Coil size and depth

[Icewing]

Ok as for my machine, it's a Minelab X-terra 705. I have the 18.75kHz 10x5 Gold Pack coil as well as a 7.5kHz 9.5x5.5 CORS Fortune (same as NEL Sharpshooter) that I purchased for my X-terra 305 before upgrading to the 705. Both are virtually the same as far as depth is concerned because they are virtually the same size, and both are pretty good for hunting well manicured yards.

However the more I hunt the less yards I have to hunt, and the more I find myself hunting either in cow pastures, out in the woods. If you've ever hunted either you know how thick the leaves and junk can be in the woods and how hard it can be to keep your coil near the ground when the grass is thick in the fields.

I've saved my clad and now I have enough to buy a new coil, even if I think they are ridiculously overpriced. The coil I have been looking at is the 14.5x10.5" CORS Cannon because they claim to get 35% more depth. Of course everyone claims their this or that gets 35-40% more depth, but that's marketing 101. This brings me to my question.

In the real world I know a bigger coil will provide more groumd coverage, but do the bigger coils actually help with depth, especially in those situations like I mentioned above? Or should I just keep saving my money for a whole new machine, like one of those that feels like it has a powerwheels battery hanging off the back?

I have three kids so I freely admit to being a frugal tight wad who squeaks when I walk, but that's because I have to be. I don't like wasting money on hype, or just a little bit. If it's not worth the investment I'd like to know. So lay it on me T-Net, is a bigger coil truely worth dropping another $220 for the single frequency to as much as $330 for the three frequency. Those being the lowest prices I could find.

 

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[cactusman]

The gains of large coils (say above 10 inches or so) are marginal on coin-sized objects. In highly mineralized soil larger coils frequently get less depth. The real gains to be had with large coils are in cache hunting, where the target is bigger. Your best bet for getting deeper coins is using the all-metal mode.

 

[Icewing]

The gains of large coils (say above 10 inches or so) are marginal on coin-sized objects. In highly mineralized soil larger coils frequently get less depth. The real gains to be had with large coils are in cache hunting, where the target is bigger. Your best bet for getting deeper coins is using the all-metal mode.

I already run in all metal mode quite a bit, especially in places that I know had civil war activity because that's the only way to find exploded cannonball fragments. In fact I found a couple nice chunks of 12 pound case shot not long ago, but the hay was freshly cut and baled.

Thanks for your input, I'll put it in the 'Don't Waste My Money on a Coil' category.

 

[G.A.P.metal]

I have not hunted in a yard in a very long time ...i hunt the woods and fields ...but not just any.
Try getting some old maps ,then meet the farmer...get permission ... hunt in close proximity to where older house/cabin/picnicking spot/crossroads... once stood.Look for broken fire brick,pottery,the iron patch,little pieces of very thin window glass.

Gary

 

[Icewing]

I have not hunted in a yard in a very long time ...i hunt the woods and fields ...but not just any.
Try getting some old maps ,then meet the farmer...get permission ... hunt in close proximity to where older house/cabin/picnicking spot/crossroads... once stood.Look for broken fire brick,pottery,the iron patch,little pieces of very thin window glass.

Gary

You seem to have misunderstood my question.
I'm not asking where to hunt.
I'm asking if bigger coils actually achieve greater depths as advertised, or if they are just a gimmick?

 

[RW]

You seem to have misunderstood my question.
I'm not asking where to hunt.
I'm asking if bigger coils actually achieve greater depths as advertised, or if they are just a gimmick?

Yes in optimum, probably even most, conditions larger coils achieve greater depth at the slight expense of sensitivity. OTOH I have had some small coils that were so stable you could crank the bejesus out of the sensitivity and achieve astounding depth for the size.

 

[Terry Soloman]

It depends. A 15" Concentric coil in moderate ground will give you up to 17" on a Large Cent - depending on your machine. Large DD coils can also give decent depth, if used with lower frequency machines. Frequency has as much - or more - to do with depth as the proper gain setting. If you have been in the hobby for 10-years or more, the realization that 95% of all good targets are 10" or less deep hits you at some point. Study target responses to different operating freqs, and know your soil types. Farm fields can be tricky because of fertilization minerals. For having to run 4" off the ground in the woods, use a large CONCENTRIC coil

 

[cudamark]

As mentioned, it will depend on your particular hunting area. All things being equal and with relatively mild ground, the larger coil will get a bit more depth. I find it's main benefit is ground coverage. You can hunt a much larger area in a given period of time, which should translate into more targets per hunt. Large coils can be more effected by EMI, ground mineralization, and tend be a little less sensitive to tiny targets, but, sometimes that's a good thing! Trashy areas are another thing where using a big coil might not be the best choice. Having multiple targets under your coil at the same time can be frustrating and time consuming. I use a 15" coil for large fields and at the beach. At other areas, I use something smaller.

 

[Icewing]

Well it seems the consensus is the a big coil isn't going to help enough to justify its cost, so I think I'll just hold off and keep saving my clad.

Thanks everyone!

 

[rick67]

Wise move

 

[Loco-Digger]

Well it seems the consensus is the a big coil isn't going to help enough to justify its cost, so I think I'll just hold off and keep saving my clad.

Thanks everyone!

Back in 2014 when I started, my 1st detector had an 8" concentric and I wanted more depth so I upgraded to a used F4 with the stock DD and got more depth. I still thought I needed to go deeper so after upgrading to the F75LTD (with boost) I asked the wife for a 12" x 15" nel butterfly coil for my birthday. Man it added some weight to the detector. Truth be known that it has not found me any coins deeper than the stock DD. Of course most of my hunting is in yard, parks, schools and other public lands. It did help me cover more ground quicker with less sweeps of the coil, but over time I have evolved to appreciate smaller coils since they get better target separation. You see even though I hunt permissions I find that most of these sites have been hit over the decades (at least cherry picked) since people have been detecting since the 1970's in my area. Getting better separation has allowed me to concentrate in the trashier areas and to eke out some old coins missed by those who have previously hunted the site. My large coil has been relegated to field hunting in harvested soybean and in cur wheat/hay fields. I do use a make-shift harness since it is hard to swing for more than an hour or two without a harness due to the additional weight. I now switch between the stock DD, the nel sharpshooter and the 5" DD with the sharpshooter being my main coil.

 

[beep1971]

I'd disagree, all my hunting here in the UK is on large fields for small coins.
Over the years i've tried many detector/coil combos and it's a minefield.

Think about the targets your likely to be hunting for, their size and conductivity and the ground minerals greatly influence the freq you need to choose.
Some years ago i had a 705 with a WOT 15" coil, it was very good on big coins, though i now limit my coil size to 13", i find any bigger has little advantage, and a round coil will be easier to push through the grass than an elliptical !

My fields, being mostly heavily fertilized with animal poo, are high mineralised, but with correct freq/coil size i can hit 9"-10"deep hammered silver coins (dime size but paper thin, low to mid conductors) and larger silver and copper coins the size of quarters at 12"+, in comparison to my etrac with stock coil that's a good 3"+ deeper.

If you can get your hands on a 2nd hand multi freq coil for the right money, dive on it !

Well it seems the consensus is the a big coil isn't going to help enough to justify its cost, so I think I'll just hold off and keep saving my clad.

Thanks everyone!