Comprehensive Operating Manual & Guide to Metal Detecting
Comprehensive Operating Manual & Guide to Metal Detecting
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F75
F75
Discrimination Mode
The Discrimination Mode is used to eliminate trash metal objects from detection, e.g. nails,
aluminum foil, or pull-tabs. The searchcoil must be in motion for metal objects to be detected.
Discrimination incurs some loss of sensitivity to small or deep objects.
The
F75
discrimination system is much improved over conventional discrimination systems,
and may function quite differently than other discriminators you may be accustomed to. In
older systems, the apparent sensitivity decreases as discrimination level increases. The
F75’s
sensitivity may increase as discrimination increases, depending on the process number and
notches being used. Therefore,
do not use the discriminator to control sensitivity.
First set the
discrimination level and notches to establish objects to detect or eliminate; then adjust
sensitivity downward to eliminate interference, or upward to “work into the noise,” if preferred.
SENSITIVITY
This controls the
signal gain,
and is adjustable from 1 to 99. Unlike the All Metal modes, the
Discrimination mode is designed to operate silently. If you hear noise when there is no metal
present or when the searchcoil is not in motion, reduce the Sensitivity setting until the machine
goes quiet. NOTE: there is no interaction between the sensitivity settings of the All Metal
and Discrimination Modes.
The sensitivity system has two stages, 1-29 (low gain), and 30-99 (high gain). As you lower
sensitivity and cross the transition from 30 to 29, you may notice the background noise
increase.
You may need to adjust to a setting of 29 or less to silence electrical interference, or
to prevent overload on highly mineralized ground or in salt water. You may also notice a shift
in the ground balance setting over difficult ground conditions as you cross this transition.
DISCRIMINATION LEVEL
This is adjustable from 0 to 65, and controls the range of objects to be eliminated from
detection (discriminated out or rejected). Objects with numeric values below the selected
discrimination level will not be detected. NOTE: the numerical range that pertains to each
class of object is printed at the top of the visual display. To eliminate iron, a setting of 15 is
usually about right. A setting of 65 will eliminate aluminum trash and zinc pennies, but nickels
will also be lost, unless you notch-in nickels with the NOTCH feature.
To use DISC LEVEL
1. Highlight DISC LEVEL using the MENU button.
2. Rotate the SETTINGS knob.
As you rotate the knob, a number between 0 and 65 appears.
3. Press MENU when you reach the desired target discrimination value.
• If you do not press MENU, and let the display time-out, the last displayed value
will be stored as the discrimination value.
• All targets, up to and including the value selected, will be eliminated from
detection, unless notched-in.
5. A slash will appear over the target words being eliminated. Notice that two slashes
can appear over each word. The left slash represents the bottom half of the range; the
right slash represents the top half of the range. When you select a value within any
range, the slash will appear,
even though all values within that range might not be
eliminated from detection.
To recall the discrimination setting, press the MENU button
until you enter the DISC LEVEL feature.
LCD Visual Display (continued)
BATTERY CONDITION INDICATOR
Fresh alkaline batteries will illuminate all three bars. When no bars are displayed and the
batteries are about to go dead, the
BATT
legend will start flashing. The detector should operate
for an additional 30 minutes from the time the
BATT
legend starts flashing. If using NiMH
rechargeable batteries, the display will remain stuck on the second or third bar for most of the
battery life; when it drops to the first bar, the batteries will go dead within several minutes.
G.B.
This is the ground balance setting, 0-99. It is displayed when in the Manual G.B. menu
setting, or when the trigger is pushed for FASTGRAB computer-assisted ground balancing.
SETTING
This is illuminated when you are in the menu. When the word “SETTING” is indicated, the
number being displayed is a setting, and not, for instance, a Target ID indication.
MESSAGES
The small rectangular box at the bottom-center of the LCD displays advisory messages.
If a metal object or highly magnetic soil is so close to the searchcoil that the signal is
overloading the circuit, the message
OVERLOAD - RAISE COIL
will appear.
Such overloads will not harm the detector, but the detector will not detect metals properly
under these conditions. Raise the coil until the message disappears; the siren sound will also
stop. Resume normal detection.
The message
RAISE COIL
only appears when using the
bc
process, accessed through the
PROCESS # menu selection. This message indicates the presence of a target which may be
too close to the searchcoil to be accurately identified. For better target identification, sweep
the searchcoil farther away from the surface of the ground.
The message
PUMP COIL TO GB
will appear when you push the trigger forward to ground
balance. See the Ground Balance section of this manual for instructions.
The message
CAN’T GB
can only appear when the trigger is pushed forward, invoking
FASTGRAB automatic ground balancing. This message appears when the detector is unable
to measure the soil in a manner suitable for ground balancing. This message is usually the
result of the presence of metal. Try another spot to find an area free of metal.
BACK LIGHT
The LCD is back-lighted for use in low light and dark conditions.
The backlight is always illuminated, but the illumination is usually not evident in daylight.
You cannot turn the backlight off. The single high-efficiency light emitting diode providing the
illumination is a low current device, and has a negligible impact on battery life.
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