Black Hawk FS Future, User Manual

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Field Procedure 29
The Black Hawk metal detector is actually a dual detector. Besides the pulse induction metal detector,
there is also a built in magnetometer which enables the unit to discriminate between ferrous and non-
ferrous metals. When a ferrous metal is detected there is a notification which will appear on the display
notifying you that the metal detected is ferrous. It will show up on the top left portion of the screen as
"FE".
The Black Hawk is fully automatic in terms of knowing which detector coil is attached. So whether it is
the small coil or the large coil the unit knows where to set many of the automated processes.
The process of detection is done by using an eddy current. An eddy current uses an electromagnetic
induction to create a reaction within metals. This reaction within the metals creates electrical
conductivity or an anomaly which actually disturbs the flow of the current. When this disturbance is
realized, the detector then reports the anomaly. The surface of the material being detected must be
accessible to the current. Various finishes and coverings may cause bad or weak readings.
An alternating current in the coil generates a changing magnetic field. The larger the coil, the larger the
field is. With a large field only larger items can be found. When using a smaller coil the field is also
smaller enabling the detection of smaller items. All of this is done by reporting the variations within the
magnetic field which is created by the coils. After an item is detected, allow for a recovery time or
enough time for the creation of another magnetic field.
6.1 Detection Depth
In theory, the larger the item is and the longer it has been in the ground, the deeper it can be detected.
With a pulse induction detector, there is a high voltage surge sent into the ground creating a large
magnetic field. Items with an electrical conductance will distort the magnetic field causing the detector
to react. The Delay function initializes the recurrence of the pulse. This in combination with the size of
the coil will affect the ultimate possible depth.
Varying soils and layers within the soil will also affect the ultimate depth of the detector. Using a pulse
induction metal detector enables you to search in soils with a higher magnetic permeability (highly
mineralized) or susceptibility than other soils. Although in such highly mineralized soils, determining if
an object is ferrous or non-ferrous becomes exponentially more difficult depending on the amount of
mineralization.
Air tests typically will be able to detect a metallic object twice the distance as the size of the coil.
6.2 Ground Balancing
The ground balance of the Black Hawk detector is mandatory for the proper operation of the unit. Half
of the balancing is done automatically, the other half by making a few simple adjustments:
1. Connect a fully charged battery to the Black Hawk unit.
2. Hold the unit 5 to 10 cm above the ground.
3. Turn on the unit and after 8 to 10 seconds the display will turn on.
4. Set the volume to the desired level or set to low and turn on the wireless headphones.
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