Fisher Impulse User Manual

Impulse

Pulse Induction Metal Detector

Operating Manual

FISHER RESEARCH LABORATORY

CONTENTS

About Your Impulse................................................................pg. 1

Condensed Operating Instructions ...................................... pg. 3

Assembly .................................................................................pg. 4

Setting Up ................................................................................. pg. 6

For Land or Shallow Water ................................................. pg. 6

For Diving ............................................................................. pg. 7

For Hipmounting..................................................................pg. 8

Control Panel .......................................................................... pg. 9

Tuning.......................................................................................pg. 10

Searching ................................................................................ pg. 10

On land or Shallow Water ................................................. pg. 10

Underwater.......................................................................... pg. 12

Pinpointing............................................................................... pg. 13

Target Recovery ..................................................................... pg. 15

Recovery Tools ................................................................... pg. 15

Operating Tips ......................................................................... pg. 16

Batteries ...................................................................................pg. 17

Home Recharger ................................................................pg. 18

Auto Recharger ..................................................................pg. 18

Tips about Nicad Batteries ................................................. pg. 19

Maintenance ..........................................................................pg. 20

Storage................................................................................. pg. 20

Cleaning..............................................................................pg. 20

Battery Compartment ........................................................pg. 20

Treasure Hunter’s Code Of Ethics .......................................... pg. 21

Where To Use Your Metal Detector In The U.S. .................... pg. 22

Specifications .........................................................................pg. 23

ABOUT YOUR DETECTOR

Fisher Research Laboratory has been producing rugged, high quality, high performance metal detectors since 1931, longer than any other company in the world. Your IMPULSE is a product of that proud heritage. Designed for deep-sea treasure hunting, the IMPULSE will also do the job in surf, on the beach, in fresh water or on land.

Pulse induction (PI) metal detectors have been around for years. Their ability to detect metal in black sand and salt water make pulse induction metal detectors particularly suited to underwater treasure hunting, wreck diving, shallow-water treasure hunting and beach combing.

However, pulse induction metal detectors have had their drawbacks. Most have been heavy, expensive and unstable, requiring the operator to retune frequently. Pulse induction metal detectors also have had high battery drain, creating frustrating power loss and added expense.

But worst of all, pulse induction metal detectors have been plagued by slow response. Because the search coil is slow to respond to a target, sensitivity and depth can be maximized only at slow sweep speeds, forcing the operator to slow down, thereby covering less ground. “Autotune” pulse induction detectors do have a rapid response, but the search coil must be in motion to detect a target.

In 1985, engineers at Fisher Research Laboratory began work on a new pulse induction metal detector, one that would combine extreme depth in salt water with high battery performance, stability, low cost and fast target response.

Their answer is the IMPULSE—a no-motion detector that responds instantly to targets and frees the operator to hunt fast, slow or with no motion at all. In addition, battery life of the IMPULSE has been greatly extended over previous pulse induction detectors. In fact, battery life of the IMPULSE is better than most inductionbalance metal detectors. And stability is greatly improved. There’s no need to retune the IMPULSE every few feet.

ABOUT YOUR DETECTOR

Here are some important features built into your IMPULSE:

1. LCD: A liquid crystal display gives a visual indication of signal strength; with a bar graph that climbs as the signal strength increases. The LCD also constantly monitors battery strength.

2. LED: A light emitting diode flashes when a target is located.

3. VCO Pinpointing: An audio signal tone increases in pitch and volume as the center of the search coil passes over the target.

4. Leak proof: The IMPULSE is leak proof to 250 feet.

5. Salt Water Operation: Salt water or wet sand is

no problem for the IMPULSE. Its pulse induction technology virtually ignores salt water, making it the ideal underwater and beach-hunting machine.

6. Black Sand Operation: The IMPULSE penetrates black sand and some highly mineralized soils where ordinary detectors won’t work at all.

7. No-motion Pinpointing: You can sweep the IMPULSE search coil, or hold it motionless over your target and still get a target response.

8. Target Response: Sweep your search coil fast, slow or not at all. The IMPULSE responds to targets no matter how fast or slow you sweep the search coil.

9. Spider Coil: The 8-inch, open-center Spider coil makes pinpointing easier. It’s lightweight, tough, Electro-Static Insulated (ESI shielded) and 100 percent waterproof. Unlike most single-coil pulse detectors, the IMPULSE has a receiver coil in the center for easier and more accurate pinpointing.

10. Lightweight, Balanced and Comfortable: Only about 5 pounds total weight with a cushioned armrest and foam grip.

11. Hip-mountable: For almost effortless searching, the

control housing slides off the handle and onto your belt.

12. Battery Life: About 40 hours on carbon-zinc batteries. Even more with alkalines.

ABOUT YOUR DETECTOR

13. All Metals: The IMPULSE detects all metals. It

has no “discrimination” circuitry, which drastically reduces the ability of a pulse induction metal detector to detect gold and silver.

14. Easy to Use: Just pick it up, turn it on and adjust the TUNER control to the threshold level. You’re ready to hunt.

CONDENSED OPERATING INSTRUCTIONS

Your IMPULSE is fairly simple to operate; however, its no-motion design makes it operate differently from more-common, VLF, induction-balance metal detectors. Therefore, even if you are an experienced detector user, we strongly recommend that you read this entire manual before starting. But if you just can’t wait, here are some quick instructions to get you going on land.

1. Hold the coil up and away from any metal.

2. Set the tuner full counter clockwise, just before

it clicks into the “BATT TEST” position.

3. Set the VOLUME control knob to “10.”

4. Hold the search coil 1 to 2 inches above the

ground and adjust the TUNER control knob until the audio tone can just barely be heard (usually one

or two bars on the LCD).

5. Readjust the volume control to a comfortable level,

when the search coil is passed over a large target.

6. You’re ready to go. Walk slowly and keep the coil

close to and parallel to the ground.

7. To pinpoint a target, locate the spot where the volume and pitch of the audio signal peak. The LCD signal-strength meter will also peak when the center of the search coil is directly over the target.

8. To pinpoint the target more precisely, detune the detector by readjusting the TUNER control counter clockwise. This will reduce the sensitivity of the search coil until only the center, or hot spot, responds to the target.

CONDENSED OPERATING INSTRUCTIONS

9. Retune your IMPULSE before resuming your

search.

10. Good Hunting!

ASSEMBLY

Light emitting

diode (LED)

Liquid crystal

Display

Control panel

Foam hand grip

Adjustable

arm rest

Arm rest

screws

Fisher M-Scope IMPULSE pulse induction metal detector.

Battery access panel

(not shown)

Fiberglass upper stem

8-inch Spider coil

Nylon wing nut

Fiberglass

reinforced

lower stem

Coiled

cable

Headphone

plug

Submersible

headphones

Your Fisher IMPULSE requires very little assembly. Unpack it carefully and save the carton, which may come in handy for future storage or shipment.

1. Remove the headphone, handle and searchcoil assemblies from the carrying case. Be careful not to damage the foam-rubber inserts or put any strain on the cable connections.

2. Adjust the lower stem to the approximate length you will be using; extended for stand-up use or as short as possible for diving. To extend the lower

ASSEMBLY

stem, push in the spring lock, pull out the lower stem and let the spring lock snap into another hole.

3. If you will be using the IMPULSE on the handle and not body mounted, wind the search coil cable around the handle assembly as shown in the diagram on page 4. Secure the cable with the two Velcro straps included with your IMPULSE. Make sure there is some slack at the control-housing end and enough at the other end to attach the search coil.

4. Remove the Delrin bolt and nylon wing nut from the search coil. Line up the hole in the lower stem between the two holes in the search coil “ears”. Attach the coil to the stem with the bolt and wing nut and finger tighten.

5. The armrest may be repositioned for maximum comfort by removing the armrest screws, sliding the armrest to the next screw hole and reinstalling the arm-rest screws.

Arm rest

Built-in detector stand

Upper stem

The arm rest can be repositioned by readjusting two screws on the upper stem.

SETTING UP

FOR LAND OR SHALLOW WATER

Put the headphones around your neck to keep them out of the way while making the following adjustments:

1. Adjust the stem length and coil angle so the search coil rests flat on the ground about 6 inches in front and slightly to the right of your right foot (to the left of your left foot if you’re left handed). Your arm should be straight and relaxed with the handle grip held firmly but comfortably.

Remember, as you increase the shaft length, you also increase the strain on your wrist and arm. The IMPULSE is balanced for comfortable searching in a tight semicircle around the front of the operator.

2. Leave enough slack in the coil cable to allow the coil to swivel as far as it can in either direction. The coil wing nut should be tight enough to prevent the coil from moving.

You should now be able to move into your “search” position by leaning slightly forward and raising the search coil approximately 2 inches above the ground. Your arm should still be straight and the coil should be parallel to the ground, about 12 inches in front of your foot. The coil angle may have to be slightly readjusted at this point.

When searching on land or in shallow water, keep your arm straight and your search coil no more than 2 inches above ground.

SETTING UP

FOR DIVING

Unlike induction-balance metal detectors, the IMPULSE ignores the disruptive influences of salt water and black sand. This capability, along with its deep-seeking sensitivity to iron, makes it ideal for underwater treasure hunting and wreck diving. The IMPULSE is also waterproof to a depth of 250 feet. Remember, always practice safe diving methods.

Caution: Hipmounting the IMPULSE control housing is not recommended for underwater use. The search coil cable may become entangled with a submerged object, making it difficult for the diver to resurface quickly in case of emergency.

1. Adjust the stem length as short as you can without having the search coil detect your diving gear.

2. Adjust the search coil parallel to the seabed, river or lake bottom.

3. Make sure extra cable is coiled tightly on the upper stem as closely as possible to the control housing, with just enough slack near the search coil to allow it to swivel as far as it can in either direction. Extra cable near the search coil may generate false signals.

4. Remove the tethered earphone plugs for rapid pressure equalization as you dive and return to the surface.

Shortened stem length Extra cable

When diving with your IMPULSE, use the shortest possible stem length, with the extra cable wrapped tightly around the stem, as close as possible to the control housing.

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