K3 - Filter suggestions for new builder
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K3 - Filter suggestions for new builder
 
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I'm asking for a little help with filter choices. I've read all I can on the subject
and have come up with what I think is a good choice for me. I'm going to be getting the sub-receiver so I'm going to be getting 2 of each filter. At almost $300 a filter set I would hate to make a choice that I later have to replace. I'm new to CW and spend about an hour a night working CW on 80/40/30/20. I like to chase DX both CW and SSB. I do some contesting but I usually only have an hour or two in each contest to operate. I'm just too busy with family and work to put more into it. I would like to do more. I've never worked FM or AM/ESSB because I've never had the capability. I'm coming from an Orion II and really liked the diversity reception and want that back. I'm pretty sure about getting the: 2.8 Khz, 8 pole 1.8 Khz, 8 pole 400 Hz, 8 pole Wondering if I should put in the: 1.0 Khz, 8 pole 13 Khz FM Thanks for any thoughts on the choices. 73 Stan AE7UT |
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Stan,
Your first 3 selections mirror mine. I think you'll find them all useful. I have only the 2.8 and 400 in my second receiver, however, and find that to be good for me. You do not have to install filter pairs for every IF width. Filters are pretty easy to install, so there's no penalty for waiting on the AM and FM (which I do have for the main receiver). I do some SWLing and use synchronous AM and the AM and FM filters for that. (For AM bandwidths above 3Khz you need the FM filter.) Monty K2DLJ 2.8 Khz, 8 pole 1.8 Khz, 8 pole 400 Hz, 8 pole Wondering if I should put in the: 1.0 Khz, 8 pole 13 Khz FM Thanks for any thoughts on the choices. 73 Stan AE7UT -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Filter-suggestions-for-new-builder-tp7563280.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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In reply to this post by Stan AE7UT
You have chosen the bread-and-butter choices. You may find they are all
you need. You can add others later, if needed. Could you go with less? Personally, I only use the sub-receiver for chasing split DX. I don't need razor sharp filtering - in fact, I need to hear a broad spectrum so I can figure out where the DX is listening. Therefore, I elected no special filters in the sub. If you use the sub for diversity reception, you probably need to filter it up. Buck k4ia On 9/25/2012 1:20 PM, Stan AE7UT wrote: > I'm asking for a little help with filter choices. I've read all I can on the > subject > and have come up with what I think is a good choice for me. > I'm going to be getting the sub-receiver so I'm going to be getting 2 of > each filter. > At almost $300 a filter set I would hate to make a choice that I later have > to replace. > > I'm new to CW and spend about an hour a night working CW on 80/40/30/20. > I like to chase DX both CW and SSB. > I do some contesting but I usually only have an hour or two in each contest > to operate. > I'm just too busy with family and work to put more into it. I would like to > do more. > I've never worked FM or AM/ESSB because I've never had the capability. > I'm coming from an Orion II and really liked the diversity reception and > want that back. > > I'm pretty sure about getting the: > 2.8 Khz, 8 pole > 1.8 Khz, 8 pole > 400 Hz, 8 pole > > Wondering if I should put in the: > 1.0 Khz, 8 pole > 13 Khz FM > > Thanks for any thoughts on the choices. > 73 > Stan AE7UT > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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In reply to this post by Stan AE7UT
> I'm pretty sure about getting the: > 2.8 Khz, 8 pole > 1.8 Khz, 8 pole > 400 Hz, 8 pole I doubt that the difference in performance justifies the "upgrade" charge for 2.8 vs. the standard 2.7 KHz filters - particularly if one is also getting 2.1 or 1.8 KHz "narrow" SSB filters. The savings nearly pays for the cost of one of the other filters. > Wondering if I should put in the: > 1.0 Khz, 8 pole > 13 Khz FM If/when Wayne enables the use of the FM filter for AM and ESSB, adding the FM filter allows use of the remaining modes as well as providing wide AM for BCB/SWL listening. That makes the FM filter worthwhile (particularly if the cost is offset by using the standard 2.8 KHz SSB filter). My preference is for the 200 Hz filter (in only the main RX) rather than 1 KHz. I've not seen a place where the 1 KHz filter provides any benefit over the 1.8 KHz or 400 Hz filters. 73, ... Joe, W4TV On 9/25/2012 1:20 PM, Stan AE7UT wrote: > I'm asking for a little help with filter choices. I've read all I can on the > subject > and have come up with what I think is a good choice for me. > I'm going to be getting the sub-receiver so I'm going to be getting 2 of > each filter. > At almost $300 a filter set I would hate to make a choice that I later have > to replace. > > I'm new to CW and spend about an hour a night working CW on 80/40/30/20. > I like to chase DX both CW and SSB. > I do some contesting but I usually only have an hour or two in each contest > to operate. > I'm just too busy with family and work to put more into it. I would like to > do more. > I've never worked FM or AM/ESSB because I've never had the capability. > I'm coming from an Orion II and really liked the diversity reception and > want that back. > > I'm pretty sure about getting the: > 2.8 Khz, 8 pole > 1.8 Khz, 8 pole > 400 Hz, 8 pole > > Wondering if I should put in the: > 1.0 Khz, 8 pole > 13 Khz FM > > Thanks for any thoughts on the choices. > 73 > Stan AE7UT > > > > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/K3-Filter-suggestions-for-new-builder-tp7563280.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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I sceond Joe's comments.
here: 2.7 , 2.1 , 400 and 200 in Main rx; 2.7 , 2.1 and 400 in Sub. 73 Arie PA3A Op 25-9-2012 20:08, Joe Subich, W4TV schreef: > > I'm pretty sure about getting the: > > 2.8 Khz, 8 pole > > 1.8 Khz, 8 pole > > 400 Hz, 8 pole > > I doubt that the difference in performance justifies the "upgrade" > charge for 2.8 vs. the standard 2.7 KHz filters - particularly if one > is also getting 2.1 or 1.8 KHz "narrow" SSB filters. The savings > nearly pays for the cost of one of the other filters. > > ...... > My preference is for the 200 Hz filter (in only the main RX) rather > than 1 KHz. I've not seen a place where the 1 KHz filter provides > any benefit over the 1.8 KHz or 400 Hz filters. > > 73, > > ... Joe, W4TV > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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In reply to this post by Stan AE7UT
Hi Stan
Mine is with FM/2.7k/2.1k/400/250 on both RX's. If you have on both RX same filters the diversity RD is a dream, otherwise if you are not planning to go for diversity you can mix any filter selection. My two cents  73 VE3GNO Daniel ________________________________ From: Stan AE7UT <[hidden email]> To: [hidden email] Sent: Tuesday, September 25, 2012 1:20:37 PM Subject: [Elecraft] K3 - Filter suggestions for new builder I'm asking for a little help with filter choices. I've read all I can on the subject and have come up with what I think is a good choice for me. I'm going to be getting the sub-receiver so I'm going to be getting 2 of each filter. At almost $300 a filter set I would hate to make a choice that I later have to replace. I'm new to CW and spend about an hour a night working CW on 80/40/30/20. I like to chase DX both CW and SSB. I do some contesting but I usually only have an hour or two in each contest to operate. I'm just too busy with family and work to put more into it. I would like to do more. I've never worked FM or AM/ESSB because I've never had the capability. I'm coming from an Orion II and really liked the diversity reception and want that back. I'm pretty sure about getting the: 2.8 Khz, 8 pole 1.8 Khz, 8 pole 400 Hz, 8 pole Wondering if I should put in the: 1.0 Khz, 8 pole 13 Khz FM Thanks for any thoughts on the choices. 73 Stan AE7UT -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Filter-suggestions-for-new-builder-tp7563280.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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Thanks for all the feed-back. It looks like I'm at least in the right ball park.
I definitely want the diversity reception so I'll be doubling most if not all filters. I've decided to stick with the 2.7 for now. I doubt my ears could hear the difference. Interesting that most here have gone with the 2.1 vs. the 1.8 KHz filters. I'm going to have to go home and listen closer to see if I like 2.1 or 1.8. Thanks again. You guys have been a tremendous help. 73 Stan AE7UT |
Re: K3 - Filter suggestions for new builder
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In reply to this post by Stan AE7UT
I would not assume "most" users prefer this. I have 2.8/1.8 and it suits me
just fine, thank you. The 1.8 works well under contest conditions, when needed. Remember there is almost always a silent majority. 73, Bruce, N1RX > Interesting that most here have gone with the 2.1 vs. the 1.8 KHz filters. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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That's right Bruce, Everyone to their own. I like the 2.8k filter too, and
did try the 2.7k filter which you get mandatory in any case. I just preferred the difference I could hear in the tx/rx audio (tx sent back me recorded on test). I use both the 2.1k & 1.8k and would not give up either. Also use 250hz > cw & rtty. If I could use that 13k for AM without a config change it would be perfect, I was hoping Wayne was serious when he asked Joe to be the guinea pg. -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Bruce Beford Sent: Wednesday, 26 September 2012 6:13 AM To: [hidden email] Subject: Re: [Elecraft] K3 - Filter suggestions for new builder I would not assume "most" users prefer this. I have 2.8/1.8 and it suits me just fine, thank you. The 1.8 works well under contest conditions, when needed. Remember there is almost always a silent majority. 73, Bruce, N1RX > Interesting that most here have gone with the 2.1 vs. the 1.8 KHz filters. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Stan AE7UT
The subject of extra-narrow SSB bandwidths comes up fairly regularly. These 1.8
kHz (and even 1.5 kHz in use out there) bandwidths are not effective for everybody. The older I get, the less I can tolerate these narrow bandwidths for SSB, even in a contest. They give me listener's fatigue. I am amazed at those who are happy as clams listening in an 1800 Hz bandwidth. As has been said many times before, nothing beats the ear-brain combination's filtering ability. I find that hams who started copying signals at a young age can almost always do this better than others. The next time you work me in a contest I will be listening to you in a bandwidth of 2.5 kHz or greater, with QRM and splatter flying everywhere and my brain easily picking out signals in the midst of all of that. Stan, you're doing the right thing... spend extended time listening to these bandwidths before committing. Al W6LX ________________________________ I'm going to have to go home and listen closer to see if I like 2.1 or 1.8. 73 Stan AE7UT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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G'day,
2700Hz and 500Hz in both main and sub RX here. Nothing else, not felt the need, however, an FM filter could be added in one RX one day. There have been measurements which show that the 5-pole filters have superior group delay characteristics when compared to the 8-pole. Regards, Mike VP8NO On 25/09/2012 19:42, Al Lorona wrote: > The subject of extra-narrow SSB bandwidths comes up fairly regularly. These 1.8 > kHz (and even 1.5 kHz in use out there) bandwidths are not effective for > everybody. The older I get, the less I can tolerate these narrow bandwidths for > SSB, even in a contest. They give me listener's fatigue. I am amazed at those > who are happy as clams listening in an 1800 Hz bandwidth. > > As has been said many times before, nothing beats the ear-brain combination's > filtering ability. I find that hams who started copying signals at a young age > can almost always do this better than others. > > The next time you work me in a contest I will be listening to you in a bandwidth > of 2.5 kHz or greater, with QRM and splatter flying everywhere and my brain > easily picking out signals in the midst of all of that. > > Stan, you're doing the right thing... spend extended time listening to these > bandwidths before committing. > > Al W6LX > > > > ________________________________ > > I'm going to have to go home and listen closer to see if I like 2.1 or 1.8. > > 73 > Stan AE7UT Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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On 9/25/2012 4:22 PM, Mike Harris wrote:
> 2700Hz and 500Hz in both main and sub RX here. Nothing else, not felt > the need, however, an FM filter could be added in one RX one day. The only reason to agonize over roofing filters is, "How many strong stations do you have near you?" I have the two "stock" filters with my K3, no second RX, I have two very strong contesters within 2 KM of me, I don't have any problems. I can get within a KHz or so of either and work the station I'm calling. I don't know if my close neighbors like that, but I know them well and they haven't complained. :-) > > There have been measurements which show that the 5-pole filters have > superior group delay characteristics when compared to the 8-pole. Might be a problem for some digital modes [not CW, the "First Digital Mode"], but some of the more esoteric modes could be affected. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 Weekend after next - www.cqp.org ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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In reply to this post by Stan AE7UT
I originally chose the 8-pole filters thinking the steeper skirts
would be useful should I ever take the radio into a dense RF environment like it is in the lower-48 states. MY experience with CW indicated 400-Hz was adequate as I could narrow this down with the DSP filter. I chose the 2.8 KHz SSB filter and 13-KHz filter for FM use with a VHF transverter. One note is that changing filters on the main board requires removal of the sub-Rx so probably good to figure out what you want from the beginning. I installed a 2.8 and 13 KHz filter in my sub-Rx, thinking I could get the full bandwidth in audio to use with soundcards for SDR sw. But I learned that audio is limited to 4-KHz regardless of IF filter so I ended up selling the extra 13-KHz filter. I have thought of adding a 1.8 or 2.1 KHz filter for working tough SSB signals. I do try running the DSP down to that bandwidth but find that the DSP audio distortion sometimes is counterproductive to hearing weak SSB. I do not have trouble with dense local QRM up here in Alaska. I wonder if the roofing filters are easier to listen thru than the DSP filter? I did not install a second 400-Hz filter in the sub-Rx and that may be an error when I start running dual-pol diversity reception for CW-eme. At present, I only run diversity Rx in USB since I am running JT-65 on 2m-eme. I am testing a new program called MAP65 which maps and decodes all JT65 signals in a 90-KHz window. This covers 144.090-144.170 digital eme sub-band, nicely. Someday it would be interesting to set up a crossed dipole on 20, 15 , or 10m and listen in diversity Rx. Crossed horizontal dipoles actually sample different polarities of refracted HF. According to KL7AJ all HF is converted to circular polarity upon refraction in the ionosphere (see the recent article in QST by him). 73, Ed - KL7UW ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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Ed,
I would think you are hearing the results of a narrow passband rather than DSP audio distortion. I say that because in all cases with the K3, it is the DSP that determines the filter width rather than the roofing filter. What I am saying is that even if you put in a 1.8k filter, SSB at a 1.8k width will sound the same as it does right now using only the DSP. I trust you are using the HI-Cut to narrow the receive passband, leaving the LO-Cut set to the 200 to 300 Hz range rather than trying to use the Width and Shift controls. If you are using Shift and Width, you have to re-position Shift with every change in Width or the speech will become more distorted. Using HI-Cut, you just reduce the high frequency end - no other change is required. 73, Don W3FPR On 9/26/2012 1:35 PM, Edward R Cole wrote: > I have thought of adding a 1.8 or 2.1 KHz filter for working tough > SSB signals. I do try running the DSP down to that bandwidth but > find that the DSP audio distortion sometimes is counterproductive to > hearing weak SSB. I do not have trouble with dense local QRM up here > in Alaska. I wonder if the roofing filters are easier to listen thru > than the DSP filter? > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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In reply to this post by Edward R Cole
On 9/26/2012 1:35 PM, Edward R Cole wrote:
> ... But I learned that audio is limited to 4-KHz > regardless of IF filter so I ended up selling the extra 13-KHz filter. > > ... > > 73, Ed - KL7UW I really hope that this does not apply to received audio to the headphones or loudspeaker! I just purchased two FM filters (one for sub-receiver to monitor wide splits) specifically to open up the receive passband (audio included) for SWL and BCB reception. I have no intention of actually transmitting FM or AM for that matter -- just want the wider audio bandwidth for receive. So... is the received audio bandwidth *really* limited to 4 KHz? 73, Dale WA8SRA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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Sorry, but yes, the K3 audio is limited at 4 kHz, no matter whether it
is to the headphones or to the speaker. Please do not "shoot the messenger". but that information is in the archives of this reflector in several places - it has been discussed periodically. If you want to lobby for extended audio response, that is fine, but I am just saying what the limits are today. Whether those can be extended or not is for the DSP designer to answer. 73, Don W3FPR On 9/26/2012 7:11 PM, Dale Boresz wrote: > On 9/26/2012 1:35 PM, Edward R Cole wrote: >> ... But I learned that audio is limited to 4-KHz >> regardless of IF filter so I ended up selling the extra 13-KHz filter. >> >> ... >> >> 73, Ed - KL7UW > I really hope that this does not apply to received audio to the > headphones or loudspeaker! I just purchased two FM filters (one for > sub-receiver to monitor wide splits) specifically to open up the receive > passband (audio included) for SWL and BCB reception. I have no intention > of actually transmitting FM or AM for that matter -- just want the wider > audio bandwidth for receive. > > So... is the received audio bandwidth *really* limited to 4 KHz? > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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Hello Don,
Thanks for the quick response. I was just going through the K3 manual and KE7X's excellent book, but haven't seen any reference to that. For general ham radio operation I don't see it as a limitation, but it's a bit disappointing that the FM filters that will arrive tomorrow along with the 2nd RX, won't provide the capability I was hoping for. 73, Dale WA8SRA On 9/26/2012 7:23 PM, Don Wilhelm wrote: > Sorry, but yes, the K3 audio is limited at 4 kHz, no matter whether it > is to the headphones or to the speaker. Please do not "shoot the > messenger". but that information is in the archives of this reflector in > several places - it has been discussed periodically. > > If you want to lobby for extended audio response, that is fine, but I am > just saying what the limits are today. Whether those can be extended or > not is for the DSP designer to answer. > > 73, > Don W3FPR > > On 9/26/2012 7:11 PM, Dale Boresz wrote: >> On 9/26/2012 1:35 PM, Edward R Cole wrote: >>> ... But I learned that audio is limited to 4-KHz >>> regardless of IF filter so I ended up selling the extra 13-KHz filter. >>> >>> ... >>> >>> 73, Ed - KL7UW >> I really hope that this does not apply to received audio to the >> headphones or loudspeaker! I just purchased two FM filters (one for >> sub-receiver to monitor wide splits) specifically to open up the receive >> passband (audio included) for SWL and BCB reception. I have no intention >> of actually transmitting FM or AM for that matter -- just want the wider >> audio bandwidth for receive. >> >> So... is the received audio bandwidth *really* limited to 4 KHz? >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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In reply to this post by Don Wilhelm-4
The limit occurs several places ... adjust the "HI" setting and one will find 4.20 is the maximum available. There is also an analog lowpass filter in the audio (headphone and speaker) between the DAC and the headphone/speaker amplifiers. I'm sure this limitation derives from the roughly 10 KHz clock/sample rate used for the DAC ... Nyquist says the maximum frequency can not be more than half the sample (clock) rate. 4.2 KHz is plenty good enough for communications audio ... and not bad for AM with fading, noise, and interference typical of medium and high frequencies. The FM filter still provides noticeably better double sideband AM response (4.2 - 4.5 KHz with DSP/LPF skirts) than the AM filter (3.0-3.3 KHz depending on the IF filter response). 73, ... Joe, W4TV On 9/26/2012 7:23 PM, Don Wilhelm wrote: > Sorry, but yes, the K3 audio is limited at 4 kHz, no matter whether it > is to the headphones or to the speaker. Please do not "shoot the > messenger". but that information is in the archives of this reflector in > several places - it has been discussed periodically. > > If you want to lobby for extended audio response, that is fine, but I am > just saying what the limits are today. Whether those can be extended or > not is for the DSP designer to answer. > > 73, > Don W3FPR > > On 9/26/2012 7:11 PM, Dale Boresz wrote: >> On 9/26/2012 1:35 PM, Edward R Cole wrote: >>> ... But I learned that audio is limited to 4-KHz >>> regardless of IF filter so I ended up selling the extra 13-KHz filter. >>> >>> ... >>> >>> 73, Ed - KL7UW >> I really hope that this does not apply to received audio to the >> headphones or loudspeaker! I just purchased two FM filters (one for >> sub-receiver to monitor wide splits) specifically to open up the receive >> passband (audio included) for SWL and BCB reception. I have no intention >> of actually transmitting FM or AM for that matter -- just want the wider >> audio bandwidth for receive. >> >> So... is the received audio bandwidth *really* limited to 4 KHz? >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3 - Filter suggestions for new builder
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Joe,
Good observations, all. I agree that 4.2 KHz is certainly good enough for communications audio. The only reason I had for putting the FM filter in the 2nd receiver was to be able to hear more of the split in a broad pileup situation (like the extremely large split widths that we saw a few months ago with 7O6T), figuring that being able to simultaneously hear the wider bandwidth and see it on the P3 would be a great combination. I'll just have to be a bit quicker with the VFO-B knob ;-) 73, Dale WA8SRA On 9/26/2012 8:10 PM, Joe Subich, W4TV wrote: > The limit occurs several places ... adjust the "HI" setting and one > will find 4.20 is the maximum available. There is also an analog > lowpass filter in the audio (headphone and speaker) between the DAC > and the headphone/speaker amplifiers. > > I'm sure this limitation derives from the roughly 10 KHz clock/sample > rate used for the DAC ... Nyquist says the maximum frequency can not > be more than half the sample (clock) rate. 4.2 KHz is plenty good > enough for communications audio ... and not bad for AM with fading, > noise, and interference typical of medium and high frequencies. > > The FM filter still provides noticeably better double sideband AM > response (4.2 - 4.5 KHz with DSP/LPF skirts) than the AM filter > (3.0-3.3 KHz depending on the IF filter response). > > 73, > > ... Joe, W4TV > > > On 9/26/2012 7:23 PM, Don Wilhelm wrote: >> Sorry, but yes, the K3 audio is limited at 4 kHz, no matter whether it >> is to the headphones or to the speaker. Please do not "shoot the >> messenger". but that information is in the archives of this reflector in >> several places - it has been discussed periodically. >> >> If you want to lobby for extended audio response, that is fine, but I am >> just saying what the limits are today. Whether those can be extended or >> not is for the DSP designer to answer. >> >> 73, >> Don W3FPR >> >> On 9/26/2012 7:11 PM, Dale Boresz wrote: >>> On 9/26/2012 1:35 PM, Edward R Cole wrote: >>>> ... But I learned that audio is limited to 4-KHz >>>> regardless of IF filter so I ended up selling the extra 13-KHz filter. >>>> >>>> ... >>>> >>>> 73, Ed - KL7UW >>> I really hope that this does not apply to received audio to the >>> headphones or loudspeaker! I just purchased two FM filters (one for >>> sub-receiver to monitor wide splits) specifically to open up the receive >>> passband (audio included) for SWL and BCB reception. I have no intention >>> of actually transmitting FM or AM for that matter -- just want the wider >>> audio bandwidth for receive. >>> >>> So... is the received audio bandwidth *really* limited to 4 KHz? >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> 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:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Don Wilhelm-4
Right, Don!
I still believe that many K3 users are under the erroneous impression that the roofing filter determines the receiver bandwidth. It does not. The HI and LO knobs do. The only thing the roofing filter does is determine the MAXIMUM possible bandwidth of the receiver. In 99% of cases, an SSB roofing filter is good enough. (That statement is going to draw some fire.) It's a little bit like this: the roofing filter is like the credit limit on your Visa card. You can't go any higher than that. But in any typical month, you spend far less than that... and on the K3 the amount you *actually* spend is set by the HI and LO cut controls. This is why I advised the original poster: you wanna know what 1.8 kHz sounds like? Set your HI LO controls to a bandwidth of 1.8 kHz. Then decide whether it 1/ is tolerable; and 2/ increases intelligibility enough to make the investment worth it. I happen to think that 1.8 kHz is too narrow. But that's just me. ________________________________ I say that because in all cases with the K3, it is the DSP that determines the filter width rather than the roofing filter. What I am saying is that even if you put in a 1.8k filter, SSB at a 1.8k width will sound the same as it does right now using only the DSP. 73, Don W3FPR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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