Fisher TW-6 User Manual
TW-6
Operating Manual
Pipe and Cable Locator
F I S H E R R E S E A R C H L A B O R A T O R Y
CONTENTS
Introduction ...............................................................................pg. 3
Receiver
.....................................................................................pg. 4
Transmitter
..................................................................................pg. 5
Component Descriptions
.........................................................pg. 6
Modes of Operation
.................................................................pg. 7
The Inductive Mode
..................................................................pg. 7
How to Assemble
......................................................................pg. 7
How to Tune
...............................................................................pg. 8
Inductive Locating (with handle)
............................................pg. 10
High Power (with handle)
.........................................................pg. 11
Inductive Tracing (without handle)
........................................pg. 12
Inductive Locating When Only Approximate Position of a
Linear Conductor is Known
......................................................pg. 13
Pinpointing Centering of the Pipeline
.....................................pg. 13
Determining Conductor Depth by Triangulation
..................pg. 14
Locating Manhole Covers, Valves, Tees and Risers
..............pg. 15
Locating Pipe When Other Lines are Close by
......................pg. 15
Conductive Tracing (without handle)
....................................pg. 16
Tracing Procedure
....................................................................pg. 18
The Tracer Probe
.......................................................................pg. 18
The Coupling Clamp
................................................................pg. 19
Locating Non-Metallic Pipes
....................................................pg. 20
Operating Hints
.........................................................................pg. 21
Changing Batteries
...................................................................pg. 22
Specifications
............................................................................pg. 23
INTRODUCTION
Since 1931, utility and construction craftsmen have looked to Fisher
to set the standard of quality in the design and manufacture of
locating equipment. The Model TW-6 with its many timesaving
accessories continues the Fisher M-Scope tradition of giving you
even greater speed and precision in locating underground pipes
and cables.
The surest way to effectively use the TW-6 and its new accessories
is to practice on known “conductors”. Such items a valve box
covers, manhole covers, or valves clearly visible at the surface of
the ground are excellent items to start locating. This way you will
quickly get the “feel” of the instrument before taking it into the
eld.
WARNING: Batteries can contain hazardous materials and must
be disposed according to the laws in your country.
This Category II radiocommunication device complies with
Industry Canada Standard RSS-310.
Ce dispositif de radiocommunication de catégorie II respecte
la norme CNR-310 d’Industrie Canada.
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4
RECEIVER
1. Carrying Strap: Keeps one hand free for marking
ground or pavement while using Tracer Probe.
2. Meter: Indicates signal strength up to a point
from metallic conductors while locating or tracing.
Meter also gives a visual indication of battery
strength.
3. Accessory Input: Use this jack to plug in all
accessories except the headphones.
4. Sensitivity:
A. Toggle switch to select NORMAL or HIGH
range.
B. Knob to control sensitivity level within the
NORMAL or HIGH range.
5. Depth Level: This bubble indicates the angle of
the receiver to the ground. Use it to keep Receiver
and Transmitter level during Inductive Locating
and for making the 45-degree angle necessary in
depth determination.
6. Headphones: Use this jack to plug in
headphones only. It automatically silences
speaker. Use in particularly noisy areas.
7. Battery Test: Turn unit ON then press this red
button and observe battery strength on meter. If
meter reads below 80, replace receiver batteries.
Usually transmitter & receiver batteries are
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1
2
3
4
7
8
6
5
1 2
3
replaced at the same time.
8. Power: Pull out for ON, push in for OFF.
9. Speaker: Produces the audible signal, which
increases in volume and pitch as signal strength
increases. The volume and pitch increase even
after the meter has peaked at 100.
RECEIVER
TRANSMITTER
1. Battery Test Meter: Gives a visual indication of
battery strength. Battery test is activated
automatically when unit is turned ON.
2. Constant Signal/Warble Tone Switch:
A. When toggle switch is in left position a constant
signal is generated/transmitted.
B. When Toggle Switch is in right position, the TW6
generates a warble tone. This results in a pulsating
sound and an oscillation of the needle between
zero and 100.
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6
3. Accessory Output: The Ground Plate Assemblies
Coupling
Clamp or Ground Rod Assembly connects into
this jack for a Conductive Trace or Direct Induced
Trace.
TRANSMITER
COMPONENT DESCRIPTIONS
1. Ground Rod/Harness Assembly: Provides a
“ground” for greatest efficiency in CONDUCTIVE
TRACING. For hard ground, the accessory GroundRod /Harness Assembly is recommended.
2. 3-Piece handle: For use in INDUCTIVE LOCATING.
3. Handle Carrying Strap: Allows you to lower handle
closer to the ground for greater depth penetration
and sensitivity in locating. The same strap is used for
carrying the receiver.
4. Handle Carrying Case: Protects 3 piece handle
and makes a neater bundle.
5. Carrying Case: Sturdy protection for your TW6 and storage for accessories, such as coupling
clamp, headphones, mini probe, and ground plate
assembly.
6. Headp hones: Stereotype headphones are
available for the TW-6. They are switch selectable
from monaural to stereo and may not work with the
TW-6 when switched to mono. You may prefer to use
the stereo phones because volume is adjustable
separately to each ear. The VCO sound is shrill and
without a volume control on the mono headphones,
the sound may be uncomfortable.
MODES OF OPERATION
Your Fisher Model TW-6 allows two modes of operation: INDUCTIVE
and CONDUCTIVE. In the INDUCTIVE mode, the Transmitter
induces the electromagnetic eld around the object sought.
The Transmitter radiates this eld through both soil and water.
INDUCTIVE is subdivided into two modes: (1) On the handle for
LOCATING and (2) Transmitter placed on the ground directly
above and in line with the conductor for TRACING and the path
of the conductor.
The CONDUCTIVE mode operates when you connect the
Transmitter directly to an exposed portion of the pipe or cable in
question with the Ground Plate Assembly, or with the Coupling
Clamp, or the Ground Rod Assembly.
THE INDUCTIVE MODE
HOW TO ASSEMBLE
1. If you have the 3-piece handle, insert the two
end sections into the central section and turn the
knobs until they are “nger-tight”.
2. Place the Transmitter on its back and insert
handle end with one screw into V-shaped slot.
3. Turn the knob until it is “nger-tight”.
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MODES OF OPERATION
4. With the Transmitter still on its back, align the two
holes in the panel of the Receiver with the knobs.
5. Turn the lower knob of the two knobs until it is
“nger-tight”. Turn the knob with the arrow until the
spring is compressed and the panel is pulled within
3/8” of the handle at the end.
HOW TO TUNE
1. C h eck ba t teries on bo t h Transmitter and
Receiver.
2. Place the Receiver Sensitivity Switch in the
NORMAL position.
3. Turn SENSITIVITY knob to 7.
4. To turn ON, pull POWER switches on Receiver and
Transmitter.
5. Pick the unit up by the handle and balance it so
that it is level with the ground and at normal carrying
height (arms length). For a deeper search, hold with
the carrying strap which has been fully lengthened.
You will need to hold the instrument at this lower level
while tuning if you plan to use it lowered. On some
highly mineralized ground and some asphalt, you
may not be able to use it with strap fully lengthened.
You will know this if you cannot reach a “null”. Not
reaching a null can also indicate the presence of
nearby metal.
CAUTION: Never attempt to tune the TW-6 in the presence of metal
objects like cars, metal walls, roofs or heavy metal reinforcements
in any structure. Their presence will make proper balancing
impossible.
6. Turn front knob on handle counter-clockwise, until
lowest meter and speaker indications are reached.
You have reached the lowest point if a 1/8- l/4th turn
in either direction results in an increase in sound and
meter reading. If at the lowest point there is still sound
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