[Elecraft] K2 clix

[lhlousek]

For the MP, running the keyed signal through narrow IF filters was suggested as a way to improve keying wave form, not as the cause for the broad signal.  The problem is not spurs, per se, but the width of the transmitted signal due to fast keying transients.  Rise time alone doesn't tell the whole story.  Sharp transitions to and from the rising or falling envelope adds to the problem and is the culprit in the case of the MP.  The "ideal" keying waveform (as shown in ARRL pubs)  is not really ideal because there is an abrupt start of the ramp at the start of the keying envelope and an equally abrupt start of the downward ramp at the end.  These corners need to be rounded as well and would be if the keyed signal was passed through a narrow band-pass filter or if an appropriate second order filter was applied to the keying envelope.  For illustrations and a rather technical discussion, see

http://fermi.la.asu.edu/w9cf/articles/click/index.html

Lou W7HV 


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