I took my recently arrived machine into the backyard and started digging some of the trash signals we have out back. Seems that the depth readings on this machine are off. Nails were reading at 5", but when I dug them up they were only about 3". I don't have any coins in the back yard, but foil targets and other stuff is reading the same 2" off. I know its calibrated on coin size targets, but none of my other machines is this far off on iron targets unless their real small or real big. Is the F75 calibrated to the 11" coil it comes with? I got an F75 a couple of weeks ago for my wife to use and the depth reading on that seems real close and not as far off as this F75.