7
18
ELECTROMAGNETIC INTERFERENCE
Use the Sensitivity Control is to eliminate
Electromagnetic Interference (EMI).
The F4 metal detector is an extremely sensitive
device; the searchcoil creates its own magnetic
field and acts like an antenna. If your detector
beeps erratically when the searchcoil is motionless,
the unit is probably detecting another
electromagnetic field.
Common sources of EMI are electric power lines, both suspended and buried,
motors, and household appliances like computers and microwave ovens. Some
indoor electronic devices, such as dimmer switches used on household lighting,
produce severe EMI and can cause the detector to beep erratically. Other metal
detectors also produce their own electromagnetic fields; so if detecting with a friend,
keep two metal detectors at least 20 feet apart.
If the detector beeps erratically,
REDUCE THE SENSITIVITY
by pressing the
Sensitivity
-
Pad on the left of the control panel.
In most urban environments, you should be able to search without chatter from
interference at the default sensitivity setting (default setting is the sensitivity level at
power-up, 4 bars), or at one level reduced from default. At maximum sensitivity, the
F4 will “chatter” in proximity to underground or overhead power lines, or to indoor or
outdoor electrical devices. In fact, if you notice rapid chatter with the searchcoil near
the ground, you may be able to trace the approximate location of the underground
power lines by following the chatter.
To manage chatter, which is most likely from electrical interference:
1. REDUCE the SENSITIVITY
until the chatter stops.
2.
Try sweeping it over the ground.
If the F4 chatters while held still, or held up in the air, it may be much quieter
when sweeping over the ground.
3.
Operate in AUTOTUNE Mode
Interference is much more tolerable in this mode, even at high sensitivity.
SEVERE GROUND CONDITIONS
A secondary use for the Sensitivity Control is to reduce false detection signals caused
by severe ground conditions. While the detector contains circuitry to eliminate the
signals caused by most naturally occurring ground minerals, 100% of all ground
conditions cannot be anticipated. Highly magnetic soils found in mountainous and
gold-prospecting locations can cause the detector to emit tones when metal objects
are not present. High saline content soils and sands can sometimes cause the
detector to beep when no metal target is present.
If the detector emits false, non-repeatable, signals, REDUCE THE SENSITIVITY.
SENSITIVITY ADJUSTMENT
VI. Wave the Nail over the Searchcoil
a. The Nail will not be detected.
b. The Nail has been "Discriminated Out."
VII. Press the “DISCRIMINATION
+”
touch pad 3 times.
Five “R”s are now displayed.
VIII. Wave all objects over the
Searchcoil
The Nail and Pull-Tab will not
be detected.
The other objects will be
detected with their own
distinctive tones.
IX. Press the NOTCH touch pad.
A flashing “s ” will appear under the IRON-1 segment.
X. Press the DISCRIMINATION
+
touch pad 3 times.
The flashing “s ” will move to
the 5¢ segment.
XI. Press the NOTCH touch pad
again
The “R” will disappear under 5¢
segment.
XII. Wave the nickel over the
searchcoil.
The nickel is detected.
XIII. Wave the penny over
the searchcoil.
XIV.Press the NOTCH touch pad
twice.
The arrow under the 1¢ segment will flash & then the “R” will illuminate.
XV. Wave the penny over the searchcoil again.
The penny (the most recently detected item) is eliminated from
detection.
XVI. Press the PINPOINT touch pad.
Hold one of the metal objects motionless over the searchcoil.
• All Metal objects are now detected.
•
One monotone sound indicates the presence of any type of metal.
•
A 2-digit numerical display indicates approximate target depth, in inches.
QUICK-START DEMONSTRATION
(continued)
F4manual-SPREADS(24pg).qx_MF4B-F4manual 4/2/15 12:29 PM Page 7
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