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22" GPZ X Coil Concentric Results


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On 3/20/2021 at 3:16 PM, jrbeatty said:

As the illustrations posted show, you have to be over the target to hear it (big surface junk excepted)

Ah yes, you did say you were going back over worked patches and that would have removed the shallow targets.  You would be left with deep, under the coil stuff which you also said you were getting.

Is there a required spacing between the outer coil and the inner coil like a wave length fraction or something like that?  That may be the reason why the inner coil can't be bigger ...

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22 hours ago, jrbeatty said:

No NE, I'm happy my settings got all that was available on the ground I have covered.

I have done exhaustive tests on the Maryborough and Laanecoorie test sites with Tony Honey (who has had long experience with GPX concentrics) as well as undug gold targets in situ, I'm satisfied there are no "holes" in the settings I am using.

James, the hole is there whether you like it or not, the Normal timings do not do well on a range of solid targets at depth (14 inches plus), so you cannot say you’ve covered off on that size if you have not gone back over the ground using Difficult. The same applies to the GPX 5000 and GPX 4500 using Normal over Enhance or Fine Gold. I would also advise American users to go back over deeper ground and use Difficult just to check off on the possibility of a missed decent sized nugget especially in the washes.

The 1/2 ounce nugget in the video was a good example of just such a target. (scene starts at 2:10 for those in a hurry 😆)

 

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42 minutes ago, Jonathan Porter said:

James, the hole is there whether you like it or not, the Normal timings do not do well on a range of solid targets at depth (14 inches plus), so you cannot say you’ve covered off on that size if you have not gone back over the ground using Difficult. The same applies to the GPX 5000 and GPX 4500 using Normal over Enhance or Fine Gold. I would also advise American users to go back over deeper ground and use Difficult just to check off on the possibility of a missed decent sized nugget especially in the washes.

The 1/2 ounce nugget in the video was a good example of just such a target. (scene starts at 2:10 for those in a hurry 😆)

 

Jonathan:

I'm not doubting that hole exists on "normal" setting with conventional  GPZ DOD coils, but, as stated, our exhaustive tests with the big 22" GPZ X Coil concentric failed to reveal it. 

I understand you have access to the 17" X Coil concentric. Have you also tested it for holes?

You may be in for a surprise  :)

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1 hour ago, jrbeatty said:

Jonathan:

I'm not doubting that hole exists on "normal" setting with conventional  GPZ DOD coils, but, as stated, our exhaustive tests with the big 22" GPZ X Coil concentric failed to reveal it. 

I understand you have access to the 17" X Coil concentric. Have you also tested it for holes?

You may be in for a surprise  🙂

Just so we are clear here I’m not disparaging the X coils, trying to make the correlation that somehow a different coil magically fixes a hole in a timing is like putting on a pair of sunglasses and saying the 18 wheeler bearing down on them has now gone away because they can no longer see it!!  A hole is a hole and no amount of magical coil voodoo is really going to change that!! The nature of the timing still exists because the coil has not changed the timing, the coil just does what the timing will allow and behaves the way the coil is wound.

Where the coil will have an effect is in the amount of ground noise signal it creates relative to the timings and the amount of saturation and salt signal it creates also relative to timings, all those signals will compete with target signals. The timings will do their best to deal with the Rx behaviour of the coil, but the timing will always hold sway because it’s the ultimate interpreter of the ground signal, its design and any holes or weak spots will hold sway and remain regardless of the coil attached.

In the case of the 17” CC X coil I have on hand the target signal that is available can sound louder over conventional DOD wound coils (similar to a Mono compared to a DD coil), technically this means more depth assuming the extra ground signal a more sensitive coil produces does not negate the target signal advantage. The 17” CC I have is showing it has been quite well designed because I can easily lift the sensitivity of the GPZ in variable ground so the designer has made the coil quite sensibly for variable ground, he obviously has a good understanding of the increase in ground signal a CC coil generates.

If a target falls into a hole in the timings and only procures a weak response using a conventional wound SuperD then obviously a more aggressive coil like the Spiral wound DODs or the new CC coils will help if the ground conditions do not negate the advantage, but this does not mean the CC coils have fixed the hole because they can’t so a target that is extremely faint for a CC coil will still observe the rule created by the timing, so there will still be gold missed by the CC coil in Normal compared to Difficult. You might hit some targets that were extremely faint using conventional coils which is the whole point of the coils in the fist place but there will now be a fresh set of new missed targets relative to the rule created by the timings.

I am very impressed with the 17” CC coil I have received, I was already impressed based on videos put up by Rick in WA so was not overly surprised when I tried it out for the first time. The Gain of the coil is set very well for Australian conditions but the Rx size side of things is quite tight so requires careful sweep methods on the deeper targets, this was also mentioned by Rick. X balance is very good and surprisingly saturation signals and even salt signals are minimal even slightly better than ML Super D’s, once aGAIN (pun intended 😂) pointing to the Gain of the coil.

JP

First session I used the CC17” in variable ground

573C2C9C-D641-405F-B84F-C2275C5E31B1.thumb.jpeg.55a46446c8e35357f1cf053027585069.jpeg

 

It pays to have a listen to this video as well as Steve and Chris and I discuss the differences with Steve going on to find a nice sized lump himself.

 

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Good to see you're now an x coil supporter JP.

Since over 70% of my deeper finds so far made in "normal" timings could not even be heard in "difficult" I'll just continue as I am, since detecting a large area twice has little appeal. 

Of course I am sometimes forced to use "difficult" by ground conditions but do so reluctantly in the full knowledge that I'm leaving gold behind. On Tertiary gravels (which are usually very quiet) "normal" timings give maximum depth on all targets and are my favourite and most productive haunts.

I stand by my test results which indicate CC coils leave little behind on these quiet soils on "normal" at depth. It's apparent we differ on this topic so it's pointless discussing it further.

Go the CC coils!

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1 minute ago, jrbeatty said:

Good to see you're now an x coil supporter JP.

Since over 70% of my deeper finds so far made in "normal" timings could not even be heard in "difficult" I'll just continue as I am, since detecting a large area twice has little appeal. 

Of course I am sometimes forced to use "difficult" by ground conditions but do so reluctantly in the full knowledge that I'm leaving gold behind. On Tertiary gravels (which are usually very quiet) "normal" timings give maximum depth on all targets and are my favourite and most productive haunts.

I stand by my test results which indicate CC coils leave little behind on these quiet soils on "normal" at depth. It's apparent we differ on this topic so it's pointless discussing it further.

Go the CC coils!

Tom-ate-oh, Tomato 🍅 I’m not saying do any specific thing just that the rules still apply irrespective of the magical swizzlestick you have at the end of your shaft! 😝 If you stick to one timing type, irrespective of how AMAZING the coil is, you will miss some gold. We all miss gold, and you will especially miss gold with a very tight Rx CC coil so overlapping your sweep is now the order of the day. Could be a little embarrassing if a heavy GPZ19 ‘dog’ wielding coil user pings a lumpskee in your boot prints!! 😆 

I’ve not changed my stance on X coils, if they ferrite balance properly and behave in most ground types then more power to them, if those promoting them stuck to being factual then all would be well in the world. 😊 

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Thanks AussieMatt for the picture, I was confused about what a concentric coil is also. 

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1 hour ago, MSC said:

Thanks AussieMatt for the picture, I was confused about what a concentric coil is also. 

No need to thank me. I plucked the pic from Detector Prospector after recalling I'd seen it before so thank Steve. 👍

The pic to me shows the difference in coils better than I could put into words.

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Here is a good video of a detectorist using a 15" Concentric X coil.  He finds 15 bits each day for about a 7 gram total.

 

Simon mentions JW in this video.  If you want to contact him send him a message Simon's on YouTube.

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Aye Simon is gaining his wings in style, on ya Phrunt. 

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