Comprehensive Operating Manual & Guide to Metal Detecting
Comprehensive Operating Manual & Guide to Metal Detecting
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F75
F75
3. Turn the SETTINGS KNOB to adjust the setting.
The goal is to eliminate the sound as the coil is being pumped over the ground. In
some soils, the sound is not completely eliminated.
If the ground balance adjustment is incorrect, there will be a difference in the sound as the
searchcoil is either moving toward or away from the ground. It sounds like you are either
pulling the sound out of the ground,
or
pushing the sound into the ground.
• If the sound is louder as you raise the searchcoil, increase the ground balance setting.
• If the sound is louder as you lower the searchcoil, reduce the ground balance setting.
NOTE: Experienced users often prefer to adjust the ground balance to get a weak but audible
response when lowering the searchcoil. This is called
adjusting for positive response.
Positive and Negative Response
The purpose of ground balancing is to adjust the metal detector to ignore ground minerals. If
the setting is incorrect, ground minerals will give either a
positive
or a
negative
response,
depending on which direction the adjustment is off.
POSITIVE RESPONSE
If the G.B. setting is too high a number, the response of minerals will be
positive
. This means
that when the searchcoil is lowered to the ground in PinPoint, Stat, or Motion All Metals mode,
the sound will get louder as the searchcoil approaches the ground. The sound will grow
quieter as the searchcoil is raised. What, if anything, you will hear in discrimination mode
depends on the discrimination setting.
When searching in an All Metals mode, if ground balance is properly set to cancel the ground,
and you sweep over a
positive hot rock,
the rock will give a “zip” sound similar to that of a
metal object.
NEGATIVE RESPONSE
If the G.B. setting is too low a number, the response of minerals will be
negative.
When the
searchcoil is lowered to the ground in PinPoint, Stat, or Motion All Metals mode, the machine
will be silent. The machine will sound off as the searchcoil is lifted away from the ground.
What, if anything, you hear in discrimination mode depends on the discrimination setting.
When searching in Motion All Metals mode, a
negative hot rock
will produce a “boing” sound
after passing over it, making it difficult to know where it is located. It will not have the sound
and “feel” of a metal object.
Ground Balancing (continued)
GROUND BALANCING
To achieve maximum depth in any detection mode, as well as when using the PinPoint
feature, the
F75
offers the ability to cancel out ground minerals either by manual adjustment,
or automatically using the FASTGRAB feature.
If you do not perform the ground balancing operation, the Discrimination mode will usually still
work fairly well, but the ALL METAL modes will not. The Pinpoint feature can be used for
pinpointing objects at moderate depth in most soils without prior ground-balancing.
The internal computer will not cancel salt water, so when detecting on wet ocean beaches,
ground balancing must be done manually.
DISCRIMINATION
Discrimination refers to a metal detector's ability to ignore metal objects in selected categories,
especially iron and aluminum. This makes searching much more pleasant in an area with a lot
of metal trash. The
F75
offers a wide variety of discrimination features which you can select
according to the search conditions and your personal preference.
DEPTH READING
The estimated Depth Reading displayed when pulling the PinPoint toggle is based on the
strength of the signal. It is calibrated to coin-sized objects. Smaller objects will read deeper
than they actually are, and large objects will read shallower than they actually are.
AIR TESTING
There may be times when you want to test or demonstrate the metal detector without sweeping it over
the ground, for instance, if not fully assembled, or if you are indoors. To air test, place the searchcoil in
a spot where the detector is stable and more than two feet away from any large masses of metal,
including the reinforcing steel usually present in concrete. If you are wearing a wristwatch or jewelry
on your hand or arm, remove it. Then, test or demonstrate by waving metal objects over the
searchcoil; wave objects briskly, several inches over the top of, and parallel to, the searchcoil.
Ground balancing cannot be tested or demonstrated in air unless you happen to have
appropriate specimens of iron minerals available.
SWEEP SPEED
The
F75
is noted for its quick response. This gives it unsurpassed ability to locate and identify
good targets surrounded by trash. It also permits the user to sweep the searchcoil quickly in
order to cover more ground with very little risk of losing targets. In general, if you are
searching an area where the desirable targets are more than 8 to 10 inches deep, a faster
sweep speed will detect to a greater depth and yield more accurate target IDs.
CHECKING A TARGET
In order to most accurately verify a detected target with most other metal detectors, users will
narrow their sweep and loiter over the top of the target. The
F75
is different. The
F75'
s quick
response and advanced signal sampling system produces the most accurate target IDs with
deliberate (shoulder width) sweeps all the way across the target, even if there are other
targets nearby. If you check targets using sweep techniques learned on some other detectors,
you run the risk of getting less accurate target IDs. You can use the confidence level indicator
to improve your technique.
Capabilities And Limitations (continued)
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