Comprehensive Operating Manual & Guide to Metal Detecting
Comprehensive Operating Manual & Guide to Metal Detecting
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F75
F75
Discrimination Mode (continued)
4:
FOUR DIFFERENT AUDIO TONES This selection is similar to
3,
but with a fourth medium-
high tone for targets in the numeric range of 53 to 65. This four-tone system is useful for
searching in areas where there may be very old coins which register in this range.
dP:
DELTA PITCH This setting produces a tone whose pitch varies in relation to the visual ID
number -- the higher the ID, the higher the pitch. Good for relic hunting. This setting is
also useful in areas with a high concentration of steel bottle caps. Coins will produce a
fairly constant pitch as you sweep back and forth. Bottle caps produce inconsistent
tones, often with a
squawk
at the beginning of the sound.
Process Number (Process #)
This menu selection offers the user a choice among several different methods of audio
discrimination to accommodate a variety of search conditions and personal preferences.
These methods differ in the way the signals are processed for analysis.
The Process Number selections are:
dE:
DEFAULT PROCESS
This is the best process to use for most conditions, and is thus the default.
JE:
JEWELRY PROCESS
Detector will be more sensitive to small and low-conductivity metals like jewelry, but will
run noisier in trashy areas.
bc:
BOTTLE CAP MODE
Response is modified so that steel bottle caps will usually produce inconsistent, or non-
repeatable, tones and broken sounds. There may be a slight reduction in the ability to
separate adjacent targets. Use this process in areas with a high concentration of steel
bottle caps. Also refer to the Capabilities & Limitations section for sweep techniques to
aid in the identification of steel bottle caps
PF:
for use in plowed fields.
Some users may prefer this process for hunting in irregular ground, especially plowed
fields.
WHAT YOU SEE VS. WHAT YOU HEAR
The visual target ID displayed on the LCD is based entirely on sampled processing; the
number displayed represents a
snapshot
of the target’s identification as the searchcoil passes
over the object. When using these different processes, or methods, the detector’s audible
response may differ from the visual. When using the different processes, there is not a 100%
correspondence between what you see and what you hear, especially on buried targets where
ground minerals influence target ID and audible response. By making the audio and visual
systems independent, the
F75
allows each system to do what it does best. The audio is
optimized for quick response and target feel, whereas the visual system provides the best
numeric resolution of target ID.
PinPoint Feature
After a buried target has been located using the All Metal or Discrimination modes, you want
to pinpoint the exact location of the target in order to facilitate its recovery. Accurate target
pinpointing will minimize digging.
Activate the PinPoint feature by pulling the trigger switch located under the housing. Unlike
the motion All Metal and Discrimination modes, PinPoint does not require motion to detect
metal. PinPoint will detect objects while the coil is in motion and will continue to detect metal
if searchcoil motion stops over the target.
Ground Pick-Up
If you have not performed the ground balancing procedure, the PinPoint feature usually
causes the ground to sound off. This means that while pulling the pinpoint trigger, the audio
tone will get louder as you lower the searchcoil to the ground; this is called
ground pick-up.
Since you want to hear the target, rather than the ground, we recommend first ground
balancing in order to eliminate ground pick-up. Alternatively, if you experience ground pick-up,
you may place the coil very close to the ground, off to the side of the target; then pull the
trigger, and raise the searchcoil slightly while passing it over the target.
How to Pinpoint
Position the searchcoil an inch or two (2.5-5cm) above the ground, and to the side of the
target. Then pull the trigger. Now move the searchcoil slowly across the target, and the sound
will indicate the target’s location. As you sweep from side to side, and hear no sound at the
ends of the sweep, the target is located in the middle of that zone, where the sound is loudest
and the audio pitch is highest. If the sound is loud over a wide area, the buried object is large.
Use the PinPoint feature to trace an outline of such large objects.
Narrow It Down
To further narrow the field of detection, position the searchcoil near the center of the
response pattern (but not at the exact center), release the trigger, and then pull it again.
Now you will only hear a response when the searchcoil is right over the top of the target.
Repeat this procedure to narrow the zone even further. Each time you repeat the
procedure, the field of detection will narrow further.
Buy a Pinpointer
When you kneel down to unearth the desired object, you may find it frustrating as the object
may appear exactly like the surrounding soil. You may hold the object in your hand, and find it
necessary to pass a handful of dirt over the searchcoil to see if it contains metal. An easier
way is to use a handheld pinpointer. It is a probe-like device which is poked into the ground,
making close up pinpointing a snap, reducing digging time, and minimizing the size of the
holes you will dig. Fisher Research Labs offers the
FPoint™
pinpointer, a robust and
inexpensive device designed for this purpose.
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