Garrett AT Max Manual page 20

In order to fully search an area, overlap the swings of your searchcoil by half the
length of the coil (about 5.5 inches). Sweep the searchcoil in a straight line or with
a slight arc at a sweep speed of about 3 ft/sec.
• Isolating adjacent targets: The narrow detection field of
the AT Max's DD searchcoil allows better separation of adjacent
targets versus a similar size concentric searchcoil. Use narrow
swings of the searchcoil in trashy areas to isolate good targets
amongst the trash.
DD
Searchcoil
38 Garrett Metal Detectors
Concentric
Searchcoil
• Tips for saltwater use: Hunting in a saltwater environment
is challenging for any Continuous Wave (VLF) metal detector.
Saltwater is conductive and produces signals similar to foil and
fine jewelry. Although the AT Max is not specifically designed for
saltwater use, it can be used in this environment.
Proper ground balance is the most important step for stable
saltwater operation. To achieve stable operation:
• First, auto Ground Balance the detector to the area that will
be hunted (see pages 22–25). Saltwater beaches typically
Ground Balance between 0 and 20.
• If necessary, reduce Sensitivity until signals become stable.
• Swing the searchcoil flat and at a constant height. Do not
bounce the coil or lift the coil at end of swings.
• Swing the searchcoil parallel to the water's edge.
• The detector will be less stable in shallow, breaking surf
where the searchcoil is in and out of the saltwater. In
this area the detector is encountering a constantly changing
environment produced by the surf, making it difficult for the
detector to stabilize.
To improve stability, negatively bias the ground balance
by several points, if needed. To do so, simply press the SHIFT
button and use the (-) MAN. GND BAL button to manually
reduce the ground balance setting. For example, if the
Ground Balance number was 11, reduce the Ground Balance
number to 7 or 8. Introduce only enough negative bias to
achieve sufficiently stable operation. Reduce the detector's
Sensitivity as needed.
Note: While some background chatter may remain, the
more definitive response of a target can be recognized.
• If necessary, notch out the first pixel under Foil. It is
important to note that by notching out this pixel, detection
of some small jewelry items will be reduced.
39
AT Max
™