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TEKNETICS
Comprehensive Operating Manual & Guide to Metal Detecting
TEKNETICS
Comprehensive Operating Manual & Guide to Metal Detecting
CAPABILITIES AND LIMITATIONS (continued)
STEEL BOTTLE CAPS & FLAT IRON TRASH
Modern motion-type target ID metal detectors usually have difficulty consistently identifying
steel bottle caps and other flat iron trash objects. Double-D searchcoils also have a reputation
for being unable to distinguish steel bottle caps from coins, and for being unable to eliminate
steel bottle caps from detection. If you are searching in an area where there are many steel
bottle caps or other flat iron trash targets, minimize the amount of unnecessary digging with
the following methods:
1. Search with the 3b (bottle cap) method
using the # OF TONES feature. This
method calculates visual ID differently in order to cause steel bottle caps to read lower
on the scale, and to register less consistently. A desirable object such as a coin will
usually produce numeric values that are fairly consistent in both directions of sweep.
See # OF TONES under the DISCRIMINATION Mode section of this manual.
2. Search in dP mode.
This method calculates visual ID differently in order to cause
steel bottle caps to ID lower on the scale and to register less consistently. It also
produces more audio clues to the character of the target.
3. Lift the searchcoil or sweep at an angle.
Within 2 inches of a Bi-Axial
searchcoil, the crossed magnetic fields of the Double-D construction can produce
anomalous responses. If the object feels shallow (strong signal, narrow response, or
multiple responses in a single sweep) and is giving consistent high readings like a
coin, raise the searchcoil 2 to 3 inches and try again. A coin will almost always
continue to give consistent readings unless it is right next to an iron object. A steel
bottle cap that is at least 3 inches away from the searchcoil will
usually produce readings that bounce around from medium to
low numbers.
4. Sweep REAR of coil over the target or sweep fast
1. If the ID# is repeatable around 81 to 84, when passing over
center of searchcoil at normal speed, then target should be a
dime or copper penny.
2. If not in the range of 81 to 84, then:
a. Sweep the back end of searchcoil over the target. If
tones change from high to a low tone, it is probably a
bottle cap.
b. Sweep center of searchcoil fast
across target.
i. If tone and ID-value drop, it is
probably a bottle cap.
ii. If a bottle cap, the faster you
sweep, the lower the tone.
Sweep back end
of searchcoil over
suspected bottle cap.
(Low Tone = Bottle Cap)
GROUND CANCELLATION (continued)
MANUAL GROUND CANCELLATION
In most situations, it is preferable to push the trigger switch to activate FASTGRAB automatic
ground cancellation. Generally, it is best to first let the computer automatically cancel
interference from ground minerals. However, for gold prospecting, searching on a wet
saltwater beach, or searching in an area with so much metal trash that there is no clean
ground for the computer to sample, we recommend that you cancel ground manually. Manual
ground cancellation requires a bit of skill, acquired with some practice.
The range of ground cancellation settings indicated on the display range from 0 to 99;
however, each displayed number spans 5 detent steps on the settings knob. The actual
internal ground cancellation setting changes with each step; there are a total of 500 different
settings. Under some ground conditions you may be able to hear the individual steps in the
setting.
The Fe
3
O
4
bar graph on the LCD display indicates the amount of magnetic mineralization. The
searchcoil must be in motion to measure Fe
3
O
4
. The most accurate measurement is obtained
by pumping the searchcoil, as in the Ground Cancellation procedure.
The two-digit G.C. Phase number displayed on the LCD indicates the type of ground
mineralization.
Some typical ground mineralization types are:
0
– 10
Wet salt and alkali
5
– 25
Metallic iron (very few soils in this range. You may be balancing over metal)
26 – 39
Very few soils in this range — occasionally some saltwater beaches
40 – 75
Red, yellow, and brown iron-bearing clay minerals
75 – 95
Magnetite and other black iron minerals
When manually ground canceling, try to “feel out” a spot on the ground to make sure there is
no metal present. In order to avoid locking onto metal, the computer will not cancel ground
where the numbers are less than 40. Where the ground reads less than 40, manual ground
cancellation is required.
GC PHASE 90
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