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4 STRONG SIGNALS AND TARGET PINPOINTING
Whereas the signal from an object at its maximum detection distance is weak, the signal from the same
object very close to the coil is between one hundred and one thousand times stronger and will cause the
circuits to overload. Whilst no damage is caused, this produces two effects: the unit will tend to give a
saturation signal over a wide area surrounding the object, and even when the coil is moved well away, the
indication will persist for a finite time until the circuits recover from the overload. To minimise this,
progressively turn the GAIN control anticlockwise.
Accurate pin-pointing may also be helped by moving the search coil into the region of strong signal, and
pressing the ZERO button to subtract the ‘edges’ of the response. If this is done, remember to re-zero the
instrument away from metal to restore full sensitivity before resuming searching. If the signal is still too
strong, try raising the search coil away from the object.
5 EXTRANEOUS METAL
Although the user may be searching for just one specific object, the instrument will react to all metal that is
within its detection range. This may yield a number of confusing extra responses, and indeed an object
which is nearer or larger than the target may well mask its presence. The user should therefore carefully
appraise the environment for suitability of application, bearing in mind extraneous metal.
Signals from objects such as structural metal (piles and girders), ferroconcrete, fencing and railings, and
pipelines and conduit will be received over long distances. Short-range signals can come from finger rings,
watches, metal toe-caps - even wooden benches and trestles containing screws.
Note: Always remember to keep the control unit well away from the search head - otherwise the control unit
will be detected also.
