32 Garrett Metal Detectors
AT Pro International™ 33
balance values indicate conductive soil; high ground balance
values indicate ferrous soil.
Manual Ground Balance:
You may want to use the Manual
Ground Balance function to ground balance slightly positive
to enhance detection of small targets or balance slightly
negative to reduce detection of "hot rocks," terra cotta and
saltwater.
Press and release the GND BAL pushbutton and continually
bounce (pump) the searchcoil from 2 to 20 cm above the
ground. If low tones are produced, increase the Ground
Balance setting using the (+) NOTCH DISC pushbutton. If high
tones are produced, decrease the setting using the (-) NOTCH
DISC pushbutton. Press and release the (+) or (-) NOTCH DISC
pushbuttons to make single-step adjustments, or press and
hold to make large adjustments.
Continue bouncing the coil and making adjustments until a
minimum audio response is obtained, indicating the detector
is ground balanced. The Ground Balance setting will be
indicated on the LCD.
Press and release the GND BAL pushbutton again to exit
Manual Ground Balance mode. The Ground Balance setting
will be retained when the detector is switched OFF.
Typical Ground Balance Ranges:
80–99: Highly ferrous (magnetite, ferrous oxide minerals,
black sands, hot rocks, terra cotta)
60–80: Moderately mineralized soils (red clay, brown clay,
iron-bearing clay minerals, etc.)
20–60: Likely an iron object
0–20: Highly conductive, non-ferrous minerals such as
saltwater
FREQUENCY ADJUSTMENT
SENSITIVITY
Pushbutton
PINPOIINT/
Freq Adjust
Pushbutton
Use the PINPOINT/Freq Adj pushbutton in conjunction with
the (+) or (-) SENSITIVITY pushbuttons to adjust frequency.
The
AT Pro
is capable of operating at four slightly different
frequencies in order to minimize the interference caused by
electrical sources (e.g. power lines) or other metal detectors.
To adjust frequencies, hold down the PINPOINT button and
press the (+) or (-) SENSITIVITY pushbuttons to change the
frequency to find one with the least amount of interference.
The frequency setting (F1–F4) will be indicated on the LCD.
Release the PINPOINT button when finished.
Note: Frequency adjustments are small and therefore do
not affect target detection capabilities.
