Sniffer Probes with patented E-Field Probe The PS-400 Near Field Probe Set is designed to assist in troubleshooting EMI problems both at the board level and at the component level. It is used to detect radiation from cables, cases, traces and ICs. Typically the broadband probe is used to locate the general area of emission. Then the tip probe is used to isolate the source to a specific trace or pin. Further analysis can be done using the contact tip probe ( available with PS-500 probe set) by making direct contact with the curcuit and then following the noisy trace to find the cause of emissions such as a broken transmission line or impedance mismatch. A typical use for the H-field probe is to verify the integrity of the chassis of your computer. This is done by moving the probe along the seams of the chassis which may be acting as slot antennas. This probe is also very useful for detecting magnetic noise sources such as large current switching circuits or transformers.