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Air tests of search coils

B

BH505Man

Active member
I've read many posts in the MD forums about air tests of search coils. Come on guys, when have you ever found a coin in the air with your metal detector? About the only thing air tests tell me is how far away a coil is capable of sending and receiving the magnetic field to a given target. Air tests of a coil do not take into account how well the coil will actually perform sending and receiving those magnetic impulses through ground mineralization, iron sand and rocks with minerals etc. A more practical and realistic test for a coil is how deep that coil will enable the user to detect an object in the ground where it's being used. So the next time you test a given coil, I would like to see realistic comparisons of the coils in actual field testing.
 
You make a valid point. However, air tests do give a quick indication of what you might expect performance wise (allowing for somewhat less real word perfomance) between diffrent coils and also can be used as a base mark to compare performance if a detector coil combination seems to have lost performance over a period of time. It's a pretty sure bet that a combination that gives 8" on a given target won't give that depth in most ground conditions, but should outperform a combination that gives 6" performing the same air test on the same target.
BB
 
The original coil that came with my Pioneer 505 did good on air tests but gave nothing but false signals and would not find a coin in the ground. When I sent it to First Texas, they tested the coil and confirmed my suspicions (yup, it was bad)
That's another good reason I don't put a lot of credibility on air tests.
 
My Soil, Your Soil, Their Soil, Northern Soil, Southern Soil. The point is The soil is different from one region to another, but! everybody's air is pretty much the same.

Moving on.
Other then the halo effect of ferrous objects (Iron) I've never seen a detector detect deeper in the ground than the in an air test. Now, you ask 'Why air test a coil/detector'?
Well, I would say this,
Nope, its not a real comparison to targets in the field!
But, if I know the silver coin I'm going after is in the seven to eight inch range and I air test a certain detector/coil and I can only get 5" to 6" out of it then I know its not going to get the depth I need in the field.
On the other hand, If I air test something my 1270 and the 8" coil for it and I get eleven inches then I'm thinking this one has a change even if I it loses two inches of depth in the field.

Here is another example of a good use for air testing,
Lets say I have a LandStar and you have one, mine air test a quarter to four inches, yours in the same air test goes 12" easily, seeing how air is pretty much the same, then I could contact you, verify are settings are the same and I could conclude that my LandStar is broken and needs to be sent in for repairs.

No, air test doesn't tell the real story of depth in the field, but that doesn't mean that air test has no purpose at all.

Mark
 
Something to keep in mind, some detectors require factory calibration to get the best performance from non stock accessory search coils.
 
BH505Man said:
Something to keep in mind, some detectors require factory calibration to get the best performance from non stock accessory search coils.
Click to expand...

These would most likely be ones that the coils are "Hardwired" and or ones that has no form of ground balancing, manual or automatic and not the ones designed for interchangeable coils.

Mark
 
That's what First Texas recomends on non OEM coils. In other words, all coils that didn't originally come with your metal detector. That way your detector can be calibrated to obtain the best performance with that particular coil. Like a race car has to be tuned to obtain it's best performance when you install non stock high performance parts.
 
BH505Man said:
That's what First Texas recomends on non OEM coils. In other words, all coils that didn't originally come with your metal detector. That way your detector can be calibrated to obtain the best performance with that particular coil. Like a race car has to be tuned to obtain it's best performance when you install non stock high performance parts.
Click to expand...
I don't think so!
Only the underwater units and units that have the coils hardwired with factory internal preset ground balance need to be coil matched tuned.

Mark
 
Not so. We're talking about any nonstock coil whether or not it's hardwired. We're talking about for peak performance.
 
BH505Man said:
Not so. We're talking about any nonstock coil whether or not it's hardwired. We're talking about for peak performance.
Click to expand...
So, if I buy a new detector that comes with a three coil package to get peak performance out of it whenever I change coils I need to send it back and ask them to "Tune" it for this coil today, and then I would need to request an overnight shipping for my hunt tomorrow??
Come on, think about it?? what your saying doesn't make any sense.

I know that they are certain models of Tesoro's with hardwired coils that's recommended to be returned for a coil match tune up, (hardwired coils)
They're is some Fisher underwater units with hardwired coils that are required to be sent back for a coil swap and coil tuning and these are not sold with multi coil packages, nor are they accessory coils even sold for them, if you want a specific coil size you have to order it with the coil you want, or send it in and have it changed.
I'm sure there is other brands and models like this, but somebody is over thinking this whole thing.

Mark
 
No, If a detectector comes with a coil, more then likely it's tuned for that coil. I'm talking about after market coils like say a Fisher 11"DD coil or a NEL Tornado coil that didn't come with the metal detector in question. Like say that I purchased one of those coils for my Bounty Hunter Pioneer 505. Even though these coils may work with the 505, they weren't OEM on the 505 so it wasn't originally tuned for optimum performance with the 505. But the 8" and 4" coils were OEM and the 505 was already tuned by the factory for use with them.
Walt
 
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