Discriminating Within Holes - Minelab Eureka Gold Instruction Manual

Page 13
If the detector is swept across the target more than once in 'hot' ground it
is possible that the detector's automatic features will adjust the balance to
the target and not discriminate out a ferrous target on subsequent passes.
This is normal behaviour for an automatic ground balance detector.
Because of the different speeds of adjustment in the two ground tracking
modes there will be a difference in the speed of this automatic adjustment.
In Fast Track only the first pass over the target will achieve accurate
discrimination. In Slow Track the first two passes are accurate.
To ensure that you are not digging ferrous targets it is best to carry out the
following procedure once you suspect a target has been discriminated:
•
Move the detector off the target and ground balance the detector over
metal-free soil.
•
Set the detector in Fixed balance mode.
•
You can now pass the coil over the target as many times as you like
and the discrimination will be accurate.
10.3

Discriminating within Holes

The discriminator must not be used to test a target by pumping the coil
into the hole. Always pass the coil smoothly across the top of the hole.
Moving the detector coil within the hole will often produce a 'non-ferrous
type' target signal when the target is really ferrous.
Similarly, the discriminator should not be used to test a target within the
pile of soil which has been taken from this hole as again 'non-ferrous type'
signals are likely to occur, particularly in highly mineralised ground. The
discriminator will give the most reliable result when the target is tested
while it is on or within undisturbed ground.
When the search coil is passed over large targets near the surface, the
discriminator electronics may sometimes overload. This is indicated by a
high pitch 'chirp' or 'bell-ringing' sound. Sweep the search coil further above
the target or so that the target signal is less strong.
The Minelab Eureka Gold