Page 26
The Minelab SD2200v2
Each sweep should overlap the area covered by the previous sweep. This
will ensure a full coverage of the searched area. Be aware of the search
pattern of the
coil
and overlap your sweeps to take this into account .
7.2
Prospecting Tips
The
SD2200v2
has superior ground balancing features and it is possible
to find quite large objects near the surface in well-worked areas simply
because other detectors have been unable to cope with the high degree of
mineralisation. In light of this, you should not ignore what can seem to be
unlikely responses. In other words, dig all signals, even in thrashed areas.
Very large variations in the mineralisation of an area can produce a signal
in the detector. Typically, in the Victorian goldfields you might get a response
from a concentration of orange/reddish dyke material or clay. Similarly, in
the loamy conditions of Western Australia a pocket of dark orange/reddish
clay or rock may produce a sudden signal variation.
It is not recommended that you try to ground balance the detector on top of
a signal, in an attempt to cancel a questionable response, as this can also
cancel weak signals from very deep targets. If in doubt scrape away some
soil above the suspect signal. If the signal gets stronger, it is a target, so
dig it!
If the ground is extremely variable and causes the detector to be very noisy,
you may try operating with the
Channel
switch set to the
Channel
1
position.
This will reduce noises caused by the varying mineralisation, but some
nuggets may not be detected. The full range of nuggets are only detected
when the channel switch is set to the central
B
position, not in
Channel 1
or
Channel 2
.
Charcoal can sound loud at times and rather like a metallic object when
close to the surface. Charcoal is usually created by bushfires or by farmers
burning off tree stumps. The charcoal may be below the ground level and
it is not always obvious until you have actually dug up and located the
cause of these noises a few times. Once the charcoal is removed from
the ground the signal will vanish.
Instruction Manual
Page 27
7.3
Hints for Maximum Gold Recovery
·
Keep the
coil
as close to the ground as possible.
·
Listen very carefully. This is more important than concentrating on
looking.
·
SLOW DOWN!
DO NOT
rush take your time.
7
.4
Identifying Target Signals
Metallic targets will usually give a solid sounding response when the coil
is swept across the object from any direction. Ground noises usually give
a broad uneven response when the coil is swept from different directions.
A metallic target generally sends out a short, sharp and mostly symmetrical
response.
If you are not sure whether the sound is ground noise or a target, you need
to find out if the signal is valid. Scrape a shallow hole about 70mm to
100mm deep over the suspected target. Sweep the coil over the hole at
the original ground level. Do not dip the coil into the hole. If the signal has
decreased in volume or is less defined, it is a ground noise. If the signal
remains the same or becomes louder, it is a metallic target. If you are still
not sure, make the hole deeper and repeat the process. You will also notice
that mineral noises are often experienced from one direction only, on the
return swing it is no longer there.
The Halo Effect, which is built up around a buried metal object, makes
the object appear to be larger to the
SD2200v2
than it actually is. This will
be reduced once the target is disturbed from its position in the soil.
An example of this is when a small target, detected at a substantial depth
with the
SD2200v2,
is barely or not even detectable once recovered from
the ground. Even if reburied, the Halo Effect will disappear.
It is not recommended that you try to eliminate what might appear to be a
faint, isolated ground noise by balancing the
SD2200v2
, as you might be
balancing out the response from a deeply buried metallic target.
