The Pro900 Digital Underground Cable Locator is a full-featured digital underground locator for contractors and maintenance personnel. Incorporating three different locating frequencies, the Pro900 tracks metallic cabling, including CATV, electrical, telephone, sprinkler, and lighting. The Pro900 transmits solid or intermittent signals that are easy to follow. The digital signal reception allows for crystal clear tone reception in most situations with either null or peak reception.
The Pro900 incorporates a 50/60Hz passive locating mode, which identifies electrical sources (power cables) and tracks them without using a transmitter of any kind. Contractors can identify the path of 50/60 Hz underground cables without disconnecting them or connecting to them.
Introduction: Theory of Locating
Cable locators consist of a transmitter and a receiver. In the case of the Pro900 model, the transmitter is in the long gray box and the receiver is a yellow and black wand. In operation, a transmitter places a specific tracing signal onto the metallic conductor you are trying to locate. This placing of an AC signal onto a cable produces an electrical current and an electromagnetic field around that cable. If the wand is close enough, this signal is received and amplified by the wand.
It is very important to understand that the circuit you are creating follows the laws of physics and electricity. A cable transmitter creates an electrical current (AC) that travels down the cable, through grounding to the earth, and then back to the transmitter through the ground stake. The tracing signal will always travel on the path of least resistance. If there is too much resistance or no circuit path, no current will flow and no locate will be possible. So keep in mind that when a signal is heard, it is because the signal has a complete path that is creating an electrically friendly way for the signal to travel back to the transmitter. The signal doesn't just randomly wander through the dirt. It follows a path provided for it, whether it is a pipe, wire, reinforcing bar, etc.
It is also important to note that in the tracing circuits, a return path needs to be present. Basically, the return path completes the circuit. In most cases, this will be the earth's ground as the signal transmits down the cable and returns to the ground stake. However, any return is possible, so a common wire could work. Or if you have a looped wire, like a dog fence, the loop itself returns to the start and therefore provides a 'ground' instead of the ground stake. You don't have to use a ground stake but you do have to give the signal a way to return to the transmitter.
Power
The Pro900 has two options for powering the transmitter; AC mains power or internal batteries. The AC adapter is useful when 120 Vac power outlets are available nearby. The adapter provides constant power and does not diminish batteries. To use the AC adapter, simply insert the round plug of the adapter into the “12 V” external power receptacle on the transmitter panel and the traditional bladed end into a wall outlet. The transmitter is then powered by AC mains voltage instead of batteries.
The Pro900 transmitter also can use 8 “D” (LR20) alkaline batteries that are installed inside the transmitter battery compartment. Remove the battery compartment cover and install the batteries, paying particular attention to the positive and negative poles.
A 9-volt square (6LR61) alkaline battery is needed for the Pro900 receiver. To install this battery, remove the battery compartment cover located on the back top portion of the Pro900 receiver. Install the 9-volt battery by connecting it to the battery snap boot inside the battery compartment. Don't yank or pull hard on the battery boot. Finally, replace the battery cover.
To test that the batteries have been correctly installed, turn each unit on. The control panel LCDs will come on if the batteries have been connected correctly. If not, repeat the installation procedures. The battery compartment is designed to hold the batteries tightly so if you do not get a signal for power, try adjusting the batteries by rolling them or moving them forward and backward until the power does come on.