Choosing The Right Coil For The Job - Minelab GPX-4500 Instruction Manual

Choosing the Right
92
Coil for the Job
There are five main things you should consider
when deciding which coil is best for your terrain
and target:
Coil Size and Depth
A larger coil will typically find targets buried deeper
Note: In some
in the ground but they can be less sensitive to
circumstances non Minelab
smaller targets. A smaller coil is typically more
Double-D and Monoloop
sensitive to small targets, but does not go as deep as
coils will work on the GPX-
a larger coil.
4500. However, there are
Mineralisation
limitations which mean
A Monoloop coil will often have improved
some functions will not
performance over a Double-D coil but can be more
work properly. In some
difficult to Ground Balance and therefore possibly
cases the use of coils not
more noisy. A Double-D coil is often more stable in
designed for the GPX-4500
heavily mineralised areas.
may cause the detector to
be unstable and noisy.
Terrain and Vegetation
A small coil can be easier to manoeuvre through
thick scrub or rough terrain. A smaller coil is also a
lighter weight than a larger coil.
Discrimination
In areas where discrimination is required a
Double-D coil is necessary for Iron Reject 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
– The shaded areas indicate each coils recommended uses.
– May operate well in Enhance or Sensitive Smooth timings.
Less Open Heavy Iron
Mineralised Ground Scrub Disc.
93