Got ahold of a 6" LF coil to try out on loan. (Thanx Past-Tom of the kinzli CA forum!). I used it in a demolition site of some mid 1950s apartment building tearouts last night. Got 7 wheaties, and a bunch of clad. In this particular site, since it was riddled with modern junk (the apartments were rather .... uh ... "blighted" ) I was using high disc. Was angling just to see how this little LF coil would do in a type of environment like under bleachers, where they're angling just for silver or whatever. Ie.: not in a "relic" mindset. Eg.: I had the disc. filters set so that I *just* lost square tabs. I had no problem getting a bunch of coins from amidst the tabs and foil. If they were masked by foil/tabs, then they would not give the higher tone correct TID's, but ... at least I would know a target above square tab was there.
All in all, it seemed to do no better than the 9" MF I was trying at the site the night before (but I realize there's a size difference, and also the 9" "went first". So the comparisons were "lacking", doh!
But what interested me most, is a series of air tests I've done now, with the 3 coils: 6" HF, 6" LF, and 9" MF. Starting with the HF vs LF: It is VERY clear to me now that the 6" HF *does* in fact see through iron the best. For example: If I covered a penny with a nail, the HF still squeeks through a compromise "average", to .... sort of "see through". It would only loose the hint of conductive if I added 2 nails or more. Contrast to the 6" LF, and there was utterly NO HINT WHATSOEVER that a conductor was hiding behind the nail. Hmmmm.
Then I tried the same tests with the see-through ability of trying to get penny/dimes behind foil and tabs (assuming a person was hunting where he elected to pass tabs, etc...). And in this test, the LF was the better choice over the HF. Whereas the HF could be made to disc. out tabs, no problem yet it was harder for it to detect a dime hiding behind a tab or two. Whereas the LF had an easier time of the test.
So it appears that if a person is hunting park turf (where, gasp, he's going to pass foil & tabs, and favor high conductors), he's better off with the LF coils. But if he's going to go into a ghost-townsy relicky nail-riddled site, he's better off with the HF coils.
The MF coil was about a half-half compromise between the two desires. A sort of "so-so" for each venue.
All in all, it seemed to do no better than the 9" MF I was trying at the site the night before (but I realize there's a size difference, and also the 9" "went first". So the comparisons were "lacking", doh!
But what interested me most, is a series of air tests I've done now, with the 3 coils: 6" HF, 6" LF, and 9" MF. Starting with the HF vs LF: It is VERY clear to me now that the 6" HF *does* in fact see through iron the best. For example: If I covered a penny with a nail, the HF still squeeks through a compromise "average", to .... sort of "see through". It would only loose the hint of conductive if I added 2 nails or more. Contrast to the 6" LF, and there was utterly NO HINT WHATSOEVER that a conductor was hiding behind the nail. Hmmmm.
Then I tried the same tests with the see-through ability of trying to get penny/dimes behind foil and tabs (assuming a person was hunting where he elected to pass tabs, etc...). And in this test, the LF was the better choice over the HF. Whereas the HF could be made to disc. out tabs, no problem yet it was harder for it to detect a dime hiding behind a tab or two. Whereas the LF had an easier time of the test.
So it appears that if a person is hunting park turf (where, gasp, he's going to pass foil & tabs, and favor high conductors), he's better off with the LF coils. But if he's going to go into a ghost-townsy relicky nail-riddled site, he's better off with the HF coils.
The MF coil was about a half-half compromise between the two desires. A sort of "so-so" for each venue.
