Minelab GPX-4500 Instruction Manual page 25

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