How to install the power filter?

The input and output of the power filter are installed directly on both sides of the chassis to minimize contact impedance, and the input and output terminals of the filter are separated by the chassis to prevent coupling at high frequencies. It is recommended to install electromagnetic sealing gaskets between the filter and the chassis panel (in some applications, electromagnetic sealing gaskets are necessary, otherwise leakage may occur due to contact gaps).
When using this installation method, the filtering effect of the filter mainly depends on the performance of the filter itself. When the performance of the filter itself is poor (mainly referring to high-frequency performance), it is not worth using this installation method (because it cannot improve the filtering effect of the filter).
This installation method is often used in military equipment, otherwise it may not meet the limitations of radiation emission.
For civilian equipment, although the requirements are relatively relaxed, in some cases there are strict restrictions on RF leakage (such as equipment that works with high-sensitivity receivers), and this installation method should also be adopted.
TEMPEST devices invariably adopt this filtering method, as in this application, the effective frequency of filtering needs to reach 1GHz. The filter used here is used as a common mode filtering capacitor and has good internal isolation measures. Many products install filters directly on circuit boards in order to reduce costs. This method has some benefits in terms of direct cost, but the actual cost-effectiveness ratio is not high. Because it will directly sense any part above, causing the filter to fail. Therefore, this method is often only suitable for situations where the interference frequency is very low.
If the device uses this filtering method (which is installed on some power supplies), one remedial measure is to install one at the power line inlet, which can only suppress common mode interference. Because the interference voltage induced on the wires in space is in common mode form. The circuit can consist of one or two common mode filtering capacitors. If used, it can achieve very ideal filtering effect. However, it should be noted that adding the common mode capacitance here to the original may result in excessive leakage current.
Explanation: This method of dividing the filter into two parts, on the circuit board and at the port, has a high cost-effectiveness ratio. In situations where cost control is strict and interference suppression requirements are high, this method can be considered.