Bobbing - Fisher Labs CZ-21 QuickSilver Operating Manual

GROUND BALANCING
BOBBING METHOD
1. Turn disc knob to "AUTOTUNE", this puts you into
2. Lower the coil an inch or two above the ground and
3. Your objective now is to adjust the GROUND control
a) It will fade again as you lower the coil and
b) lt will get louder as you lower the coil and go
c) The hum will remain the same, or if it changes
Autotune mode. Set the "SENSITIVITY" control so that
you just barely hear a threshold hum.
Hold the search coil 6 to 12 inches over the ground
and at least 3 feet away from any metal objects. Do
not use the PINPOINT button during any part of this
procedure.
then quickly raise it. Note that as you lower the coil,
the tone disappears then gets louder as you raise it
and finally returns to normal when you stop it 6 to 12
inches above the ground. Conversely, if you set the
GROUND control to "1," the threshold hum will get
louder as you lower the coil and disappear when
you raise it.
so that there is no change, or only a minimum
change in the threshold hum, as you move the coil
up and down. Start by lowering the GROUND control
to "9." Lower the coil and raise it again. One of three
things will happen to your threshold hum:
increase as you raise it. Continue to lower the
ground balance setting in small increments until
the threshold hum remains the same (or changes
very little) as the coil is lowered and raised.
silent as you raise it. You have gone past the
correct ground-balance setting. Increase the
ground-balance level (rotating the control
counterclockwise) in small increments until there
is little or no change in the threshold level.
slightly, the change is the same whether you
lower or raise the coil. Your CZ-21 is properly
ground balanced, and you are ready to begin
searching.
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