44
45
The Coil/Rx control changes the sensitivity and
search pattern of the coil. This improves the
versatility and characteristics of the GP series and
Commander range Double-D coils. This is achieved
by altering the pattern of transmit (Tx) and receive
(Rx) fields of the coil, and how the control box
interprets the response. Each switch position
changes the electromagnetic field of the coil, thus
giving better performance in certain situations.
Coils not specifically designed by Minelab may
behave erratically, or be ineffective, in either the
Monoloop (M) or Cancel position.
Note: You will need to re-Ground Balance every time
you select a new position for the ‘Coil’ switch.
Double-D (DD)
This is the best option for areas of medium to
very high mineralisation. It is also excellent for
pinpointing, as the target response is strongest from
the centre of the coil.
The search pattern in Double D is the conventional
blade or wedge shaped signal through the centre
of the coil.
Monoloop (M)
This setting may be used in most locations of low to
medium mineralisation. Monoloop is also suitable
for locating small nuggets with Soil/Timings set to
Sensitive Extra in the LCD menu.
Using a DD coil, running in Monoloop will often
increase the sensitivity of the detector but may
also be a little more unstable in heavily mineralised
ground. Pinpointing
(pg. 84)
is not centred in the
middle of the coil, but to the left side, and may give
a complex signal when the target is very close to the
coil. It is recommended you use the left edge of the
coil to pinpoint shallow targets.
Cancel
This setting provides a receive field that is
particularly stable in areas of electrical interference.
This position is ideal for detecting close to suburbia
or where the Tune function has difficulty selecting
a quiet operational channel (e.g. near power
lines, phone towers or under poor atmospheric
conditions).
Pinpointing in Cancel will be to the left side of the
coil and signals may be complex if the target is
close to the coil. In Cancel, sensitivity and depth are
slightly reduced.
You may be able to increase Rx Gain (pg. 67) if
using Cancel.
Coil /
Rx
Cancel
Double D
M
Coil /
Rx
Cancel
Double D
M
Coil /
Rx
Cancel
Double D
M
Coil /
Rx
Cancel
Double D
M
Salty Environments:
In highly saturated salt
conditions, such as ocean
beaches or large inland salt
lakes, the use of Cancel may
give better performance
than Salt-Coarse. As a
general performance
comparison Cancel will be
more sensitive, but Salt-
Coarse has a greater depth
potential on larger targets.
The detector will not detect targets
if Cancel is used with a Monoloop coil.
Coil/Rx
Changing the Transmit and
Receive (Rx) Fields of the Coil
Transmit
Receive
Double D
Monoloop
Cancel
+
–
T
R
T
R
R
T
R
R
+
+
+
Tip: Minelab Monoloop
coils can be used on the
GPX-4500 with excellent
results. For maximum
stability we recommend
their use in conjunction
with the Coil/Rx switch in
Monoloop (M).
It is very important that you always switch off the
detector before changing coils.
This diagram is a plan view of the internal
coil windings, showing the different receive
characteristics of the three Coil/Rx switch options.
Summary of Contents for GPX-4500
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