The LF coil is designed for detecting higher conductivity targets such as copper and silver coins.
The HF coil is well suited for low-medium targets which is why the prospectors will like it on the X-70. Many of you that have tried the HF coil for coin hunting found how hot it was on TINY pieces of aluminum . . . . the HF coil on the X-70 does an amazing job on tiny targets such as sample nuggets and other items like ear ring backs.
I have used the LF coil at several sites with the X-70 over the past few weeks (actually have used the X-70 now for a few months) and found that it did detect coins deeper than the MF coil did; i.e., stronger, more consistent signal.
The X-30 only uses the MF, the X-50 only the MF and HF while the X-70 uses the LF, MF and HF coils.
As far as maximum depth, I am not one to claim to have found coins at 3 feet . . . . there have been some really deep coins on the forums but I have not found any - including with the X-70 - at 12"+.
The X-Terra's are single frequency machines and as such are affected by bad or rapidly changing ground conditions - the technology does reduce the affect but they are not multi-frequency detectors. The LF coil allowed me to hit some older wheats and a few silver coins at depths of 8"+.
Hope this answers your questions . . . . .
Andy Sabisch
