Re: [Elecraft] K3/K3s filter setting with the K3 Utility
Rich, Interesting food for thought. I just received my 1.8 for the sub RX and was wondering what others found most helpful seeing as there are the options to custom tailor the settings. At the same time, I really make great use of the narrow filter on CW and am always looking for something I can do with what I have that is better than I have been doing. Thanks for your reply. 73, Gary KA1J > There can be reasons to configure a roofing filter differently from > its nominal bandwidth. > > For example, I have a "250 Hz" filter. According to the filter plots > on the Elecraft web site, the 6 dB bandwidth of this filter is > actually closer to 375 Hz. I configured my filter to switch in at 350 > Hz, which makes it much more useful to me than it would be if I had > configured it to switch in at 250 Hz. > > If this filter is configured to switch in at 250 Hz in agreement with > the label, then when you set your DSP bandwidth to 300 Hz or 350 Hz, > you will be using the next wider filter in your receiver. Strong > signals outside the DSP bandwidth but inside the wider roofing > filter's bandwidth can still have bad effects, whereas if the filter > is configured to switch in at 350 Hz, you can take advantage of its > ability to reduce those unwanted signals with relatively minor impact > on signals within the DSP bandwidth. > > Of course, if the bandwidth of the 250 Hz filter really was 250 Hz, > configuring it to switch in at 350 Hz would render the 300 Hz and 350 > Hz settings of the DSP filter somewhat less useful, since the actual > bandwidth of the filter combination would now be close to 250 Hz > regardless of what the DSP control said. > > There might be reasons to go in the other direction as well, i.e. to > configure a filter to switch in only at a narrower bandwidth than the > bandwidth marked on the filter. For example, if you had 500 Hz and > 1000 Hz filters and often used a digital mode whose bandwidth was, > say, 750 Hz, you could configure the 1000 Hz roofing filter to switch > in only at 700 Hz and below. This would give you better filtering > between 500 Hz and 700 Hz than without the 1000 Hz filter, while still > permitting the 750 Hz mode signals to pass through at DSP settings of > 750 Hz and above without being restricted by the roofing filter. > > 73, > Rich VE3KI > > > KA1J wrote: > > Is there any advantage to setting the 1.8 > above, say as 2. in the utility. > > Or to have the 200Hz filter engaged at say > 250? > __ > 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/K3s filter setting with the K3 Utility
If I understand correctly what Rich is saying, it could be exemplified like this: "If you want e.g. a 2.1 kHz bandwidth to receive a digital signal, and use a 2.1 kHz roofing filter in addition to a DSP setting of 2.1 kHz, you may find that it won't decode as well as using a 2.8 kHz roofing filter along with the 2.1 kHz DSP setting." That reminds me of what I have sometimes imagined observing in receiving SSB. This may be just my imagination, but I thought the voice sounded bad if I set the DSP to the same width as the roofing filter. I have used the utility to make sure the roofing filter is always at leas slightly wider than the DSP setting. Since that change I have been much happier with SSB receive voice quality. Is this just in my head? Flames accepted. If I am right, it suggests that the crystal filters somehow have a negative effect on voice quality. My guess would be that this comes from phase non-linearity at the edges of the crystal filters. Haven't we heard that Elecraft checks/selects roofing filters to ensure minimal phase distortion? Of course, the phase distortion would negatively affect digital signal demodulation as well. 73, Erik K7TV -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Richard Ferch Sent: Friday, March 22, 2019 4:06 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3/K3s filter setting with the K3 Utility Earlier I gave an example of a situation where you might choose to enable a roofing filter at a bandwidth wider than the bandwidth marked on the filter. I also gave a poor example of enabling a filter at a narrower bandwidth. Here is a better one: You use a variety of digital modes with different bandwidths, one of which happens to be the same as or close to the bandwidth of one of your roofing filters. You find that when that roofing filter is engaged, that particular digital mode does not decode as well as it does with a wider filter setting. You might find that changing the configuration to switch that filter in at a narrower setting allows that particular mode to decode well, without having a noticeable adverse effect on the next narrower bandwidth mode you normally use. The likelihood of all this happening in combination with an actual need for a tight roofing filter because of nearby very strong signals might be quite low, but there is at least a theoretical possibility of such a scenario. There are probably more likely situations - just pointing out that it is not impossible that someone might want to do this. The good thing is, the capability is there if you somehow find that you need it. 73, Rich VE3KI __ 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/K3s filter setting with the K3 Utility
Since we are on this topic. I have a question regarding the 500hz filter. From what I have read it is rated at 525hz. So would it be best configured to come on at 500hz or should I set it to 550hz. I do not think you can set it to 525hz Thanks in advance Rich K3RWN On 3/22/2019 17:58 PM, Richard Ferch wrote: There can be reasons to configure a roofing filter differently from its nominal bandwidth. For example, I have a "250 Hz" filter. According to the filter plots on the Elecraft web site, the 6 dB bandwidth of this filter is actually closer to 375 Hz. I configured my filter to switch in at 350 Hz, which makes it much more useful to me than it would be if I had configured it to switch in at 250 Hz. If this filter is configured to switch in at 250 Hz in agreement with the label, then when you set your DSP bandwidth to 300 Hz or 350 Hz, you will be using the next wider filter in your receiver. Strong signals outside the DSP bandwidth but inside the wider roofing filter's bandwidth can still have bad effects, whereas if the filter is configured to switch in at 350 Hz, you can take advantage of its ability to reduce those unwanted signals with relatively minor impact on signals within the DSP bandwidth. Of course, if the bandwidth of the 250 Hz filter really was 250 Hz, configuring it to switch in at 350 Hz would render the 300 Hz and 350 Hz settings of the DSP filter somewhat less useful, since the actual bandwidth of the filter combination would now be close to 250 Hz regardless of what the DSP control said. There might be reasons to go in the other direction as well, i.e. to configure a filter to switch in only at a narrower bandwidth than the bandwidth marked on the filter. For example, if you had 500 Hz and 1000 Hz filters and often used a digital mode whose bandwidth was, say, 750 Hz, you could configure the 1000 Hz roofing filter to switch in only at 700 Hz and below. This would give you better filtering between 500 Hz and 700 Hz than without the 1000 Hz filter, while still permitting the 750 Hz mode signals to pass through at DSP settings of 750 Hz and above without being restricted by the roofing filter. 73, Rich VE3KI KA1J wrote: Is there any advantage to setting the 1.8 above, say as 2. in the utility. Or to have the 200Hz filter engaged at say 250? __ 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/K3s filter setting with the K3 Utility
Earlier I gave an example of a situation where you might choose to enable a roofing filter at a bandwidth wider than the bandwidth marked on the filter. I also gave a poor example of enabling a filter at a narrower bandwidth. Here is a better one: You use a variety of digital modes with different bandwidths, one of which happens to be the same as or close to the bandwidth of one of your roofing filters. You find that when that roofing filter is engaged, that particular digital mode does not decode as well as it does with a wider filter setting. You might find that changing the configuration to switch that filter in at a narrower setting allows that particular mode to decode well, without having a noticeable adverse effect on the next narrower bandwidth mode you normally use. The likelihood of all this happening in combination with an actual need for a tight roofing filter because of nearby very strong signals might be quite low, but there is at least a theoretical possibility of such a scenario. There are probably more likely situations - just pointing out that it is not impossible that someone might want to do this. The good thing is, the capability is there if you somehow find that you need it. 73, Rich VE3KI __ 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/K3s filter setting with the K3 Utility
I muffed the last part of my previous message, didn't I? Still, there are some higher-order effects that might push someone into configuring a roofing filter ti switch in at a slightly narrower setting than you might at first expect. 73, Rich VE3KI __ 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/K3s filter setting with the K3 Utility
There can be reasons to configure a roofing filter differently from its nominal bandwidth. For example, I have a "250 Hz" filter. According to the filter plots on the Elecraft web site, the 6 dB bandwidth of this filter is actually closer to 375 Hz. I configured my filter to switch in at 350 Hz, which makes it much more useful to me than it would be if I had configured it to switch in at 250 Hz. If this filter is configured to switch in at 250 Hz in agreement with the label, then when you set your DSP bandwidth to 300 Hz or 350 Hz, you will be using the next wider filter in your receiver. Strong signals outside the DSP bandwidth but inside the wider roofing filter's bandwidth can still have bad effects, whereas if the filter is configured to switch in at 350 Hz, you can take advantage of its ability to reduce those unwanted signals with relatively minor impact on signals within the DSP bandwidth. Of course, if the bandwidth of the 250 Hz filter really was 250 Hz, configuring it to switch in at 350 Hz would render the 300 Hz and 350 Hz settings of the DSP filter somewhat less useful, since the actual bandwidth of the filter combination would now be close to 250 Hz regardless of what the DSP control said. There might be reasons to go in the other direction as well, i.e. to configure a filter to switch in only at a narrower bandwidth than the bandwidth marked on the filter. For example, if you had 500 Hz and 1000 Hz filters and often used a digital mode whose bandwidth was, say, 750 Hz, you could configure the 1000 Hz roofing filter to switch in only at 700 Hz and below. This would give you better filtering between 500 Hz and 700 Hz than without the 1000 Hz filter, while still permitting the 750 Hz mode signals to pass through at DSP settings of 750 Hz and above without being restricted by the roofing filter. 73, Rich VE3KI KA1J wrote: Is there any advantage to setting the 1.8 above, say as 2. in the utility. Or to have the 200Hz filter engaged at say 250? __ 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/K3s filter setting with the K3 Utility
It seems as intuitive, the filter you use is the value you select in the K3 utility under filter configuration. I.e. a 1.8 filter is set at 1.8 in the utility. Considering there is DSP simultaneously occurring at the same time; Is there any advantage to setting the 1.8 above, say as 2. in the utility. Or to have the 200Hz filter engaged at say 250? If so, what benefits might be seen by doing this? Thanks, 73, Gary KA1J __ 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
