Thanks Ian I was about to point out those AGC data but you beat me to it. To emphasize the comments on SLP a bit, SLP = 0 gives you the best discrimination between signals of different strength ABOVE the THR level. When working a pileup I want that. Setting SLP=15 is a flat slope and makes signals of different level sound the same. You might want that for general rag chewing. However, since version 4.51, higher THR levels also affect SLP. For high THR, SLP=0 and SLP=15 are virtually the same. Alan explained that once but I'm not sure why that is so.
BTW, it is easy to make macros to switch between different THR/SLP values for different operating conditions. Cheers, Fred KE7X For all KE7X books (and other information) see www.ke7x.com<http://www.ke7x.com>. ________________________________ From: Elecraft <elecraft-boun...@mailman.qth.net> on behalf of Ian White <gm3...@ifwtech.co.uk> Sent: Wednesday, February 22, 2017 12:42 AM To: 'W0MU Mike Fatchett'; 'Elecraft Reflector' Subject: Re: [Elecraft] K3 Receiver mush Re-posting from April 2016, and earlier: 73 from Ian GM3SEK *************** The factory default AGC THReshold for the K3 and K3S is very, very low. Measurements by KE7X [1] have shown that the default setting of THR=5 corresponds to an AGC onset at less than S3, whereas competing rigs have a threshold of S7 or even higher. This very low AGC threshold is what allows the AGC to be activated by band noise. Elecraft's factory defaults of THR=5 and SLP=12 compress all signals above the AGC threshold into a very narrow range of audio output levels [see the measurements by KE7X]. This makes for comfortable broadcast-style listening - but there is price to be paid. The default settings tend to hide the real-life differences in the strengths of incoming signals - important differences that DXers and contesters *need* to hear, in order to pick individual signals out of a pileup. Following complaints from DXers, DXpeditioners and contesters about this so-called "pileup mush", and following further series of measurements by KE7X, Elecraft eventually did increase the available range of AGC THReshold settings (the v4.51 firmware upgrade). Following the release of FW v4.51, the consensus within the [K3-contesting] Yahoo group about the most important settings for DXing and contesting has been as follows. * AGC THR: increase to at least 8 (from default = 5) and preferably to 12, and then take some time to become re-accustomed to the increased range of audio levels [2]. (Some users recommend as high as 14, if your ears can handle it.) * AGC SLP: decrease to 8 or even less (from default = 12). Lower SLP settings allow stronger signals to sound somewhat louder, and thus more realistic, but the range of variation will be partly determined by the THR setting already made; so always experiment with THR first, and with SLP afterwards. * AGC DCY = SOFT (not default=NOR). The User Manual claims that "The SOFT setting can reduce IMD caused by traditional AGC, and is especially useful in 'pileup' conditions, in some cases making it unnecessary to turn AGC off." The settings recommended above have essentially solved the problem of "pileup mush" for those who have tried them... but regrettably, Elecraft has done almost nothing to make DXers and contesters aware that such changes are possible. More than 3 years after the firmware release notes boasted that v4.51 "greatly improves signal clarity in pile-ups and other high-noise or dense-signal situations, especially with threshold set to 12 or higher", that information is *still* missing from the User Manual. There is also no information on how to create different 'profiles' of AGC settings for different types of users. Meanwhile, Elecraft's factory AGC defaults remain exactly as they were, still optimized apparently for comfortable 'listening', while many DXers and contesters remain unaware that their K3/K3S could actually be *so* much better. [1] http://www.ke7x.com/home/miscellaneous-k3-information [2] It is important to give any increased AGC THReshold setting an extended trial. To anyone accustomed to an artificially restricted range of audio signal levels, a higher setting will initially sound quite 'aggressive' - even though the new setting is much closer to real life. ************ >-----Original Message----- >From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of >W0MU Mike Fatchett >Sent: 22 February 2017 00:39 >To: Elecraft Reflector >Subject: Re: [Elecraft] K3 Receiver mush > >I can run with 400 or 250hz filters. > >I have tried it with AGC fast, slow off etc. > >I just think this is something that most people just never see. This was >a major point of discussion a while back. I guess it is just the way >the radio is. I will have to try another rig to see if I notice the >same effects. > >In a pileup there is no offending station they are all calling me. > >I was just curious if other contesters or DXpeditioners settings might >be and if they are still seeing this issue. > >W0MU > > > >On 2/21/2017 8:48 AM, Don Wilhelm wrote: >> Mike, >> >> Think about it - if there are multiple signals in the passband, the >> AGC will respond to the strongest, there is just no way around that fact. >> If the signals can be separated by the DSP, and one is really strong, >> that strong station may be activating the Hardware AGC. The only >> solution for the latter is a more narrow roofing filter - put the >> offending strong signal out of the passband of the roofing filter and >> use shift to get your sidetone for the desired signal back in order. >> >> That may be too much "fiddling" for a run station in a contest, but it >> is a viable way to operate when trying to copy a weak station working >> close to a strong station. >> >> 73, >> Don W3FPR >> >> On 2/21/2017 9:25 AM, W0MU Mike Fatchett wrote: >>> We noticed again during the contest hat when 3 or 4 stations called, all >>> those signals would be flattened to the same level. Once you got to >>> where one or two stations were calling the signal level would pop up >>> substantially. >>> >>> I have played endlessly with slope and threshold with little effect. >>> >>> My K3 has the new syn boards as well and filters from 2.8 to 2.5. >>> Latest firmware etc. >>> ______________________________________________________________ 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 fc...@montana.edu ______________________________________________________________ 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
