What is the cause of receiver overload?

Receiver overload occurs when the front-end circuitry of a radio receiver is overwhelmed by a massively strong RF signal. This typically happens when a transmitter is operating very close to the receiver, pumping more voltage into the receiver's antenna than its amplifiers and mixers can handle. When the receiver is overloaded, it becomes desensitized, meaning it goes 'deaf' to weaker signals you actually want to hear. It can also cause severe distortion or phantom signals appearing across the tuning dial. The distractors represent issues with the transmitter's signal quality—such as overmodulation, frequency instability, or parasitic oscillations. While those can cause interference, true receiver overload is purely a function of sheer signal strength overwhelming the receiving equipment, even if the transmitted signal is perfectly clean.