Fisher Labs TW-7700 Operating Manual

TW-7700

Operating Manual

F I S H E R R E S E A R C H L A B O R A T O R Y

Digital Line Tracer

Description .............................................................................. pg. 3

Transmitter ............................................................................ pg. 4

Receiver ................................................................................... pg. 5

Accessories .............................................................................. pg. 7

Operating Instructions ........................................................ pg. 8

Depth Accuracy ...................................................................... pg. 9

Specications ......................................................................... pg. 10

Using Headphones................................................................. pg. 11

Treasure Hunter’s Code of Ethics ..................................... pg. 11

CONTENTS

DESCRIPTION

1

3

The TW-7700 Digital Line Tracer consists of a transmitter, receiver,
ground-plate/ground-rod assembly, carrying case (hard or soft),
and

an operators manual. The TW-7700 is a single frequency line

tracer.

The TW-7700 is an active locating line tracer. There
are three methods of active locating that an operator
can use to trace a utility. The conductive method is
the most preferred method, since a strong transmit­ter signal is transmitted through the intended target.
The inductive method is the easiest method to use,
but may not yield the best results. When a direct
connection is not available, but the operator has good
knowledge of where one point of the utility may be,
the operator can place the Transmitter over the utility
making sure that the arrow on top of the transmitter
is parallel to the path of the utility. The third method
of active locating involves using the coupling clamp
accessory. The coupling clamp is used when the utility
is exposed, but a direct connection is not available. The
clamp jaws are opened and placed around the utility.
The clamp never makes a direct connection with the
utility, that is, the utility can move freely with the
clamp around it.

The features of the TW-7700 make it a very easy and
practical instrument in today’s world of underground
locating.

4

TW-7700 TRANSMITTER

Transmitter

WARNING:

Do not handle output leads unless power is off.

ELECTRIC SHOCK HAZARD:

Servicing to be performed by

qualied personnel only.

Located on the transmitter are the power mode and
the accessory output. The power mode enables the
operator to turn the transmitter on or off, and to
check the condition of the batteries. When checking
the batteries, a reading if 50 or greater on the dis­play meter indicates that batteries are usable.

The accessory output is for the ground plate/ground
rod assembly, and for the coupling clamp. There is
a Red LED light that blinks when the transmitter
is on. The batteries are located underneath a lid on
top of the transmitter housing.

The TW-7700 Transmitter.