Hi Bob,
Thanks for making the measurements and posting your results.
I would like to know what really is the right way to measure rise time
of a CW keying envelope. I cannot see how measuring from 0% to 100%
power output can ever give an accurate and repeatable measurement,
because the noise level in your instrumentation would have to be
absolutely zero in order to discern exactly when the power output has
gone above zero. The same is true of determining exactly when the power
has reached 100%.
Also I believe that the highest slew rate is what determines the
bandwidth that the signal will occupy. The steepest slope of the
amplitude increase should occur somewhere near the middle as the power
level is rising through the 50% area. In the zero to 10% and 90% to 100%
areas the slope is not as steep, and averaging those portions into the
measurement may give a measurement which if used to calculate the
occupied bandwidth, would result in a lower bandwidth than what the
signal actually occupies.
Sure, I'm being picky. Inquiring minds want to know. Perhaps there is
some ITU defined standard for measuring CW keying envelope rise time.
Maybe someone will tell us.
DE N6KB
I was interested in total rise time, so I measured from 0% to 100%, plus or
minus 0.1 ms as best I could judge by eye, but the very distinct and uniform
waveform made it pretty easy to do at 2.5 ms per division. Quick and dirty,
just to get a rough idea of the relationship between indicated and actual.
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