Yes, as I understood it, the Icom rise time default is a BAD choice, but recent (e.g. IC7300 and others) radios permitted changing this to a better value, although still behind the cleaner output of Elecraft & Kenwood.
The other interesting part of the discussion was the use of “pre distortion”. Again I read this as a way for the exciting transmitter to compensate for non-linearity (and resulting dirty emissions) introduced by a modern semiconductor based “linear” amplifier (one place where tubes excel). All new and interesting stuff to me - and apparently the driving force behind the ARRL “Clean Signal Initiative” to both define better standards, then rate transmitters in ARRL testing against these standards. And of course, encourage/coerce manufacturers to clean up their outputs! Steve > On Jul 1, 2023, at 3:33 PM, Jim Brown <j...@audiosystemsgroup.com> wrote: > > On 7/1/2023 10:34 AM, Steve L wrote: >> The IC7300 was among the better commercial transceivers in terms of spurious >> emissions, clicks, splatter, etc. It wasn’t at the top of the list (the K3s >> is however), but was in the “better” category. However, Rob recommended a >> change in the CW signal rise time to no less than 6 milliseconds - I forget >> which menu item it was - but he criticized Icom specifically for a default >> setting that induced key clicks. > > ICOM rigs are NOT among the cleaner ones -- that spot falls to Kenwood, which > is second to Elecraft (and, I suspect, Flex 6000 series, which I haven't > measured). > > Yes, adjustable rise time is a REALLY bad idea, which K6XX pointed out in > 2013, and which I measured on the air for K6XX's talk, in a neighbor's ICOM > rig. Slower is better, but Elecraft's is best by far, carefully shaped keying > waveform. > > 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 Message delivered to arch...@mail-archive.com
