Yes I know that Don, the purpose of the test was to see how much overshoot we got with an CESSB processed audio verses with normal audio and compare them. As part of my experiments I needed to see how much influence the audio drive level had and tried different audio drive levels from 0 to 5 bars of VU on the initial reference tone at the start of the transmission, to study how the power levelling worked on the KC3. I totally understand the function of the VU meter aspect of the "ALC" meter on the KX3.
What I didn't want to do was have -any- ALC taking place as it may have masked the effect I was trying to see on the output envelope, hence the experimentation on levels which I knew should be below ALC, though as it is impossible to to turn off the closed loop power levelling in the KX3 it is hard to do the test at all. I did try at the normal drive levels as well, and with compression on/off, with SSB in ESSB and just about any other setting you care to mention. It was an experiment, that is all. What is apparent from looking at the output RF envelope is that the power levelling system always adjusts the peak power to what you have set in PWR very rapidly whatever speech audio drive level you apply to the radio. In this respect it is quite different to other radios, as we know from the instructions on how to set up levels for data and so on. The KX3 does show some envelope overshoot even with an external CESSB signal, showing that the current system is not "CESSB ready" as W9GR would put it. Meaning that even if an external box was available to produce CESSB audio in realtime, it would not be of very much benefit with the existing KX3 SSB modulator. See the QEX article this month (link in earlier post). I am still interested to know if it would be possible for Elecraft to implement CESSB (which is freely available) within the KX3 DSP modulator. CESSB isn't a new MODE, and doesn't need a new receiver demodulator or anything. Can I just finish by saying that I have no connection at all with W9GR or any other radio manufacturer. I and am purely interested in whether this method of increasing average speech power within an SSB signal without production of clipped overshoot could be of benefit to Elecraft radios. From the detailed articles in QEX and QST it sounds to have great potential and is already available by one of the other USA radio manufacturers as I understand from the referenced article. 73 from David GM4JJJ > On 12 Jan 2016, at 22:05, Don Wilhelm <w3...@embarqmail.com> wrote: > > David, > > Reducing the audio drive level "well below ALC indication" is not a good idea > because the KX3 will 'power hunt'. > You should have at least 4 bars indicated on the ALC meter with the 5th bar > flickering. > ALC action is indicated by the 5th bar and above. Below that the "ALC" meter > is more or less like a VU meter to allow you to adjust the audio drive. > > 73, > Don W3FPR > > >> On 1/12/2016 4:26 PM, David Anderson wrote: >> I just finished playing the two test files that the author supplied, through >> the sound card to the KX3 and used the Data A input so that there was no >> compression or TX equalisation taking effect. I had the scope connected to a >> sampler on a dummy load and the KX3 set to 14.3 MHz at 3 watts PEP. >> >> The RF power levelling in the KX3 does a very good job. Reducing the drive >> level of the audio well below ALC indication made almost no difference as >> the KX3 just went ahead and levelled the power again to 3 watts PEP ... >> >> I captured the peak output on the digital sampling scope for both the >> conventional and CESSB signal from the KX3 RF output and here are links to >> the scope screen shots. >> >> First the CESSB >> https://www.dropbox.com/s/0kjrvzispyb45jy/CESSB%20ESSB%204KHz.BMP?dl=0 >> >> The conventional SSB >> https://www.dropbox.com/s/m4mmlwkcb77540c/conventional%20ESSB%204Khz.BMP?dl=0 >> >> Not a lot of difference, certainly not as much as there is if you compare >> the audio files going into the rig. >> >> 73 from David GM4JJJ >> >> >>> On 10 Jan 2016, at 18:36, Michael Walker <va...@portcredit.net> wrote: >>> >>> Hi David >>> >>> I doubt you ever will. If I remember correctly, what the CESSB does is >>> correctly clamp the gain while ensuring you continue to get full power. >>> >>> The micro second you go over 100%, the radio starts to clamp RF out and in >>> fact reduces it considerably. You would only be able to tell by watching >>> your RF envelope in a scope. >>> >>> This is all off the top of my head, but that is what I remember. I'll have >>> to read the paper on it again. >>> >>> There are likely others that know more about it than I do. >>> >>> Mike >>> >>> >>>> On Sun, Jan 10, 2016 at 11:44 AM, David Anderson <gm4...@yahoo.co.uk> >>>> wrote: >>>> >>>> Mike, >>>> >>>> I don't know why but I kept using ECSSB when I meant CESSB obviously, >>>> sorry for any confusion! >>>> >>>> Although the Elecraft power levelling is excellent, and I have not ever >>>> had bad reports of audio quality or splatter with my KX3 with the processor >>>> on or off, it certainly would be nice to be able to increase the talk power >>>> further as CESSB promises. >>>> >>>> 73 from David GM4JJJ > ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
