Posted by lytle78 on 3/21/2008, 3:06 am
85.154.19.195
I've read posts and articles about using PI detectors for deep relics and coins. Steve Hershbach's article (http://www.akmining.com/mine/coins_garrett_infinium.htm) is probably the best example. With the new white's machine and possibly others in the offing, I expect that there will be a lot more activity along these lines.
The main limitations which have been discussed are the lack of sensitivity to higher conductive targets and lack of reliable discrimination at depth. These issues seem to be on the verge of being solved.
I am wondering however if there isn't another factor which may make discriminating PI detectors "the next big thing". I recently read T. Dankowski's article "Beneath the Mask" (http://www.dankowskidetectors.com/behindthemask.htm)where he details experiments in which he dug all targets on a ball diamond which could be detected by a couple of different VLF motion detectors in the all metal mode and then found an additional 1151 targets including 39 coins with a Minelab SD2200. There are apparently some who doubt the existence this effect - iron not only "masking" a good target, but causing the VLF detector to ignore both targets - but it does make you wonder.
I have likewise read praise for various detectors which can "see through" iron nails, etc and detect good targets. Especially noted in this context are Compass and other older detectors operating at 100kz. These however apparently don't detect beyond 4" or so.
Is it possible that the shift to VLF motion detectors and the resulting "working out" of popular parks, beaches, playgrounds, schools, etc. left behind very substantial numbers of “orphan” silver coins masked by iron - and masked in such a way that even "beep - dig" techniques didn't detect them??
If so, the development of discriminating PI detectors may start a "silver rush" not unlike what happened in the Australian goldfields with the introduction of the Minelab PI's.
Or perhaps I just read too many metal detecting forums!
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