Ground Balancing - Fisher Labs F5 Operating Manual

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 as strong as the
signal from 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.
H H o o w w t t o o G G r r o o u u n n d d B B a a l l a a n n c c e e y y o o u u r r d d e e t t e e c c t t o o r r : :
Ground Balancing procedure with the "Phase Lock" touchpad.
1 1 . . Turn the F5 on and select AM (All-Metals) mode.
2 2 . . Find a clear piece of ground with no metal
present, using All-Metals or Pinpoint mode.
(Note: Pinpoint preferred)
3 3 . . Set the threshold to a slight background hum.
(Note: default setting of "0" is adequate)
4 4 . . Press and hold the Phase Lock touch pad, and
pump coil over clean ground.
(Note: pump coil from 1" off ground to 6-8" off ground)
5 5 . . When the phase value "settles down" to only one or two numbers
in variation, release the Phase Lock touch pad 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 setting changed to match the Phase Value, giving
you a visual AND audio Ground Balance confirmation. After
balancing, you can hunt in All-Metals... or return to Disc Mode.
To maintain the best ground balance setting for your detector, the GND
BAL setting on the left of the screen should always approximate the
PHASE value on the right of the screen.
The most accurate PHASE value is the value displayed when "pumping"
the coil over the ground in an area free of metal.
1 1 2 2