The Amprobe AT-3500 discovers the location and depth of pipes, cables, and wires that have been buried up to 16 feet in the ground. It has a transmitter and a receiver and offers three location modes. In passive power mode, the receiver detects current emitted by buried power lines. In passive radio mode, the receiver detects radio waves conducted by buried objects. In active mode, the transmitter induces a frequency into a buried pipe, cable, or wire, and the receiver detects the frequency to trace the buried feature. The transmitter operates at a 33 kilohertz (kHz) frequency signal, which provides more reliable results in locating a buried feature compared to higher or lower frequencies. The transmitter can provide a pulsing signal to conserve battery life, improve detection when there is a weak signal, or distinguish the transmitted signal when there is interference in the area. It can also provide a continuous signal for an accurate depth reading. The transmitter has two signal strength settings. The low-output 0.1 watt (W) signal strength setting conserves battery life, and the high-output 0.5W signal strength setting is for tracing long distances. The receiver has two signal gain settings for adjusting its signal sensitivity. In automatic signal gain mode, the receiver adjusts its sensitivity based on the strength of the signal being emitted by the buried feature, for quick locating. In manual signal gain mode, the user adjusts the receiver’s sensitivity for precise locating in areas with interference. The Amprobe AT-3500 comes with a connection cable and alligator clip for connecting the transmitter to the buried pipe, cable, or wire to be traced. It also comes with a ground stake, cable, and alligator clip for grounding the transmitter when it is directly connected to the buried fixture. A nylon carrying case helps protect the receiver and transmitter from damage during transportation and storage, and a pouch organizes the ground stake, cables, and alligator clips. Both the receiver and transmitter have a battery charge indicator. As defined by International Electrotechnical Commission (IEC) standard 60529, the unit has an ingress protection rating of IP 56, meaning it resists the ingress of dust and powerful jets of water.SpecificationsReceiver power supply1.5 volt (V) AA batteries (ten, included)Transmitter power supply1.5V D batteries (six, included)Standards metInternational Electrotechnical Commission (IEC); European Conformity (CE); N10140 AustralianReceiver weight5.51 lb. (2.5 kg)Transmitter weight3.75 lb. (1.7 kg)Receiver dimensions3.90 x 9.92 x 25.98 inches/99 x 252 x 660 mm (H x W x D)Transmitter dimensions10.04 x 10.24 x 5.5 inches/255 x 260 x 140 mm (H x W x D) H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.Pipe and cable locators, also called utility locators, find pipes, cables, and wires that are buried in the ground for determining where to excavate on a site and for locating buried fixtures in need of maintenance or replacement. Pipe and cable locators are used in electrical, plumbing, telecommunications, utility maintenance, construction, and home repair applications. They have a transmitter and a receiver and use active or passive methods of location. In active location, the transmitter induces a signal at a specific frequency either into the ground, where it"s picked up by buried utilities, or directly into a pipe, cable, or wire that is connected to the transmitter. As the signal is being transmitted into the buried utility, the receiver is passed over an area until it detects the signal and locates the buried pipe, cable, or wire. In passive location, the receiver searches for alternating current (AC) frequencies or radio waves emitted by energized cables, wires, and pipes without the need for a transmitter. Pipe transmitters, signal clamps, and grounding stakes can be used to help improve locator accuracy.Amprobe manufactures electrical testing equipment for commercial, industrial, and home use. The company was founded in 1948 and is headquartered in Everett, WA.What’s in the Box?R-3500 receiverT-3500 transmitter(2) Cables(2) Alligator clips(1) Ground stake(10) 1.5V IEC R6 AA batteries(6) IEC R20 D batteriesNylon carrying casePouchInstructions