Running The 15" Cc X Coil Over A 6000 Patch

[Norvic]

There you go, we all have different experiences, I put my 6K/11mono on top of the Z, with down to the 10" X coil plus against the older Xs, SDC etc on nuggets 0,5gram and under for depth, no I haven`t dug test holes, not into that, I`m talking actual gold that`s been there undisturbed in amongst grass/rocks. The type of ground where any coil bigger than 12" isn`t in the hunt unless fire has been through. I`ll add nothing has changed in this respect since year one GD (Gold Detector) every new detector has naturally been put under pressure by us users, some positively some negatively, tis our individual nature.

A judgement of ML gold detectors I`ve made based on my experience is I adopt almost every new ML gold tech detector as soon as I can get one. To date not once has ML not put extra weight in the pocket, detector wise I`m not talking coil wise. I feel no doubt experience and age influences this to some degree.

[phrunt]

5 minutes ago, Norvic said:

I feel no doubt experience and age influences this to some degree.

I agree wholeheartedly with that, a more experienced operator than myself is likely to do a lot better than I do regardless of equipment, JW proves this almost every time we detect ?

[Aureous]

6 hours ago, jasong said:

Were there ever any CC's made for GPX's that were around the same size as the 11" and 17" elliptical on the 6000 by any chance? Would be cool if someone had one sitting in their closet they wanted to sell.

PMC made a couple 12" CC coils with 8" receive windings. A mate trialed one and I watched on, plus gave some test gold to use. On my 4500 and his 5000, it blew away the stock mono and 2 NF advantage monos on small targets up to a gram in size. Maybe a 50% improvement by memory.The tech who designed them still has them apparently. When I get an adapter made up for my 6000, I'll try to obtain one. 

[Aureous]

6 hours ago, jasong said:

Also I'm curious: with a PI there will only be 2 windings on a concentric instead of 3 like with the GPZ. What are the reasons/advantages of putting the TX on the outside vs the RX on the outside?

For PI detectors, Transmit is best on the outer winding to saturate the ground with energy, the receive winding is best on the inner so as not to be saturated with too much remnant ground signal. 

[jasong]

9 minutes ago, Aureous said:

For PI detectors, Transmit is best on the outer winding to saturate the ground with energy, the receive winding is best on the inner so as not to be saturated with too much remnant ground signal. 

Thanks, kinda what I was wondering but unsure about without asking. That leads to what you probably already guessed my follow up question is then:

With the GPZ, would there be some even further performance gains to be had by stacking both 1 TX and 1 RX flat winding of the full coil diameter on the outside. Then 1 smaller inner RX winding inside those?

Idea being the TX saturates the entire ground under the coil, and thus the larger RX can still detect large deep nuggets just like a mono, but the smaller inner RX also allows added sensitivity and depth to the smaller, less deep nuggets. Best of both worlds? Or no free lunches?

Guessing the two RX windings need to be separated from the TX by some specific distance for capacitive or inductive coupling reasons, rather than stacked?

Edit: diagram for clarity

[Aureous]

5 hours ago, phrunt said:

No I didn't say that, I said they're not going to make GPX coils at this time not what the reason was,  It's nothing to do with the adapters and they've got their guy in Australia willing to make everyone's adapter there which is the biggest market for X-coils outside of their own region, it's no different to the GPZ situation except GPX coils are a lot cheaper. 

Yeah I get ya... their location brings a lot of problems with freight etc. Ya know, their whole business model could be destroyed in a single day if any of 3 or 4 coil techs here in Australia decided to make Zed coils. Only a small investment to get them made. No doubt they did the 'hard lifting' and started the whole concept and did all the R&D on several great designs but they are woefully overpriced for what they are. 

[Aureous]

10 minutes ago, jasong said:

Thanks, kinda what I was wondering but unsure about without asking. That leads to what you probably already guessed my follow up question is then:

With the GPZ, would there be some even further performance gains to be had by stacking both 1 TX and 1 RX flat winding of the full coil diameter on the outside. Then 1 smaller inner RX winding inside those?

Idea being the TX saturates the entire ground under the coil, and thus the larger RX can still detect large deep nuggets just like a mono, but the smaller inner RX also allows added sensitivity and depth to the smaller, less deep nuggets. Best of both worlds? Or no free lunches?

Guessing the two RX windings need to be separated from the TX by some specific distance for capacitive or inductive coupling reasons, rather than stacked?

Edit: diagram for clarity

Flat windings benefit Tx, not so much Rx. The Rx windings should remain bundled. If properly designed, the outer Tx can be used in mono mode as a pseudo-mono. The distance between windings is dependent on the size of the winding dimension. A general rule is to make the Rx coil 50-65% the size of the Tx. This allows the inductive coupling effect to be minimized. The PMC example used an overlaid bucking coil on top of the Tx, out of phase. The 8" Rx was its maximum without being over noisy. It should have been a little smaller ideally.

[jasong]

Anyone know if anyone published a good book on coil design for PI's by any chance? I used to have Carl Moreland's book that I read through entirely in 1 day when it first came out, but now I can't find it anywhere (I think it was stolen with my other books when my land/base was burglarized) and I can't remember if it went over coil design or not.

Also, anyone know the best way to make plastic coil...uh...cases? I don't even know the proper term. The plastic body of the coil. I saw an Adam Savage vid on vacuum forming, would it be done with something like that? I know zero about physical manufacturing processes.

Yet another edit: Ok - awesome. For a decade I've been saying that physically speaking, there is no reason we couldn't have discriminating PI's by making a hybrid PI/VLF, mostly getting ignored. in the process. I just went to look to buy another of Carl's books and saw that his co-author just published a book on exactly such a project. As well as another on building a detector with an Arduino, which is exactly what I told Whites I wanted to do in 2004 when I tried (unsuccessfully) to submit a resume there after I graduated from OSU right next door (well, not Arduino specifically but a Microchip branded MCU dev kit), then tried to get people on forums interested in and told there wasn't much purpose to it since analog was already sufficient and PI tech was near maxed out anyways.

Gonna give those two new books a read out of curiosity. Linking them in case anyone else is into that kind of stuff.

[Aureous]

Jasong, I think visiting Carl's forum (Geotech) would be your best bet. The term you're looking for is 'Coil shell' or coil housing perhaps. Couple good sites are here: Don Bowers site  and: MM Shells There used to be a good Bulgarian supplier but its not online anymore...