12 inch super coil question

[airborne]

Is the 12 inch coil used to just go deeper and to cover more area faster?? Thomas

 

[Monte]

Is the 12 inch coil used to just go deeper and to cover more area faster?? Thomas

You are basically correct. The 12" coil can add a little better depth on moderate-to-larger size targets. Very little advantage in coin-depth on small coin-sized targets, especially the smaller coins.

You can cover more ground per sweep for shallower targets, but not on deep targets. The deepest targets that produce a small audio response due to their small size and just being able to disrupt the effective portion of the electromagnetic field at the farthest point from the center of the coil's axis means that to get the best depth and find it all, you still have to overlap the same. That is, you have to advance the coil no more than the short distance required to lose the responsiveness to the small target.

As for faster, you usually can't sweep the larger, heavier coil faster than a smaller coil, and you wouldn't want to, either, because you lose control of coil presentation, and with the larger coil seeing more ground you can create a problem trying to process (filter) all the ground signal with a slow-sweep detector.

So, the benefit of the 12" coil is that in a large, open area, such as a beach, plowed field, sports field or similar site, you can cover more ground per sweep for surface to mid-depth targets and, possibly, get slightly better depth on smaller objects.

For relic hunters and cache hunters it will provide improved depth on larger-size targets. I've used in and in good ground I got maybe an inch better depth on some coins compared with the stock 950. But most of the ground I search is of higher mineralization and there is a trade-off in performance. I find the new 10" DD coil, or the 10X12 SEF aftermarket coil, to get better ground handling performance over the 12" concentric coil

Monte

 

[Tom_in_CA]

And to expand on what Monte says: Don't get lost on the "more depth and more coverage" truth. Each of those has inherent drawbacks too: More masking and fishier operation. Sometimes when switching to larger coils, you have to drop down your sens. a little to compensate for the fishiness, (loss of threshold, etc...). Perhaps this is because the coil is now "seeing" more mineralization than a smaller coil "sees" in each pass?