White’s Electronics MXT 300 User Manual

Page 17

Another example of when Lock would be used is if

a particular mineralized rock or patch creates dif-

ﬁ culties in searching an area. A hard rock mine for

example with a low mineralized base rock and ran-

dom high mineralized rocks or patches. Place the

TRAC control in the Ground position and balance

"pump the search coil" over a representative sample

of the high mineral rock or patches. Then Lock in

that ground rejection setting "place the TRAC con-

trol in the Lock position". The entire area can then

be searched without the distraction of the inconsis-

tencies the high mineral patches create.

The Salt position provides an extended ground

balance and tracking range to compensate for

conductive salts also called alkali. Ground rejec-

tion against salt/alkali slightly overlaps the lower

end of the conductive target (metal) range. In other

words if you ground balanced against signiﬁ cant

salts, some loss of sensitivity to lower conducting

metals (metals low on the VDI target scale) can be

expected. The advantage and performance improve-

ments of rejecting the salt, however, far outweighs

any loss. Because the Salt TRAC setting can track

well into the target range it is not recommended for

normal conditions, only for areas known to contain

salt. Salt water beaches for example or alkali desert

regions. The Ground setting will not track into the

nonferrous metal region. The Salt setting will. The

MXT 300 ground rejection system is capable, in

both the Ground and the Salt settings, of consider-

ing some iron a ground mineral.

If operating in a known salt area, salt water beaches

for example, it is not necessary to balance in the

is not

Ground TRAC setting. Simply select the Salt

TRAC setting and proceed to pump the search coil

over the ground to be searched. The Salt setting

will balance and then track to changes identically

to the Ground setting only with an extended range,

well into the conductive target area.

Summary - The Ground TRAC setting is recom-

mended for most searching conditions. Lock is

used to hold a ground rejection setting that is ﬁ rst

established in the Ground or Salt TRAC positions.

Lock is recommended for areas that cause detector

instability due to extreme ground peculiarities such

as a lot of decomposing man made iron. Salt pro-

vides extended ground rejection range to compen-

sate for conductive salt/alkali conditions. The Salt

setting can ground cancel extreme enough to reduce

sensitivity to low conducting metals, metals that ap-

pear low on the VDI scale. The Ground TRAC set-

ting will not balance nor track into the nonferrous

metal region. Despite this draw back the Salt setting

still provides improved overall performance while

operating in the salt/alkali ground condition.

Chapter 5 MXT 300 Controls