Which of the following could be a cause of interference covering a wide range of frequencies?
Not using a balun or line isolator to feed balanced antennas
Lack of rectification of the transmitter’s signal in power conductors
Arcing at a poor electrical connection✓Bonne réponse
Using a balun to feed an unbalanced antenna
Explication
An arc at a corroded or loose connection switches current abruptly and repeatedly, and abrupt current steps have energy spread across an enormous span of frequencies. The result is broadband hash rather than interference on one frequency, which is what distinguishes it from a single unwanted signal.