9
X. Click the MODE knob to the right.
The detector is now in the ALL-METAL Mode
a. Keep GAIN set at the 12:00 position
b. Rotate the THRESHOLD knob
slowly from the far counterclockwise
position to the full clockwise position.
Notice these attributes of the THRESHOLD control, with no metal
over the searchcoil.
i. at low settings you will hear no sound
ii. at mid-scale, there will be a transition point from no sound to
a barely audible, choppy sound.
iii. at full scale you will hear a loud, constant tone. It may also have
an irregular or choppy sound, as a result of electromagnetic
interference emitted from other electrical devices.
Use with headphones
(not included)
The Gold Bug DP is equipped with both a 1/8” and 1/4” headphone jack. Any
headphones with a stereo plug will work; headphones with a mono plug will not
work. Using headphones extends battery life, and also prevents the sounds from
bothering bystanders. It also allows you to hear subtle changes in the sound more
clearly, particularly if searching in a noisy location. Gold nuggets are often very
small, so closely monitoring changes in sound using headphones will improve your
gold prospecting results. For safety reasons, do not use headphones near traffic
or where other dangers, like rattlesnakes, are present. This device is to be used
with interconnecting cables/headphone cables shorter than three meters.
IX. Press-and-hold and hold the nickel over the searchcoil
a. Notice that motion is not required.
A motionless object induces a hum.
b. Notice the variable pitch & volume hum.
c. Move the nickel closer to and farther away from the searchcoil.
Notice the changing “depth” values.
28
HOT ROCKS
A hot rock is a rock which causes the metal detector to sound off because the
rock contains iron minerals. They come in two basic types.
Negative hot rocks (also called cold rocks) are usually magnetite or
contain magnetite, and give a negative response because their ground
balance value is a higher number than the soil they are found in. They
tend to be dark in color, usually black, and usually heavy. In some cases
they will have rust stains. They are usually attracted to a magnet, and for
this reason gold prospectors always carry a magnet -- the ultimate
ferrous/nonferrous discriminator. In All Metal mode, negative hot rocks
produce a
boing sound rather than the zip sound of a metallic target;
recognize the difference and you will learn to ignore them. As the
searchcoil passes over a hot rock, this
boing sound, or negative response,
is quite distinctive. To hear this response, you must be properly Ground
Balanced and in All-Metal mode with an audible threshold hum. First, as
the center of the searchcoil passes over the negative hot rock, the
detector will go quite; the threshold hum momentarily silences. Then,
passing beyond the negative hot rock, you hear the
boing sound. As you
pass the searchcoil back and forth over a negative hot rock, it will be
impossible to pinpoint and will seem as if it
moves around.
Positive hot rocks are iron-bearing rocks which have been oxidized by
natural weathering processes so that their GRND BAL value is a number
lower than the soil they are found in. They are often small, right on the
surface, sound just like a gold nugget, and are common in many gold
prospecting areas. They are usually, but not always, drawn to a magnet.
They are most often reddish in color but are often black, brown, or yellow.
On relic hunting sites, red clay bricks and rocks which have lined a fireplace
or a campfire will often be
hot rocks. The discriminator will usually eliminate
them without difficulty if widely scattered, but if there is a large concentration
of them, the discriminator may not quiet them all. In that case, you can
revert to the rule of thumb -- “don’t dig non-repeatable signals.”
Remember to always carry a magnet to help discriminate gold from hot rocks
and iron.
• Gold will not
be attracted to a magnet.
• Pieces of iron will always
be attracted to a magnet.
• Negative hot rocks will almost always
be attracted to a magnet.
• Positive hot rocks will usually
be attracted to a magnet.
QUICK-START DEMONSTRATION
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