Electrical signal filter

摘要

The object of this invention is to provide an electrical signal filter for improving electrical characteristics and reliability of the electrical signal filter for use in a cable television by protecting it from moisture. In an electrical signal filter having a filter portion provided inside a cylinder-shaped shield case, the filter portion includes a first filter circuit and a second filter circuit respectively mounted on circuit boards, and a shield member arranged between the first filter and the second filter. In the electrical signal filter, a moisture-proof material is applied to an entire surface of the filter portion and a contact area where the cylinder-shaped shield case containing the circuit boards and the filter portion therein contacts external components.