I just bought a bug (a Vibroplex Original, it's so awesome) as part of a New Year's resolution to get into CW. I followed the instructions to calibrate it, which required playing dits into an Ohmmeter until they showed 50% deflection. Since I didn't have an analog Ohmmeter, I took a spare Arduino and wrote a program to measure duty cycle directly. It's fascinating to see how fine adjustments effect the cycle. Having done that, I played a string of DAHs. I am told that a proper DAH is three elements in duration, and if I am not mistaken (???) that implies a 75% duty cycle on a long string of them. Is that right? Because if I play the DAHs at the proper "clock speed" relative to the dits, I measure a duty cycle in the 50s, and it's hard to reach the low 60s. I don't think I can even hit 70%.