Two things that can help eliminate deeply buried nails when using the 3 kHz coil.................
One, after locating the target, slowly X back and forth over the target while at the same time slightly working the coil away from the target. When using zero discrimination and multiple tone mode, as the target leaves the field of detection, you will hear that deeply buried iron will provide a harmonic blending of tones instead of locking in on the high tone represented by the number 46. Reason being is that audio responses will "reset" more quickly than visual TID. So even if the number locks on (46 in your example), the audio tone will generally fluctuate between two or more tones on deeply buried iron. Although all three frequencies of coils will do this to a certain degree, the 3 kHz will provide more distinctive "harmonic tones" because it is more sensitive to to higher conductive targets (therefore less sensitive to lower conductive targets) than the other two freqs.
Two, after locating a target in C/T mode, switch your 70 or 705 over to Prospecting mode with minimal Iron Mask. With this setting, the Prospecting mode is a true "all metal" mode and will allow you to determine the size and shape of the target. Nails are typically flat in the ground. As such, you can tell by the Prospecting mode that the target signal will be "longer" when sweeping one direction compared to a perpendicular sweep. On the 705, Pinpoint Sizing allows us to better identify the size and shape of a target, without using Prospecting mode. But in my case, old habits die hard! JMHO HH Randy
