Minelab GP Extreme User manual

Minelab USA Inc
871 Grier Drive, Suite B1,
Las Vegas, Nevada, 89119
United States of America
Telephone: [phone]
Facsimile: [phone]
Email [email protected]

THE MINELAB ‘GP extreme’
I
Minelab‘GPextreme’
4901-0036 Version 0.1

4901-0036-Revision 1.2

THE MINELAB ‘GP extreme’
II
www.minelab.com
©Minelab Electronics Pty Ltd
Thisdocumentcontainsproprietaryinformationwhichisprotectedby
copyright. Apart from any use as permitted under the Copyright Act
1968, no part may be reproduced by any process without written
permission from Minelab Electronics Pty Ltd, 118 Hayward Avenue,
Torrensville, SA 5031, Australia.
WARNING. This document contains Minelab Electronics Pty Ltd
rights, technical data or restricted rights data, or both. Patents and
trademarksapply.
THE MINELAB ‘GP extreme’
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TABLE OF CONTENTS
INTRODUCTION ................................................................................................................... 1
Aboutthismanual ..................................................................................................................................... 2
IntroducingtheMinelab‘GPextreme’ ..................................................................................................... 3
ASSEMBLY............................................................................................................................ 5
Unpacking your ‘GP extreme’[easy reference] ..................................................................................... 6
List ofpre-assembledsectionsandparts................................................................................................. 7
Complete assembly instructions.............................................................................................................. 8
BATTERY ............................................................................................................................. 13
Batteryandcharging ..............................................................................................................................14
CONTROLS.......................................................................................................................... 17
Detectorsounds[easyreference]..........................................................................................................18
Controlfunctions:rearpanel .................................................................................................................. 19
Controlfunctions:frontpanel..................................................................................................................23
OPERATION......................................................................................................................... 27
Quickstart instructions[easyreference]...............................................................................................28
Detailedoperating instructions................................................................................................................ 29
Groundbalancing ...................................................................................................................................33
Irondiscrimination ..................................................................................................................................35
Level Ajust Control................................................................................................................................. 37
contents
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4
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TABLE OF CONTENTS
contents
6DETECTING TECHNIQUES ............................................................................................... 39
Detectingtechniques...............................................................................................................................40
Prospecting techniques .......................................................................................................................... 42
Identifying targetsignals ......................................................................................................................... 43
Recovering thetarget ............................................................................................................................. 45
USER INFORMATION ........................................................................................................ 49
Technical specifications forthe Minelab‘GP extreme’ .......................................................................... 50
Troubleshooting ....................................................................................................................................... 51
Service repair form.................................................................................................................................52
Warranty ................................................................................................................................................. 53
Accessories ............................................................................................................................................54
Glossary of common terms ................................................................................................................... 55
Detector careand safety ........................................................................................................................ 59
An important message from Minelab ..................................................................................................... 60
7
THE MINELAB ‘GP extreme’
INTRODUCTION
1
1
1
Introduction
The ‘GP extreme’ incorporates new
technological advances and control
functions which have resulted in a
detector that combines stable and
effective ground balancing with
‘extreme’ depth and ‘extreme’
sensitivity.

THE MINELAB ‘GP extreme’
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INTRODUCTION
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ABOUT THIS MANUAL
This manual is designed to introduce the detector’s features. It gives you step-by-step
directions for everything from assembling and adjusting your detector, to basic and
advanced detector use.
1. INTRODUCTION
Basic overview of the ‘GP extreme’
and this User’s Manual.
2. ASSEMBLY
This chapter provides details and
instructions on assembling and
adjusting the ‘GP extreme’.
3. BATTERY
The ‘GP extreme’ is powered by a
rechargeable battery pack. This
chapter provides details on battery
installation, use and performance.
4. CONTROLS
This chapter is designed to
familiarize you with the various
features of the ‘GPextreme’ control
panel. A few minutes spent reading
this chapter will be a worthwhile
preliminary to basic or advanced
detecting.
5. DETECTOR OPERATION
However experienced you are at
using a metal detector, it is important
that you read this.
6. DETECTOR TECHNIQUES
Once you are comfortable with the
basic detector use, there are a few
techniques you should be aware of.
7. USER INFORMATION
This chapter provides a glossary of
terminology, user guides, technical
specifications, warranty and repair
details and troubleshooting tips.
ABOUT THIS MANUAL

THE MINELAB ‘GP extreme’
INTRODUCTION
1
3
Minelab ‘GP extreme’ is the first detector to use ‘Dual Voltage
Technology’ (DVT).
Minelab have developed this new Dual Voltage Technology
(DVT) based on the Bi-Polar technology used in our military
detector range.
The New Features
The new features of the ‘GP extreme’ are
• new DVT technology giving greater depth than ever before
• selectable Tx (transmit) modes for different Soil conditions
• selectable Rx (receive) modes for increased sensitivity and
less susceptibility to interference
• adjustable Signal response for target tone variation
• volume limiting for users own preference
• and new ‘GP extreme’ 1100 and ‘GP extreme’ 1800 coils
which have been specially designed to take advantage of the
new DVT.
Minelab are confident that you will find the ‘GP extreme’ to be the
ultimate detector for finding metallic objects in highly mineralised
and/ or salty environments. Simple operation means that both the
beginner and professional will find this detector very easy to use.
Old gold fields, where mineralised ground and too much rubbish
have shielded many nuggets from the ‘prying eyes’ of other
detector operators, will likely yield new finds.
Minelab thanks you for purchasing this ‘GP extreme’
detector and wish you every success in your quest for gold
and treasure.
INTRODUCING THE MINELAB ‘GP extreme’
INTRODUCING THE MINELAB ‘GP EXTREME’
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THE MINELAB ‘GP extreme’
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ASSEMBLY
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2
Assembly
This chapter provides details and
instructions on assembling and
adjusting the ‘GP extreme’.
THE MINELAB ‘GP extreme’
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INTRODUCTION
1
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Minelab is always interested in your opinions so if you have any questions or comments
regarding the ‘GPextreme’ or any other Minelab product, please feel free to contact us via your
local Authorized Minelab dealer, or write to us:
Minelab International Limited
Laragh, Bandon
Co. Cork
IRELAND
email: [email protected]
tel: + 353 (23) 52101
Contact Minelab
Minelab Electronics Pty Ltd
PO Box 537 Torrensville Plaza
South Australia 5031
AUSTRALIA
email: [email protected]
tel: + 61 (8) 8238 0888
Visit our site on the World Wide Web: http://www.minelab.com for the latest information
on Minelab products and services.
Minelab USA
2700 E Patrick Lane, Suite 11
Las Vegas, Nevada 89120
UNITED STATES OF AMERICA
email: [e-mail]
tel: + 1 [phone]

Minelab USA Inc
871 Grier Drive, Suite B1,
Las Vegas, Nevada, 89119
UNITED STATES OF AMERICA
email: [email protected]
tel: [phone]

THE MINELAB ‘GP extreme’
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ASSEMBLY
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UNPACKING YOUR ‘GP Extreme’
A. ‘GPextreme’1100 Coil with Skid Plateand
FibreglassLowerShaftattached.
B. IntermediateShaft.
C. ‘GP extreme’ControlBoxwithUpper
Shaft,Handle,ArmRest,ArmStrapsand
NeopreneArmrestCoverattached.
D. Headphones.
E. BatteryandBatteryPack.
F. Velcro Straps, Knuckle and Bungy Cord.
G. Battery Cable.
H. Vehicle Charger.
I. MainsCharger.
J. Backpack Strap.
K. Instruction Manual, Field Guide and RubbishBag.
L. Hard Carry Case.
M. ‘GPextreme’ 1800 coilwithskidplate (in separate
carton).
The ‘GP extreme’ as shipped Figure 2.1 Contents of the ‘GP extreme’ pack
P0501-A
easy reference
UNPACKINGYOUR‘GP extreme’
THE MINELAB ‘GP extreme’
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LIST OF PRE-ASSEMBLED SECTIONS AND PARTS
PRE-ASSEMBLED SECTIONS
Figure 2.2 Pre-assembled sections and parts list
A. Lower Shaft Assembly
1. Extreme 1100Coil
2. CoilCable
3. SkidPlate
4. FibreglassLowerShaft
5. Nylon Nut & Bolt
6. Teardrop Washers
B. Intermediate Shaft Assembly
7. IntermediateShaft
C. Upper Shaft Assembly
8. UpperShaft
9. HandlewithWristStrap
10. Control Box
11. ArmrestParts(2)
12. Nylon Bolt (2)
13. Nylon Nut (2)
14. Arm Straps(2)
15. Armrest Cover
D. Headphones
16. Headphones
E. Battery and Battery Pack
17.Battery
18. BatteryPack
19.Battery PowerCable
F. Extras
20. Velcro Cable Straps (3)
21.Bungy Cord
22. Bungy Knuckle
A.
B
C
D
E
F
P0502-B

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Inventory
Whenunpacking your ‘GP extreme’, you will find that a number of
thecomponentshavebeenpre-assembledforyourconvenience.
Figure 2.1 (page 6) shows a list of the parts as they are packed.
Figure 2.2 (page 7) shows the pre-assembled sections and a list
ofparts.
Should you need to assemble the ‘GP extreme’ from
all the various components, here are detailed
assembly instructions.
Assembling and fitting the armrest
Figure 2.3, refer also Figure 2.2
STEP 1 Place the two armrest halves (11) on either side of the upper
shaft(8)andensurethattheboltholesarealigned.
STEP 2 Slidethetwonylonbolts(12)throughthe boltholesand
screw the nylon wing nuts (13) onto the bolts by a couple of
turns.
STEP 3 Slidethe ‘T’ section on top of thecontrol box (10) into the
armrestwiththebatteryplugattherear. Tightenthenylon
wingnutsbyhand.
STEP 4 Attachthearmreststraps(14)usingthepressstudsonboth
sidesof thearmrest.
STEP 5 Push the arm rest straps(14) through the slots in the
neoprene arm rest cover (15) and then push the cover over
the arm rest (11).
COMPLETEASSEMBLYINSTRUCTIONS
COMPLETE ASSEMBLY INSTRUCTIONS
Figure 2.3 Armrest assembly
P0518-A
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COMPLETE ASSEMBLY INSTRUCTIONS
Attaching the handle and bungy cord
Figure 2.4, refer also Figure 2.2
STEP 1 Slidethehandle(9)ontotheotherendoftheuppershaft(8)
and set it to a comfortableposition. Tightenthetwo screwsin
the baseof the handle witha small flattipped screwdriver to
holdthe handle in position.
STEP 2 Slide the bungy cord knuckle (22) of the bungy cord onto the
uppershaft(8).
Assembling the Intermediate and Upper shaft sections
Figure 2.5, refer also Figure 2.2
STEP 1 Slidetheintermediateshaft(7)intotheendoftheupper shaft
(8) and snap into place.
STEP 2 Checkthat the coil (1) has a skid plate (3)attached.
STEP 3 Check thatthecoilpivot end of the lower fibreglassshaft (4)
hastwoteardropwashers(5)installed.
NOTE The washers should always be full thickness
and should be replaced regularly as they wear out and
allow the coil to become loose.
STEP 4 Pushthelowerfibreglassshaft(4)intothemountingbrackets
on the coil and ensure that the spring clip at the rear of the
fibreglassshaftfacesthe rear of the coil.
Attaching the coil
Figure 2.5
STEP 1 Line up theholes in the coil with thepivot endof the
fibreglassshaft(4).
STEP 2 Push thenylon boltthrough the holes and fitthenylon wing
nutthentightenbyhand.
NOTE Do not over tighten the nut as the coil housing
may be crushed or damaged.
Figure 2.4 Handle and bungy cord
Figure 2.5 The coil pivot end of the lower
fibreglass shaft
P0519-A
P0520-A

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COMPLETE ASSEMBLY INSTRUCTIONS
Securing and connecting the coil cable
NOTE Always ensure that the control box is turned off
completely before connecting or disconnecting the coil.
STEP 1 Wind the coil cable around the shaftandplugthecoil
connector into thecoilsocket on thecontrolbox.Check that
thecableiswoundfirmlyaroundtheshaftwithoutstrain,
leave enoughslack atthe bottom of thecable near the coilto
allowfor adjusting the angle ofthe coil withoutplacing strain
on the coilcable.
STEP 2 Fasten the cable into positionusing theVelcro straps
provided (20).
Fitting and connecting the battery pack
Figure 2.6
STEP 1 Fitthebattery(17)intothebackpackpouch(18).
STEP 2 Connecttheheadphones(16)and the powercable(19)to
theappropriatesocketsinthecapofthebattery.
STEP 3 Put on the back pack (18).
If the coil cable is able to move
around, especially near the coil, it
will be ‘seen’ by the detector and
cause random noises which may be
confusing.
HINT
Use only the 6v DC battery supplied
CAUTION
Attaching the lower fibreglass shaft
Figure 2.2
STEP 1 Slidethelowerfibreglassshaft(4)intotheintermediateshaft(7).
STEP 2 Adjust shaftlengthand coilangleforacomfortableposition.
Minelab recommends that the shaft lengthbe setto give a
comfortablesweeplengthofapproximately2meters. The
lowerfibreglass shaft can beset into position bylocatingthe
spring clip into the holes provided in theintermediate shaft
and handtightening the locking nut at the endof the
intermediateshaft.
THE MINELAB ‘GP extreme’
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COMPLETE ASSEMBLY INSTRUCTIONS
STEP 4 Ensure that the power switch onthecontrol box is switched
offandplugtheconnectoronthepowercable(19)intothe
batteryconnectorplugonthecontrolbox.Thiscable
connectsthebatteryandheadphonestothedetector.
Adjust for your own comfort
STEP 1 Adjust the bungy cord (21) from the knuckle (22) on the shaft
to correctlength to take some of theweightwhen
prospecting.
STEP 2 Adjustthe handstraponthehandle(9)foryourowncomfort.
Figure 2.6 The ‘GP extreme’ battery assembly
P0503-A

THE MINELAB ‘GP extreme’
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THE MINELAB ‘GP extreme’
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BATTERIES
3
3
Battery
The ‘GP extreme’ is supplied with a 6v
DC rechargable battery pack plus both
mains and vehicle chargers. This chapter
provides details on battery installation,
use and performance.

THE MINELAB ‘GP extreme’
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BATTERIES
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The Battery
The6vDCrechargeablebatteryshouldprovideenough power to
operatethedetectorfor10-12hrs,whenfullycharged.
Thebatterymayberechargedatanytimeduringthedischargecycle.
Itisveryimportanttofullychargethebatterybeforestorage.
Do not leave a battery fully discharged for longer than one day.
CAUTION Never use a 12v DC battery because this would
damage the detector. This damage is not covered by
warranty.
Low Battery Indication
Ifbatteryleveldropsbelowthedesired powertogivefullfunction,a
series of signal pulses are given at 0.5 second intervals.
Charging the battery
STEP 1 Turn thedetectorOff beforedisconnectingthebattery.
STEP 2 Disconnectthebatterycablefromthedetectorandconnect
totheappropriatecharger.
Battery Chargers
Twotypesofbattery chargers(Mainsand12vVehicle Charger)
aresupplied.
BATTERYANDCHARGING
BATTERIES AND CHARGING
Do not leave the mains charger
on for extended periods because
reduced battery life may result.
Caution
When charging, the battery must
be kept in an upright position.
Important
THE MINELAB ‘GP extreme’
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BATTERIES
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BATTERIES AND CHARGING
Mains Battery Charger
Themainsbatterychargerwillchargethebatteryfromlocalmains(AC)
poweroutlets.
STEP 1 Connectthemainschargertoamainsoutlet.
STEP 2 Switchthemainsoutleton.
Checkthechargernameplate;itshouldberatedat500mA
or1000mA.The500mAchargerwillrechargea completelyflat
batteryinapproximately20hours.The1000mAchargerwill
rechargeacompletelyflatbatteryinapproximately10hours.
Partiallydischargedbatteriesrequireashorterperiodtorecharge.
Allowapproximately1.5to2hourschargingforeachhourthe
battery was in use if using a 500mA charger and about 0.5 to 0.75
hoursforeachhourusageona1000mAcharger.
Vehicle Battery Charger
Thevehiclebatterychargerwillchargethe batteryfromthecigarette
lightersocket of mostmotorvehicles.
STEP 1 Connectthechargertothecigarettelightersocketandturn
theignitionswitchtoAccessories.
Thissupplies12vDCpowertothecigarettelightersocket.Thisvoltage
isconvertedbythechargertochargethedetectorbattery.AredLED
indicatorwillflashwhilethebatteryischarging.Whenthebatteryisflat
theLEDmayflashfastenoughsoastoappearconstantlyon.Asthe
batterycharges,theLEDwillflashataslowerrate.
STEP 2 Leavethebatterytochargeforapprox.10hoursusingthischarger.
If the battery voltage of your vehicle drops below 11v, the charger
willstopoperating.Thereforethebatterychargershouldnotflatten
the vehiclebattery.
Check that yourvehicle battery isin good conditionbeforecamping
in remote areas.
Run your engine above idle speed for at least 30 minutes each day
tokeepyourvehiclebatterycharged.
The Vehicle Battery Charger is
designed for use with vehicles
which have a negative earth
electricalsystem.
Mostcarsmanufacturedafter1970
shouldhavenegativeearthelectrical
system.
Connecting thecharger to a vehicle
with a positive earth system will
cause thefuseinthecigarette lighter
plugto blowand the LED indicator
will not light.
Caution

THE MINELAB ‘GP extreme’
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BATTERIES
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THE MINELAB ‘GP extreme’
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4
CONTROLS
4
Controls
It is important to familiarise yourself with
the features of the ‘GP extreme’ control
panel. A few minutes spent reading this
chapter will be a worthwhile preliminary
to detecting.

THE MINELAB ‘GP extreme’
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CONTROLS
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www.minelab.com easy reference
DETECTOR SOUNDS
DETECTOR SOUNDS
Threshold and Tone
This is the background sound produced by the detector. The level
is set using the Threshold control. The tone of the threshold is
set using the Tone control.
Target Signal
This is the abrupt change of the tone and volume of the threshold
sound when a target is detected.
• The maximum level is set by the Volume control.
• The amount of tone variation is set by the Signal control.
• If the tone falls first and then rises, as the coil is passed
over a target, this generally indicates a small target.
• If the tone rises first and then falls, as the coil is passed
over a target, this generally indicates a large target.
Ground Noise
These are irregular noises that are difficult, or impossible, to pinpoint
when moving the coil over the ground. Ground noise is caused by
the changing chemistry or 'mineralisation' of the ground. When the
Balance switch is set to Tracking these effects are greatly reduced.
Tune Indication
An initial beep sounds then, while the detector is testing the range of
frequencies for the most stable, the threshold may become more quiet
or chattery. Once selection is complete three sharp ‘beeps’ are given.
Low Battery Indication
If the battery level drops below the desired power to give full function,
a series of signal pulses are given at 0.5 second intervals.
THE MINELAB ‘GP extreme’
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CONTROLS
P0504-A
Power (On/Off)
Figure 4.2
This switch turns the power from the battery to the detector On
and Off.
NOTE Always switch the detector Off before connecting or
disconnecting the coil or battery pack and when not in use.
CONTROL FUNCTIONS
Figure 4.1 Rear Panel
There are two control panels: the rear panel and the front panel.
CONTROL FUNCTIONS
Rear Panel
Figure 4.1
Figure 4.2 Power (On/Off) switch
Power
P0518-A

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CONTROL FUNCTIONS
Boost (Shallow/N/Deep)
Figure 4.3
Enhances the signals produced by different types of targets.
•Shallow enables target signals, from small objects close to
the surface of the ground to be amplified. This allows for
easier detection. This setting is best suited for 'quiet' ground.
•N (Normal) may be used for normal detecting conditions.
This setting responds to all signals without boosting.
•Deep may be used when searching for large targets at
greater depth in 'noisy' ground. Random soil signals are
smoothed, making small changes in the audio signal from
large deep targets easier to hear. This may mask some
signals from very small targets near the surface.
Threshold
Figure 4.4
Adjusts the background audio signal or 'threshold' level.
The Threshold control should be set just above the point where
the threshold is just audible and stable.
This level should not be at a level where prolonged use may be
irritating. Ideally it should be a smooth, gentle hum.
NOTE Small targets or large deep targets may not produce a
distinct target signal, but may cause only a small variation in
the threshold level. If the threshold level is set too high or
too low, these very small variations may be missed.
In Figures 4.5 - 4.7, the dotted line represents the level at which
the audio output becomes audible; signals cannot be heard if
they are below the dotted line.
If the threshold level is set too high then small variations in audio
signalmight not be discernible above the threshold level (Figure 4.5).
An example of this would be to hear a whisper within a crowded
noisy room.
Figure 4.5 Threshold control too low
P0509-A
Figure 4.6 Threshold control too high
P0509-B
Figure 4.3 Boost switch
Boost
P0519-A
Figure 4.4 Thresholdcontrol
Audio
P0520-A
THE MINELAB ‘GP extreme’
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CONTROL FUNCTIONS
If the threshold level is set too low there is no audible background
signal and small target signals will not go above the threshold of
audibility (Figure 4.6).
HINT A soft audible headphone signal which is comfortable to
listen to for extended periods is recommended (Figure 4.7).
Volume
Figure 4.8
Sets a maximum limit on the loudness of the target signal
obtained from a large target. Refer to Figures 4.9 - 4.11. The
dotted line in these figures represents the level of volume set by
the volume control.
• If the Volume is set to maximum (fully clockwise), the target
signal is unaltered and proportional to the target size and depth
(see Figure 4.9).
• If the Volume control is turned down to half way, the target
signal is unaltered for a small target, but is limited for a
bigger target (see Figure 4.10).
• If the Volume were to be turned down close to minimum, it
potentially will limit all signals to such a degree that most
targets will be lost (see figure 4.11).
NOTE Thresholdshould bereset afteradjustingtheVolume level.
Figure 4.8 Volumecontrol
Audio
P0521-A
Figure 4.9 Maximum volume
P0508-A
Figure 4.7 Threshold control just right
P0509-C
Figure 4.11 Minimum volume
P0508-B2
Louder
Mid-rang
e
Figure 4.10 Mid-range volume
P0508-B

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Tone
Figure 4.15
Adjusts the tone of the threshold. The user may set this to the
preferred tone, e.g. the tone at which the operator’s hearing is
most sensitive.
At minimum position, threshold is set at a low tone. Turning
clockwise increases the tone to higher pitch.
Signal Pitch
Figure 4.12
Adjusts the pitch response of the target signal.
In Figures 4.13 and 4.14 the curving line represents the high/low
pitch response to a target. The dotted line represents the
threshold tone.
• At minimum position the high/low pitch variance to a target is
reduced.
• At maximum position the high/low pitch variance to a target is
increased.
CONTROL FUNCTIONS
Figure 4.12 Signal control
Audio
Figure 4.13 Reduced pitch variance
Figure 4.14 Increased pitch variance
P0522-A
P0510-A
P0510-B
Audio
Figure 4.15 Tone control
P0523-A
THE MINELAB ‘GP extreme’
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CONTROLS
Front Panel
Figure 4.16
Figure 4.16 Rear Panel
CONTROL FUNCTIONS
P0510-A
Tune
Figure 4.17
Reduces the effects of electromagnetic interference from sources
such as power lines, radio transmitters and other metal
detectors.
Automatic tuning is started by pressing and releasing the Tune switch.
The tuning process takes approx. 60 sec. and completion is
indicated by three sharp ‘beeps’.
Figure 4.17 Tunecontrol
P0524-A

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CONTROL FUNCTIONS
Iron Discriminate (All Metal/Disc)
Figure 4.18
Selects between discrimination or to turn off the discrimination
altogether (All Metal).
In All Metals, the detector will give varying volume and pitch
signals but this information does not indicate the type of metal in
the object.
In Disc, a strong response from a ferrous (iron) object will cause
the threshold to be 'blanked' or silenced.
NOTE If the target response is too weak for accurate
discrimination, the detector will give a normal target signal.
Level Adjust
Figure 4.19
Level adjust gives the user the ability to select the sensitivity
and likelihood of a target being ferrous or non-ferrous.
It also affects how the detector recognises mineral effects in the
ground, as opposed to metal targets, when 'ground balancing'.
NOTE It is important that you read pages 37 and 38 in
Chapter 5 for more information.
Soil (Normal/Sensitive/Salt)
Figure 4.20
Optimises the detector for different soil conditions and targets by
changing the signal processing.
•N ( Normal ) may be used in all areas, including areas with
highly mineralised soil. This position has very good sensitivity
to a wide range of nugget sizes and is the most versatile of
the three positions.
Iron Discriminate
Figure 4.18 All Metal/Disc switch
P0525-A
Iron Discriminate
Figure 4.19 Level Adjust control
P0526-A
Soil
Figure 4.20 Soil (Normal/Sensitive/Salt) switch
P0527-A
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Rx (Receive) (Normal/E/Cancel)
Figure 4.21
Changes the sensitivity and search pattern of the coil to allow the
‘GP extreme’ range of coils to become multi-versatile coils with
different characteristics to suit different environments. 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.
•Normal can be used in most areas of medium to very high
mineralisation, being the most able to cope with ground
noise. It is also excellent for pinpointing targets as the
response is strongest from the centre of the coil.
•E (Enhance) may be used in most locations of low to medium
mineralisation and for locating small nuggets with Soil switch
set to Sensitive. Pinpointing is not centred in the middle of
the coil, but to one side and may give a complex signal when
the target is very close to the coil.
•Cancel may be used in areas with very high electrical
interference where the Tune function has difficulty selecting
a quiet operational frequency (e.g.: near power lines, electric
fences or under poor atmospheric conditions). Pinpoint in
CONTROL FUNCTIONS
Rx
Figure 4.21 Rx (Receive) switch
P0528-A
•Sensitive may be used when searching for small nuggets,
especially in areas with highly mineralised soil. The extra
stability allows the coil to be used closer to the ground in
areas of excessive ground noise. Sensitive may not work
well if the ground is salty.
This setting may also reduce the depth at which large
nuggets are likely to be found.
•Salt may be used in areas containing high salt content, be
they neutral or heavily mineralised. In highly mineralised
areas without salt, this setting may be less sensitive than
Normal or Sensitive to small nuggets.

THE MINELAB ‘GP extreme’
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Cancel will again be to one side of centre and signals may
be complex if target is close to the coil. This setting will limit
sensitivity to deep targets.
NOTE Coils not specifically designed for the ‘GP extreme’
may behave erratically or be ineffective in either E (Enhance)
or Cancel modes.
Balance (Fixed/Tracking)
Figure 4.21
The ‘GPextreme’ may be operated with fixed ground balance or
automatic ground balance.
• When Balance is set to Fixed, the ground balance remains
at the current level.
• When Balance is changed from Fixed to Tracking, the
detector begins to automatically ground balance through a
two stage process that is described on page 33.
To obtain the best performance from your detector, it is important to
know how different ground conditions affect the detecting process.
See “Ground Balancing” on page 33 for more detailed information.
Balance
Figure 4.22 Balance (Fixed/Tracking) switch
P0529-A
THE MINELAB ‘GP extreme’
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OPERATION
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5
Operation
However experienced you are at using a
metal detector, it is important that you
read this chapter to understand how to
use the ‘GP extreme’ to its full capacity.

THE MINELAB ‘GP extreme’
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OPERATION
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DETAILEDOPERATINGINSTRUCTIONS
Turn the ‘GP extreme’ On
• Holdthecoilaway from the ground and metal objectsandswitch
Power to On.
NOTE When the ‘GP extreme’ is turned Off, important
information (e.g. tuning frequency and ground balance) is
saved in internal memory.
If detection recommences in the same location, the user
should not have to re-tune or re-ground balance the
detector.
Set the Volume Control
Volumeshould be set so that targetsignalsareclear andeasyto
hearbutloudsignalsarenotuncomfortable toyourhearing.
Set Volumeby testingvolumelevels by passingcoil across a large
target andsetting volume at comfortable level.Now test verysmall
targetat this level.
Set the Threshold control
• AdjusttheThresholdcontrol until thethreshold is just audible
throughtheheadphones.
NOTE Small surface objects, as well as large deep objects,
will produce very small changes in the threshold. It is
important to set the Threshold control correctly to ensure
that these targets are heard. Experiment with known targets
to assist in setting all controls to suit your hearing.
DETAILED OPERATING INSTRUCTIONS
HINT
Take time to read this manual
thoroughly to obtain the best
performance from your new
‘GP extreme’ detector.
THE MINELAB ‘GP extreme’
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OPERATION
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www.minelab.com
QUICK START INSTRUCTIONS (EASY REFERENCE)
easy reference
STEP 1 Turn Power switch On.
STEP 2 SetBoost to N (Normal) forgeneraldetecting.
STEP 3 SetVolume to maximum, and Signal tomidway.
STEP 4 Adjust the Threshold control so that afaint sound isheard
throughtheheadphones.
STEP 5 Adjust Toneforthresholdlevelthatsuitsyourhearing.
STEP 6 Totune the detector,hold atwaistheight withthe shaft
horizontal. Keepthe coilvertical.
STEP 7 Slowly move coil around your body through a half-circle
untilthenoisefrominterferenceisloudest.
STEP 8 Hold thisposition,keepthe coil motionlessand push the
Tuneswitchonce to start thetuningfunction.
STEP 9 Tuning takesapproximately 60 seconds.A series ofthree
beepswillindicatethattheoptimumfrequencyhasbeen
selected.
STEP 10 For Discrimination, change the Iron Discriminate
switch to Disc and set Level Adjust to the middleof its
range.
STEP 11 Set Soil switch to N (normal)
STEP 12 SetRx switch to Normal
STEP 13 Set the Ground Balance by moving the coil up and down.
While coil is in motion, change Balance switch fromFixed
to Tracking.
STEP 14 The detectorisnowreadyforoperation.
QUICKSTARTINSTRUCTIONS

THE MINELAB ‘GP extreme’
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OPERATION
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DETAILED OPERATING INSTRUCTIONS
Set the Tone control
• AdjusttheTonecontroluntilthethresholdisatacomfortabletone
foryourhearing.Interpretationofthetargetsignalsinvolves
understandingthedifferencebetweentherisingandfallingtone
andvolumeofthethresholdinresponsetodifferenttargets.
HINT Setting Tone to a high pitch may be more fatiguing, but is
moresuitablefor identifyingthefaintesttargetsignals.
Set the Signal control
The human hearing is sensitive to changes in tone, so the operator
is morelikelyto hear a targetsignal when both the volume and the
tonechangeratherthanvolumealone.
TheSignal controlgivestheoperator, theabilitytochoosebetween
a target signal that has a large variance of tone or one which has
lessvariation.
High variancecan give the operatormore signal definition to
interpret,howeverinhighlymineralisedgroundthis highvarianceof
signalmaycauseconfusionandalowersettingpreferred.
Soil switch
Usethis switchtooptimisethedetector's abilitytodetectindifferent
groundconditions(seepage24forfulldescription).
Rx switch
Selectionofdifferent positions ofthisswitch,changesthe
electromagneticfieldofthecoilthusgivingbetterperformancein
certainenvironments(seepage25formoreinformation).
Normal has the coil operate in a conventional Double D search
patternwithallthesameadvantagesanddisadvantages.
IMPORTANT
You will need to
re-ground balance every time you
select a new position for either the
‘Soil’ or ‘RX’ switches.
THE MINELAB ‘GP extreme’
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OPERATION
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DETAILED OPERATING INSTRUCTIONS
E (Enhance) changes the way the coil transmits and receives its
signals.Operating in enhanced,the coilhas someof the
characteristicsof a Monoloop coil.Use of Enhance will often
increase the sensitivityof thedetectorbut mayalsobe a little more
unstablein heavily mineralisedground.Pinpointingwillbe off to the
leftofcentre.
Cancelchangesthe electromagneticfieldof thecoilsothatitis
particularlystable in areasof electricalinterference.Thispositionis
idealinareaswheretheoperatorwantstodetectcloseto suburbia
orunderpowerlinesetc.
Set the Tune control
Figure 5.1
TuningshouldbedoneinitiallywiththeRXswitchinNormalorin
E(Enhance). If the interferenceis still severe aftercompletingthe
tuningoperation,changetheRX switch to Cancel andthenre-tune
detectoragain.
• Holdthe detectorat waist heightand the coilvertical.
• Keepingthecoilvertical, slowly moveit througha half-circle
around your body.
• Listen foran increase in interference as you move thecoil.
• Whentheinterferenceisloudest,stopmovingthedetector, hold
itmotionless in that positionand momentarilypressthe Tune
switch.
The detector will then scan through the available range of
transmissionfrequenciesandautomaticallyselectthefrequency
thatresultsinthegreatestreductionofnoisefrom
electromagneticinterference.
• The end of tuning process (which takes approx. 60 sec.) is
announcedbythreebeeps.
NOTE While the detector is selecting the preferred
frequency, the coil must be kept motionless and clear of
metal objects.
Figure 5.1 The tuning process
P0517-A2
IMPORTANT
When tuning detector in close
proximity to other detectors, each
operator needs to take turns
tuning. Do not try to tune two
detectors at one time.

THE MINELAB ‘GP extreme’
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OPERATION
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www.minelab.com Sometimesitmay notbepossibleto removethe effects of
interferencecompletelybyusingtheTunecontrolalone.
Oncethe detector hasbeentuned for aparticularlocation, itshould
notrequirereadjustmentunlessconditionschangeornew
interferenceisintroduced,e.g.otherdetectorsbeingusedinthe
samearea.Iftheinterferencepersistsaftertuning,considerusing
theRx switch set to Cancel position.
Boost (Shallow/N/Deep)
Boostselects the type ofprocessing andfiltering appliedto the
detectorsignals.
•N (Normal) may beusedforgeneraldetectingconditions.This
doesnot boost anysignals.
•Shallowboostssignals fromsmalltargets close tothe surface.
This makesfainttarget signalseasier to hear.Thissetting may
alsoboostanygroundnoise,thereforeShallowiswellsuited
for'quiet'groundconditions.
•Deepmaybeusedwhensearchingforlargetargetsatdepth.
Thissmoothsthe thresholdandtargetsignalsfromsmalltargets,
making smallchangesin thresholdeasier to hear.
Selection ofthemore suitablepositionshouldbe after considering
bothtargetsize/depthandgroundconditions.
NOTE When Boost is changed, Threshold may also need to
be adjusted.
External amplifiers may be used in addition to the Boost switch,
provided that theyhave loudnesslimiters builtin.This preventsloud
signalsbecomingunpleasantordangeroustotheuser'shearing.
DETAILED OPERATING INSTRUCTIONS
THE MINELAB ‘GP extreme’
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GROUND BALANCING
GROUNDBALANCING
Thegroundcontainsnotonlysand,butalsomanydifferentchemicals,
mineralsandsalts.Theseextramaterialsarereferredtoasground
mineralisation.
Thisgroundmineralisationmayoftenproduceasoundfromthedetector,
knownas'groundnoise'.
The ‘GPextreme’ hastheabilityto canceloutthe effectsof ground
mineralisation.This minimisesgroundnoiseand retainsmaximum
sensitivitytometaltargets.Cancellingtheeffectsofgroundmineralisation
isreferredtoas'groundbalancing'.Thisensuresthattargetsignalsfrom
objects,suchasgold,arenotconfusedwithinterferinggroundnoise.
The‘GPextreme’hasautomaticgroundbalancing.Thiscontinually
adjuststominimisetheeffectsofgroundmineralisationwhenBalanceis
settoTracking.
The ‘GP extreme’ may beoperatedwithfixedgroundbalanceor
automaticgroundbalance.
• When Balanceis set to Fixed, the groundbalanceremainsat
the current level.
• When Balance is changed from Fixed toTracking,thedetector
beginstoautomaticallygroundbalancethroughatwostageprocess.
The first stage is a veryrapid adjustment tothe ground
mineralisation. This lasts for 5 sec.so coilmovementshould beat the
same time as Balance is changed from Fixed to Tracking.
The secondstagecontinues to adjust to the groundmineralisation,
butatagreatlyreducedspeed.
Thisadjustmentcontinuesallthetimethat BalanceissettoTracking.
While inTracking mode,thedetectorusuallystopsgroundbalancing
whenatargetsignalisdetected. However, aweaktargetresponse
may notbe recognised asa target ifthecoil isrepeatedly passed
over an object, it may be 'balanced out'.For this reason Balance
should be changed to Fixed whenpinpointingatarget.
HINTS
• Use ‘Tracking’ in areas with
high ground noise for best results.
If ‘Balance’ is changed to ‘Fixed’,
the detector will no longer adjust
to changes in ground
mineralisation, but will stay fixed at
thelevelpreviouslycalculated
while in ‘Tracking’ mode.
• Change from ‘Tracking’ to ‘Fixed’
when pinpointing a potential
target.
NOTE
The Level Adjust control also
effects the Tracking mode by
altering the detectors perception of
what is ground noise and what is a
weak target (see pages 37 and 38).