Chapter 5 GMT Searching
Field Use & Tuning Tips
Putting it all together:
Once you have achieved the initial ground bal-
ance, you are ready to start searching. Move the
coil just over the ground and listen for the distinct
zip-zip sound produced by a target. It is wise to
plant a nugget just under the soil to practice on
in order to learn to recognize what it will sound
like. If you don’t have a nugget, use a nickel or
piece of lead (sinker or bullet). A very shallow
bird shot sounds just like a tiny piece of gold. You
can practice with different sized nuggets and at
different depths. Remember, planting a target dis-
turbs the ground mineral, which usually reduces
the depth it would have been found in undisturbed
ground. It will take practice to determine the
proper search speed and technique. Do not go too
fast. Try to overlap your sweep path so that you
won’t miss the tiny and deeper nuggets. When
you hear a zip-zip, perform the “X” pinpoint
technique or use the non-motion pinpoint feature
(page 16) over the loudest portion and eyeball the
center.
Rather than concentrating on all of the controls of
the detector, think of the detector’s systems as an
extension of your senses that are working togeth-
er to tell you what is below ground. You will be
tuning yourself to the search area. The SENSI-
TIVITY, the GROUND BALANCE, the VSAT
speed, the THRESHOLD, the IRON CANCEL,
all working together at the same time. Soon the
detector will not even be noticed and your senses
will take over, painting a mental picture of what
lies below.
Dig ALL Metal Targets at first then Reject
Iron:
At first, dig all targets until you get used to the
sound of various items. As with other VLF detec-
tors, a nail or oblong piece of iron laying horizon-
tally will produce a double beep. A “good target”
is considered anything that is not IRON. You want
to detect lead, brass, copper, aluminum and silver.
18
Chapter 4 GMT Searching
Any of these metals can simulate the sound of a
gold nugget and must be dug. Keep a particular
lookout for the tiny lead bird-shot so common
in mining areas. If you are detecting these tiny
targets, you are doing everything right and will
eventually find gold.
Locked GROUND BALANCE tuning for very
small nuggets:
While the XGB automatic ground balance makes
nugget hunting easy for prospectors of all expe-
rience levels, a LOCKED ground balance can
greatly improve your odds of finding gold in
some situations.
The reason for this is simple - the smallest nug-
gets can produce only a slight threshold raise,
and often vary only a few phase degrees off of
the ground due to their tiny size. If small gold
is your gold, locking the ground tracking allows
those faint variances to push through the ground
balance point and create a target signal for the
GM24k.
However, in challenging ground conditions this
is not always an option. This is where using the
Ground Grab feature is useful, as you can man-
ually update the ground balance at any point as
you detect.
Another option is to run the GM24k in XGB
mode, and after hearing a faint target signal, im-
mediately locking the ground balance. Now you
can double check the target from different angles
without the XGB “tracking out” that target. This
provides the best of both worlds - automatic
tracking but the option to freeze it after acquiring
a signal.
If hot rocks are driving you crazy, you can also
ground balance directly over the hot rock, then
lock the tracking. If the rest of the ground matrix
does not give you a false signal after doing this,
you have successfully cancelled not only the
ground but also hot rocks!
Summary of Contents for GM24k
Page 32: ...QUICK START ...
