Fisher F70 User Guide

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Metal Detector

Users Manual

Also available with 11”DD coil (Item# F70-11DD)

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, Call 915-225-0333 or 1-800-685-505, and ask for Fisher Hobby Technical Service.

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

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 109 root Hertz (detectivity)
Lag Coefficient:	78 milliseconds
Overload:	standard 10” elliptical concentric
	Reactive approximately 10,000 micro-cgs
	Resistive approximately 1,200 micro-cgs
	accessory 11” bi-axial
	Reactive approximately 30,000 micro-cgs
	Resistive approximately 3,700 micro-cgs
Resistive Overload:	approximately 1,200 micro-cgs units (volume susceptibility)
	4,800 micro-cgs units with sensitivity < 30.
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
	Estimated 80 hours with nickel oxyhydroxide batteries
	Estimated 65 hours with lithium iron disulfide batteries
Operating
Temp Range:	4 to +122 degrees F (-20 to +50 degrees C)
Operating
Humidity Range:	0-90% non-condensing

Quick Start

Use your F70 right out of the box

1.Assemble the detector (see instructions beginning page 4).

2.Install four AA alkaline batteries. All positive (button-end) terminals point up.

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 F70 starts out in the Discrimination mode, with presets at: 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.

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.

OPERATING MANUAL & GUIDE TO METAL DETECTING

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.

Optional

Arm Strap

Coil

Knob

Biaxial

Search Coil

Top

Locking

Collar

Lower

Locking

Collar

Coil Bolt

Assembly (continued)

Assembly is easy and requires no tools.

● Position detector upright.

●Rotate the LOCKING COLLAR fully in a counter clockwise direction.

LOCKING

COLLAR

INTERNAL

CAM LOCK

SILVER BUTTON

MIDDLE

STEM

S-ROD

●Insert your finger inside the tube and make sure the INTERNAL CAM LOCK is flush with the inside of the tube.

●Insert the MIDDLE STEM into the S- ROD.

S-ROD

MIDDLE STEM

●Rotate the MIDDLE STEM until the SILVER BUTTON locates in the hole.

●Twist the LOCKING COLLAR fully in the clockwise direction until it locks.

●If your detector has 3 tubes and 2 Locking Collars, repeat this process on the Lower Stem.

●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.

●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.

●Wind the Cable securely around the Stems.

A loose or moving Cable can cause false signals.

●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.

●Tighten both Locking Collars.

●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.

Hand-	Cable
grip	Plug
S-Rod	Velcro
	Velcro
	Strap
	Locking
	Collar
	Middle
	Stem
	Locking
	Collar
	Velcro
Lower	Strap
Lower
Stem
Knurled
Kno
	Bolt

Searchcoil

OPERATING MANUAL & GUIDE TO METAL DETECTING

Mechanicals

BATTERIES (not included)

The F70 requires four AA batteries.

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, they die suddenly with little warning.

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 positive terminals facing upward.

The LCD screen shows battery condition on the right.

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. Any headphone with a 1/4” stereo plug should work; headphones with a mono plug will not work. A few electronic head phones may not be compatible. This device is to be used with interconnecting cables/headphones shorter than three meters.

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 traffic or where other dangers, like rattlesnakes, are present.

This device is to be used with interconnecting cables/headphone cables shorter than three meters.

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 F70 operates at 13 kHz for good sensitivity to gold nuggets and jewelry as well as to coins. The F70 comes with a 9 3/4”-inch open-frame waterproof 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 AA alkaline 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 F70 design team was John Gardiner. John’s previous Fisher design credits include the F75, F4, and F2. Assisting John Gardiner were John Griffin, Dave Johnson, Mark Krieger, and Gerhard Staiger.

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.

OPERATING MANUAL & GUIDE TO METAL DETECTING

Controls

ON-OFF & VOLUME Knob (Under the elbow)

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.

		Frequency
		Shift
	Menu
	Control
		Ground
	Minus	Balance
	Minus	Activation
	Programming	Activation
	Programming
		Plus
	Pin-Point	Programming
	Pin-Point

On/Off &

Volume

Controls (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 ■ indicator will remain 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.

+ 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.

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. Note that after changing frequencies, you need to ground balance the detector again, as changing operating frequencies will move the ground balance point.

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 Autotune mode:

1. Press MENU until the DISC LEVEL line of the menu system is highlighted. 2. Press “-“ until the display reads“At”.

To return to Discrimination mode:

1. Press MENU until the DISC LEVEL line of the menu system is highlighted.

2. Press “+” until a value other than“At” is displayed.

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 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.

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 “At” with “-“

2.Then press MENU until “PROGRAM” is 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 “At”.

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 ■ symbol.

+ 28 hidden pages