The Electro-Metrics Model EM-7847 Tunable Notch Filter Network is a tunable cavity rejection filter operating from 3.0 to 6.5 GHz and used to perform specification compliance testing as stated in MIL-STD-462 and other related standards. The cavity exhibits very sharp resonances at the tuned frequency with low insertion loss and low skirt attenuation.

The EM-7847 has optimum performance when resonance in the TE₀₁₁ mode and can operate over a wide range of power levels. The cavity and associated tuning mechanism is constructed of copper, brass, and aluminum alloys.

Due to the precise nature of the cavity for operation in the designated frequency range, care should always be taken to ensure that the network mechanisms are not damaged when being used or transported.