Field Use & Tuning Tips
Adjusting SENSITIVITY with XGB:
If while searching with XGB you experience erratic behavior such as false signals or
constant beeping and popping, you may be using a SENSITIVITY level which is too high
for the ground mineralization. This is often the easiest thing you can do to increase
your ability to hear gold in bad ground. Simply tap the down button to lower the sensi-
tivity on your machine. Try searching again. Continue this until you can hunt without
having erratic signals. Your detector is cancelling ground mineral as you sweep, so you
may notice a slight fluctuation in the threshold hum as the various ground minerals are
tracked out.
Even though it may seem counter-intuitive, adjusting the sensitivity down in tough
ground conditions can actually increase your chances of finding a nugget. This is due to
the fact that your ears are an extension of the metal detector. Hearing one faint signal
against a smooth threshold is much easier than hearing a medium signal against hun-
dreds of smaller ones.
Even though the GMX comes with advanced features like SAT, Iron Cancel, and XGB,
don’t overlook the first step you should take on any outing - finding the right sensitivity
level for the ground your are walking over.
Positive Hot Rocks:
Positive hot rocks are usually red or various shades of red to almost black. They sit
above your current ground balance point. They are sometimes as small as BB’s and
sound just like nuggets. These positive “hot rocks” are difficult to tune out and ring up
very low on your Target I.D. scale. They actually give a positive signal like metal and that
is why they are so hard to differentiate. The XGB will track some of these out automat-
ically. Using a higher SAT setting can also decrease your GMX’s response to these
positive hot rocks. Using a Double D coil on the GMX will allow the detector to operate
amongst hot rocks better than a concentric. And as a last resort, the Iron Cancel fea-
ture should all but silence any remaining hot rocks.
Wet alkali washes can be extremely difficult to work due to the sensitivity of high
frequency gold detectors to conductive dis-solved salts and their similarities with the
responses of small gold. But you can use the same techniques for alkali as you use for
positive hot rocks.
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