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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
