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Underground magnetic locators detect the magnetic field of iron and steel objects and energized power lines when held over the target.

Narda THM1176 Magnetometer
Narda THM1176 Magnetometer

The Three-axis Hall Magnetometer is used to measure the magnetic field (flux density). Its unique, extraordinarily compact design allows it to be used as a portable instrument or directly connected to a PC.

The total magnetic flux density is provided no matter the orientation of the probe, which greatly facilitates many measurement tasks such as field mapping. Outstanding features are as follows:

  • Three axes
    Simultaneous measurTHMement of all three axes of the magnetic field provides the total field, no matter the orientation of the probe.
  • Microscopic field sensitive volume
    The High Field sensor volume of only 150 x 150 x 10 µm3 provides excellent localization and a self-consistent measurement of the three axes even in highly inhomogeneous fields. The Low Field sensor volume is 6 x 3.4 x 10 mm³.
  • Magnetic fields up to 20 T
    The High Field probe allows measuring even very strong fields as far as 20 Tesla. The standard calibration covers the range up to 3 T. The Low Field probe measures up to 8 mT with a resolution of 2 µT.
  • Bandwidth of DC to 1 kHz
    The 1 kHz bandwidth allows measuring AC fields generated, for example, by transformers and motors.
  • Graphical results display
    Magnetic flux density vs. time can be displayed as a graph. Measurement data can also be recorded to file.
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Schonstedt Magnetic Locator Model GA-72 Cd
Schonstedt Magnetic Locator Model GA-72 Cd


The GA-52Cx and GA-72Cd Locators detect the magnetic field of iron and steel objects and energized power lines. Both provide audio detection signals that peak in frequency when the locator's tip is held directly over the target. The GA-72Cd has the option of nulling or peaking

No. 1 Around the World in Performance and Reliability.

Quality Is Our Hallmark

Schonstedt's underground magnetic locators have been setting the standards for reliability and dependability for over 30 years. They are designed to withstand the rigors of daily on-site usage and a wide range of environmental conditions. In fact, the Model GA-52Cx is so rugged and dependable it's backed by a 7-year warranty and the Model GA-72Cd is backed by a 5-year warranty.

Only two Controls

Designed for one-hand operations, the On/Off-Sensitivity and Volume controls are located on the underside of the cover on both locators. This provides easy access, protects the knobs and contributes to their overall ruggedness and dependability.

The GA-72Cd also has easy-to-read digital and bar graph which displays of signal strength and polarity. Once you have located a target using the audio signal, the digital readout and polarity indicators will help you to visually pinpoint the target and, in some instances, even determine its orientation.

Signal Strength and Polarity Indications

The GA-72Cd's audio signal and the 3-digit LCD readout will peak, and the (+) or (-) bar graph will expand to full scale when its tip is directly over a vertical iron pipe. One end of a horizontal target will be (+) and the other will be (-). This difference is very significant because it helps you to distinguish between vertical and horizontal pipes.

With the GA-72Cd you can select any one of four sensitivity settings; the GA-52Cx offers five sensitivity settings. The GA-72Cd's LCD bar graph shows the selected gain and the battery status. The GA-72Cd's headset jack can be connected to your data logger using a standard stereo audio plug.

Choice of Two Audio Modes

The GA-72Cd is configured initially to provide an audio signal that is always present (Audio Output switch set to ''B''). If you do not want to hear a signal until the locator is within the detection range of a target, you can set the Audio Output Switch to ''A''.


  • Five Year Warranty
  • Digital readout and expanding bar graph displays signal strength and polarity
  • 4 Sensitivity settings: Low, Medium, High, and Extra High
  • Piezoelectric speaker
  • Analog output for data logger entry
  • 60-Hours operational life (intermittent usage) on 2 lithium 9-volt batteries
  • First locator to use Environmentally Friendly and Safe, lithium batteries. The unit is shipped with two 9-volt lithium batteries installed, and a spare set of batteries stored in the case. Lithium batteries provide twice the life of alkalines, and have a 10-year shelf life.
  • 4-Segment BATT LCD monitors battery charge
  • Lightweight, easy-to-use-design reduces search time
  • Modular construction; high performance components
  • Patented HeliFlux
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