Per Jim’s note below: I recently upgraded to the new Synthesizers for my ancient K3 #951.
I have 5 Pole 2.7s in both receivers, but multiple 8 Pole narrower filters as well as a 5 pole 200Hz that always was hard to listen to. I read through the manual and Fred’s excellent K3 book and found that higher gain was not recommended. I had 4dB or more gain on a few filters especially narrow CW. I decided to experiment with lower gain settings. When I reduced the gain to 2-3 dB the “ringing” in the narrow filters reduced a LOT! That coupled with the new Synths has made the old K3 come to life all over again. It is truly amazing in pileups. Individual signals just pop out of the mess. Thanks to Howard at Elecraft for digging up old invoices with factory mods and updates. And thanks to Elecraft for engineering such an amazing upgrade to an old radio! Cheers, Ken N6TZV > > ------------------------------ > > Message: 3 > Date: Fri, 26 Feb 2016 09:07:03 -0800 > From: Jim Brown <j...@audiosystemsgroup.com> > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 5 pole vs 8 pole filters - attenuation in > the passband > Message-ID: <56d08637.5020...@audiosystemsgroup.com> > Content-Type: text/plain; charset=windows-1252; format=flowed > > On Fri,2/26/2016 8:50 AM, lstavenhagen wrote: >> Quick question - do the 8 pole roofing filters have more attenuation, as a >> general rule, in their passbands than the 5 pole? > > Yes, but the difference doesn't matter -- it's in the IF, not the front > end. Further, there is an menu adjustment for each filter to equalize > the IF gain when switching between filters. > > The advantage of 8-pole filters is smoother response in the passband of > wider filters, and steeper skirts. In general, roofing filters are only > needed for high QRM conditions like contesting. Their function is to > protect the DSP from overload by strong signals outside the desired > passband. When the DSP IF is set to a bandwidth close to that of the > roofing filter, the two filters cascade to provide even steeper skirts. > Again, needed only under contest conditions. > > It's amazing the things one can learn by reading the manual. :) > > 73, Jim K9YC > > > ------------------------------ > > Message: 4 > Date: Fri, 26 Feb 2016 10:22:37 -0700 (MST) > From: lstavenhagen <lstavenha...@hotmail.com> > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 5 pole vs 8 pole filters - attenuation in > the passband > Message-ID: <1456507357324-7614639.p...@n2.nabble.com> > Content-Type: text/plain; charset=us-ascii > > Well, yes, to spill the beans on this: it was when I was reviewing the filter > gains on my K3 the other day that this came up. I built my K3 with the stock > 2.7khz 5 pole filter in FL1 and an 8 pole 400hz in FL2 - however, to even > out FL1 and FL2 requires the gain to be nearly maxed out for FL2 (8 db gain, > IIRC). My K3S, however, has 8 pole 2.8khz and 400hz in goth FL1 and 2, > respectively. But they're almost dead even in terms of attenuation with FL2 > set at only 2 db gain. > > So that led me to wonder if the 5 pole in my K3 had less attenuation in > general, accounting for the difference. Just a curiosity for me. > > 73, > LS > W5QD > ______________________________________________________________ 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
