Static All Metal Mode - Fisher Labs F75 User Manual

STATIC ALL METAL MODE

This mode is useful for finding large, deep objects, i.e. larger than a coin and deeper than
12 inches (30cm). STATIC functions the same as PinPoint but occupies a different
position on the user interface. The audio signal gets stronger as the searchcoil approaches
the ground. Unlike the other modes, the detection sound will not disappear if you stop
moving the searchcoil.
The four adjustments are performed the same as with MOTION All Metal Mode, as
described on the preceding page.
THRESHOLD
While holding the searchcoil in the air, adjust the audio threshold to hear a constant
background hum. Expect to hear some random noise "riding on top of" the audio threshold.
If the machine runs silent, with no audible threshold, you will lose sensitivity.
Retuning: The audio threshold will slowly drift when searching in this mode. If you
move quickly between temperature environments, such as from shade to sun, audio
threshold may drift more rapidly until the searchcoil temperature stabilizes. When
the audio threshold drifts in this fashion, pull the trigger back momentarily to
retune the detector. You will need to retune periodically when searching in this
mode.
Special Technique : Suppressing Audio Threshold.
If looking for a known large object at shallow depth, i.e. a survey marker or valve
box, you will not want to hear small shallow trash items. In this case, set the
detector up normally, and then reduce the threshold setting well into the silent zone.
Search with the searchcoil several inches above the ground. If you still detect small
metallic trash items, reduce the sensitivity until they are no longer detected. When
detecting in this manner, occasionally raise the searchcoil at least one foot (30cm)
above the ground and pull the trigger momentarily to retune.
AUDIO PITCH
Works the same as in MOTION mode; see previous page.
SENSITIVITY
Set the sensitivity high enough too hear some random background noise and/or a slight
amount of ground response. If you do not hear these noises, you will sacrifice detection
depth. If the background chatter is too annoying, or the ground noise is so high that it
impedes operation, reduce sensitivity. Such a downward adjustment in sensitivity improves
depth detection as you can now hear weak signals better.
GROUND BALANCE
Always perform the ground balance procedure before searching in STAT mode, using the
trigger or with the manual adjustment.
If you do not ground balance before searching in STAT mode, most ground will produce an
audible tone as yo u lower the searchcoil; the ground will "sound off." Some soils will not
sound off, but will remain quiet with a loss of sensitivity.
Depth Display
To see a target's depth, in inches, pull the toggle switch.
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