Teknetics Tek-Point Owner's Manual page 13

OPER TION
As a result of the Tek-Point's extreme sensitivity, you may
encounter ground mineralization conditions that require an
alternate calibration method. If the pinpointer "falses", or
beeps erratically, when touched to the ground you may want
to turn it on after touching it to the ground.
Alternate Calibration Procedure:
1. Start with power OFF.
2. Touch the tip of the probe to the soil.
3. Quickly press-and-release the button to turn power ON.
4. Pinpointer is silent and ready to detect.
Caution: If you turn on the Tek-Point in close proximity to a
metal target in the ground, you may desensitize it, or put it into
overload. If using this alternate ground calibration method, be
sure to touch the tip to the ground away from your target.
GROUND-MINERAL CAL. (CONTINUED)