Comprehensive Operating Manual & Guide to Metal Detecting
Comprehensive Operating Manual & Guide to Metal Detecting
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F75
LIMITED
F75
LIMITED
Controls (continued)
The F75 has two controls on the front panel, MENU and SETTINGS.
MENU Pushbutton (Red button on right of the front panel)
Push the MENU button to:
1. Step through the menu selections on the display.
With each push of the button, the next menu selection will be highlighted.
The SETTINGS knob then allows you to change values for the highlighted selection.
2. Recall the last setting which you adjusted.
After you have adjusted a setting, an indicator will remain highlighted next to this menu
selection. One push of the button will recall that selection and display the stored value.
This recall function is useful for a value you want to adjust frequently, such as the
ground balance setting. In order to adjust a stored value with the SETTINGS knob, you
must first press the MENU button to reactive the user interface.
3. Press-and-Hold the MENU button to temporarily switch to the dE (default) process,
only when operating in the bP or CL process.
The dE process will only be engaged while the button is depressed.
Releasing the button will return you to the process you were operating in.
When using any processes other than bP or CL, pressing-and-holding the
button will have no effect.
SETTINGS Knob (On the left of the front panel)
Rotate the SETTINGS knob to:
1. Change the setting (or value) of the highlighted menu selection you have chosen.
2. Select the operating MODE when the top line of the menu is highlighted.
When used to switch back and forth between the DISCRIMINATION mode and ALL METAL
modes, the detector changes modes as soon as the corresponding selection is highlighted.
The All Metal modes are used to detect all metal objects, including small or deep objects.
Use the Discrimination mode to ignore trash metal such as nails, foil, or pull-tabs.
NOTE: When the menu selection highlight disappears, the SETTINGS knob is deactivated.
If settings values do not change when the SETTINGS knob is rotated, press the MENU button
to reactivate the user interface.
TRIGGER SWITCH (Under the display in front of your hand)
While the trigger is pulled back, metal objects are temporarily detected without the need for
searchcoil motion. This aids in pinpointing the exact location of objects which were found
while searching in the Discrimination or motion All Metal modes.
When in static all metals mode, pulling the trigger zeroes the audio threshold to the signal
level currently preset. If the searchoil is up in the air away from metal, this maneuver corrects
for threshold drift due to temperature changes.
When the trigger is pushed forward, FASTGRAB automatic ground balancing is activated. The
internal computer measures the magnetic properties of the soil in order to cancel interference
from naturally-occurring minerals in the ground. After the detector measures the soil in this
manner, the detector then uses this information to control operation in both the All Metal and
Discrimination search modes. FASTGRAB can be used at any time during operation.
Search Techniques (continued)
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 Motion 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.
Positive hot rocks are iron-bearing rocks which have been oxidized by natural weathering
processes so that their Ground Balance number 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”.
Using the sensitivity control
When the F75 is first turned on, the Sensitivity is at a medium setting appropriate for most
coinshooting. For relic hunting or gold prospecting, higher Sensitivity settings are usually
preferred.
In the event of detection of electrical interference from electrical power lines, electrical or
electronic appliances, or another metal detector, it is usually necessary to reduce the
Sensitivity setting to achieve quiet operation. Alternatively, use the Frequency Shift feature
described earlier in this manual.
If, while searching, you are constantly getting signals from which you cannot recover metal
targets, you may be detecting small or deep targets which are not recoverable using the
methods at hand. So, you may do better if you reduce the Sensitivity setting.
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