Us old f*rts have got to quit thinking analog. K3 CW is not keyed. It's effectively data-graphed and fed directly into a digital-analog converter (DAC). Remember, ZERO SIGNAL OUT in TX state is A STREAM OF DATA VALUES sent to a DAC that is RUNNING, not a stage that is switched off. The "keying circuit" is a subroutine. Paddle dash dot and Key In are read as a binary state on three lines to a CPU that go low when input is grounded. Shows up as a value in a register.
There may be a bit more (or less depending on your point of view) to the "lack of choice" than it seems. When I look in the schematic for TX RX switching, all I see is unshaped on/off diode circuits all over the place that are switching from a common line or two, transiting the K3 circuits from TX state to RX state. You cannot follow the key line to an analog circuit that is turning an oscillator on and off, or breaking the feed of a steady oscillator to a following stage. So there is no capacitor to discharge for shaping the CW waveform, no resistor to adjust. This is not at all like my FT1000MP, where very loosely controlled cap values made some MP's clicks far worse than others. The K3 lets the RX to TX state change complete before it feeds the DAC any data that implies signal power output. Turning on the CW baud consists of some subroutine feeding some other subroutine numbers that are sent to the DAC, AFTER the K3 has gone RX state to TX state. Reverse for RX to TX. On the straight key side of 15 kHz TX IF, it's nuthin but arithmetic. The shape of the CW baud rise and fall transitions is a pile of numbers. It is oh so possible to monkey with the numbers to get a clear baud transition that has no artifacts in the adjacent channel once transmitted. And a baud transition, by the way, that is impossible with any analog component switch. Having a "choice" of keying waveshapes means that there has to be alternate piles of numbers or subroutines, and the extra running code to switch them. Why bother. They made it the cleanest CW signal on the band and went to work on something else. 73, Guy. On Thu, Sep 13, 2012 at 2:21 PM, Bill W4ZV <btipp...@alum.mit.edu> wrote: > > Matt Zilmer wrote >> >> Phase noise and key clicks are the enemy. I respectfully suggest that >> Wayne emphasize (as well) that designing a transceiver to >> intentionally not produce either of these is a worthy objective more >> on a moral plane than an operating advantage. Tactically, having >> clicks and wideband noise could be put to advantage against other FD >> groups. >> > > Regarding your last sentence, to my knowledge, Elecraft is the ONLY > manufacturer who does not allow adjustment of CW Rise/Fall time (Ten-Tec, > Yaesu and possibly others do). Adjusting this time to less than ~5ms can > cause clicks which, as you said above, can be useful in contests to keep > others away from your run frequency. > > Kudos to Wayne for not allowing the user to adjust this parameter and > therefore keeping our K3s cleaner than other rigs. > > 73, Bill W4ZV > > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/K3-Phase-Noise-CW-Key-Clicks-tp7562575p7562615.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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 ______________________________________________________________ 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
