Fisher F70 User Guide
Also available
with 11”DD coil
(Item# F70-11DD)
Metal Detector
Users Manual
OPERATING MANUAL &GUIDE TO METAL DETECTING
The F70 is a multipurpose metal detector.
It’s most popular uses are coinshooting and relic hunting.
Product Features
• Light weight and well-balanced
• Menu-driven user interface
• Large LCD screen
• Visual indicators of important values such as:
Target Identification
Target Confidence
Target Depth in Pinpoint Mode
Ground Mineralization (Dirt indicator)
• Two Search Modes:
Discrimination
Autotune
• GroundGrab™ touch pad ground balancing
• Waterproof 9 3/4” open-frame concentric elliptical search coil
• Touch pad actuated target pinpointing with variable audio pitch
• Adjustable Arm Rest
• Notch and discrimination controls
• Two retrievable user-programmed memory settings
If you have any questions, or need assistance with your metal detector,
915-225-0333 or 1-800-685-505, and ask for Fisher Hobby Technical
Call
Service.
Copyright Fisher Research Labs, Inc., 2011
2
Table Of Contents
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Quick-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Mechanicals
Assembly Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-7
Mechanicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Arm Rest Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Using Headphones (not included) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Introduction to the F70
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-11
Menu System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Ground Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-15
Autotune Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Discrimination Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17-19
Pinpoint Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
LCD Visual Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21-23
Frequency Shifting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Capabilities & Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25-26
Tips & Techniques
Search Techniques
How to Sweep the Search Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Pinpointing Targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Estimating Target Size, Depth, & Shape . . . . . . . . . . . . . . . . . . . . . . . . .28
False Signals & Chatter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Adjusting Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Tips on Ground Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Detecting Activities
Coinshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Relic Hunting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33-34
Gold Prospecting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35-36
Cache Hunting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Shallow Water Hunting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Salt-Water Hunting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
How Metal Detectors Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Treasure Hunter’s Code of Ethics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Back Cover
3
OPERATING MANUAL &GUIDE TO METAL DETECTING
Specifications
Mechanical: 3-piece breakdown aluminum pole system, batteries under elbow,
Armrest adjustment - forward/backward.
Search coil: 9 3/4” open-frame waterproof concentric elliptical search coil.
Batteries: 4 AA, alkaline (not included).
Weight: 2 pounds 15 ounces (1.3kg), with alkaline batteries installed.
Operating Principle: VLF induction balance
Operating Frequency: nominal 13 kHz, quartz crystal timing reference
Basic Sensitivity: 6 x 10
Lag Coefficient: 78 milliseconds
Overload: standard 10” elliptical concentric
Resistive Overload: approximately 1,200 micro-cgs units (volume susceptibility)
Ground Balancing
Range: From ferrite to salt, inclusive
Discrimination
Ground Suppression: combination of second and third order methods
ID Ground
Suppression: third order
Battery Life: Typically 40 hours with high quality alkaline batteries
9
root Hertz (detectivity)
Reactive approximately 10,000 micro-cgs
Resistive approximately 1,200 micro-cgs
accessory 1
Reactive approximately 30,000 micro-cgs
Resistive approximately 3,700 micro-cgs
4,800 micro-cgs units with sensitivity < 30.
Estimated 80 hours with nickel oxyhydroxide batteries
Estimated 65 hours with lithium iron disulfide batteries
1” bi-axial
Operating
T
emp Range: 4 to +122 degrees F (-20 to +50 degrees C)
Operating
Humidity Range: 0-90% non-condensing
4
Quick Start
Use your F70 right out of the box
1. Assemble the detector (see instructions beginning page 4).
2. Install four AA
3. Turn the knob, located under the armrest, fully clockwise.
This turns the machine on and sets audio volume to maximum.
4. When first turned on, the
Discrimination Level = 15 (iron eliminated) in both program-1 and -2.
Speed = dE
Sensitivity = 60
Threshold = 0
Number of Tones = 3
Sweep the search coil from side to side, parallel to the ground. Keep the search coil
moving over the ground. If you stop moving the search coil, the sound will also stop.
Probable target type will be indicated at the top of the LCD screen.
5. If the search coil is not in motion and not close to metal, the detector should be silent.
6. If you experience false signals from electrical interference, from the soil itself, or from lots
of trash metal, press MENU button until:
Sensitivity is highlighted.
Press “-” as needed
Reduce the sensitivity setting until the false signals go away.
After 7 seconds, the machine will exit the menu, unless you exit
by pressing MENU first.
7. Toss a coin on the ground and sweep back and forth over it a few times to get a feel for
how the machine responds.
alkaline batteries. All positive (button-end) terminals point up.
F70 starts out in the Discrimination mode, with presets at:
8. You are now ready to search.
9. Press-and-Hold the PINPOINT button to pinpoint the exact location of targets, making
them easier to unearth.
When Pinpoint is held ....
The search coil need not be in motion to detect an object.
The 2-digit numeric display indicates approximate target depth, in inches.
5
OPERATING MANUAL &GUIDE TO METAL DETECTING
Coil
Knob
Coil Bolt
Top
Locking
Collar
Lower
Locking
Collar
Biaxial
Search Coil
Optional
Arm Strap
Assembly
Adjusting the Arm Rest
The Arm Rest may be moved forward or
backward by removing the single screw and nut,
and then repositioning the 2-piece Arm Rest.
Users with shorter arms may find the Arm Rest
more comfortable in the forward position. In order to
move the Arm Rest backward, the plastic plug must
be removed from the aluminum tube.
Arm Rest Strap
(optional accessory)
The Arm Rest Strap accessory can be purchased
separately. Some users prefer to use the strap
when swinging the detector vigorously, in order
to hold the detector securely against the arm.
The detector can always be used without the
strap, with no compromise to detector balance
and stability under most conditions.
6
Assembly (continued)
Loc
kin
g
Col
lar
Loc
kin
g
Col
lar
S-R
od
Vel
cro
Str
ap
Vel
cro
Str
ap
Knurle
d
Kno
b
Bolt
Hand
-
grip
Low
er
Stem
Middle
Stem
Cab
le
Plu
g
Sea
rch
coil
S-ROD
LOCKING
COLLAR
INTERNAL
CAM LOCK
SILVER BUTTON
MIDDLE
STEM
S-ROD
MIDDLE STEM
Assembly is easy and
requires no tools.
1
Position detector upright.
●
2
Rotate the LOCKING COLLAR fully in
●
a counter clockwise direction.
3
Insert your finger inside the tube and
●
make sure the INTERNAL CAM LOCK
is flush with the inside of the tube.
4
Insert the MIDDLE STEM into the S-
●
ROD.
5
Rotate the MIDDLE STEM until the SILVER BUTTON locates
●
in the hole.
6
Twist the LOCKING COLLAR fully in the clockwise direction
●
until it locks.
7
If your detector has 3 tubes and 2 Locking Collars, repeat this
●
process on the Lower Stem.
8
Position the Lower Stem with the Silver Button toward the back.
●
Using the Bolt, Single Rubber Washer, and Knurled Knob, attach
the Searchcoil to the Lower Stem.
9
Adjust the Lower Stem to a length that lets you maintain a
●
comfortable upright posture, with your arm relaxed at your side,
and the Searchcoil parallel to the ground in front of you.
10
Wind the Cable securely around the Stems.
●
A loose or moving Cable can cause false signals.
11
Connect Cable Plug to housing.
●
Do not twist the Cable or Plug. Turn Locking Ring only. Use
minimal finger pressure to start the threads. Do not cross-thread.
When the Locking Ring is fully engaged over the threaded
connector, give it a firm turn to make sure that it is very tight.
When the Locking Ring is fully engaged over the threaded
connector, it may not cover all of the threads.
12
Tighten both Locking Collars.
●
13
Secure the Cable with the 2 Velcro Straps provided, one on the
●
Lower Stem close to the Searchcoil, and one on the Upper Stem,
close to the housing. Leave just enough slack in the Cable, at the
Searchcoil end, to be able to rotate the Searchcoil a small amount
about the Bolt. After full assembly and upon first use in the field,
check this adjustment. It is very important to keep the Cable secure
against the Stem, especially at high Gain, as movement in the
Cable may cause false signals.
7
OPERATING MANUAL &GUIDE TO METAL DETECTING
Mechanicals
BATTERIES (not included)
The F70 requires four AAbatteries.
These
non-rechargeable chemistries may be used: Alkaline, Nickel Oxy-Hydroxide
(Panasonic Oxyride or Duracel PowerPix), and lithium iron disulfide (Energizer L91).
Nickel metal hydride and nickel-cadmium
rechargeable chemistries may also be used.
Zinc-carbon and so-called “heavy duty” batteries may not work, especially in cold weather
Do not use these batteries.
Expect 40 hours of service in the field with one set of alkaline batteries.
Rechargeable batteries will usually deliver over 25 hours of service without recharging, but
when they start running low
Always install batteries which are of the same type and the same state of charge. Otherwise
battery life will be determined by the weakest battery, because the good batteries cannot
deliver their power with a dead battery blocking the current.
All 4 batteries are installed with the
The LCD screen shows battery condition on the right.
, they die suddenly with little warning.
positive terminals facing upward.
.
ARM REST
The arm rest is adjustable up and down the pole.
If you notice unwanted movement while swinging the detector, check the tightness of the
locking collars.
The locking collars must be rotated a full 270° to reach the locking position.
HEADPHONES (not included)
The F70 is equipped with a standard 1/4-inch stereo headphone jack at the rear of the unit,
located under the elbow as you hold the detector for use.
plug should work; headphones with a mono plug will not work.
may not be compatible.
shorter than three meters.
This device is to be used with interconnecting cables/headphones
Any headphone with a 1/4” stereo
A few electronic head phones
Using headphones (not supplied) improves battery life, and prevents the sounds from
annoying bystanders. It also allows you to hear subtle changes in the sound more clearly
particularly if searching in a noisy location. For safety reasons, do not use headphones near
traf
fic or where other dangers, like rattlesnakes, are present.
This device is to be used with interconnecting cables/headphone cables shorter than three meters.
,
8
Introduction to the Fisher F70
HIGH PERFORMANCE The F70 is a multi-purpose high-performance computerized metal
detector. It has the high sensitivity and ground balancing control needed for even the
most challenging soil conditions, the discrimination responsiveness needed for serious
relic hunting under difficult conditions, and visual target ID considered essential in
searching for coins. The
jewelry as well as to coins. The
concentric elliptical search coil for broad sweep yet narrow target pinpointing.
USER COMFORT The F70 is among the lightest and best balanced of all high-performance
metal detectors, so you can hold and swing it almost effortlessly. The grip is durable highfriction foam elastomer, comfortable in any kind of weather. The controls are
conveniently located and easy to learn how to use. Locking collars on the tubes
eliminate rattling.
EASY-TO-USE & INFORMATIVE INTERFACE The entire menu is always visible on the
LCD display. The LCD display indicates the electrical signature (target I.D.) of the
detected metal object. The display provides continuous information on battery condition
and on ground mineralization, which affects detection depth.
LOW OPERATING COST The F70 is powered by four AAalkaline batteries, which will
typically last for more than 40 hours of use before needing replacement.
DESIGNED BY SOME OF THE INDUSTRY’S MOST TALENTED ENGINEERS The lead
engineer on the
credits include the F75, F4, and F2. Assisting John Gardiner were John Griffin, Dave
Johnson, Mark Krieger, and Gerhard Staiger.
F70 design team was John Gardiner. John’s previous Fisher design
F70 operates at 13 kHz for good sensitivity to gold nuggets and
F70 comes with a 9 3/4”-inch open-frame waterproof
MECHANICAL ENGINEERING
While the F70 is robustly engineered for outdoor use, it is not indestructible and it is not
waterproof.
RESET function
The F70’s microprocessor will save all settings which you input, even after the power is
turned off.
If you wish to reset the settings to the factory preset, follow this process:
1. Turn detector off.
2. Press-and-hold both the GROUNDGRAB and MENU buttons.
3. Turn the detector on, while you are still pressing the buttons.
4. Detector displays “88”.
5. Release the buttons.
6. The detector is reset, and operating in program-1.
9
OPERATING MANUAL &GUIDE TO METAL DETECTING
Frequency
Shift
On/Off &
Volume
Pin-Point
Menu
Control
Minus
Programming
Plus
Programming
Ground
Balance
Activation
Controls
ON-OFF & VOLUME Knob
This knob turns the machine on or off, and controls speaker volume and headphone volume.
Knob position has no effect on detector’s sensitivity or susceptibility to noise from electrical
interference
The F70 has six controls on the front panel.
(Under the elbow)
10
Controls (continued)Search Techniques (continued)
MENU button
Push the MENU button to:
1. Step through the menu selections on the display.
With each push of the button, the next menu selection will be
highlighted.
The - or + buttons then allows you to change values for the highlighted
selection.
2. Recall the last setting which you adjusted.
After you have adjusted a setting, the
highlighted next to this menu selection. One push of the MENU button
will recall that selection and display the stored value.
This recall function is useful for a value you want to adjust frequently.
■
indicator will remain
+ and - buttons
Press + or - buttons to change the settings (or value) of the highlighted menu selection
you have chosen.
PINPOINT button
While the button is depressed, metal objects are temporarily detected without the need for
search coil motion. This aids in pinpointing the exact location of objects which were found
while searching in the Discrimination or Autotone modes.
GROUND GRAB
Press-and-hold the button to activate automatic ground balancing. The internal computer
measures the magnetic properties of the soil in order to cancel interference from naturallyoccurring minerals in the ground. After the detector measures the soil in this manner, the
detector then uses this information to control operation in both the Discrimination and Autotune
search modes. GROUND GRAB can be used at any time during operation. The coil must be
pumped up and down over the ground while holding the button. See section on ground
balancing.
Hz
Pressing this button changes the detector’s operating frequency. Use this feature if you
suspect that the detector is behaving erratically due to the presence of electrical interference
from some other electronic device. Press and release one time to change to another
frequency. Default value is 4. There are a total of 7 frequencies.
frequencies, you need to ground balance the detector again, as changing operating
frequencies will move the ground balance point.
Note that after changing
11
OPERATING MANUAL &GUIDE TO METAL DETECTING
The Menu System
The entire menu is printed on the LCD display.
There are two search modes, Discrimination and
Autotune.
To select the
To return to
Each search mode has several adjustable function
settings:
AUTOTUNE: Speed, Sensitivity, Threshold.
DISCRIMINATION: Discrimination Level, Speed, Sensitivity, Threshold, # of Tones, and Notch.
You can establish two different sets of program settings
Autotune mode:
1. Press MENU until the DISC LEVEL line of
the menu system is highlighted.
2. Press “-“ until the display reads
Discrimination mode:
1. Press MENU until the DISC LEVEL line of
the menu system is highlighted.
2. Press “+” until a value other than
displayed.
for recall, using the PROGRAM selection.
- The number next to “PROGRAM” indicates
which program is active.
- To change from one program to another, press
“+” or “-“ while “PROGRAM” is highlighted.
- Press “+” to choose program-2.
- Press “-“ to choose program-1.
“At”.
“At” is
One convenient application for PROGRAM is to
change easily between the Autotone and
Discrimination modes.
To do this, program the two modes as follows:
1. Go to DISC LEVEL. Select
2. Then press MENU until “PROGRAM” is highlighted.
Press “+” or “-“ to change the program number.
Then press MENU to move down to DISC LEVEL and press “+” or “-“ to choose a DISC
LEVEL setting other than
Then toggle between the two modes, or programs, as follows:
1. Press MENU until PROGRAM is highlighted.
2. While “PROGRAM” is highlighted, press “+” or “-“ to change between modes.
If you are programming the detector after pressing MENU and do not press a button after 7
seconds, the detector will exit the menu system automatically, and resume normal operation.
Any value currently displayed will be saved into memory.
If you press the MENU button while the machine is in normal operation, the user interface will
return to the last menu selection you had adjusted. The last menu selection is indicated while
the menu system is inactive with a highlighted
“At”.
“At” with “-“ button.
■
symbol.
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