Many receivers can be affected by strong signals outside of their band. The strange analog world has effects like desensitization and intermodulation, which can

Many receivers can be affected by strong signals outside of their band. The strange analog world has effects like desensitization and intermodulation, which can produce in-band signals or attenuate the ones you intended to hear. The degree to which a receiver is immune to these effects is part of the engineering of the receiver. They likely didn’t consider strong C-band transmissions with a high duty cycle in their design at the time.