Fisher Impulse User manual

Impulse
Operating Manual
Pulse Induction Metal Detector
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. 19
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 induction-balance metal detectors. And
stability is greatly improved. There’s no need to retune the
IMPULSE every few feet.
1

ABOUT YOUR DETECTOR
2
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.

3
12. Battery Life: About 40 hours on carbon-zinc
batteries. Even more with alkalines.
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.
ABOUT YOUR DETECTOR
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
CONDENSED OPERATING INSTRUCTIONS

4
ASSEMBLY
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 search-
coil assemblies from the carrying case. Be careful
not to damage the foam-rubber inserts or put any
strain on the cable connections.
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.
9. Retune your IMPULSE before resuming your
search.
10. Good Hunting!
Fisher M-Scope IMPULSE pulse induction metal detector.
Liquid crystal
Display
Light emitting
diode (LED)
Adjustable
arm rest
Foam hand grip
Control panel
Armrest
screws
Fiberglass upper stem
Coiled
cable
Headphone
plug
Submersible
headphones
Fiberglass
reinforced
lower stem
Nylon wing nut
8-inch Spider coil
Battery access panel
(not shown)
CONDENSED OPERATING INSTRUCTIONS

5
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 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 illustration above. 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 Upper stem
Built-in detector stand
The arm rest can be
repositioned by
readjusting two
screws on the upper
stem.
ASSEMBLY

6
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.
3. 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.

7
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.
SETTING UP

8
FOR HIPMOUNTING
For almost effortless treasure hunting, the control housing is
easily removed from the handle and attached to a belt clip.
“Hipmounting” the IMPULSE in this manner takes half the
weight off the handle and allows the land or shallow-water
Treasure Hunter to search much longer without arm fatigue.
1. Grasp the handle grip firmly with one hand and the control
housing with the other.
2. Slide the control housing off the mounting bracket by pulling
it toward you.
3. Slide the belt clip into grooves on the bottom of the control
housing. This is a snug fit, and you’ll have to bend the belt clip
slightly.
4. Unwrap just enough of the coil cable to allow for searching.
5. Slip the control housing onto your belt, left side for right-
handers, right side for left-handers.
NOTE:
Because of the extreme sensitivity of the IMPULSE search coil,
hipmounting the control housing may produce a false signal
when the search coil reaches the end of its arc (on the side
that the control box is attached to your belt). Depending on
your stem length and how high you have the housing hip
mounted, the search coil may actually detect the housing.
You can hipmount your IMPULSE by sliding the control housing
off the handle and attaching it to your belt. This reduces the
weigth of the stem, creating nearly effortless hunting.
SETTING UP