Yes 99% of all CW stations clicks at the "break" side. I didn´t think about the ALC but that is right, thanks.
However by increasing the envelope fall time we will "help" a bad ALC system if you understand what I mean. Anyway I better can this before HHQ puts the lid on. /SM2EKM QRT ------------------ On 2010-12-03 19:18, Joe Subich, W4TV wrote: > > > Waveform? When you have a 1 ms raise/fall time no way you > > can shape the waveform so it doesnt click. > > That's not the case. If the first and second derivatives of > the power output are minimized, the waveform does not click. > There are many studies about bandwidth vs. rate of change in > digital modulation that will provide the information to show > that principle. > > In the specific case of CW as long as the transitions from > the "rise" to the steady "on" state and from the steady "on" > state to the fall are properly shaped (first/second derivative > minimized) the apparent clicks will be minimized. > > The traditional "feedback" ALC system almost guarantees clicks > on the *trailing edge* of the CW element. Traditional ALC > attempts to maintain the output as the key is opened and will > increase system gain as the driving waveform starts to decay. > The output level will only begin to fall when the ALC gain > has reached maximum - at which point there will be a major discontinuity > in the waveform. A properly designed feedback > ALC system would be incorporate sample and hold to maintain > steady system gain during the "ramp up" and "ramp down" parts > of the CW waveform to prevent the "corner sharpening." > > Again, rise time controls the basic CW bandwidth but "clicks" > are a feature of discontinuities in the CW envelope. Please > do not confuse the two. > > 73, > > ... Joe, W4TV > > On 12/3/2010 9:46 AM, Jan Erik Holm wrote: >> Waveform? When you have a 1 ms raise/fall time no way you >> can shape the waveform so it doesnt click. >> >> /Jim SM2EKM >> --------------- >> On 2010-12-03 15:29, Guy Olinger K2AV wrote: >>> All the click complaints for years and still Yaesu doesn't take care >>> of the waveform. It's not like there aren't tons of reads on the >>> subject, no excuse at all since Google. It's more like they just >>> don't care, or are simply convinced it doesn't matter. After all, >>> isn't CW obsolete, and nobody uses it anymore, right? >>> >>> 73, Guy. >>> >>> On Fri, Dec 3, 2010 at 9:08 AM, Paul Christensen<w...@arrl.net> wrote: >>>> 4 ms. Given that the FTdx5K rise/fall is roughly double the time of the >>>> K3 -- and that the K3 at 2 ms consumes significantly less bandwidth >>>> than the >>>> FTdx5K at 4 ms, the CW transmit quality of the K3 is far superior. I >>>> would >>>> like to hear QSK on the Yaesu, compare it with the K3's QRQ mode, >>>> and note >>>> any audible artifacts in the headphones -- especially for signs of >>>> clicks >>>> and DC thumps. >>>> >>>> Referring to the December, 2010 QST Product Review on p.45, take a >>>> look at >>>> the leading edge of the second pulse (lower trace) in Figure 1. The >>>> sharp >>>> rise and sharp edge at the top of the waveform is what is consuming the >>>> bandwidth. Based on that waveform, it was absolutely generating >>>> clicks at >>>> some distance from the Fc. That pattern is characteristic of a >>>> deficient >>>> ALC system. >>>> >>>> A deficiency in the ALC system then takes us into SSB Tx IMD. The >>>> published >>>> FTdx5K Tx IMD numbers look great with the ARRL's steady tone method but >>>> arguably, that's probably more relevant to data modes. The question is >>>> "what is the FTdx5K's ALC doing to undermine the rig's otherwise >>>> excellent >>>> SSB Tx IMD numbers, especially in Class A?" Really, the published Tx >>>> IMD >>>> figures are meaningless unless dynamic testing is conducted to simulate >>>> rapid changes in power associated with voice modes. >>>> >>>> Paul, W9AC >>>> >>>> ----- Original Message ----- >>>> From: "Jan Erik Holm"<sm2...@telia.com> >>>> To:<elecraft@mailman.qth.net> >>>> Sent: Friday, December 03, 2010 8:27 AM >>>> Subject: Re: [Elecraft] Fwd: New Sherwood report >>>> >>>> >>>>> Yes but to what rise/fall time was the radio set? AFAIK in >>>>> the FT5000 it can be changed. >>>>> >>>>> /Jim SM2EKM > > ______________________________________________________________ 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
