[Early_S_Man]

Chris,

It is very possible that the bandwidth of the scope you were using is responsiblr for the sine wave display, rather than the sharp waveform you expected. If the scope is a relatively inexpensive model with bandwidth under 1 MHz, then that is the problem. Many scopes these days do not have the bandwidth to accurately display complex waveforms -- any 'sharp' waveform components require bandwidth many times higher than the fundamental frequency of the basic 'rep' rate.

Even a 500 MHz scope displays a sine wave when fed the sharp waveform from a time mark generator at the 2 ns setting!