Fisher Labs CZ-21 QuickSilver Operating Manual page 26

TARGET IDENTIFICATION
5. The DISC control provides increments of rejection and
6. If you're getting a high-tone response for example,
7. The same is true of the mid-tone targets: Round pull
8. Your CZ-21 will correctly identify most of the targets on
9.
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coin.
identification within the mid- and high-tone target
classifications. Take a look at the target I.D. decal
on your control housing to see what gets rejected
at which DISC point.
you may well be over a U.S. coin. If you want to know
what kind of coin it is, advance the DISC control to
"5." You know from the I.D. decal that if you lose the
signal your target is probably a nickel (or something
conductive and very similar). If you don't lose it, go
up to "6." If you lose it at "6," your target may well be
a U.S. zinc penny. If you still get a signal, your target, if
it is indeed a coin, will probably be a copper penny,
an older silver coin or a clad coin. Most other small
targets will be ignored.
tabs are rejected at "2," foil at "3" and rectangular
tabs at "4." If, for example, you're looking for gold
rings in an extremely trashy area, you have the ability
to reject at least some of the trash (like iron, round
tabs and foil) and still get those rings falling into the
rectangular tab and all coin categories. Of course
you'll have to dig rectangular tabs as well.
your I.D. decal most of the time, but it can be fooled.
Large targets, uneven ground mineralization, good
targets lying next to bad targets, deep targets, all
of these and more are sources of error. Remember,
the CZ-21 is designed to I.D. small, coin-sized targets
only, and even some of these may be deep enough,
bent, damaged, or corroded enough to give a false
signal.
You should also realize that there are many good
targets which are not classified by the CZ-21, as
mentioned earlier. Gold rings, for example, may fall
into any category except iron. Many foreign coins,
especially the new ones, may I.D. as foil or pull tab.
Gold nuggets, depending on their size and shape,