http://www.elecraft.com/K3/Roofing_Filters.htm
> What is the best way of determining the gain setting? Seem to recall an app > for this. > > David Wilburn > NM4M > Sent from my Verizon Wireless BlackBerry > > -----Original Message----- > From: Brett Howard <br...@livecomputers.com> > > Date: Sat, 15 Aug 2009 15:51:46 > To: Merv Schweigert<k...@flex.com> > Cc: <Elecraft@mailman.qth.net> > Subject: Re: [Elecraft] K3 new V3.25 NR not so good for CW week signal > > > Not saying I'd do it. (and I'm not with the 8 filters I have in my > radio) but one can if thats what they wish to do. > > ~Brett > > On Sat, 2009-08-15 at 12:42 -1000, Merv Schweigert wrote: > >> Not really, if you read the recommendations for the filters you will >> notice >> that caution is warranted for setting the gain higher than >> recommended, >> for IMD prevention if I remember correct. Kind of like the Inrad >> roofing >> filters, in some cases the gain is set to high and causes more IMD >> than >> without the filter. >> Some Inrad roofers for the FT-1000D had too much gain and the radio >> was worse with them installed than without. W8JI had some >> measurements >> on those issues. >> Merv KH7C >> >>> This is sorta already there if you have multiple roofing filters. You >>> can define the gain that is added when each filter kicks in. >>> >>> >>> On Sat, 2009-08-15 at 13:50 -0600, William Carver wrote: >>> >>> >>>> I've noticed in homebrew receivers as the bandwidth narrowed, shedding >>>> noise and QRM I preferred the gain to go up, increaseing the in-passband >>>> signal amplitude. I always attributed it to formative years with a >>>> Heathkit Q multiplier. It may be an effect similar to AGC with >>>> adjustable flatness (May 1996 analog circuit, in DSP of K3). I found I >>>> preferred to have strong signals sound louder rather than perfectly >>>> flat. Prolly a psycho-acoustic explanation (or maybe just get my head >>>> examined?). >>>> >>>> In firmware one could increase the audio gain by an adjustable amount as >>>> the IF bandwidth was decreased, with an operator-settable scaling >>>> number. Say 0 = gain independent of bandwidth, to 100 = gain multiplied >>>> by K * (2800/DSP bandwidth). Very similar to the AGC rise scaling. That >>>> sounds good to me. >>>> >>>> >>>> >>>> ______________________________________________________________ >>>> 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 >>>> >>>> >>> ______________________________________________________________ >>> 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 >>> >>> >>> > > ______________________________________________________________ > 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 > ______________________________________________________________ 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
