DETECH 80 cm Concentric to suit GPX

Well it’s been a while but we have released a new concentric coil

80 cm in diameter just under 32” testing has gone very well and the first stock coils are on there way to Australia
And will be listed on our page soon

A couple of videos done recently

https://youtu.be/mdmRo_aBqXM

https://youtu.be/BcEwLG1sMmc

Regards Pete

Pete was kind enough to lend JR Beatty and myself his new carbon fiber monster coil for 2 days testing. We took it up to Wedderburn where we put it over some very nasty and highly mineralized ground. We hooked it up to James's GPX5000 and ran it on 'normal' where it purred like a kitten. Even on 'sharp' it did not misbehave, and only on the very odd occasion did it react to strong ground noise, which would easily tune out with a few sweeps in auto tracking.
All round, this was a very pleasant coil to operate despite it's large diameter, showing quite startling depth on even small targets, although large targets at depth was where it was truly outstanding. I believe a slightly smaller version is planned, and both Beatty and I will be dead keen to be the first to buy one each.
In short, this coil was a surprise, and a delight to use.

Interesting & thanks for the update Pete, JR & Reg. Considering the size of the coil, as compared to the size of the buried targets, certainly does look promising. Although coils of that size are definitely designed for the multi-ounce slugs at great depths, It surprises me to see such great sensitivity on/over the smaller slugs.
The signal response near the pool of water, I do believe reading somewhere as being a 5oz lead sinker, down at 2 feet.
Do keep us informed.

Cheers Kon.

Yes kon, the deepest target is a 5oz lump of lead. The concentric coil picks out this target better than anything tested here so far, even in the very wet ground, which has defeated even the most expensive detector and coil combinations.

I guess as a large coil it should run smooth aye, compared to the usual size coils.
I notice that the target needs to be almost dead centre to be detected, so a good minimum 50% overlap is required .
Very sensitive for a very biggish coil....Impressive.

Well I '' DON'T '' doubt the tester's credibility's Reg & J Beatty for one second ,I mean this a bloody big coil ,and how would a 20'' or 25'' DD coils gone compared    and for $1800 it would want to find you Gold .But would I be right in assuming by watching the video ,that the outer ring of the coil is the TX , and the inner ring is the Rx  hence by listening to the audio response on the video .Hence also I guess this is why it's called a Concentric coil     Then I also wonder of this coils size and configuration ,that there is ''MAYBE '' more of a time delay ,( marginal at least i'd think ) between the PULSES between TX & RX , allowing the detector more time to G/B ,filter out unwanted Ground noises
            But whilst I welcome more DD coil development ,but what I cant get my head around ,is the fact that this coil ,and including the X coil ,is there made and developed from overseas coil makers ,when they must obviously think our market place must be sufficient enough to explore and our own domestic coil makers seem to be just sitting idly by

G'day Hugh

One thing I can't help you with, is understanding the operational workings of a concentric coil, for I have little clue/knowledge in how they work.
Cost of coils aside etc, don't think for one moment that Nugget Finder or Coiltek (2 of our leading, Australian & world wide renowned, detector coil manufacturers) who specialise in nothing but the manufacturing of detector coils, wouldn't have jumped at the opportunity, towards making a string of aftermarket coils for the GPZ 7000, if  Minelab had only given them permission or the opportunity to do so, without the need of one working on a solution to by-pass Minelabs encrypted coil chip, via an adaptor.
Quite obviously it was not meant to be, (& I'm assuming) neither did Coiltek or Nugget Finder want to degrade the good long standing relationship they've had with Minelab in the past.
Myself as a loyal consumer/buyer of Minelab products though, I'm glad in a way, that someone else did find a way to produce aftermarket coils suited to the GPZ 7000, for 4.5 years living in hope/wait, for something that may never come our way, I find, is a bit long in the tooth for me. As long as no infringements/copy rights have been proven broken & the aftermarket coils work & work well for the better, it matters not from whom or where they come from?  The unfortunate/shame part is, that It wasn't offered or at least been given the opportunity to our own local coil manufacturers, to make coils/accessories first, considering Minelab (for what ever their reasons) had no plans of producing any further size/shape coils for the GPZ in the near future.
Loyalty, like respect, is a 2 way street. Minelab, why not give your loyal clients what they'v longed for & loyalty/respect is sure to follow.
BTW, I'v had good success with the earlier lineup of Mono, DD & spiral wound coils from Detech in they past, so look forward to seeing what this new range of Concentric coils have to offer.

Cheers Kon.

It does look like a Concentric configuration and all of us coin, jewellery  and relic hunters know how they perform with vlf detectors (mainly as discriminator coils).
They are sensitive and can punch quite deep and the only draw back is the narrow detection field and are noisy over hot ground. However on a PI that will not be the case. So I reckon this 80cm beast is going to prove to be very useful in finding deep large and small nuggies.

Interesting & that is what would concern us detectorists the most Adrian. Do concentric coils perform well on positive targets, buried in undisturbed soils, of high or variably changing high mineralized ground on Pulse Induction detectors?  For the depths that we're seeing on/over those slugs of gold, surpass all that we currently have in use today, even on the mighty GPZ 7000. Mind you, if they can & do handle hot ground with ease when coupled to PI units, I would like to see what they would be capable of, on the GPZ 7000 (if they were ever made to suit)

Cheers Kon.  

Good point Kon. If the concentric coil could be made to perform on ZVT technology who knows what advances may be accomplished. I wonder if Mr. Candy is playing with this idea?

I sure hope he is Reg.

Cheers Kon.

Kon61gold wrote:Interesting & that is what would concern us detectorists the most Adrian. Do concentric coils perform well on positive targets, buried in undisturbed soils, of high or variably changing high mineralized ground on Pulse Induction detectors?  For the depths that we're seeing on/over those slugs of gold, surpass all that we currently have in use today, even on the mighty GPZ 7000. Mind you, if they can & do handle hot ground with ease when coupled to PI units, I would like to see what they would be capable of, on the GPZ 7000 (if they were ever made to suit)

Cheers Kon.  

If you mean hot rocks then yes they can be noisy over these but that is with vlf gb discriminators.
As a separate tx and rx coil in concentric configuration on a PI set up for iron mineralisation and gold field conditions I see no reason why there would be any probs . The coils are sensitive but do need careful scanning technique and more so when the TX winding is very much larger than the inner RX as is the case with this 80 cm job.
In the early days of the PI that were originally used for salt-water scuba work, separate tx and rx windings was the norm if I recall correctly.

So basically what you're saying Adrian, is to go low, slow & most likely overlapping each coil swing. Not a problem. If these new range of Concentric design coils for PI, handle mineralized ground without to much of an issue, the depth advantage over positive targets alone, will well be worth looking into.

Cheers Kon.

I guess somebody is going to have to bite the bullet and give one a tryout.
The only reason I will use a concentric is when I want accurate vlf discrimination and good depth in mild ground. At the beach where the wet salt is a problem for concentric coils I use the DDs in order to achieve good ground balance and donot bother too much about accurate disc.

The Ground balance system of a PI is a totally different principle to that of a vlf as we all know and as such the PI mono, concentric and DD can be made to handle iron mineralisation and salt far better than the vlf in tough ground and wet salt conditions.

I can see this big coil being seriously good on deep large nuggets but the the overlap of the scan will have to be adhered to so as to not miss those weak signals from deep biggies. So the tactic would be to imagine that the inner RX coil is the coil that has to be overlapped with each swing.

I am actually a bit surprised that this type of coils has not been used in the gold fields prior to this time.......Maybe our ground is a bit tough for them, although I doubt that.

adrian ss wrote:I guess somebody is going to have to bite the bullet and give one a tryout.
The only reason I will use a concentric is when I want accurate vlf discrimination and good depth in mild ground. At the beach where the wet salt is a problem for concentric coils I use the DDs in order to achieve good ground balance and donot bother too much about accurate disc.

The Ground balance system of a PI is a totally different principle to that of a vlf as we all know and as such the PI mono, concentric and DD can be made to handle iron mineralisation and salt far better than the vlf in tough ground and wet salt conditions.

I can see this big coil being seriously good on deep large nuggets but the  the overlap of the scan will have to be adhered to  so as to not miss those weak signals from deep biggies. So the tactic would be to imagine that the inner RX coil is the coil that has to be overlapped with each swing.

I am actually a bit surprised that this type of coils has not been used in the gold fields prior to this time.......Maybe our ground is a bit tough for them, although I doubt that.

                 This coil has really pricked my curiosity ,for one its configuration ,the TX ring & RX ring ,compared to a normal DD configuration of two D'S facing each other ,and with only one D being the receiver ,and this coil being so bloody large ,and in what was supposedly noisy and wet ground ,why did it appear to run so smooth Why didn't it swamp the detector with excessive ground noise ,much like a Mono can ,particully for that type of ground they put it over .and the fact that the 5 was running in normal and even in sharp .
                  And the other thing that's curious to me is ,I wonder what made the designer build the coil out of carbon ,( presuming of course that it running carbon wires in the windings of the coils )

I guess a large coil averages out the ground noise and hot rock signals better than a small coil that responds to every hot rock and magnetic ground within the field. So over ground that has widely varying ground minerals the large coil is going to produce less noise.
There are of course a bazillion other more techo reasons for the smooth functioning of large coils with separate tx and rx windings over hot ground that would fill several pages on this topic.
Bit of basic info here re coil design.
https://www.geotech1.com/pages/metdet/info/coils.pdf