Discrimination
Each of the MX 7 programs begins with Discrimination settings pre-selected
for most hunting.
√/X and "x" the area, return to Discrimination (press √/X again), then pass
the search coil over target center and note the sound and display indication.
When a metal target doesn't indicate as expected, peculiarities within that metal's
alloy mix (metal types) are usually to blame. As alloyed steel bottle caps age, the
iron deteriorates and the better (non-iron) alloys remain and become prominent
(e.g., very old bottle caps are likely to indicate as quarters). The longer they are
in the ground, the more the iron dissolves and the stronger/better the non-iron
looks to a metal detector. Soil conditions, corrosion factors, depth, and other vari-
ables can skew the audio and display indications and, thus, Discrimination settings.
Used properly, however, Discrimination will more than double your time spent
digging valued targets. The point is to reject the most common trash and accept
the most common good targets. The MX 7 has 20 rejection ranges. Discrimina-
tion comes already set up for the Program you have selected.
The MX 7 has the ability to accept or reject metal types
based on their conductivity and/or electrical phase. Target
conductivity/phase is indicated on the display VDI scale (Visu-
al Discrimination Indication) with a VDI reference number. By
learning what targets consistently indicate specific VDI num-
bers, you can be sure to accept or reject the different target
VDI ranges that interest you.
Many types of targets share similar VDI number ranges. For
example gold jewelry of varied sizes/types shares the same
VDI number range as aluminum of varied sizes/types. Deeper
depths suggest the target being heavier gold; shallow depth
indications suggest the target being lighter-weight aluminum.
However, due to the wide variety of gold alloys and sizes, to
find all the gold jewelry, digging lead, pull tabs, and screw caps
is to be expected.
Trash metals (iron) often produce some beep, different from
an accepted good target. In most cases, iron will produce a
broken or inconsistent tone whereas an accepted good target
produces a more consistent beep.
The display can help, but an inconsistent tone is most likely a
rejected target. If you have trouble recognizing these inconsis-
tent beeps and displays, find the sweep speed that enhances
the rejection sound to the point you can recognize it when
compared to the sound of a good target. Accuracy is greatly
increased sweeping the center of the target. Pinpoint (press
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