It should be mentioned that FT8 and JT65 are constant envelope and therefore there should not be any AF envelope to follow. Actually when I recently measured the AF output from WSJT-X there was a tiny amount of AM, around 1.4% in fact which so small as to be of no consequence. ALC can introduce AM quite easily if not properly implemented or adjusted. The recommended method of adjusting the K3S AF drive for digital modes works very well but each radio is different. The recent Icoms (IC-7300, IC7610 and IC9700) 50% indication on the ALC meter does not cause any degradation or spreading even for MSK144 which has 16.5% AM. Presumably there is a small delay introduced to prevent overshoots, a so called 'look ahead' algorithm.
Regards Conrad PA5Y -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Fred Jensen Sent: 13 July 2019 00:33 To: elecraft@mailman.qth.net Subject: Re: [Elecraft] ALC implementation Well ... I think it depends on your definition of distortion. One can argue that, if the RF envelope does not exactly equal the original AF envelope, the signal has been distorted and that is certainly the case when the dynamic range has been reduced with compression. It doesn't increase the occupied bandwidth however [at least not by much]. Clipping mows down the peaks, leaving sharp "edges" or signal transitions which do increase the occupied bandwidth. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 7/12/2019 2:41 PM, Bob McGraw K4TAX wrote: > Don't confuse compression and clipping. Compression reduces dynamic range > while clipping sets a hard ceiling and does generate distortion. Compression > used correctly does not generate distortion. > > 73 > Bob, K4TAX > > > Sent from my iPhone > >> On Jul 12, 2019, at 4:00 PM, Wes <wes_n...@triconet.org> wrote: >> >> What distortion? >> >>> On 7/12/2019 1:15 PM, Jim Rhodes wrote: >>> Nothing when it is done correctly on a mode that can stand the distortion. >>> I personally won't use it on digital modes as my rigs tend to turn it off >>> by default. >>> >>> Jim Rhodes >>> K0XU >>> >>> On Fri, Jul 12, 2019, 15:10 Wes <wes_n...@triconet.org >>> <mailto:wes_n...@triconet.org>> wrote: >>> >>> And what exactly is the problem with compression? It's used all over >>> the >>> place. >>> >>> Wes N7WS >>> >>> On 6/28/2019 11:38 AM, Brian Denley wrote: >>> > I have always thought that ALC is not appropriate for power control. >>> It’s a protection system. Over use of ALC acts like compression. No? >>> > >>> > Brian >>> > KB1VBF >>> > Sent from my iPad >>> >>> ______________________________________________________________ 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 g0...@g0ruz.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 Message delivered to arch...@mail-archive.com
