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Comprehensive Operating Manual & Guide to Metal Detecting
PRO-TECH
CONTROL PANEL (continued)
GAIN versus THRESHOLD
“Gain” increases, or multiplies, the strength of signals from buried metal objects.
For maximum detection of the smallest or most deeply buried objects, increase
the Gain. To minimize the weakest signals, reduce the Gain.
“Threshold” controls the detector's audio level. Positive threshold values amplify
the audio response of weak target signals. Negative threshold values suppress
sensitivity.
For searching at maximum sensitivity, first set the gain at a low level. Then set
threshold into the positive region, with a comfortable background-hum volume
level. Then increase Gain to a comfortable level, free of chatter.
For silent searching, set threshold to a negative number, and also reduce Gain if
necessary. Silent searching will result in the loss of some sensitivity.
TOUCHPAD CONTROLS
1. GG / PINPOINT
This button has a dual function, depending on the detection mode.
a. In DISC Mode, press-and-hold the button to activate PINPOINT.
Pinpoint temporarily engages a no-motion detection mode. Searchcoil motion
is not necessary to detect metal. Any metal within the searchcoil's detection
field will induce a sound. Pinpoint is generally used to verify a target
previously detected in Discrimination Mode.
b. In ALL METAL Mode, press-and-hold the button to activate GROUND GRAB
®
.
Ground Grab
®
allows you to set the detector's internal ground setting equal to
the phase of the ground you are searching over. See the section on Ground
Balancing for a more thorough explanation of this feature and the reason for
using it.
2. + and -
a. In Discrimination Mode, + and - change the level of discrimination (target
rejection)
b. In All Metal Mode, + and - provide a manual override to the Ground Balance
Setting.
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PRO-TECH
Comprehensive Operating Manual & Guide to Metal Detecting
GROUND BALANCING
What is Ground Balancing?
Why do I need to Ground Balance?
All soils contain minerals. Signals from ground minerals are often tens
or hundreds of times stronger than a buried metal object. The
magnetism of iron minerals, found in nearly all soils, causes one type
of interfering signal. Dissolved mineral salts, found in some soils, are
electrically conductive, causing another type of interfering signal.
Ground Balancing is the process by which the metal detector
cancels the unwanted signals coming from the ground minerals
while still detecting the signals from buried metal objects. This is
accomplished by matching the detector's ground
balance setting to the phase of the ground signal.
When the detector is calibrated to the soil, the
result will be deeper target detection, quieter
operation and more accurate target identification.
How to Ground Balance
your detector:
Ground Balancing procedure with the “GG”
touchpad.
1.
Turn the detector on and set GAIN at the 12:00 position.
2.
Click on the right knob to the ALL METAL Mode.
3.
Rotate the THRESHOLD control knob to the point where you hear a slight
background hum.
4.
Sweep searchcoil across the ground to find a clear patch of ground with no
metal present.
5.
Press and hold the GG touch pad, and pump coil over the clean ground.
See illustration.
Pump coil from within 1” of ground to 6”- 8” above ground.
6.
When the GND PHASE settles down to only 1 or 2 numbers in variation, release
the Gnd Grab button while still pumping the coil. Note that the audio response to
the ground changed and “Evened Out” when you released the button. Also note
that the GND BAL value changed. After balancing, you can hunt in ALL
METAL... or return to Disc Mode.
The most accurate GND PHASE value is the value displayed when “pumping” the
searchcoil over the ground in an area free of metal.
Ground Balancing continued on next page
Pumping coil
to ground
balance with
GG button.
