MFC Series 7894D C-Band Bandpass Filter
The Series 7893D (7894D) waveguide bandpass filter is installed between a TVRO feedhorn and the LNA or LNB to suppress strong out-of-Band interference caused by marine, airport, or military radar systems.
Coastal and marine navigational radar frequencies (2.9-3.65 GHz) are just below the TVRO band and frequently wipe-out transponders 1-5 in TVRO's installed near harbors. The airport altimeter band (4.25-4.40 GHz) will affect channels 22-24 at TVRO sites near airports.
The series 7893D (7894D) interference filter operates at RF, before block down conversion. This prevents the generation of undesirable mixer products and receiver "desensitization" due to strong out of band signals.