Coil Choices For Maximum Depth

[phrunt]

Yep, no better way to find out than to do it, looks like I'll have an even bigger Concentric coil to run over it too, that'll make it even more interesting for depth.  I have two ML 19" coils so I'll run them both just to be safe.

[GB_Amateur]

I don't know about the availability of Carl's recent book in other parts of the world but this is covered in Chapter 7.  I hesitate to quote because to understand it you need to read more than just one sentence.  The summary is in section 7.16 (all of that on page 131) but to best understand the why it helps to read the full chapter.

Seriously most of us don't blink about spending $200 and up for an accessory coil.  A $50 book containing 500 pages on metal detectors seems like a bargain.  I digress, but that's the most valuable thing in this post.

OK, here's the quote:

...The size of the RX coil should be appropriate for the expected size of the target.  This is likely why some Tesoro concentric coils (intended for coin hunting) have smaller-than-usual RX coils.

 

 

[phrunt]

It's interesting if you look at the large Concentrics on the market, these are two for the earlier GPX Series.

The Nexus 30", this one has two cables from the windings that join together as one, interesting design.

They have a marketing video for the Nexus coil, I haven't watched it yet only than the first few minutes, seems to have good depth on the can he's holding up over it.

And the Detech 32", I was at one point going to get one of these big Detech coils for my GPX for the beach, never got around to it.

Then the 22" GPZ X-coil

It has the wider outside transmit winding as its spiral wound but the inner looks much bigger than the others in relation to the coil size, yet the others also appear very deep coils on bigger targets.

[Aureous]

1 hour ago, phrunt said:

It's interesting if you look at the large Concentrics on the market, these are two for the earlier GPX Series.

The Nexus 30", this one has two cables from the windings that join together as one, interesting design.

They have a marketing video for the Nexus coil, I haven't watched it yet only than the first few minutes, seems to have good depth on the can he's holding up over it.

And the Detech 32", I was at one point going to get one of these big Detech coils for my GPX for the beach, never got around to it.

Then the 22" GPZ X-coil

It has the wider outside transmit winding as its spiral wound but the inner looks much bigger than the others in relation to the coil size, yet the others also appear very deep coils on bigger targets.

Yes you will notice that the internal coil winding (receive) is significantly larger and closer to the outer (transmit) coil winding, just like the prototype I saw way back in 2013. The crucial part is that there is a gap in the shielding (the entire shell is not shielded internally, but only around the windings) and the shield specs on each winding are wildly different from each other.  The 'secret sauce' has vodka in it.... 😁

[Reg Wilson]

The Nexus coil above is discontinued and has been replaced by one that they claim is even better. The two cable system has been retained but the spoke design is quite different. Very expensive coils with the largest 42" concentric being about au$5,500. Mind you it only has to pull a 2oz colour to be in profit.

https://www.nexusdetectors.com/contact.html

[geof_junk]

34 minutes ago, Reg Wilson said:

The Nexus coil above is discontinued and has been replaced by one that they claim is even better. The two cable system has been retained but the spoke design is quite different. Very expensive coils with the largest 42" concentric being about au$5,500. Mind you it only has to pull a 2oz colour to be in profit.

https://www.nexusdetectors.com/contact.html

Even less Reg 1½ oz. would do the trick if you don't count the cost, of footwear $, getting it. 😉

[Reg Wilson]

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