sef coils on excal

[Critterhunter]

If you do a search in the Etrac and Explorer forums you'll find that most of those guys thought the 12x10 was deeper and all around better than the 11" Pro Coil and the Explorer 10" coil. The one main complaint about the Pro Coil is it tends to cause guys to chase false signals more. Also, the 12x10 has got them coins on edge, masked, or deeper than the Pro Coil did. Not saying it ain't an awesome coil because it is. Huge improvement over the old 10" Explorer coils, but then again that coil was one of the worst I've ever used on any machine. Stunk at pinpointing and separation. I like the stock 10" Tornado on my GT much better in those respects.

In the "official" field tests of the 12x10 and 15x12 SEF coils they were found to both be deeper on coins than the stock Explorer 10" coil. The 15x12 was deeper on most coins than the 12x10. However, the 12x10 was a half inch deeper on a cut quarter penny (smaller than a half dime) than the 15x12. Regardless, both coils were a big improvement over the stock coil.

Now, as I'm sure just as sick reading it as I am re-hasing it...I think the difference in which of these two SEF coils is deeper than the other comes down to mineralization. Both will run more stable and at higher sensitivity settings than the stock coil over minerals or iron, but to me higher sensitivity doesn't translate into more depth in medium to high minerals. That's were I'm hoping the 12x10 will show improvement on land over the stock 10" coil yet not go past that point where the machine is seeing too much ground matrix and thus getting less depth (15x12). The 15x12 is a good 2 or 3" deeper in mineralized sand for me than the stock coil, that's why I can't figure out why it isn't also that way on land. The only thing I can figure is that the level or mixture of mineral content in my soil makes the 15x12 too big (even if it runs smoother at higher sensitivity levels), where as in the sand it must just be the right mixture of minerals (though high) were the 15x12 can show a depth advantage.

I was just hunting that same beach I've been talking about again today. Today the sand was wet from a rain but the stock 10" coil showed no improvement in performance. Still had to run in Auto to keep the threshold stable and the depth was still lousy at like 5 to 7" and still will broken or nulled responses from coins and such. The 15x12 was smooth as silk on this beach in manual, as good or better than the stock coil in Auto is. And the 15x12 gets excellent depth with much better responses at that beach. Not all my beaches are like this. It's just this one particular one that seems to give the 10" stock coil fits, though the 15x12 has gone deeper/done better at all the beaches even where the 10" coil has run real well. I'd say I'm getting another 2 or 3" depth in the sand with the stock coil than it does on land, but by the same token the 15x12 is going from about 9" max depth on coins on land to about 14 to 16" or so in the sand. It's an awesome coil. Just wish it showed me greater depths on land than the stock coil. Since land hunting for old coins is where I spend most of my time, I'm opting for the 12x10 in the hopes it will show greater depth on land than stock. Not to say the stock 10" coil isn't one of the best coils I've ever used and also has got me coins deeper on the GT than I've ever dug on land with any machine (including my Explorers). I'm just always looking for the edge so even if this coil gets me a half inch deeper it'll be worth it. By the same respect, even if it only matches the stock coil in depth on land I'll be happy, because based on my experience with the 15x12 I have no doubt the 12x10 has got much better sepearation like the 15x12 over the stock coil. The 15x12 is just draw dropping in how well it separates compared to smaller coils, so long as you know how to use it right (use the tip to try to separate targets where it's pure DD).

 

[synthnut]

I'm not sure WHAT to make of these SEF coils ....I know that they're good, and got the same results with the 12 x 15 coil in the sand .....How a larger coil can seperate better than a smaller coil is beyond me ....Then it runs more quiet than the smaller coil ....THIS doesn't figure either .....????.......My question has always been ....Is it becuase the SEF coils are more quiet, and can seperate better what makes the coil retrieve DEEPER targets because they are eaiser to hear ? .....or it do they have more power ? ...or both ? .... ......Jim

 

[Critterhunter]

Probably a combination of both...A quieter coil allows you to hear and take notice of any thing that does sound off and thus be more apt to take a chance on digging it. You know how it is, when a bad location causes a lot of falsing we tend to ignore that stuff and only dig real good solid signals. By not being bothered by these phantom targets we're probably more apt to investigate and dig what does sound off.

One of the reasons why I think these SEF coils run so much smoother is the way the coils are probably aligned to mirror each other more precisely. On a DD coil the TX and RX coils are mirror images of each other, hence the "D" shape to one side of the coil and a mirror/reversed image of a "D" on the other side. Detech probably is more picky about how tight the parameters these two windings must fall into. Coil shielding can also have a role in how smooth a coil is, as well as how well the windings are secured to prevent them from shifting due to things like temperature changes. Beyond all that I think the unique design of these coils makes them more stable. At the very least I think they are seeing less ground left/right width wise than conventional DD designs and this makes them more stable as well, along with providing very good separation. For whatever reasons it might be all I know is the 15x12 was so much smoother in iron or mineralized ground. It's performance at this one bad beach I hunt compared to the stock 10" coil is like night and day as well. Even if the 12x10 only matches the stock coil in depth I would still expect to find more deeper targets with the SEF due to it's more quiet and stable operation. Combine that with the ability of these coils to unmask coins better and hit on ones on edge as well and the 12x10 will be a winner to me even if it doesn't get me deeper. I can't wait to put this coil through it's paces. Also, just talked to somebody who has used the S-12 and 12x10 and this person said the 12x10 is more sensitive to small items like chains for them. I know the 15x12 was oustanding at hitting hard on earring backings and such for me, more so than the stock 10" coil.