Choosing The Right Coil For The Job - Minelab GPX-4000 Quick Start Manual

78 Choosing the Right
Coil for the Job
There are five main things Coil Size and Depth
that you should consider A larger coil will typically find targets buried deeper
when deciding which coil in the ground, but they can be less sensitive to
is best for your terrain and smaller targets. A smaller coil is typically more
target: sensitive to small targets, but does not go as deep as
a larger coil.
In some circumstances,
non Minelab Double-D and
Mineralisation
Monoloop coils will work
A Monoloop coil will often have improved
on the GPX-4000. However,
performance over a Double-D coil but can be more
there are limitations which
difficult to Ground Balance and therefore possibly
means that some functions
more noisy. A Double-D coil is often more stable in
will not work properly. heavily mineralised areas.
In some cases the use of
Terrain and Vegetation
coils not designed for the
A small coil can be easier to manoeuvre through
GPX-4000 may cause the
thick scrub or rough terrain. A smaller coil is also a
detector to be unstable and
lighter weight than a larger coil.
noisy.
Discrimination
In areas where discrimination is required, a Double-
D coil is needed for discrimination to work. In high
trash concentrations, a smaller coil is preferable.
Search Pattern
A Double-D coil will typically provide a 'blade-like'
detection pattern from the toe to the heel of the coil,
which gives excellent ground coverage. A Monoloop
coil has a detection field that is typically cone
shaped, which requires overlapping of sweeps to
ensure thorough ground coverage.
Small, Large, Deep Highly
Shallow Nugget Mineralised
Nugget
10" x 5"
Elliptical
Double-D
15" x 12"
Semi-Elliptical
Double-D
18" Round
Double-D
8" Round
Monoloop
11" Round
Monoloop
15" x 12"
Semi-Elliptical
Monoloop
18" Round
Monoloop
Less Open Heavy Iron
Mineralised Ground Scrub Disc.
79