VLF Concentric Vs DD Coils

[auminesweeper]

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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[Ivansgarage]

Good thread guys, this is why I hang out at Steves forum, detectorprospector.com

 

Ivan

[Ringmoney]

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.

[auminesweeper]

On 1/26/2015 at 2:38 PM, Jonathan Porter said:

Manufacturers are afraid of negative feedback from customers complaining about noise so opt for the soft solution of providing DD coils only!! Case of not understanding what is required to be effective when searching for gold or worse trying to do too much at once.

If the GB II, an outdated design, can do it effectively and IMHO MUCH quieter than the GB PRO with its DD coil and lower FREQ, why can't the more modern offerings, especially with the benefit of reasonable auto tracking features, be able to do it? 

How bout giving me a GB II in a modern GB PRO housing with a concentric coil and Minelab auto ground tracking with three frequencies say 19Khz, 32Khz and 70Khz? 

JP

Maybe it would be a good Idea to supply machines with the Coil as per Customer Choice at the Time Of sale, This would save you having to buy an extra coil at the Time Of Purchase. and If A Person did want extra coils that's what the machine would come with Instead Of being stuck with a coil that you wont use.

The Companies will Listen to people Like You and Steve, but Convincing them is the Hard Part,

John

[amergin]

Steve this is fantastic, thank you spending the time on all this, it see like concentric is worth the consideration

 

i will read all in depth after work

 

it is for a friend who has the MX Sport

[EL NINO77]

 

From my observations and also the measurement of mineralization -may say from a medium-sized 23x20cm CC coil it shows 2x a higher mineralization value as well as a 23x20cm DD coil.

When comparing dimensionally larger CC and DD coils, I feel the differences will be even more important ..

[auminesweeper]

22 minutes ago, EL NINO77 said:

 

From my observations and also the measurement of mineralization -may say from a medium-sized 23x20cm CC coil it shows 2x a higher mineralization value as well as a 23x20cm DD coil.

When comparing dimensionally larger CC and DD coils, I feel the differences will be even more important ..

In my ground I have not seen any major changes between the 2 types of coils, The only thing I have seen is I tend to get more Iron and crown caps ID'd as good targets with a DD  and the Etrac with it's DD was all over the place, giving up to 9 or 10 different sets of figures for crown caps, The Sovereign GT was really good when it came to IDing things and having the meter on it helped a bit on targets that were a bit iffy, The only down side to it was the very slow recovery speed.

Most of my ground measures between 57 and 67 on the GND on the MXT and pulling coins from over a foot deep is quite common using the 950 coil and using the 12"/300mm Coil can be seriously Deep, being old Farm land that has seen every thing from modern man back to the Neolithic there is a lot of Iron junk down there so a Concentric and a fast recovery seems to work best even using the 12" Concentric it still sniffs out the keepers.

[Argyris]

Was reading all the incredible info in this old thread regarding coil differences...so I have a question:

For underwater salt conditions, if you had a 7'' concentric, and a 9.5''x5'' DD eliptical....which one would you use? (as you see both coils are small, but that fits me for snorkelling much more than a larger coil)

I think depth wise would be almost the same (maybe concentric would be deeper)....but I also think that the 7'' concentric will be more sensitive to small gold vs the 9.5''x5'' DD coil. However:

- Will the 7'' concentric handle salt underwater conditions, since concentrics are more affected from difficut grounds?

- Which will have the greater real coverage area under the coil, regarding their transmition "shape"?

Which one would you choose and why? I read all the info here but still a little confused for what to choose for underwater-salt use...concentric or DD?

Thanks

[Steve Herschbach]

I'd try them both and see which worked better. What happens next depends on the detector. Theory is nice guide, but never replaces actual comparative tests with your own detector and coil, on your own ground. If I simply had to choose one without knowing which is best, I'd go with the DD first due to the ground canceling capability that tends to be inherent in DD coils.