Hey pmike, here is some minerals information provided from another member's question along the same line. HH....How.
Hi nocaljim: nc-joe has some good advice. To elaborate a little further, getting an accurate ground VDI reading requires the ground balance to be spot on, or the VDI reading will bounce all over the place. Other cause of bounce, even with a correct ground balance, is very high positive or negative mineralization (testing for ground balance, holding back the trigger or locking it forward to place in all metal mode, as the loop is lowered toward the ground, a perfectly balanced machine will not change in threshold loudness or pitch). A positive balance means the threshold will get real loud as the loop reaches an inch of the ground. Likewise, a negative balance means the threshold will go quiet as the loop reaches the ground, neither one being a good ground balance point. On the other hand, measuring the mineralization level of the ground is better done (rarely seen on most forums), by reading the ground's coarse GEB measurement, after a careful perfect ground balancing point is achieved. Furthermore, there is a lot of information in the GEB reading. For instance,CGEB 117 to 121 (really heavy Magnatite black sand) is extremely negative soil requring the adjusting of both the Fine GEB and Coarse GEB settings, and the ground balance test is so non linear that a good ground balance point is almost impossible to achieve. However, CGEB 122 to 127 (slightly gray, orange, red or pale soil) is pretty neutral ground and does not need such a precise ground balance point (unless a darker color from moisture, making the CGEB read much higher), which in these middle GEB readings, except at near the ends, almost any balance point will work nicely. But, at the high ,very positive end of CGEB, non linearity again rears its ugly head at about CGEB 128, and gets impossible to to get a usable operating balance when reading near 129,5 (white Caliche/alkali soil or red Heimitite soil) but could still be balanced out to near CGEB 133 (on very black sand Maghemite soil, the worst stuff imaginable). All this information is provided to expalin roundabout that if this area reads the same CGEB ground condition as the other place your were hunting, it should be huntable with no ground balancing or other adjustments necessary. I hope this might be of help in understanding some of the meanings of ground minerals and the importance of a good ground balance.All this is meant to show that an VDI reading on a coin is easy and fairly accurate, but can be a bear to get a repeatabler ground reading, whereas a GEB reading is made solely for reading the ground mineral conditions to aid in maintaining ground balance. Also see Larry-il comments below ..Best of hunting ot you in your area,....How
