>>However, Gianfranco of SPE (Expert) suggests running the >>exciter at full power. He says there is no splatter and >>the proof of the pudding is in the eating. >>That seems >>to be true. I can't see any splatter on the WaveNode and >>several on the air tests report fine audio with no >>splatter.
>>I repeat: There is something here we don't understand. We went through this ALC stuff just one month or so ago. The problem with ALC is the ALC system response delay and the propagation delay through the radio, especially narrow filters. The leading edge of everything takes a hit until the ALC level comes up. The time delay to interact with the system is the problem. With a reasonable ALC hang time the splatter is not too objectionable on a crowded band, but on real quiet bands it can be disruptive to weak signals. It is a very broad bandwidth short duration problem. In my opinion it isn't the major problem we face with SSB bandwidth and we may be over focusing a little on it. The duration is so short the average power is very low, but it is there. It would be very easy to miss on a spectrum analyzer, as a matter of fact I would say it is nearly impossible to catch. A selective level meter would be a far better detector. The real problem is the K3 has a unique ALC system that is in front of the filtering, so leading edge delay isn't an issue. Since the K3 has no leading edge transients, and since anything after the radio (except a clamp or fast attenuator) can not fix the transients, I don't see why anyone would want to run external ALC with the K3. Here is what Wayne said: <<<<<<<<<<<<<<<<<<<<<<< K3 external ALC setup is covered on page 27 of the owner's manual. Please read this page before attempting to use external ALC with any amplifier. Executive summary: 1. DO NOT turn the K3's power all the way up and use amplifier ALC to maintain peak power at the output of your amplifier. This WILL NOT work. 2. Instead, adjust the power level at the K3 to provide just enough drive to hit the peak power desired at the amp. You may want to set CONFIG:PWR SET to PER BAND so you don't have to adjust power each time you change bands. (This is also covered on page 27.) 3. External ALC is accommodated as a safety backup in the event that peak power suddenly increases, etc., due to a failure or load change. When properly applied, it will rarely be needed. Technical details: The K3 is designed to *not* depend on fast external ALC, because that absolutely, positively causes splatter. We studied lab work from several authors on this topic and decided to take a different approach: our fast ALC is all applied *ahead* of the 1st I.F. crystal filter (it's handled by DSP, at the AF and 2nd I.F. stages). We do apply slow, long-term ALC after the crystal filter, but this can't cause splatter because of the long time constant. External ALC, if used, is factored into this part of the equation. Yes, the K3 is unique in this regard. It may be slightly inconvenient, but it will result in a cleaner signal. 73, Wayne N6KR >>>>>>>>>>>>>>>>>> 73 Tom ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
