White’s Electronics Goldmaster GMT - Manual (Page 20)

18
Chapter 4 GMT Searching
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 disturbs 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(page16) over the loud-
est 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 tuning
yourself to the search area. The GAIN, the
GROUND BALANCE, the VSAT speed, the
THRESHOLD, the IRON I.D., 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 G.E.B.
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
Field Use & Tuning Tips
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.
Manual GROUND BALANCE tuning for very
small nuggets (flakes of gold):
Instead of manual tuning for "perfect" GROUND
BALANCE (no sound increase or decrease when
"pumping the searchcoil up and down a few inches)
you might try using the minus(-) and plus(+) touch
pads to maintain a slight increase in the sound as
the search coil is moved toward the ground. This
will make the very tiniest nuggets (flakes of gold)
visible to the detector. Here, you are trying to keep
the GMT at its highest sensitivity to detect metal
which might result in living with more noise from
the ground mineralization. It takes experience to
know what good targets sound like and the more
noise you can put up with, the more sensitive you
can tune the GMT, the more gold you will find.
If small red “hot rocks” (positive mineralization)
create problems when searching this way then
return to "perfect" ground balance described above
Note, this method only applies to detecting with the
Manual Ground Balance Method (-) and (+) pads.
Checking the Ground Balance (by pumping the coil
up and down over the ground and listening for any
threshold change) is periodically necessary during
searching in the Manual Mode. Ground mineraliza-
tion changes from place to place and fine tuning the
Ground Balance is required for optimum perfor-
mance. After a while you will automatically pump
up and down a few times every so often as you
prospect, noting whether you are still maintaining
the slight increase in threshold as you pump the coil
toward the ground, making fine adjustments by
tapping the (-), or (+) buttons. In most areas, once
Chapter 5 GMT Searching