It's basic physics, Jim. A keyed signal is amplitude modulated and an amplitude modulated signal produces sidebands.
Your are quite right that the rise time affects the amount of spectrum the sidebands make. Of course, higher keying speeds require faster rise and fall times, otherwise one code element would begin before the fall time allowed the previous element to stop. Indeed, the way to reduce clicks is to extend the rise and fall times. The slower the rise and fall the less "click" energy around the carrier. In the extreme you make the rise and fall times infinite (that is, you don't key the carrier at all). Then you'll have no sidebands (clicks) at all. If you modulated the signal 100% with a pure sine wave, you'd only have two sidebands at discrete frequencies above and below the carrier separated by the frequency of the modulating signal. The issue with CW is that we don't use a sine wave. No matter how we look at it, we distort the keying signal by stopping it at the point the carrier is full on during the rise and full off at the fall. That distortion produces further sideband energy beyond the sideband produced by the keying waveform. Advanced shaping techniques such as those used in the K3 minimize that energy in the sidebands, but it's still there. Poorly designed and operated rigs can produce keying sidebands far in excess of what's needed for good communications, just as poorly designed and operated AM or SSB rigs produce sidebands far in excess of what's needed. It sounds like you've run into one of those. I think anyone who spends enough time on the CW bands will find them. They come from two sources. One is the design of the rig itself. You are quite right that some rigs are better than others. Considering that just about any transmitter built since the demise of spark in the 1920's is perfectly legal on our bands today, sometimes it's a limitation of the design. Among current designs, some are better than others. The other is operator error. In these days of mostly factory-designed and built rigs, it's usually caused by over-driving an amplifier in the mistaken belief that linearity isn't important in CW. Linearity is very important to retain the keying waveform of the rig driving the amplifier, just as it's very important to preserve the waveform of an SSB signal. It's also why it's bad practice to turn the POWER knob on a K3 or K2 full clockwise, even on CW. IMD (distortion) increases as you go past the rated 100 watts output. On CW distortion is heard as clicks as Jim notes. Indeed, for over half a century that I know of, we've always defined "clicks" as excessive CW sidebands, recognizing that normal sidebands are always present. Until fairly recently, it was not possible to listen to the sidebands in a CW signal using a typical communications receiver without hearing the carrier too. They were just too close together. Nowadays our advanced receivers can split the sideband off of the keyed signal, just as for years we've been able to split the sidebands off of an AM signal. On CW those sidebands sound like clicks. Ron AC7AC -----Original Message----- And I strongly DISAGREE with Ron's statement that clicks are an essential part of CW. Clicks are a function of a FAST RISE TIME and DISTORTION, not keying speed. There's a KH6 contester who moved from K4 with a monster signal, monster clicks, monster SSB splatter, and monster attitude to go with it. I've told him about his clicks and splatter several times, but the clicks, splatter, and attitude are still there. 73, Jim K9YC ______________________________________________________________ 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
