Teknetics G2 Owner's Manual page 30

ELECTRICAL INTERFERENCE (EMI)
line of defense against electrical interference. The Threshold control only applies to
the All-Metal mode.
Electrical interference is usually more controllable in the All-Metals mode than in the
Discrimination mode.
On the G 2 , setting the discrimination level between 60 and 70 will usually reduce
electrical interference. In the Discrimination mode, the detector may chatter if the
searchcoil is not in motion, but once you start sweeping it over the ground, the signal
from the ground will usually suppress the electrical interference chatter, except for an
occasional pop or click which will not sound like a real target.
If you are conducting an indoor demonstration, you may find that changing the
orientation of the searchcoil will reduce the pickup of electrical interference.
If you carry a cell phone or other high-tech electronic equipment while metal detecting
and you encounter electrical interference, try turning the device off and see if that solves
the problem. Turn such devices completely off, not just into standby mode.
When working near overhead power lines, you may get the best results right under the
power line and the worst results when standing at a 30° to 45° angle to the power line.
Many sources of electrical interference are intermittent. You may find that an area which
is difficult to search at one time of day may be easier after 5 PM, or on weekends.
Power lines are usually quietest late at night, and on weekend mornings.
Small searchcoils usually pick up less electrical interference than larger searchcoils. On
a site with severe electrical interference, a small searchcoil is often a better choice than
a large one.
Distinguishing electrical interference from other problems
Electrical interference will often vary as you walk around from place to place, and it will
also vary with changes in the orientation of the searchcoil. This is almost never the
case if there is a functional problem with the metal detector itself.
The most common cause of a noisy metal detector, where the problem is not electrical
interference, is a defective searchcoil. If striking the searchcoil with your hand causes
the noise to start or stop, the problem could be a defective searchcoil. Also, a defective
searchcoil often causes noise of a more intermittent nature than electrical interference.
The second most common cause is a loose searchcoil connector. The noise from a
loose connector will usually be very erratic or intermittent in nature. Try unplugging the
searchcoil and then reconnecting it to ensure the connector is firmly installed.
If you use a searchcoil cover, dirt or water can accumulate inside it, and movement of
those materials can cause false signals while sweeping the searchcoil. Searchcoil
covers must be periodically removed and cleaned.
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