Fisher Labs M-66 User manual

FISHER RESEARCH LABORATORY
1465-H Henry Brennan,
El Paso, Texas 79936
Tel [phone] Fax [phone]
www.fisherlab.com email:info@fisherlab.com
QUALITY
Fisher detectors are renowned for their quality.
Each detector is hand crafted in the USA with pride
PERFORMANCE
Our detectors and locators are durable, dependable, and
search deeper.
REPUTATION
Fisher produced the first patented metal detector in 1931. For
over 70 years, the Fisher logo has been a mark of excellence.
2 YEAR WARRANTY
Fisher believes in the products we produce and backs this belief
with a 2 year limited warranty. Warranty may vary outside the
United States. See your dealer for details
SERVICE
Fisher is committed to providing you, our valued customer, with
superior service. Each and every instrument is rigidly tested
and carefully inspected during assembly and before shipment.
Should you have any questions or problems, contact:
FRL 8700005-D
M-66
Operating Manual
Valve and Box Locator
(Metal Detector)
FISHER RESEARCH LABORATORY
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176 - TestEquipmentDepot.com

7
M-66 SPECIFICATIONS
Search Loop Configuration....Double D (direct wired)
Output Frequency of Loop....4.5kHz,
Output Indication....................Speaker 16 ohm impedence
............................................Audio fequency 450 Hz
Power Supply...........................9V, each
Power Consumption...............(-9V) 17 mA
............................................(+9V) 4mA min, 6 mA sound
............................................threshold, 125 mA max sound
Weight with 8” coil ..................4.25 lbs.
Operating Temp......................-40 to +1580F (-200to +700C)
............................................search loop immersible in water
Dimensions...............................Length 28” to 48” adjustable
............................................(71cm to 122 cm)
Shipping Weight ......................7 lbs.
Shipping Dimensions...............34.75” x 12.75” x 5.25”
............................................(88.3 x 32.4 x 13.3cm)
Subject to improvement or modification without notice.
Fisher Research Laboratory does not warrant suitability to specific use. Fisher Research
Laboratory shall in no event be liable for any direct, incidental, consequential or indirect
damages.
Description.................................................................................pg. 3
Control Panel ............................................................................pg. 4
Setting Up...................................................................................pg. 5
Tuning ........................................................................................pg. 5
Searching...................................................................................pg. 6
Headphones..............................................................................pg. 6
Specications ............................................................................pg. 7
Treasure Hunter’s Code of Ethics.............................................pg. 7
CONTENTS

6
M-66 SEARCHING
It is a good idea to establish a methodic search pattern.
Avoidswingingthe M-66 like a golf club,swingthe detec-
torsideto sidekeepingthe searchcoilthesamedistance
abovethe ground. Yoursweeppattern shouldbeaslow,
half-circle motion. If you are searching for a small target,
it is a good idea to overlap your sweeps.
Whenthedetector’ssearchcoilstartstopassoverametal
object, the sound will increase and the meter readings
will increase. Depending upon the size and depth of the
target,thetargetmayappear(respond)tobelargerthen
it should. To get a visual outline of the target, you need
to reduce the sensitive of the M-66. An easy way to do
that is to raise the coil and pass over the target. This can
help establish the edges of the target.
Anothermethod that will give a visual outline is to reduce
the Tuning Control (sensitivity) of the M-66. Move the
coil away the target. Reduce the Tuning Control (turn
counter-clockwise) approximately ¼of a turn. Sweep
across the target area. The sound and meter readings
willbemoreresponsive as the searchcoilpassesover the
target. You may need to repeat this step more times if
the target is at a shallow depth. Be aware that you can
loose responsiveness of the target by over reducing the
Tuning Control (sensitivity) of the M-66.
DESCRIPTION
1
3
The Model 66 Valve and Box Locator (M-66) offers the utility indus-
try an uncomplicated detector for finding buried metal objects.
This all-metal metal detector can even search through concrete
and asphalt. Please note that the M-66 is a Metal Detector which
should not be a substitute for a Utility Line Tracer. Fisher Research
Laboratory manufactures a complete line of equipment for Line
Tracing.

MeterThe meter of the M-66 serves two purposes for
the operation of the machine. When used with
the battery test button, the meter gives a visual
indication of the battery strength. A reading
between 80 – 100 is desirable. If the reading
is below 80, search depth can decrease and
accuracy may be in question. When searching
with the M-66, the meter gives a visual indication
to any change occurring in the field of detec-
tion. This is primarily due to the coil passing over
a metal object, but can also occur when the
ground mineral conditions change.
Battery Test
With the detector turned on, depressing the
Battery Test button will indicate battery
strength.This is a no-load battery test.
On/Off Ground Rejection
This control turns the M-66 on and off. It is used
to electronically balance the M-66 to compen-
sate for the natural mineral content of the soil or
ground surface. When tuned properly, raising
and lowering the search coil above the ground
will not cause a change in the meter reading or
audio tone.
Tuning Control
This control is used to adjust the detector to the
thresh old point. This threshold point is a point at
which a very faint audio tone is heard and the
meter reads 10. The Tuning Control can also be
thought of as the Sensitivity control for the M-66.
4
M-66 CONTROL PANEL
The M-66 Control Panel.
5
M-66 SETTING UP
The M-66 comes ready to use.
Extend the lower stem of the M-66 so that the search coil
rests between 6 to 12 inches in front of your feet. Your
arm should be straight and relaxed with your grip held
loosely.Tighten the locking knot at the bottom of the up-
per stem.
When the proper length is selected, the excess cable
should be wound around the stem. This can be done by
slightly loosening the locking knot and turning the lower
stem, or by removing the search coil and winding the
cable by hand. Be sure to leave a some slack in the
cable.
M-66 TUNING
Select an area that is free of metal near and under the
search coil.
Turn the M-66 on by setting the Ground control to the po-
sition “5”. If the M-66 is sounding, turn the Tuning control
counter-clockwise until the sound vanishes.In the same
respect,if you have no sound then turnthetuningcontrol
clockwise until the needle moves to about “10” and the
sound is heard. NOTE: the tuning control is a multtiturn
control
Check the batteries by pressing the Battery Test button.
A reading between 80 and 100 indicates the batteries
are OK.
Setthe coil on theground. Adjustthe Tuning Control(turn
knob clockwise) so there is a slight threshold sound, and
the meter reads 10.
Lift the coil approximately 12 inches off the ground.
Note any change of sound. If there is no change, the
M-66 is balanced and ready to search. If the sounds
changes:
Soundincreases–IncreasetheGroundsetting.Repeat
above procedure.
Sound decreases – Decrease the Ground setting.
Repeat above procedure.
Repeat until the no change of sound occurs.
Proper tuning is essential for accurate locating.

MeterThe meter of the M-66 serves two purposes for
the operation of the machine. When used with
the battery test button, the meter gives a visual
indication of the battery strength. A reading
between 80 – 100 is desirable. If the reading
is below 80, search depth can decrease and
accuracy may be in question. When searching
with the M-66, the meter gives a visual indication
to any change occurring in the field of detec-
tion. This is primarily due to the coil passing over
a metal object, but can also occur when the
ground mineral conditions change.
Battery Test
With the detector turned on, depressing the
Battery Test button will indicate battery
strength.This is a no-load battery test.
On/Off Ground Rejection
This control turns the M-66 on and off. It is used
to electronically balance the M-66 to compen-
sate for the natural mineral content of the soil or
ground surface. When tuned properly, raising
and lowering the search coil above the ground
will not cause a change in the meter reading or
audio tone.
Tuning Control
This control is used to adjust the detector to the
thresh old point. This threshold point is a point at
which a very faint audio tone is heard and the
meter reads 10. The Tuning Control can also be
thought of as the Sensitivity control for the M-66.
4
M-66 CONTROL PANEL
The M-66 Control Panel.
5
M-66 SETTING UP
The M-66 comes ready to use.
Extend the lower stem of the M-66 so that the search coil
rests between 6 to 12 inches in front of your feet. Your
arm should be straight and relaxed with your grip held
loosely.Tighten the locking knot at the bottom of the up-
per stem.
When the proper length is selected, the excess cable
should be wound around the stem. This can be done by
slightly loosening the locking knot and turning the lower
stem, or by removing the search coil and winding the
cable by hand. Be sure to leave a some slack in the
cable.
M-66 TUNING
Select an area that is free of metal near and under the
search coil.
Turn the M-66 on by setting the Ground control to the po-
sition “5”. If the M-66 is sounding, turn the Tuning control
counter-clockwise until the sound vanishes.In the same
respect,if you have no sound then turnthetuningcontrol
clockwise until the needle moves to about “10” and the
sound is heard. NOTE: the tuning control is a multtiturn
control
Check the batteries by pressing the Battery Test button.
A reading between 80 and 100 indicates the batteries
are OK.
Setthe coil on theground. Adjustthe Tuning Control(turn
knob clockwise) so there is a slight threshold sound, and
the meter reads 10.
Lift the coil approximately 12 inches off the ground.
Note any change of sound. If there is no change, the
M-66 is balanced and ready to search. If the sounds
changes:
Soundincreases–IncreasetheGroundsetting.Repeat
above procedure.
Sound decreases – Decrease the Ground setting.
Repeat above procedure.
Repeat until the no change of sound occurs.
Proper tuning is essential for accurate locating.

DESCRIPTION
1
3
The Model 66 Valve and Box Locator (M-66) offers the utility indus-
try an uncomplicated detector for finding buried metal objects.
This all-metal metal detector can even search through concrete
and asphalt. Please note that the M-66 is a Metal Detector which
should not be a substitute for a Utility Line Tracer. Fisher Research
Laboratory manufactures a complete line of equipment for Line
Tracing.
6
M-66 SEARCHING
It is a good idea to establish a methodic search pattern.
Avoid swinging the M-66 like a golf club, swing the detec-
tor side to side keeping the search coil the same distance
abovethe ground. Yoursweeppattern shouldbeaslow,
half-circle motion. If you are searching for a small target,
it is a good idea to overlap your sweeps.
When the detector’s search coil starts to pass over a metal
object, the sound will increase and the meter readings
will increase. Depending upon the size and depth of the
target, the target may appear (respond) to be larger then
it should. To get a visual outline of the target, you need
to reduce the sensitive of the M-66. An easy way to do
that is to raise the coil and pass over the target. This can
help establish the edges of the target.
Another method that will give a visual outline is to reduce
the Tuning Control (sensitivity) of the M-66. Move the
coil away the target. Reduce the Tuning Control (turn
counter-clockwise) approximately ¼ of a turn. Sweep
across the target area. The sound and meter readings
will be more responsive as the search coil passes over the
target. You may need to repeat this step more times if
the target is at a shallow depth. Be aware that you can
loose responsiveness of the target by over reducing the
Tuning Control (sensitivity) of the M-66.
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c or where
other dangers are present. This device is to be used with
interconnecting cables/headphone cables shorter than three
meters.
USING HEADPHONES

Description.................................................................................pg. 3
Control Panel ............................................................................pg. 4
Setting Up...................................................................................pg. 5
Tuning ........................................................................................pg. 5
Searching...................................................................................pg. 6
Specifications ............................................................................pg. 7
CONTENTS
7
M-66 SPECIFICATIONS
Search Loop Conguration....Double D (direct wired)
Output Frequency of Loop....4.5kHz,
Output Indication....................Speaker 16 ohm impedence
............................................Audio fequency 450 Hz
Power Supply...........................9V, each
Power Consumption ...............(-9V) 17 mA
............................................(+9V) 4mA min, 6 mA sound
............................................threshold, 125 mA max sound
Weight with 8” coil ..................4.25 lbs.
Operating Temp......................-4 0 to +1580F (-200to +700C)
............................................search loop immersible in water
Dimensions ...............................Length 28” to 48” adjustable
............................................(71cm to 122 cm)
Shipping Weight ......................7 lbs.
Shipping Dimensions ...............34.75” x 12.75” x 5.25”
............................................(88.3 x 32.4 x 13.3cm)
Subject to improvement or modication without notice.
Fisher Research Laboratory does not warrant suitability to specic use. Fisher Research
Laboratory shall in no event be liable for any direct, incidental, consequential or indirect
damages.
TREASURE HUNTERS’ CODE OF ETHICS
LETS PRESERVE OUR TREASURED SPORT!
Laws governing the use of metal detectors are becoming more
and more common. In many countries, the use of metal detectors
is illegal or severely restricted. Don’t let this happen in your area.
• Always check Federal, State, County and local laws before
searching.
• Respect private property and do not enter private property
without the owner’s permission.
• Take care to rell all holes and try not to leave any damage.
• Remove and dispose of any and all trash and litter found.
• Appreciate and protect our inheritance of natural resources,
wildlife and private property.
• Act as an ambassador for the hobby, use thoughtfulness,
consideration and courtesy at all times.
• Never destroy historical or archaeological treasures.
• All treasure hunters may be judged by the example you set; always
conduct yourself with courtesy and consideration of others.

QUALITY
Fisher detectors are renowned for their quality.
Each detector is hand crafted in the USA with pride
PERFORMANCE
Our detectors and locators are durable, dependable, and
search deeper.
REPUTATION
Fisher produced the first patented metal detector in 1931. For
over 70 years, the Fisher logo has been a mark of excellence.
2 YEAR WARRANTY
Fisher believes in the products we produce and backs this belief
with a 2 year limited warranty. Warranty may vary outside the
United States. See your dealer for details
SERVICE
Fisher is committed to providing you, our valued customer, with
superior service. Each and every instrument is rigidly tested
and carefully inspected during assembly and before shipment.
Should you have any questions or problems, contact:
FRL 8700005-D
M-66
Operating Manual
Valve and Box Locator
(Metal Detector)
FISHER RESEARCH LABORATORY
110606
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com