The EM16 is the most widely used EM instrument of all time. It measures the local tilt and ellipticity of VLF broadcasts, and resolves these values into inphase and quadrature components of VLF response. The EM16 has discovered several base and precious-metal orebodies, and many water bearing faults.The EM16R attaches to the EM16 and, using a pair of electrodes, measures the apparent resistivity of the earth. The combined EM16/16R instrument can detect a second earth-layer if the layer occurs within the VLF skin-depth. In addition, the EM16/16R can map resistive alteration for gold exploration.
The TX27 is a portable VLF transmitter supplying a VLF field for surveying with the EM16/16R, if remote broadcasts are weak, intermittent or poorly coupled with the target. For EM16 surveys, the TX27 antenna consists of a long (1 km) grounded wire.