[Elecraft] K3: Real world use of 1.8 filter
My 2 cents: For rag chewing the stock wide filter is fine. In fact, I still use the stock SSB filter in both of my K3s and I am a pretty serious contester (nobody holds more current CQWW USA contest records than I do). Remember that a roofing filter is NOT what determines your final IF bandwidth. It does, apparently, contribute a little, but the DSP filtering is mostly what is doing that. So for me, the difference between how many signals are going to fall inside your passband when from 2.7 to 2.1 to 1.8 on SSB is, well, not much. If anyone in the USA has such a concern, for me, is appropriate only for contesting. Even when DXing, either your calling on his frequency or if split, well, hopefully he is asked for a split of more than just up 1. Remember, this is SSB. Some will say that on 80/160, there are a very few number of DXing occasions where the narrower SSB filter can help. I won't argue that. I have to wonder out loud how many guys are feeling the DSP filter width impact when they go from their 2.7 to 2.1 to 1.8 on SSB versus how much of that is improvement in IMD reduction specs. For 99%, they probably are feeling the narrower DSP filter impact (which means the narrower roofing filter has essentially no impact at all). If the SSB band is packed with wall-to-wall very, very, very strong signals, then I'm betting that the roofing filter BW just won't matter for the vast majority of ops. Are there times when the narrower roofing filters are better? Probably a handful per contest. But for me, when contesting, I really don't want to deal with such a situation. I can probably have a better rate (if I'm running) by finding a better QRG to attempt to run (call CQ). It's mostly how much you want to defend your frequency versus how much you want to improve your QSO rate. YMMV. So to summarize...for my 2 cents, for rag-chewing the stock SSB filter is VFB. de Doug KR2Q __ 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] K3: Real world use of 1.8 filter (oops)
I would like to change one word in the following paragraph. In the last sentence, If the SSB band... change the word If to Unless Sorry about that. de Doug KR2Q I have to wonder out loud how many guys are feeling the DSP filter width impact when they go from their 2.7 to 2.1 to 1.8 on SSB versus how much of that is improvement in IMD reduction specs. For 99%, they probably are feeling the narrower DSP filter impact (which means the narrower roofing filter has essentially no impact at all). If the SSB band is packed with wall-to-wall very, very, very strong signals, then I'm betting that the roofing filter BW just won't matter for the vast majority of ops. __ 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
Re: [Elecraft] K3: Real world use of 1.8 filter (oops)
I will roll with the current setup for awhile but i have seen on several occasions how I can deploy the use of the 2.1 kHz filter in noisier band conditions say on 40m to improve intelligibility and readability of weaker signals. If the 1.8 kHz filter will continue in that line of improvement, it would probably be warranted down the road to add the 1.8 khz filter and reconfigure my current setup on this K3. I do have to hold off for more spending on the radio since I focusing my green stamps on a SteppIR 3 element antenna upgrade project and my wife wants an incredibly expensive baby room for our first. Keith AG6AZ Sent from my iPhone please excuse typos On Jan 14, 2012, at 6:28 AM, DOUGLAS ZWIEBEL doug...@gmail.com wrote: I would like to change one word in the following paragraph. In the last sentence, If the SSB band... change the word If to Unless Sorry about that. de Doug KR2Q I have to wonder out loud how many guys are feeling the DSP filter width impact when they go from their 2.7 to 2.1 to 1.8 on SSB versus how much of that is improvement in IMD reduction specs. For 99%, they probably are feeling the narrower DSP filter impact (which means the narrower roofing filter has essentially no impact at all). If the SSB band is packed with wall-to-wall very, very, very strong signals, then I'm betting that the roofing filter BW just won't matter for the vast majority of ops. __ 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
Re: [Elecraft] K3: Real world use of 1.8 filter (oops)
Not sure what you mean by feeling. As the filter BW is narrowed, I usually shift the Fc down as well. This gives more balance to the heard spectrum, which is a change of course. When the roofing filter shifts from 2.8 to 1.8, I can't feel a transition, maybe because of this operating method. The only way I've really ever perceived a transition is when using the XFIL key to change roofing filter. The transition is abrupt, as expected. I notice a reduction in distortion using the 1.8 filter in crowded conditions. Seems like most folks would notice better intelligibility, but can't really sense distortion as such. Contesters excluded, of course. They can and do notice. I feel a lot more IMD reduction in CW, while changing the DSP filter bandwidth. Much more. Filters here: 0.25, 1.8, 2.8, 6.0, 13.0. 73, matt W6NIA On Sat, 14 Jan 2012 09:28:00 -0500, you wrote: I would like to change one word in the following paragraph. In the last sentence, If the SSB band... change the word If to Unless Sorry about that. de Doug KR2Q I have to wonder out loud how many guys are feeling the DSP filter width impact when they go from their 2.7 to 2.1 to 1.8 on SSB versus how much of that is improvement in IMD reduction specs. For 99%, they probably are feeling the narrower DSP filter impact (which means the narrower roofing filter has essentially no impact at all). If the SSB band is packed with wall-to-wall very, very, very strong signals, then I'm betting that the roofing filter BW just won't matter for the vast majority of ops. __ 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] K3: Real world use of 1.8 filter (oops)
This topic has been pretty thoroughly discussed, so excuse my additional comments. In summary, I think the majority feel either the 2.7 or 2.8 KHz filter adequate for general use, since one has the ability to narrow bw using DSP. I have only the 2.8 (in both Rx) and 400-Hz filter (in the main Rx). I do mainly weak-signal work where narrow bw is important to reduce white noise. On CW-eme it is common to run at 100Hz for this purpose as it increases SNR. The DSP filter handles that really well since the objective is to eliminate noise at the detector (which the DSP filter does). A narrow roofing filter has significant use keeping strong off-freq RF from causing IMD, or affecting the RF gain stages. This is typically found in high-density HF contests (which I do not participate in). I chose the 8-pole filters thinking the steeper skirts might offer a slight advantage in crowded band conditions. For HF CW the 400-Hz filter makes copy really arm-chair nice as it almost results in hearing only the one intended station in the passband. On CW-eme I haven't decided if 400-Hz roofing filter offers any advantage over the DSP filter. I suspect not. That all being said, I did order the roofing filter for my new KX3. Why? Because I expect to travel with it to areas where that will be more important. Hill-toping with it portable can expose one to nearby strong signals (even IF feed-thru when running with VHF-mw transverters). Being a direct-conversion SDR, RF filtering is more important to keep out unwanted RF energy. So roofing filters generally will not hurt performance if used and may help in some situations. 73, Ed - KL7UW, WD2XSH/45 == BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep dubus...@gmail.com Coming Soon - Kits made by KL7UW == __ 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
