TW-7700 Digital Line Tracer Operating Manual FISHER RESEARCH LABORATORY
CONTENTS Description.............................................................................. pg. 3 Transmitter ............................................................................. pg. 4 Receiver ................................................................................... pg. 5 Accessories .............................................................................. pg. 7 Operating Instructions ......................................................... pg. 8 Depth Accuracy .............
DESCRIPTION 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.
TW-7700 TRANSMITTER Transmitter 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.
TW-7700 RECEIVER Receiver The TW-7700 Receiver. Controls Mode This button does not have a function on the TW-7700. (It allows users of the TW-8800 Multi-Frequency Line Tracer to change frequencies.) Power On/Off Turns the receiver on or off. Light Lights up the display for usage in dark areas. When the display is backlit, LIGHT is shown on the bottom left hand side of the display screen. Bat Press and hold this pad to check the battery level of the receiver.
TW-7700 RECEIVER Display Frequency Modes The frequency at which the receiver is operating. << Left/Over Target>/Right>> Indicates where the receiver is in relation to utility. Numeric Display Serves a dual function: •Relative signal strength of the transmitted signal (% shown). Responds in conjunction with the bar graph. •Depth to the center of the target (when DEPTH pad is pressed - IN or CM shown) Light Indicates the display is lit (activated by pressing LIGHT pad).
ACCESSORIES Coupling Clamp The coupling clamp is useful when the utility is exposed, and a direct connection is not possible. It is plugged into the same plug-in socket as the ground-plate/ground-rod assembly. The coupling clamp only operates at the 82 kHz frequency. The coupling clamp will fit around utilities that are 3-¼ inches in diameter or smaller. The length of the cable is approximately 10 feet. Coupling Clamp Applications Diagram A.
OPERATING INSTRUCTIONS The following instructions are designed for a safe and effective method of line tracing and utility avoidance. Some of the steps may not be applicable in all situations. The underlying guideline is that operator safety must be maintained at all times. Use of safety equipment, extra personnel, and up to date as-built plans should be considered when necessary.
DEPTH ACCURACY Depth measurement is a feature of the TW-7700. Accuracy is defined on an ideal target, that is, one that is continuous, a good conductor, and not surrounding by other utilities. There are factors that can cause the operator to question the accuracy of the utility being traced. Inductive Transmitter Setup Inductively, only a small portion of the signal attaches itself to the utility. With a weakened signal, trace should be accurate, but depth may not.
SPECIFICATIONS Subject to improvement or modification without notice. RECEIVER Depth Accuracy ...................... +1 inch per foot in nominal conditions Readout Units ........................ Inches or cm (factory preset) Left/Right Guidance ............... Audio: continuous tone=Left, pulsed tone=Right. VCO (varying pitch) output for easy over ........................................... target location. Visual: Left/Right/ ...........................................
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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.
