Looking at the scope picture of a single Morse dit at G4AON's site http://www.astromag.co.uk/k3/k3_envelope2.jpg indicates the trailing edge might be a bigger contributor to potential clicks than the leading edge of the waveform. Note the upper right corner has a fairly "sharp" transition from "on" to "falling" and compare that to the nicely shaped transition at the upper left corner.
>From all reports the K3 is more than acceptable but if any additional effort is put into CW shaping, the "upper right" transition may be a place to look. 73, ... Joe, W4TV > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brian Alsop > Sent: Sunday, March 30, 2008 11:01 AM > Cc: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 CW rise time mod - Definition > > > For what it is worth, I've just completed a Fourier analysis of the > original K3 and revised K3 waveforms presented by G4AON on > his website. > > I was a bit concerned that the sharpening of the leading edge would > adversely affect bandwidth and possibly generate clicks. > > Bottom line for the region of the spectrum between 0 and +/- 200 Hz > there is a slight increase in average power (maybe 3 db) for the new > "sharper" waveform. In the range of 200 to 300 Hz the average power > increases maybe 10 db. However at this point the spectral energy is > down 50 db anyhow. Beyond this 350 Hz, the spectrum energy of the > "sharper" waveform actually falls off relative to the 8ms case. > > These conclusions are "eyeball averages" of the sawtooth > looking output > produced. The teeth go above and below the zero db level. > > I was pleasantly surprised. Apparently it isn't all in "rise > time" it > is also how that waveform is shaped. > > Here are the assumptions/limitations of the analysis. > 1) Code used "Fast Fourier Transform" by M.F. Hajen > 2) A single dit was modeled. > 3) Both dits had the same length in the model (about 70ms > representing > about 20 wpm). > 4) Waveforms were digitized in 1 ms steps. > 5) The assumption that the waveforms given represented > voltage and hence > db was calculated by 20 log (amplitude/amplitude at 0 Hz) > > This doesn't reflect repeating dits or CW made up of dots and > dashes. > However, it is probably a worse case analysis or close to it. > I don't have a web site to post on. There is a .jpg file > available of > results. > > Disclaimer > I'm not an expert on this or on using the calculational tools. The > output does at least agree with the position of the first zero point > predicted by a sinx/x formula for a single pulse of near > infinite rise > time and same width. Clearly it doesn't represent other > effects in the > rig which affect spectrum. > > Like a lawyer once said: "I'm giving you some free advice, it > is worth > every penny paid for it" > > 73 de Brian/K3KO > . > > Paul Christensen wrote: > > >> I would like to see someone please take this discussion > one step > >> further and define the terms "hard" keying and "soft" keying, and > >> describe how either an operator or someone listening would > be able to > >> discriminate between the two. > > > > > > Gary, this topic has been covered in great detail in nearly > every ARRL > > Handbook for at least the last fifty years -- as well as other > > publications. Some of the most relevant material is covered in > > articles during the '40s and '50s by By Goodman and George Garmmer. > > Not all of the material pertaining to "optimum key-shaping" is > > accurate, but otherwise, the content is still accurate. > > > > Many of us do not like to be held hostage to one rise/fall > setting as > > a "one size fits all" answer to our operating practices. With > > DSP-generated raised-cosine key shaping, it's now possible > to tighten > > up key shaping at high CW speeds without appreciably consuming > > additional bandwidth. > > > > Paul, W9AC > > _______________________________________________ > > Elecraft mailing list > > Post to: Elecraft@mailman.qth.net > > You must be a subscriber to post to the list. > > Subscriber Info (Addr. Change, sub, unsub etc.): > > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > > Elecraft web page: http://www.elecraft.com > > > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com