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Summary of Contents for 902

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Page 2: ...s 7 1 Energizing a Line to be Traced 7 a Inductive Energizing 7 b Conductive Energizing 9 2 Tracing an Energized Line 11 a Peak Detection Method 11 b Null Detection Method 14 c Determining Depth of a Line 15 3 Finding Lines of Completely Unknown Location 17 4 Locating Hidden Valve Caps and Manholes 18 E Miscellaneous Notes and Suggestions 20 F Instrument Maintenance 20 1 Battery Replacement 20 2 M...

Page 3: ...at is significantly smaller than other two box locators Durability of the Model 902 is insured by solid construction in a tough Xenoy housing Also to enhance locat ing convenience sub surface metallic structures including valve caps risers and manhole covers can be found easily during tracing by pressing a single push button switch B Major Components and Accessories 1 Transmitter The transmitter g...

Page 4: ...ols the power state of the transmitter Depressing this switch so that the adjacent BATT light illuminates turns on the transmitter causing it to generate a signal Depressing the switch again will deactivate the transmit ter b The BATT Indicator This LED is lit when the transmitter is activated and the condition of the battery source is good If this LED does not illuminate when the POWER switch is ...

Page 5: ...signal that is presently being transmitted f The DIRECT OUTPUT Jack Inserting the plug of the directconnection cable hereafter referred to as the DCC into this jack switches the transmitter into con ductive mode In this mode a line may be energized directly by physically connecting the red clip of the DCC to an exposed part of the line 2 Receiver The receiver is used to detect the signal generated...

Page 6: ...his push button switch activates and deactivates the receiver The receiver is activated on when the POWER switch is depressed so that the BATT light above this switch illuminates Depressing the switch again will turn the receiver off b The BATT Indicator When the condition of the batteries in the receiver is good this LED shines when the receiver is activated If this indicator does not shine when ...

Page 7: ...e darkened in the low sensitivity mode e The LOCATE MASS Switch and Indicator Pressing this switch so that the LED indicator directly above it illumi nates changes the 902 receiver from a line tracer to a metallic mass locator Examples of buried masses that the receiver is able to find in this mode are valve caps and manhole covers Using the instrument in this mode disables normal receiving functi...

Page 8: ... supplied by the speaker will be channelled to headphones when the headphone plug is inserted here j 45 Level Guage When making a determination of line depth the operator will often find this small level helpful Oriented at a 45 angle with respect to the antenna the bubble in the level will center itself when the antenna is positioned at 45 compared to level ground See section D of this manual for...

Page 9: ...a to make a conductive hook up If the GC 2 is clamped around a specific line it will inductively energize the line with a focused signal The line will become considerably more energized than surrounding lines and therefore easily trace able The Model GC 2 clamp is sold separately 6 Headphones are also sold separately from the Model 902 Any set of headphones may be used with the Model 902 Locator p...

Page 10: ...cted for either mode and the operator may choose to pulse the signal in either mode of transmission for easier identification a Inductive Transmission In inductive mode the 902 trans mitter produces a radio signal capable of penetrating air ground and other media in order to energize a nearby conductive line Having been effected by the transmitted signal the line then conducts the signal along its...

Page 11: ...g Modes As for the transmitter there are two general modes of loca tion for the 902 receiver line tracing and mass locating For line tracing the operator may choose between two discrete levels of receiver sensitivity a Line Tracing This mode is used exclusively to detect the signal generated by the 902 transmitter and therefore to locate lines which the transmitter is energizing When tracing one m...

Page 12: ... involves having two operators each hold ing one of the locator boxes and moving together in the area that a line is suspected to be found D Operating Procedures 1 Energizing a Line to be Traced The Model 902 is an active locator This means that the 902 receiver is designed to detect lines that have been ener gized by the signal generated from the 902 transmitter Therefore the operator must prepar...

Page 13: ... transmitter is in conductive mode and will not radiate a signal through the air ii Turn on the transmitter You have activated the transmit ter if the green BATT light is glowing If you have depressed the POWER button and the light does not glow you probably need to change the batteries iii Select a power setting on the control panel of the transmitter Using the OUTPUT LEVEL switch select either l...

Page 14: ...from the transmitter to actually energize the line NOTE It should be known that when placed over a line to ener gize it the transmitter radiates signals from the sides and top as well as from the bottom Signals radiated through the bottom are used to energize the line Those coming from the sides and top travel a short distance through the air and are attenuated If the transmitter is aligned perfec...

Page 15: ...nductive energizing and is therefore the preferred method Since the signal enters the line directly through the DCC unwanted air signals are minimized Using a ground with the DCC will maximize the energizing efficiency so that tracing distance can increase dramatically More details concerning the appli cation of the DCC for direct hookup follow here and are depicted in Figure 7 i Insert the plug o...

Page 16: ...all it usually will be strong enough for short traces very close to the transmitter Working without a ground is often helpful when tracing indoors or in other con fined areas CAUTION Do not connect the red and black clips together when using the DCC Although short circuiting the output leads will not result in immediate damage to the trans mitter it will quickly drain your batteries and cause the ...

Page 17: ...e response The following steps illustrate how this is accomplished i After having energized a pipe or cable turn on the receiver At first set the sensitivity to low HI light off also make sure that the LOCATE MASS feature is deactivated LOCATE MASS light off ii If you are using inductive energizing walk down the line 20 or 30 feet moving further out of range of air signals coming from the transmit...

Page 18: ... line as you walk in the direction of the line the line will be directly below where the signal response is maximum as you walk v As you distance yourself from the point at which the transmitter is energizing the line the signal intensity will continue to diminish Thus the receiver response will decrease as well To gradually increase the relative 16 ...

Page 19: ...suddenly vanishes along the direction you are moving then the line either ends at that point or it has turned to the right or the left Figure 10 depicts a simple way to determine if the line has turned Walk back up the line about four feet and then walk in a circle either right or left Keep the side of the receiver box pointed toward the center of the circle If a lateral turn exists the receiver w...

Page 20: ...n alternate method to peaking Because the receiver relies on a directional antenna positioning it so that the front panel perfectly faces the line will cause it to detect no signal Using nulls over the line the operator can ascertain the precise loca tion of a line below the surface as well as determine its depth 18 ...

Page 21: ... This will insure that the signal is detected strongly when the receiver is not directly over the line iii Now slowly move the receiver back and forth over the line The response will be full everywhere in the vicinity of the line except directly above it At this point the response will vanish sharply Figure 11b As you walk along the line it will always be located directly below the point where the...

Page 22: ... may follow the procedure described in section a vii above using nulls instead of peaks over the line vi Please note that the null method will not indicate the direction of the line at a single point As long as the receiver is held flat to the surface it will indicate a null over the line regardless of how the box is rotated vii If you have traced beyond a detectible range you may continue your tr...

Page 23: ... will be properly posi tioned when the bubble in the level is directly in the center iv Now move the receiver away from the first null mark at a right angle from the direction of the line Figure 12 13 You will locate a null as you move the receiver horizontally Hold the receiver so that the bottom edge of the bottom of the box sets on the ground when find ing this 45 null to obtain accurate result...

Page 24: ... vi Measure the distance between the two null marks Figure 9 By triangulation this surface distance will be the same as the depth to the center of the line For excavation or trenching purposes this means that the actual top of the pipe or conduit will be shallower than the measured depth by half of the pipe s diameter For example for a 12 inch diameter pipe the actual depth to the top of the pipe ...

Page 25: ...on and setting the receiver controls so that the receiver is just out of range to detect air signals coming from the transmitter This is a two person operation a One person carries the activated transmitter and the other carries and controls the receiver b Each person must keep the boxes in line with each other and at a constant distance from each other as shown in Figure 14 A horizontal separatio...

Page 26: ...response at the receiver Thus the trans mitter may be centered over the line If the transmitter is placed on this spot it will continue to energize inductively the newly found line Using the receiver trace the line and determine depth as you normally would f NOTE This method of finding an unknown line works only if the operators cross the line at a roughly right angle Therefore the operators may c...

Page 27: ...ges from the receiver which changes frequency when brought near a metallic mass Details on using this feature follow here see Figure 15 a At any time while you are tracing a line you may press the LOCATE MASS button Once set to locate masses the receiver outputs a continuous tone b Move with the receiver held flat to the surface beneath which you a searching for a mass In this mode the receiver is...

Page 28: ...ather than the cen ter To locate the edges scan the area around the mass marking locations where a sharp frequency rise occurs If you mark 3 or 4 evenly spaced locations around the perimeter you may use these to trace the outline of the manhole Also these markings will help you more accu rately visualize the center of the manhole e The SIGNAL LEVEL control may be adjusted in this mode to provide a...

Page 29: ...may be transferred to another line through a common point Erroneous conclusions may result This kind of transfer may occur for instance when energizing a gas service that feeds into a water heater At the heater the gas service may be electrically common with the incoming water pipe the water pipe might carry the signal as well thereby leading the operator to false conclusions while tracing The ope...

Page 30: ...r size phillips head screwdriver remove the four screws at the corners of the face panel c Holding the face panel with your fingers flip the instru ment over onto your lap or onto the table and lift the blue shell off of the face panel d Remove the two phillips head screws that hold the battery strap into place and remove to battery strap At this time be very careful not to change any of the circu...

Page 31: ...io b We do not recommend the addition of large metallic objects to the shells or faces of the instrument Both the transmitter and receiver are tuned at the factory to compensate for the batteries circuit boards and other metal in the instruments Adding metal will detune the instrument and should not be done unless a trained technician is present to retune the instrument 3 Troubleshooting If proble...

Page 32: ...aline battery capacity can be cut by 50 Although the transmitter and receiver will still work despite this decline in capacity overall performance will decrease One way to solve this problem is to install cold weather batteries Eveready produces such a line of batteries called Litheon batteries c If new batteries have been installed and the BATT light still does not come on check to be sure that t...

Page 33: ... com We will inform you of any local repair stations in your area or advise you to ship the instrument directly to the factory If you ship product we suggest you a Pack the instrument carefully and securely b Include any accessory items normally used with the instrument c Include a note with the instrument stating the nature of the problem s you have encountered in using the instrument d Include a...

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