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18 Garrett Metal Detectors
GM24k Searching
Field Use and Tuning Tips
Putting it all together:
Once you have achieved the initial ground balance,
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 prop-
er 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 together
to tell you what is below ground. You will be tun-
ing yourself to the search area. The SENSITIVITY,
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
detectors, a nail or oblong piece of iron laying
horizontally 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. Any of these metals can simulate the sound
of a gold nugget and must be dug. Keep a particu-
lar 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
experience levels, a LOCKED ground balance can
greatly improve your odds of finding gold in some
situations.
The reason for this is simple—the smallest nuggets
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 manu-
ally 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, immediately
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!