Good my 5 ms measurement was the closest so far. Thank´s for the explanation on the construction, appreciate it.
After all, why should I bother, if my K3 clicks it doesn´t disturb me. /Jim SM2EKM ---------------- On 2010-12-03 17:56, Wayne Burdick wrote: > There will never be a K3 menu option that allows for clicky CW. K3s > are at or near the top in every CW contest already, thanks to the > skill of our customers rather than bandwidth-hogging signals. > > There are two factors that control how clean and click-free a CW > keying envelope will be: explicit shaping by DSP or analog circuitry, > and incidental shaping due to ALC or transmit chain effects. The K3's > CW is extremely clean and narrow-banded and click-free because we took > both factors into consideration. (Note the this is also true of the K2.) > > DSP Shaping: > > The rising and falling edges of the CW waveform are shaped by the DSP > using an optimal raised-cosine envelope. Rise and fall times are > approximately 4 ms, varying only slightly over the entire available > power output range of 0.1 to 110 W. We experimented with other > sigmoidal envelope shapes, but the raised cosine was the best overall. > > ALC: > > The K3 one of very few high-end transceivers that use open-loop > application of keying envelope shaping. This ensures that the applied > shape is not compromised by ALC action. Most transceivers, including > some recently discussed, use fast ALC to control power output level. > Even if they start with DSP or analog shaping, the ALC jumps in to > limit the peak amplitude of the transmit waveform, resulting in > envelope clipping and thus wideband clicks. > > So how does the K3's CW ALC work? First, we use a TX gain calibration > procedure to store per-band gain constants. This information is used > to preset transmit gain as you rotate the POWER control. When you hit > the key, we start off just below this target level (about 0.5 to 1 > dB), then use a slow ALC loop to adjust gain to hit the exact level > requested. Generally the power stabilizes in one or two dits. Shaping > is excellent on every code element. > > We use similar techniques to ensure virtually perfect envelope shaping > in data modes. In voice modes, we use two-stage ALC -- fast pre- > crystal-filter ALC in the DSP, slow firmware-based ALC *after* the > crystal filter -- to ensure that speech signals are completely free of > splatter. This technique also results in extremely clean and effective > speech compression. > > 73, > Wayne > N6KR > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
