In a Morse code transmission, broad bandwidth RF interference (key clicks) heard at a distance is produced by:

Broad bandwidth interference heard at a distance from a Morse code (CW) transmitter is the classic symptom of poor waveform shaping. A CW signal that turns on and off too abruptly generates a square-shaped RF envelope, which creates unwanted sidebands that spread across a wide range of adjacent frequencies. These wide sidebands are heard as disruptive clicking sounds by distant receivers tuned near your frequency. Properly designed transmitters use a wave-shaping filter in the keying circuit to gently round off the rise and fall transitions of the signal, keeping the transmitted bandwidth narrow and clean. Options like frequency shifting (chirp) or sparking at the contacts describe completely different phenomena. Chirping is an oscillator stability issue, while sparking causes purely local interference.