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VLF Concentric Vs DD Coils


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QUOTE BY STEVE-

I think John answered that already.

Using coils made by a manufacturer for the detector they made is pretty cheap insurance and not a bad idea in general. I usually do that myself unless there is a size I want the manufacturer does not make. Then I go after market.

In general though people have probably figured out I have no brand loyalties. I just try stuff out and use what works for me. You never know which company will produce tomorrow's gem, and the best companies make a turkey now and then.

Johns experience has made him quite down on Detech coils. Other people really love them. I have three (yes, I bought them) and as far as I can tell they are just coils. No better or worse than other coils I have used.

End Quote.

 

Yes that's True Steve,

But In all Fairness to Detech, Those Coils were bought just after their First Year 18 months of Production and that was about 7 or 8 years ago, So No doubt since then their Knowledge Base has grown Vastly and They Have moved on to bigger and better things now,

Would I Buy One Now ?? Only if I could Try A Demo One First, The More I see of them the More I Like them, But I still have that (What If) Nagging in the Back of my  Mind, And  I Still Really want them to be as good as I was Told they were So I can Have one again (They are Great At Keeping your Detector Up Right) (I hate it Falling Over).

The Thing with Whites Coils is they have always been Pretty Hot on small Items, But I think they Have been Tweaking them or their machines, because My New MXT All Pro with the 10" D2 coil picks up an 0.4 Grain or 0.03 gram  or just under test piece at just over an inch

I did ask Whites Via A PM privately, If they had Boosted the power of the GMT and the MXT because my New machine are Seriously A lot Hotter that the Last Pair I bought and they were very Impressive, But the answer I got was well we are always testing and doing research (Not Their Exact Words), So From that and the rest of the Message with what I see these 2 machines doing, Then I say yes,  

IE- In the Relic Mode the MXT will Bleep At my Hand between 1 and 2 Inches from the Coil and will make the 3rd Tone sound up to 6 Inches from the Coil, If you have either of these 2 machines try it and see if yours does the same, Please note that the GMT has always done that anyway, so just try it with the MXT. 

My Sovereign GT with 4 Different Coils I tested a Small Hammered Cut Half Penny and those coils air Tested between 5 & 1/4 inches to 7 & a 1/2 Inches,  MXT with the Standard 10" D2 Coil is almost Double that,

This is why I am trying to get people to Focus on the Reasons as to why they should use  Certain Coils as Required By The venue and Not by Reviewers or Dealers, And  Mates Swearing by them Does Not Mean that they are the Right Coil For your Personal Task.

I have watched Steve For A while and a lot of Info is Not so much what he says But what He does, And That Info he takes for Granted Because He Has been Detecting for Gold for a year or 2 and that Info is like an extra Limb or Second Nature to him, If you Keep going over his Stories ( I can't remember what they are Listed as) you will see all these little Gems of Info waiting to be discovered, 

And with My enquiring Mind I test everything so I get the Answers why such thing happen or have an effect, IE to map out your coils detection field, Lay the coil sideways with a large piece of paper under the coil and use different sized Lead shot stuck to a Ruler and with a pencil put dots on the paper where the coil stars to pick up the Target,

Any Coil will Pick up A Coin, But Not many can pick up lead shot and the smaller you can go the better the coil will pick up Large Items Like Coins.

Hope this Helps,  John    

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With all the air testing that you do I was wondering if you have found that these results line up with your in situ finds, in particular those in nastier type ground.

Reason being is I have read of manufacturers claiming that their machines/coils may not air test well but will perform better on in situ targets. I have also read on a UK site - Garys Detecting I think - where they say that if a detector/coil performs badly in air tests that won't/can't improve in ground. They do however note that some detectors/coils can lose up to 30% performance from air testing to in ground results whereas a poorly performing air test machine/coil may not lose anything.

Just a thought as I always prefer to hear or see actual in situ finds/results rather than air tests. Would be interesting to see any direct correlation between the two - air test v actual finds?

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On 6/11/2015 at 10:28 PM, AussieMatt said:

With all the air testing that you do I was wondering if you have found that these results line up with your in situ finds, in particular those in nastier type ground.

Reason being is I have read of manufacturers claiming that their machines/coils may not air test well but will perform better on in situ targets. I have also read on a UK site - Garys Detecting I think - where they say that if a detector/coil performs badly in air tests that won't/can't improve in ground. They do however note that some detectors/coils can lose up to 30% performance from air testing to in ground results whereas a poorly performing air test machine/coil may not lose anything.

Just a thought as I always prefer to hear or see actual in situ finds/results rather than air tests. Would be interesting to see any direct correlation between the two - air test v actual finds?

That Part about testing better In the Ground than they do in Air Relates to a machine using the Halo effect to find the Coin,  A Classic example of this is Large pre decimal pennies they Leave a huge green stain in the soil and Silver coins it is a lot less, I once found a big bronze coin and it was down about 12"+ deep, I found it with a PI machine anyway when I carefully removed the big lump of soil from it I noticed that it had a very deep dark Green staining to it and I waved it over the coil it gave off a really loud signal, So I put the Dirt In a plastic bag and took it home a few months Later it had dried out from being in my Den, so I got it out and waved it in front of the Coil and Nothing Not A Sound, So I got a spray pot and sprayed it with water and Waved it in front of the Coil and sure enough it was making a loud signal Once again, So Does the Halo Theory Exist, YES.

With Gold and Silver That Halo effect Is Very Limited, Silver goes Black and Gold stays the same, Iron Breaks down to become a Mineral But before that happens it breaks down into small pieces and either effects the Ground Balance setting as Does fertilizer, Cow C$%P and Burning etc, machines like My Sovereign it makes it Null Out so the Machine becomes Blind until the Threshold Returns and coil has been 4 foot /120cm away before the Threshold returns,

Short Answer Is Only Metals Like Copper and Bronze with make the detector see deeper in the Ground because Of staining.

 

Hope This Helps

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I am not a big fan of air tests. I have seen a detector easily out test another in the air, and in the ground have the results reverse. Air tests have uses but determining what works best in the ground is not one of those uses. You need ground for that. http://www.detectorprospector.com/forum/topic/528-using-air-tests-to-gauge-detector-performance/

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On 6/11/2015 at 10:58 PM, Steve Herschbach said:

I am not a big fan of air tests. I have seen a detector easily out test another in the air, and in the ground have the results reverse. Air tests have uses but determining what works best in the ground is not one of those uses. You need ground for that. http://www.detectorprospector.com/forum/topic/528-using-air-tests-to-gauge-detector-performance/

Yes I agree, I relate them to, IF I can get 50% depth of an Air Test and Only Use it as A Guide, and the reason I use 50% is to Pick the Machine . Coil Combination that will give me the best Chance In the Ground, Like my mate using the first model MXT and the 12"/300 coil with the gain on 6.5 and he's pulling coins at a Measured 13 inches,

I use air test mainly for mapping The Detection field of coils and to see their sensitivity.

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Ok Well I Tested that 6X10 Longscan Concentric Coil On The GMT and it Hits My Tiny Test Piece at 3 X the distance that the Twin D Coil Does,

On Bigger Items there is not much in it with the Edge going to the Longscan by about half an Inch to an Inch so it will be less in the Ground.

But On This Tiny Piece In This Picture it is Lethal,.That Tiny Piece weighs less than 0.1 Grains and about 0.002 Grams,  

Hope this answers the Question about Concentric V's DD's, I think this set up would Knock the GB2 of the top spot If Not equal It, But One thing for sure I have never seen anything like it.

Notice the size of the Piece compared to the Pin And Match Head, And In The last picture is the same test piece next to a Grain of Sugar.

John.

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A concentric coil has a search field shaped like a soccer ball cut in half. A similar size DD coil will have a search field more like a football cut in half lengthwise.

 

LOL, it took me a while to figure out what you meant, " how do you cut a foot ball lengthwise " oh yes, you lads originally used rugby balls to play football. :)

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