What could be the cause of local AM broadcast band signals combining to generate spurious signals on the MF or HF bands?
One or more of the broadcast stations is transmitting an over-modulated signal
Nearby corroded metal connections are mixing and reradiating the broadcast signals✓Richtige Antwort
You are receiving skywave signals from a distant station
Your station receiver IF amplifier stage is overloaded
Erklärung
A corroded metal-to-metal junction behaves as a crude diode, rectifying the strong broadcast signals induced in the connected metalwork and reradiating their sum and difference products. Those products then appear on frequencies where no station is actually transmitting.