Treasure Hunting Forum

When I reached the chosen area I set the F75 up in “static all-metal” mode and set the sensitivity at “99” – the highest and most sensitive setting – and began scanning the hillside. Immediately I found that the ground balance needed attention; this was easily accomplished with the “fast grab” technique. Upon resuming the search, I noticed that the machine was ultra sensitive – even the small shovel, which I normally carry somewhere below waist-high, gave it fits. I considered lowering the sensitivity, but decided, for this trip, anyway, to continue as it was in order to determine if the machine could be depended upon to actually perform at its highest setting. And I found that it could. There was plenty of extraneous noise at that setting, but the targets came through loud and clear. I managed to hunt long enough with the detector to dig a railroad spike about 18 inches deep, along with various other iron junk, before the heat, weeds and mosquitoes became more than I could bear. So I left after only a very brief visit to the hillside.

This experience with the F75 convinced me that it was more sensitive than other metal detectors I had used. Back home I set about to prove it - by pitting the F75 against other detectors in an “air test.” In my backyard (really, a concrete alley) I placed a large plastic garbage can atop of which I placed for testing (one at a time) four different metal detectors. I chose for the test two objects: a six-pounder cannon ball, and a US clad quarter, and I measured distances at a point where the detectors gave a firm signal, not a mere blip. I set each of them to all-metal (or zero discrimination) and maximum sensitivity. Of course, these tests were not scientific, nor were they made under the controlled conditions necessary for absolute accuracy, and it may be that they cannot perform satisfactorily in the field at these maximum settings. But they do seem to indicate that the F75 is capable of more depth than the other detectors chosen for this air test:

                                                                                    Detection distance, inches

                                                                        Clad quarter                 6 pounder cannon ball

Fisher 1266 with 11” coil                                              11                                22

Nautilus DMC-IIB with 15” coil                                   12                                23

Troy Shadow X5 with 9” coil                                        11                                23

Fisher F75 with 11” elliptical coil                                   16                                34

So the Fisher F75 is an impressive all-metal machine. It remains to be seen, however, whether or not the machine can perform satisfactorily in all-metal mode at depth the way it does in air. If it does… I intend to dig some artillery shells in those “hunted out” hillsides.