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Jin

How Deep Do Today's Detectors Go Compared To Older Technology?

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 According to my sources, Nuggetfinder have been field testing prototype coils for the GPZ for some time. These are somewhat lighter than existing coils.

I suppose, in relation to aftermarket licencing, the ball is firmly in Minelabs court.

 

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JR, that is good news about NF, to me ML make top detectors, the aftermarket coil manus gave us a top variety of top coils to go with those top detectors. A partnership with all gain to our time behind our MDs for us the consumer.

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2 hours ago, jrbeatty said:

Tony (an old detecting friend) has inherited Jim Stewarts coil winding expertise. They spent a lot of time together in the workshop at Laanecoorie Park experimenting with ground loops, different coil configurations, etc. He also communicates regularly with Rowan (Nuggetfinder)

Tony has wound a number of concentric (coplanar) coils for the GPX and demonstrated some of them to me at the Laanecoorie test site earlier this year. Here's one not yet painted:

mlicTv0.jpg

On deep targets this type of coil clearly outperformed (depth wise and size for size) all the other coils we tested. These included flat wound and DD's.

Tony related how, using this type of coil he had clearly heard a 14 oz colour deeply encased in solid ironstone (in WA, dug up with a Makita jackhammer) when no other coil he tried could hear it, even when partly excavated.

Although we didn't test one on the day, Tony is of the opinion that this type of coil (size for size) will outperform the GPZ on deep targets:

H9TdRQO.jpg

So far I'm unable to bribe him into making me one :sad:

So the outside wires are the Tx and the inside wires are the Rx? Was reading up on concentric coils and found this one.  41" and almost $4700 when converted to Aus dollars. Wonder if it could be made to fit the Gpx.  

Quote: Nexus Standard MP V2 equipped with the 41" (1.04 m) Carbon Fiber concentric search coil forms the deepest induction balance metal detector set on the market today. Many companies claims their detectors are the deepest, but when it comes to depth only one factor counts - absolute size of the search coil. Our 41” Carbon Fiber concentric search coil is by far the largest of all coils meant for use with hand held metal detectors.The 41” Carbon Fiber concentric search coil is extraordinarily light, in fact the lightest for its size –at only 1070 grams.

 

Nexus 41.jpg

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Big coil Jin. The impedance of the windings would need to match the GPX specs (among other factors) for it to work though. At that price I'd personally take a rain check.

Tony mentioned that it was not a straightforward coil to make (unlike mono's) with a lot of interacting factors to consider

The ground loop type coil is intriguing though, the principle being that you walk around (within the laid out transmit windings) with just the receive coil. Tony and Jim were developing a working prototype when Jim died.

Tony tells me the depth advantage is staggering, but he hasn't got a reliable system perfected yet.

Nenad probably has more info on the subject:

4hz24h.jpg

 

Edited by jrbeatty
added image
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Back in 1990 when  when we were testing the Protos, Bruce Candy brought just such a cable setup to where we were living  out of Maryborough. Unfortunately the system was full of bugs, and did not perform. I don't know if Bruce ever perservered with it.

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I open this thread each morning expecting to find it gone astray, and instead find good discussion. I want just want to say thank you all for that! :smile:

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18 hours ago, Norvic said:

That coil reminds me back in the A2B days the large concentric coil made by Dtex (spelling may be incorrect) was the coil for depth and was no slouch in sensitivity. It would be great to see these aftermarket coil manufacturers be given the green light for Z coils, I think they would do what they`ve done to the PI coils and by now maybe we`d have a selection of coil sizes and performance gain coils that push the depth boundaries even further.

Hopefully whatever it is that stops these innovative people doing so is overcome.

I bought a few of their coils back about 12 years ago and was not overly impressed with them but this last 5 or 10 years their coils are about as good as it get, Right when I had all but given up on  my quest for more depth I was doing the Ebay Tango and saw the one coil I was told not to buy back in the day so last year I bought it, Not only is it a delight to swing but it has added 2 or 3 inches on coins and close to 12"+ on larger items, So I ordered a second one just in case, It can see bits weighing 0.03gm within an inch or so and it has the power ta boot.

I have come to a point where I now believe that the extra horsepower now lies within coil technology because my detech has really opened up my machine and the other 8+ coils have become more like accessories and I am more than happy with depth on a daily bases, to the point where although my machine is getting on in years by design although it is only 2 years old I just don't want another machine and I think that this is bought on by my choice of coil/s.

I truly believe that the future lies in coil selection and design because my VLF now whoops my SL by a fair margin.

John.

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There's a key issue to think about when using larger coils which is mainly why you don't see Minelab going much above 19" and I notice no one has mentioned it here in all the dialogue. 

SALT

JP

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In one of your videos JP,  Bruce Candy said that when you get up over 20" that the magnet field in the ground starts to play havoc (or something like that)

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9 minutes ago, Jonathan Porter said:

There's a key issue to think about when using larger coils which is mainly why you don't see Minelab going much above 19" and I notice no one has mentioned it here in all the dialogue. 

SALT

JP

Most VLF's see very little effects in using coils bigger than 15", At one time large coils could be used but at the cost of sensitivity to small items, Alas now this is not the case, My 15" Concentric is as sensitive as my 6x10 (5x9) and the only coil I have for my  VLF that is hotter than the rest is my 5.3 (6") Concentric and it can go down to 0.006 grams with surface targets, where all my other coils only go down to 0.03 to 0.02 grams.

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