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Thanks for sharing this useful information, and I know I will be remembering it for a while.

Good luck and happy hunting.

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....Thank you for sharing your insights and information from 3D testing ... as well as field testing.
...
  when detecting in strong iron ..you need to be aware..one fact..and that small DD coils / less than 9 ",, and elliptical coils matches less than 9" / may have a problem detecting deep coin targets between iron ... .

you may be surprised ... what a large target can be practically invisible to a small /or narrow / coil.....

Here is my 3D test for a silver  liberty "half dollar "at a depth of 7cm... below the nails .. using a 5.5x 9.5 "narrow elliptical coil // ..

 

 

The narrow elliptical coil on the ORX cannot pass this test ... even with a coin size such as half a dollar.

..this narrow elliptical coil can only signal the signal in one case ..and it happens you change the sweeping of the coil by exactly 90 degrees ..

If you use a 9 "hf round spool (at 14 khz / .... in this test, the target will be visible when sweeping the whole spool * 360 degrees ... around the target.

My testing of various separation-good detectors and coils shows ... that you need to have a coil of at least 9 "inches.
so that even separation very well detectors can reliably pass such a test ...

..... and here the magic of the 9 "round coil is hidden ...

.....it is the smallest coil that can separate deeply ...

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So a fair conclusion could be:

The smaller coils on the Equinox (6" and 5x10) might have better target separation than the 11" or 15", but only if the target and iron are on the same plane (and presumably, the target is on a plane above the iron)? 

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13 hours ago, Tometusns said:

...the 3-D dime/Rusty nail test.

Please give details of this setup when you get a chance.  It sounds like it's a standard setup but I'm not familiar with it.  Thanks.

Separation tests are good but given the number of variables in the real world (multiple targets, relative depths, relative transverse distances) it's probably realistically impossible to draw universal conclusions.  But the more tests done, the better knowledge we have, just as long as those results don't lead to an oversimplified, erroneous picture.

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This thread illustrates the practical value of testing & experimenting with your detector(s). And it's fun!

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19 minutes ago, mh9162013 said:

So a fair conclusion could be:

The smaller coils on the Equinox (6" and 5x10) might have better target separation than the 11" or 15", but only if the target and iron are on the same plane (and presumably, the target is on a plane above the iron)? 

  Could be. I’ve sure been thinking a lot about it.🤔

   I think what EL NINO77 said about the nine inch coil makes sense. The larger coils have space between the center bar and the outside of the coil that the smaller coils don’t have. That’s the difference I can see. The nail would be in between the outer and center bar of the coil verses the outer part of the coil directly over the nail when the center passes over the dime.  Perhaps that’s why the larger coils could see the dime and the smaller ones couldn’t. Who knows? 

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24 minutes ago, GB_Amateur said:

Please give details of this setup when you get a chance.  It sounds like it's a standard setup but I'm not familiar with it.  Thanks.

Separation tests are good but given the number of variables in the real world (multiple targets, relative depths, relative transverse distances) it's probably realistically impossible to draw universal conclusions.  But the more tests done, the better knowledge we have, just as long as those results don't lead to an oversimplified, erroneous picture.

This is what I had set up.

F8F54DD6-5BFC-4BE5-8981-40CE70797E2B.jpeg

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22 minutes ago, Tometusns said:

  Could be. I’ve sure been thinking a lot about it.🤔

   I think what EL NINO77 said about the nine inch coil makes sense. The larger coils have space between the center bar and the outside of the coil that the smaller coils don’t have. That’s the difference I can see. The nail would be in between the outer and center bar of the coil verses the outer part of the coil directly over the nail when the center passes over the dime.  Perhaps that’s why the larger coils could see the dime and the smaller ones couldn’t. Who knows? 

This might explain why some people who use the 6" on the Equinox don't notice much of an improvement. 

Imagine we have 3 potential targets:

Target 1 is b/w 2 iron nails, but below the plane the nails are on.

Target 2 is b/w 2 iron nails, but on the same plane as the nails.

Target 3 is b/w 2 iron nails, but above the plane the nails are on.

Presumably:

Target 3 can be hit with any of the Equinox's coils.

Target 1 can only be hit with the larger Equinox coils.

Target 2 can only be hit with the smaller Equinox coils.

If my presumptions are correct (they're probably not), then the smaller coil will offer no benefit in target separation over the larger coils assuming targets are equally distributed amongst the iron trash.

So, how do we explain why smaller coils have better target separation? Maybe it's b/c the above observations are most evident when the trash target is iron and not say...aluminum? Or maybe it's b/c the above results depend on how big the coils is, how small the coil is, how far apart the iron nails are and how far above or below the nails are. So in the end, the small coils perform better than the larger coils in more potential scenarios.

In other words, if you took my above hypothetical "mind experiment," but you expanded it to 100 different possibilities (in regards to how far apart the nails are, how far below or above the dime is, how fast the coils is swung, the size of the coils, etc.), perhaps the smaller coils will come out ahead 55% of the time (or more)? 

It's kind of like how wearing a seatbelt, overall, improves your chances of avoiding serious injury in a car crash. But there are still narrow situations where having a seatbelt in a crash will increase your chances of injury.

TL;DR - a smaller coil helps improve target separation...MOST of the time.

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This is all very intriguing. I have a proposition:

If someone in the USA has a 6" and/or 10x5 coil they can send me, I'll run them (along with my 11" stock coil) on my Modified Monte's Nail Board and report back with results. Then when testing is done, I'll return the coils on my dime (hahaha, punny).

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