DD Coil vs Standard Coil

[OBN]

liftloop..................gust throw field around the hole lope a 360 degree effect both ways like a ball

I have noticed on the excaliburs that the more senstivity you use the bigger this Secondary field becomes, (in PP/almetal). And by the way guys this is a side view of the DD coils field, just like Treasure hunters...Not a head on.......

 

[bazinga]

Treasure_hunter, If your picture of a concentric coil is correct how is it possible to pick up a chainlink fence 1' to the side of the coil. Your DD pattern is also wrong. the DD is two coils and projects two cones with a slight dead spot near the surface in the center. You were stacking a 15 "DD coil against a 10" concentric. Lets even up the playing field. A Whites Sierra Madre/ULA-3 with a 15" concentric is rated at 5' dept. I think that beats your 15"DD. Frank

From White's website:

"A great White's metal detector for searching large metal objects at greater depths. Use the optional 15" search coil to reach an impressive 5 foot depth."

--------

My guess is that you are just a bit clueless on this entire argument of DD vs. Concentric.

 

[OBN]

bazinga
From White's website:

"A great White's metal detector for searching large metal objects at greater depths. Use the optional 15" search coil to reach an impressive 5 foot depth."

My guess is that you are just a bit clueless on this entire argument of DD vs. Concentric

Funny you would Quote The White's Website after posting this a few weeks ago..............

Our Community / General Discussion / Re: Metal Detectorist Dream Job! - Join the Kellyco Sales Team on: Feb 25, 2011, 08:47:20 AM


I If were to head out west and wanted to detect gold, I would want to hear from somebody who lives for gold hunting and knows the ins and outs of the machines best suited for gold hunting. Not what somebody can read from a sheet of paper about what the manufacturer says it can do.

http://forum.treasurenet.com/index.php/topic,384698.msg2735375.html#msg2735375

TractorNut57
My Advice for anyone purchasing Coils, Detectors, Accessories..is to check with their locals, the oldtimers that have been there done it, conditions can be so different from one area to another that what works in one place well, maynot work 20 miles down the road.........Most are willing to give you a few tips and some great stories..........worth every second........good luck....obn

 

[TractorNut57]

Thanks fellas, I have learned so much by being on this forum, that is one thing nice about these computers. To get this kind of information and tap into this much knowlege would take months or even years. Thank you all.

 

[U.K. Brian]

There's lots of "oldtimers" on most forums and many still make the same mistakes they made when they started.

There's expensive detectors using concentrics. They are not limited to "cheaper" machines.

Maximum depth might be only cover "one square inch" with a concentric. Does it matter if thats at much more depth and at the maximum depth of a DD of the same size as the concentric is live over the same width as the DD ?

DD's cover ground more quickly ? Only if you swallow the cone idea.

No mention of penguin coils (elliptical concentrics) ?

No mention of the detectors filtering. Four filter designs penetrate minerals better than two filter ones so DD coil use is not as important. Four (or more) filters require a faster sweep speed so more ground is covered. The narrow "hot" area of DD's does not suit a fast sweep. Possibly the reason that all the Whites flagship detectors for years only used concentrics.

There's both good and bad coils of both design's. You can't just assume you have the best based on theory.

 

[Frankn]

U.K. Brian, Good point! What's in the box is far more important than than what is at the end of the rod.
And in case some of you guys don't know it, there are two coils in a concentric. One is wrapped around the hole in the center and one is wrapped just inside the outer edge. Kind of whorps that cone theory!
Frank

 

[lookindown]

U.K. Brian, Good point! What's in the box is far more important than than what is at the end of the rod.
And in case some of you guys don't know it, there are two coils in a concentric. One is wrapped around the hole in the center and one is wrapped just inside the outer edge. Kind of whorps that cone theory!
Frank

It's not a theory, its the way they work. There is no mystery to it, just choose the one you like.

 

[Frankn]

There's a hole lot more to the radiation of the signal from the coil than either of those pictures show.
I can check the contents of my plastic trowl on top of my coil. Now how can that be possible according to the THEORY pictures presented. The second pictures added a "secondary field" to account for the pickup of the fence on the side. I guess someone will post a picture showing a third field to account for the top detecting.
The bull is getting to deep. In actual operation the coil transmitts in all directions. Minelab was forced to remove that coil cone picture in GB because it was deceptive. That second picture is very deceptive because it doesn't show signal down from the edge of the concentric coil. The coil in the concentric is in the very outer edge. Frank

 

[OBN]

The second pictures added a "secondary field" to account for the pickup of the fence on the side.

Secondary field on the Excalibur's I used, that I have noticed, I never said anything about a fence..........

All of these were designed by Marco Nero who at one time has worked for MineLabs Australia..does that make them 100% Correct..Nope..........But they are some of the best I have seen

There a hole lot more to the radiation of the signal from the coil than either of those pictures show.

This is so True..I don't think anyone knows all of the secrets of coils.

I guess someone will post a picture showing a third field to account for the top detecting.

Your third picture

 

[TomNWMI]

Marco made some pretty pictures but are far from accurate

regarding the detection field. Beyond mid-depth there is little if any difference between the two coil designs in detection area. To get the best out of a DD coil you have to overlap your sweeps just as you would with a concentric design. Otherwise, you are missing targets.... whether deep or partially masked by junk. Again the same as with a concentric design. I have proven it to myself over and over in field useage not some ridiculous air test. Forget the cone and blade theory, it is just that, a theory and a load of bunk!

Detection off to the side of a coil has more to do with the amount of gain built into the detector, not the coil. Anyone that has water hunted with a CZ equipped with the 10.5" concentric can attest to that as they pickup fresh drops WAY off the edge of the coil.

Tom Z

 

[Treasure_Hunter]

Re: Marco made some pretty pictures but are far from accurate

To get the best out of a DD coil you have to overlap your sweeps just as you would with a concentric design. Otherwise, you are missing targets.... whether deep or partially masked by junk. Again the same as with a concentric design. I have proven it to myself over and over in field useage not some ridiculous air test. Forget the cone and blade theory, it is just that, a theory and a load of bunk!

I have to disagree Tom, you do not need to overlap a DD coil 50% like you do the concentric coil.....I have hunted a lot with them and when hunting in patterns I am not leaving any targets behind....I hunt a lot with the WOT and the SEF Butterfly 15"x18" coils, hunted patterns in front of hotels to cover the entire wet sand, dragging my coil to mark where I have been and seen other hunters hunt the same area in front of the hotels the same day and they did not stop to dig any holes in the areas I pattern hunted unless they were using a PI, the only thing I left that I did not dig were the nulls, and I always sweep a null from multiple directions to be sure it isn't masking a good target, if it nulls in multiple directions I left it.......

 

[TomNWMI]

Re: Marco made some pretty pictures but are far from accurate

To get the best out of a DD coil you have to overlap your sweeps just as you would with a concentric design. Otherwise, you are missing targets.... whether deep or partially masked by junk. Again the same as with a concentric design. I have proven it to myself over and over in field useage not some ridiculous air test. Forget the cone and blade theory, it is just that, a theory and a load of bunk!

I have to disagree Tom, you do not need to overlap a DD coil 50% like you do the concentric coil.....I have hunted a lot with them and when hunting in patterns I am not leaving any targets behind....I hunt a lot with the WOT and the SEF Butterfly 15"x18" coils, hunted patterns in front of hotels to cover the entire wet sand, dragging my coil to mark where I have been and seen other hunters hunt the same area in front of the hotels the same day and they did not stop to dig any holes in the areas I pattern hunted unless they were using a PI, the only thing I left that I did not dig were the nulls, and I always sweep a null from multiple directions to be sure it isn't masking a good target, if it nulls in multiple directions I left it.......

I hunt fresh water beaches and older sites inland and have dug many many targets that are heard only with a perfectly centered sweep and lost when sweeping the coil no more than an inch off center. You never know what you are missing.

Tom

 

[Treasure_Hunter]

Re: Marco made some pretty pictures but are far from accurate

To get the best out of a DD coil you have to overlap your sweeps just as you would with a concentric design. Otherwise, you are missing targets.... whether deep or partially masked by junk. Again the same as with a concentric design. I have proven it to myself over and over in field useage not some ridiculous air test. Forget the cone and blade theory, it is just that, a theory and a load of bunk!

I have to disagree Tom, you do not need to overlap a DD coil 50% like you do the concentric coil.....I have hunted a lot with them and when hunting in patterns I am not leaving any targets behind....I hunt a lot with the WOT and the SEF Butterfly 15"x18" coils, hunted patterns in front of hotels to cover the entire wet sand, dragging my coil to mark where I have been and seen other hunters hunt the same area in front of the hotels the same day and they did not stop to dig any holes in the areas I pattern hunted unless they were using a PI, the only thing I left that I did not dig were the nulls, and I always sweep a null from multiple directions to be sure it isn't masking a good target, if it nulls in multiple directions I left it.......

I hunt fresh water beaches and older sites inland and have dug many many targets that are heard only with a perfectly centered sweep and lost when sweeping the coil no more than an inch off center. You never know what you are missing.

Tom

Have you tried the WOT or SEF Butterfly DD coils?