User Manual

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TEKNETICS
Comprehensive Operating Manual & Guide to Metal Detecting
TEKNETICS
Comprehensive Operating Manual & Guide to Metal Detecting
GROUND CANCELLATION (continued)
3. Turn the SETTINGS KNOB to adjust the level.
The goal is to eliminate the sound as the coil is being pumped over the ground. In
some soils, the sound is not completely eliminated; rather, the audio feedback is the
same both when lowering the searchcoil to the ground, and when lifting the
searchcoil off of the ground.
If the ground cancellation adjustment is incorrect, there will be a difference in the sound as the
searchcoil is either moving toward or away from the ground. It sounds like you are either
pulling the sound out of the ground, or pushing the sound into the ground.
• If the sound is louder as you raise the searchcoil, increase the ground cancellation setting.
• If the sound is louder as you lower the searchcoil, reduce the ground cancellation setting.
•
NOTE: Experienced users often prefer to adjust the ground cancellation to get a weak but
audible response when lowering the searchcoil. This is called adjusting for positive response.
Positive and Negative Response
The purpose of ground cancellation is to adjust the metal detector to ignore ground minerals.
If the adjustment setting is off, ground minerals will give either a
positive or negative response,
depending on which direction the adjustment is off.
POSITIVE RESPONSE
If the G.C. setting is too high a number, the response of minerals will be positive. This means that
when the searchcoil is lowered to the ground in PinPoint or All Metal Mode, the sound will get
louder as the searchcoil approaches the ground. The sound will grow quieter as the searchcoil is
raised. What, if anything, you hear in Discrimination Mode depends on the discrimination setting.
When searching in All Metal Mode, if ground cancellation is properly set to cancel the ground, and
you sweep over a
positive hot rock, the rock will give a “zip” sound similar to that of a metal object.
NEGATIVE RESPONSE
If the G.C. setting is too low a number, the response of minerals will be negative. When the
searchcoil is lowered to the ground in PinPoint or in All Metal Mode, the machine will be silent.
In All Metal Mode, the machine will sound off as the searchcoil is lifted away from the ground.
What you hear, or do not hear, in Discrimination Mode will depend on the discrimination setting.
When searching in All Metal Mode, a
negative hot rock will produce a “boing” sound after
passing over it, making it difficult to tell where it is located. It will not have the sound and “feel”
of a metal object.
TIP & TECHNIQUES (continued)
Position the searchcoil an inch or two (2.5-5cm) above the ground, and to the side of the
target. Then pull the trigger. Now move the searchcoil slowly across the target, and the sound
will communicate the target’s location. As you sweep from side to side, and hear no sound at
the ends of the sweep, the target is located in the middle of that zone, where the sound is
loudest and the audio pitch is highest. If the sound is loud over a wide area, the buried object
is large. Use the PinPoint feature to trace an outline of such large objects
Narrow It Down
To narrow the response further, position the searchcoil near the center of the response
pattern, release the trigger, and then pull it again. Now you will only hear a response when
the searchcoil is right over the top of the target. Repeat this procedure to narrow the zone
even further. Each time you repeat the procedure, the field of detection will narrow further.
Estimating Target SIZE, DEPTH, and SHAPE
When the trigger is pulled to activate Pinpoint, the LCD displays estimated depth. The
estimate is based on the presumption that it is a coin-sized target.
But what if it is not a coin-sized target? The most common example is that of an aluminum can.
Flattened aluminum cans are usually identified as dimes or quarters. Their large size will
produce a strong signal, tricking the microcomputer into thinking that it is a shallow coin.
The following technique differentiates buried aluminum cans from coins. Sweep back and forth
to get a feel for the target, keeping the searchcoil close to the ground. Now, continue to sweep
back and forth as you slowly raise the searchcoil higher and higher. If the response
diminishes quickly and never gets very broad, the target is probably a coin. If the response
diminishes slowly as you lift the searchcoil, and you get a broad response, the target is
probably an aluminum can. Practice this by laying a coin and a flattened aluminum can on the
ground; you will quickly understand how to differentiate the two and will probably never have
to dig another aluminum can again. And, you will know whether it was deep or shallow. This
technique works well in the All Metal Mode, and to a lesser extent in Discrimination Mode.
Objects which are ring-shaped, or flat and round like coins, tend to give a narrower, crisper
response than objects of similar size with irregular shapes. The easiest way to demonstrate
this is with an aluminum screwcap from a soda bottle. In its normal shape, it occupies a
volume, and gives a somewhat broader response than that of a coin. But if you flatten it, the
response will be crisper and more like that of a coin. Again, these differences are most readily
noticed in All Metal Mode.
Long skinny iron or steel objects such as nails usually produce a double response when scanned
lengthwise, and a weaker single response when scanned crossways. This is most noticeable in
the All Metal Mode. However, a coin lying on its edge can produce a similar response, so rely on
both the Target-ID as well as
target feel to distinguish between different kinds of objects. Objects
within 2 to 3 inches of the searchcoil will often produce multiple responses as you sweep across
them, because the response field close to the searchcoil is irregular.