what exactly are they and why do them? i see this pop up in the forums from time to time. thanks.n

[ochog]

An air test gives you a dry run on the use of your detector. It will act as a guide to what you are going to hear when your machine hits a target, how setting your controls affects the targets, etc. Myself I think an air test is good just to show you how your controls work and what happens when you make changes. I have always found that once the target is in the ground it acts different then what it was like during an air test.

It is also good to perform when you are making major changes like swapping out coils removing and replacing rods and such to make sure you have everything hooked up correctly. I like checking my machine out before I actually get to the field to make sure I am not going to have any problems.

[portraitartist]

That is correct. Another thing to keep in mind is that objects will usually detect a bit deeper in the ground than in an air test, due to the "halo effect" of the metal interacting with the ground. This is especially true with iron and copper-type metals, but not so much so with silver and gold.

[certified male]

thank you. that helps. i'm familiar with the halo effect from when i used to have one way back in 79. never air tested before but will use it now.

[drver]

If you really want to do it right you will need to build a test patch. Take some targets and bury them at different depths in the ground. The older the test patch is the better it'll be. The moisture will leach some of the metals out of the targets creating a kind of halo around the target, just like the ones you'll be looking for but don't know where they are. Air tests are ok but the resistance from mineralized soil, moisture etc isn't there. It will tell you what the detector sounds like on different targets, close anyway, and if it's working or not but listen to what a clad quarter sounds like in the air verses six inches down in the soil than ten inches down in the soil at an angle to the surface...you may be surprised.
What may surprise you more is how the wrong settings, ground balance, sens, threshold, bad coil angle to the soil... what ever... won't even report on a quarter at ten inches on edge but will report a quarter from two feet away in the air.