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7.
5.
Disc/All Metal Switch
This switch is located in the top centre of the control panel and is used to
select All Metal or Disc. (Discriminate) with Iron Mask, or Disc. without Iron
Mask mode.
In All Metal mode the Sovereign GT will detect both ferrous and non-ferrous
objects. In this mode the Disc and Notch controls will have no effect and the
Sovereign GT will respond in the same way to all types of metal. All Metal mode should be used in
conjunction with Fixed & Tracking ground balance, especially when searching for gold nuggets or
other targets in mineralised soils. It is also the required setting when searching for ferrous targets
such as relics.
In Disc. mode, the Disc and Notch controls become active and can be used in combination to ignore
various unwanted metal objects.
Metal objects fall into two broad categories:- ferrous and non-ferrous. A magnet can be used to
determine if an object is a ferrous or non-ferrous metal; ferrous metals are attracted to a magnet
while non-ferrous are not.
Note: All Metal mode is also the pinpointing mode.
To pinpoint, if you have been detecting in Disc,
switch up to All Metal and have the ground balance switch in Pinpoint (see 7.8.3 pinpointing).
In Disc. mode the detector will null or cancel target signals made from unwanted metals. The degree
of discrimination is set by using the Disc and Notch control knobs. When the Disc/All Metal Switch
is in Disc position and with Disc and Notch control at minimum, the Sovereign GT will cancel all
ferrous metals and signal on all non-ferrous targets. As the Disc control is increased (turned
clockwise) some non-ferrous metals will be cancelled and as the control is increased further, more
non-ferrous metals will be cancelled.
In addition, when in Disc mode, the target signals from non-ferrous objects will vary in tone
depending upon their level of conductivity. Effectively, this allows general identification of the type of
object detected before recovering it from the ground. For example, a US quarter or Australian
$1 coin will produce a high pitch signal, whereas aluminium foil will produce a low pitched signal.
Pull-tabs, rings, and other coins will produce various intermediate tones, depending upon the
object’s conductivity. The higher an object’s conductivity, the higher the signal tone will be.
Also, provided the Threshold / Silent search switch is in the Threshold position, when the
Sovereign GT rejects a ferrous or a non-ferrous object, the background threshold tone will
momentarily disappear then return again at a pitch similar to the ignored signal. A ferrous object will
cause the returning threshold pitch to be much lower than normal, while a pull-tab that is being
ignored will cause it to be higher than normal.
If the Sovereign GT produces a high-pitched, rapidly pulsing sound, the detector is being
overloaded by a substantially large piece of metal close to the coil. Raise the coil a few inches above
the ground and pass it over the area again to check the target. By lifting the coil away from the
ground, it enables the Sovereign GT to accurately analyse the object detected.
Note:
If a target signal seems to have "blanked", but the threshold hasn’t changed to a different
tone (assuming the threshold switch is selected) it may in fact be a very deep target on the edge
of the detection depth. Digging down an inch or two will get the coil closer and will enable it to
be identified.
www.minelab.com
www.minelab.com
p17
7.
5.1.
Iron Mask On/Off
A fundamental problem for most conventional detectors is the inability to recognize a
valuable target when it is located near a ferrous item. This is a particular problem in areas
heavily littered with trash, which is common on old relic sites.
The Sovereign GT, using Iron Mask / On is particularly good at making the distinction
between a non-ferrous target and iron trash, recognizing the non-ferrous target and
providing an audio signal.
With Iron Mask / On, the search depth is also a little greater and non-ferrous targets may
be located more reliably amongst ferrous trash. However, with Iron Mask /On, the
detector may give the occasional "beep" on large ferrous targets and the threshold
may not be quite as stable. For this reason, beginners may prefer to detect with Iron
Mask / Off. Also, when discriminating in mineralised soil, Iron Mask / Off may be the
preferred mode.
7.
6.
Discrimination Control
The Disc (Discriminate) control is located at the top left-hand side of the control panel
and is used when in Disc. Mode to "discriminate" or "ignore" unwanted non-ferrous
metal targets. If the Disc control is set to the most anti-clockwise position (ensure the
Notch control is also set to this position), then ferrous metals will be "ignored" and the
Sovereign GT will not produce a "signal beep" for them, however large ferrous objects
may produce short "pops" or "clicks". On the other hand, non-ferrous targets will be
"accepted" and elicit a clear "signal beep".
Typical ferrous objects encountered by treasure hunters are nails, screws, washers, bits
of wire, etc. These objects are generally not considered to be of value, so it is a distinct
advantage to be able to ignore them while detecting. Objects that will cause the
Sovereign GT to produce a "signal beep" will be non-ferrous metals, including such items
as aluminium foil, most jewellery, pull-tabs, coins, bottle tops, gold, silver, brass, etc.
Not all of these non-ferrous objects are considered valuable. Therefore, by using the
Disc control, the Sovereign GT can be adjusted to ignore some of the less valuable non-
ferrous objects while still locating most valuable targets. The Disc control is a one-turn
potentiometer, continuously variable with numerous graduations as a guide for the
setting of the control. Turning the Disc control clockwise will increase the
"discrimination" level, and non-ferrous objects of lower conductivity will be ignored.
