Fisher Labs F 75, Руководство пользователя

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Comprehensive Operating Manual & Guide to Metal Detecting
Comprehensive Operating Manual & Guide to Metal Detecting
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F75
F75
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 similar to 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
The audio threshold in the STATIC mode is internally fixed and cannot be adjusted by the user.
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.
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.
The sensitivity system has two stages, 1-29 (low gain), and 30-99 (high gain). As you lower
sensitivity and cross the transition from 30 to 29 in STATIC mode, it may be necessary to
retune by pulling the trigger switch momentarily. You may need to adjust to a setting of 29 or
less to silence electrical interference, or to prevent overload on highly mineralized ground or in
salt water. You may also notice a shift in the ground balance setting over difficult ground
conditions as you cross this transition.
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 you 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.
TARGET ID
Move coil back-and-forth over target to see visual target ID.
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Frequency Shifting
One disadvantage of a highly sensitive metal detector is its susceptibility to electrical
interference from other electronic devices. If the detector chatters while the searchcoil is not
in motion, the cause is either electrical interference or internal circuit noise due to a high
sensitivity setting. If the detector chatters or emits intermittent false signals in the field, you
are also probably experiencing electrical interference. If you suspect electrical interference,
you may change the
F75’s
operating frequency. This is a trial and error method to try to find a
frequency different from the suspected source.
To shift frequencies:
1. Hold the MENU button down. Do not release the button.
2. Push the trigger forward
OR pull the trigger back to change the frequency.
Each frequency change requires a push of the MENU button.
Each actuation will shift the frequency by one value.
The LCD will display the frequency, from F1 to F4. F1 is the lowest frequency. And the default
frequency. The
F75
does not retain changes in the frequency setting, when powered off.
See the Search Techniques section of this manual for more information on electrical
interference.