Garrett Metal Detectors Metal Detectors GTAx 550 - Manual (Page 28)

JUNK TARGETS
Your GTAx 550, in its factory set B (Coins) detection
mode, will not respond audibly to most junk items.
Occasionally, you'll encounter targets that cause
the detector to respond with a quick, sharp sound,
not like the clear, strong signal of a coin. Before you
dig up some of the targets that make irregular audio
"blips", see how they register on the Upper Scale
of the graphic display. Learn to recognize them.
Because your GTAx 550, in the factory preset Mode
B is set primarily to hunt coins, it will also precisely
identify small junk targets. Some larger objects
such as aluminum cans may, however, present a
"good" audio signal due to their composition. This
is normal.
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