What is the primary effect of extremely short rise or fall time on a CW signal?
More difficult to copy
The generation of RF harmonics
The generation of key clicks✓Bonne réponse
More difficult to tune
Explication
Making the keyed envelope switch on and off almost instantly is a near-step change in amplitude, and steps have very wide spectra. The resulting sidebands appear well away from the operating frequency and are heard on nearby signals as key clicks.