Which of the following is the best instrument to use for checking the keying waveform of a CW transmitter?
An oscilloscope✓Correct answer
A field strength meter
A sidetone monitor
A wavemeter
Explanation
Keying quality is a question of how the RF envelope rises and falls in time, and only an instrument that displays amplitude against time can show that. Too fast a rise produces key clicks, and the oscilloscope makes the shaping directly visible.