Air Testing Vs Ground Testing Coils Your Thoughts

[PI-Man]

Hopefully I put this topic in the right place.  This is always a good topic for discussion and has been discussed many times in past.   Everyone always has great input and people really do extensive testing on the subject.  So it is nice to hear everyone’s thoughts on recent testing techniques/thoughts.

Funny this started on another thread, but it needs it’s dedicated place to not take away from the other threads main topic.  Actually I was working on a PM then went back to the thread and said wow here come the responses oops should have started this thread first.

Someone did mention BASELINE — I agree that sums it up in my opinion, but I do get tunnel vision at times.  Don’t we all.

I am not a 100 percent on air test as there are many variables in the real world/environment and most notably I do not detect coins/targets in air.  This is just my thought process.  Although in past I have done a bunch for curiosity.  The data though is extremely valuable and worthy of documenting.  I applaud/thankful to everyone that provides the information and truly think it helps people understand what a coil can possibly do.  Notice I said possible.  That real world thing can throw us all for a loop at times.  My thing is get the coil/detectors out in the field on unknown targets that are in the ground and see if the different machines can pick up the target in that type of condition with its best settings.  Of course it is never apples to apples, but we try.   Like when the Karate Kid said ‘when do we get to break boards and he said boards don’t hit back’  well air doesn’t hit back like the ground. Had to poke a lil sick fun.

Would like to hear everyone’s thoughts/opinions on what they think a proper air test is and what they are trying to get at vs what’s in the ground testing.  Be respectful all points should be well taken.  A little debate is good.  Know a lot of people put a bunch of time into the testing, so it is great to see a transfer of knowledge.  Note I have been offline for awhile dealing with health issues,  so I am playing catch up on my readings.  I have seen some neat testing setups since I jumped back online while playing catch up.  Some are very elaborate in design it’s great seeing this.

Gary — ‘The Pulse is Strong with this one”

 

 

[Steve Herschbach]

My thoughts:

And my preference for how to test detectors

[Joe Beechnut OBN]

Air test might not be the best for giving results once we are hunting in the wild but does allow all of us to give feed back on the testing of the same machine in the same conditions. And since I do build my own head phones, Air test are a big help in identifying the best build for my hearing. For me, doing both Air and beach/wet sand test.......so much can be learned when comparing both performance and the audio characteristics of different targets.

[Ogliuga]

I think that air tests are almost useless and this is because ground testing is made up of many variables. Mainly mineralization and presence of iron..Did air tests but because I was asked to do them..

[phrunt]

My purpose for air testing isn't so much to establish depth, it's because I often look for the very smallest bits of gold so my air tests are generally sensitivity tests, I want to know if a coil will pick up the very smallest of targets, and I want to know which spots on the coil are the most sensitive, it helps me locate targets when they're under a coil.

This is typical of my sort of air testing, and the targets are so small depth isn't really a factor, detectors don't get much depth on them, they just have to be able to hit them in the first place even right near the surface.

And this is the other method I use air testing where I run the smallest lead pellets the detector can hit on just to see the response the coil gives and the hot spots on the coil, these hot spots are invaluable when recovering targets.

The 12" NF Z-Search on the GPZ

And the 12" X-coil on the GPZ, same settings

I don't care what anyone says, these tests to me are very valuable and provide a massive amount of information for me personally, and the results I get in the field reflect the air test results.

Air tests while possibly useless for working out the depth you'll find targets are very handy for this sort of testing, a coil that is struggling to see a target in the air isn't going to do better when the targets are in the ground.

[strick]

Klunker and I were testing out the coiltek 10x5 on his Nox this past summer up in the Motherload. He threw a dime on the ground and at about 4 inches it started missing the dime. The ground was interfering with our test. True air tests should be done in the air like in top of a box or something non conductive. OBN had a good set up for his Excalibur's. 

strick 

[midalake]

9 hours ago, PI-Man said:

Would like to hear everyone’s thoughts/opinions on what they think a proper air test is and what they are trying to get at vs what’s in the ground testing

I keep air-testing simple! I want to know the maximum performance of a detector and that is what air-testing accomplishes. Then the goal is to see how this performance can translate to the ground/beach. 

[DSMITH]

I do not and have never agreed with someone doing air test for me personally all a air test is good for is to tell you your detector will see a target and what a TID will be for a given target which even the TIDs can be skewed by ground mineralization, for depth an air test is meaningless

when I first started detecting back in 2009 i purchased two detectors the AT Pro and the Xterra 705 by all the air test I did the ATP was deeper than the Xterra 705 not by just a little deeper but by 4-6 inches deeper, but when I went out and started detecting with both in my back yard on targets that had been in the ground for who knows how long it was a completely different story the property I tried this on the house was built in 1889 with a back yard that was 3/4 of an acre all fenced in again the air test I did with the ATP and the Xterra 705 all of them showed the ATP was 4-6 inches deeper than the 705 in air test, but when we went out to the back yard and started detecting the Xterra 705 was quite a bit deeper then the ATP the ATP would not see a target in the ground over 5-6 inches deep while the Xterra 705 was hitting targets 10-14 inches deep I would locate a target with the 705 reading full depth bars then before digging run the ATP over that same target the ATP would not see a target at that depth that the 705 was seeing, so ever since then I have placed no stock in what a detector can and cant see until I go out and detect in the real world and ground.

[geof_junk]

If you screw the detector up to max and do an air test on the smallest coin you are chasing the depth is the deepest the hole has to be in the manicured lawn(handy when doing visible public locations.). The air test lets you know the max sensitivity of the detector, but not the depth in the ground, you need bucket (plastic) of hot soil from the hunt location to determine it depth for each target.

Testing is to give you information that allows you to Guess what the target is. Note lifting the coil as high as you can and get a definite signal helps. Most very deep nuggets sound like ground noise and quite wide if it is ground noise 4" off the ground it will usually disappear. If you still have the signal then you have a high chance of success. Note most tuning of detectors say to go up and down 4" to balance out the ground noise(that covers what I said above).

There has been a lot of good information posted by others and I hope (those that are not my patch) members benefit from it and more thoughts are given by others.

EDIT......One other thing to test is once you have a signal, leave it there and have a play with the setting to get the best signal then step back a yard or two and approach it at your normal scanning speed and see how it reacts.  

[Joe Beechnut OBN]

 

12 hours ago, phrunt said:

I want to know if a coil will pick up the very smallest of targets, and I want to know which spots on the coil are the most sensitive, it helps me locate targets when they're under a coil.

And this is the other method I use air testing where I run the smallest lead pellets the detector can hit on just to see the response the coil gives and the hot spots on the coil, these hot spots are invaluable when recovering targets.

 

 

Amen!! Who would think a coil would have a Hot spot? One of the little secrets that can define if you come home with the Gold!

Air Test using a audiosears 2462 element, showing the Hot spot on a excalibur coil. And this spot can be Hot at the beach and in a regular air test. Most affected targets (based on size) will be on the edge of the detecting field or the small shallows and this is only effective in All Metal.

May have to turn your volume up a little.