RE: [Elecraft] K3 Filter Configurations and Explanations
The most comprehensive writeup I've seen is here: http://www.elecraft.com/K3/Roofing_Filters.htm I'd agree that you probably don't want to order 200, 250, 400 and 500. However two of these four makes sense for some buyers, including me. If you configure the radio correctly, roofing filters are selected automatically as you turn the width knob. You may also directly select a roofing filter. I just twist the width knob to adjust the DSP bandwidth and the appropriate roofing filter is selected for me. One reasonable starting configuration is just the stock 2.7 KHz filter. If you want to transmit AM, you'll need the 6.0 KHz AM filter. If FM is important to you, you'll need the FM filter. I'm not currently interested in transmitting in either of these modes, so I skipped those two filters and I can receive AM with adequate (for me) fidelity by using my 2.8 KHz filter and listening to one sideband. Discerning AM buffs might well have a different definition of adequate fidelity. If you're interested in CW or data modes (RTTY, PSK, etc), then you'll perhaps want to invest in one or more narrower filters, perhaps one or two of 200, 250, 400, 500 Hz. If it's only one narrower filter, I'd suggest either the 400 or 500 Hz filter. I think of the 200 and 250 as alternatives and 400 and 500 as alternatives. I wouldn't think you'd want both 200 and 250 nor would you probably want both 400 and 500. I personally don't think the difference between the 2.7 and 2.8 Hz filters matters much, but I did choose all 8-pole filters. As a result I have slightly wider SSB transmit bandwidth and sharper skirts on receive with the 2.8 KHz 8-pole filter. I like the 1.0 KHz filter as a normal CW bandwidth in contest situations. It's not so tight that I can't hear off-frequency callers. The 1.8 KHz filter is a wonderful filter for phone contests and other shoulder-to-shoulder situations on phone. Others prefer 2.1 KHz for their narrowest SSB roofing filter. With the 1.8 I find that the off-frequency crud often disappears, and the signal I'm isolating is comprehensible, but communications fidelity rather than natural sounding. I have to defer to the RTTY and PSK experts, but I think a 400 or 500 Hz filter would be my 2nd filter (after the 2.7 or 2.8 decision). My experience before the Elecraft K3 was with a series of up-converting ICOM rigs including the 7800, whose narrowest roofing filter (after the roofing filter upgrade) is 3 KHz. I chose 8-pole filters at 2.8, 1.8, 1.0, 400, and 250. I probably have more than I need for almost all situations. Most of my QSOs don't tax the capability of any current-generation radio, but when the situation is very competitive I don't want to be in mid-contest or mid-pileup and at that time wish I'd spent the relatively small amount (compared to all the other expenses in building a station) that these filters cost. You don't have to decide all this at the time you receive the radio. You can add roofing filters easily at a later date. You just have to remove a handful of screws (top cover and half the bottom cover), and the filter plugs in and is held in place by one lock washer and nut. You might need to rearrange your existing filters when you add a new one so that they're in a natural sequence. Filter configuration takes a few minutes after you get the hang of it, and it'll be even quicker with the next revision of the K3 Utility. If you decide to add the 2nd receiver option, you'll need filter(s) for that receiver as well. You might make the same decisions again or maybe not. I'm going to make different choices for my 2nd receiver. Sorry it's not a crisp answer. It's like a lot of topics, the answer is always it depends... 73 de Dick, K6KR -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Miller Sent: Monday, March 31, 2008 8:59 PM To: Elecraft Reflector Subject: [Elecraft] K3 Filter Configurations and Explanations Thanks for bringing up the filter topic - This is one of my main questions now. I finally ordered mine with no optional filters and plan on adding them to the order before ship BUT I do not know which will be the best for me. I suppose the answer to that is that it will be different for everybody. I do expect to add the second reciever board at some point, maybe not before initial ship. Some sub-topics: 1) Is there any point in ordering the 200, 250, 400 and 500? Probably not. Somebody explain how the filters are selected by the radio and recommend a couple of reasonable configurations please. I want to be able to run PSK, RTTY, CW and SSB and mainly I want to not have to deal with nearby signals, I want them GONE. 2) a. Why would you order a 2.8 when you get a 2.7 with the radio? b. Can you order the 2.8 instead of the standard 2.7 and receive some credit for the 2.7 you didn't want? 3) Will the 1.8 make the SSB hard to understand vs possibly the 2.1? I almost ordered the 1.8 but wasn't sure
RE: [Elecraft] K3 Filter Configurations and Explanations
Dick Dievendorff wrote: If you're interested in CW or data modes (RTTY, PSK, etc), then you'll perhaps want to invest in one or more narrower filters, perhaps one or two of 200, 250, 400, 500 Hz. If it's only one narrower filter, I'd suggest either the 400 or 500 Hz filter. I think of the 200 and 250 as alternatives and 400 and 500 as alternatives. I wouldn't think you'd want both 200 and 250 nor would you probably want both 400 and 500. The 400 and 250 are actually very close in bandwidth. According to Elecraft's own measurements below, the 400 actually has 435 Hz BW and the 250 is actually 370 Hz, both with the same shape factor. You definitely don't need to spend $250 total for two filters that only differ in BW by about 15%. Also note that the 2.7k actually has slightly wider BW than the 2.8k. Filter BW(-6dB) Shape Factor 200 224 4.0 250 370 2.1 400 435 2.1 500 565 3.1 10001063 1.6 18001913 1.5 27002910 2.9 28002888 1.6 60006125 1.5 http://www.zerobeat.net/mediawiki/index.php/K3_Roofing_Filters FYI my 2.7k/1.0k/500 are in close agreement with the above measurements but my 200 is slightly less than 210 Hz. 73, Bill W4ZV -- View this message in context: http://www.nabble.com/K3%3A--SSB---WPX---Filters---Controls-tp16399464p16418074.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 Filter Configurations and Explanations
I think Dick has put together an excellent summary regarding the available filters. I sure don't see much to contradict based on my experience. I would mention one thing, however, and i'm curious if others are experiencing the same anomoly. I opted for both the 400 hz and the 200 hz filters (in addition to the 2.7 khz and 6 khz filters). I am quite happy with the 400 hz filter. Perhaps the 500 hz would have been sufficient, but I do like the 400 hz just fine. My question is about the narrower filters--the 200 hz and the 250 hz. I was almost certain I would use the narrow filter fairly often. With other rigs I frequently found myself trying to 'tighten things down to eliminate QRM. However, I find myself rarely needing to go down that far on the K3. I probably haven't really given it the acid test, like Field Day, but it does surprise me that I tend to not even need something narrower. I can only attribute that to the fact that the roofing filter system on the K3 is superior--that it does such a good job compared to other receivers I don't have to fight QRM as much. I'm not into the digital modes yet on any kind of serious basis, so maybe that will turn out to be where the narrower filter proves to be most useful. I would also be inclined to endorse Dick's suggestion of a 1 khz filter for casual CW use. I don't have one though, so I can't say for sure. But I strongly suspect it would be more pleasant to use. I like not having to go too narrow, but QRM usually forced me to do so. But since these are roofing filters, and not just crystal filters we usually rely on, I think QRM will still be minimized. I am thinking seriously of ordering a 1 khz filter when I get my 2nd receiver. If it works like I think it might, I may do some reassessment of my filter complement in the 1st receiver. I'd be interested in hearing how others with the 1 khz filter like using it. Dave W7AQK - Original Message - From: Dick Dievendorff [EMAIL PROTECTED] To: 'Jim Miller' [EMAIL PROTECTED]; 'Elecraft Reflector' elecraft@mailman.qth.net Sent: Tuesday, April 01, 2008 12:17 AM Subject: RE: [Elecraft] K3 Filter Configurations and Explanations The most comprehensive writeup I've seen is here: http://www.elecraft.com/K3/Roofing_Filters.htm I'd agree that you probably don't want to order 200, 250, 400 and 500. However two of these four makes sense for some buyers, including me. If you configure the radio correctly, roofing filters are selected automatically as you turn the width knob. You may also directly select a roofing filter. I just twist the width knob to adjust the DSP bandwidth and the appropriate roofing filter is selected for me. One reasonable starting configuration is just the stock 2.7 KHz filter. If you want to transmit AM, you'll need the 6.0 KHz AM filter. If FM is important to you, you'll need the FM filter. I'm not currently interested in transmitting in either of these modes, so I skipped those two filters and I can receive AM with adequate (for me) fidelity by using my 2.8 KHz filter and listening to one sideband. Discerning AM buffs might well have a different definition of adequate fidelity. If you're interested in CW or data modes (RTTY, PSK, etc), then you'll perhaps want to invest in one or more narrower filters, perhaps one or two of 200, 250, 400, 500 Hz. If it's only one narrower filter, I'd suggest either the 400 or 500 Hz filter. I think of the 200 and 250 as alternatives and 400 and 500 as alternatives. I wouldn't think you'd want both 200 and 250 nor would you probably want both 400 and 500. I personally don't think the difference between the 2.7 and 2.8 Hz filters matters much, but I did choose all 8-pole filters. As a result I have slightly wider SSB transmit bandwidth and sharper skirts on receive with the 2.8 KHz 8-pole filter. I like the 1.0 KHz filter as a normal CW bandwidth in contest situations. It's not so tight that I can't hear off-frequency callers. The 1.8 KHz filter is a wonderful filter for phone contests and other shoulder-to-shoulder situations on phone. Others prefer 2.1 KHz for their narrowest SSB roofing filter. With the 1.8 I find that the off-frequency crud often disappears, and the signal I'm isolating is comprehensible, but communications fidelity rather than natural sounding. I have to defer to the RTTY and PSK experts, but I think a 400 or 500 Hz filter would be my 2nd filter (after the 2.7 or 2.8 decision). My experience before the Elecraft K3 was with a series of up-converting ICOM rigs including the 7800, whose narrowest roofing filter (after the roofing filter upgrade) is 3 KHz. I chose 8-pole filters at 2.8, 1.8, 1.0, 400, and 250. I probably have more than I need for almost all situations. Most of my QSOs don't tax the capability of any current-generation radio, but when the situation is very competitive I don't want to be in mid-contest or mid-pileup and at that time wish I'd
RE: [Elecraft] K3 Filter Configurations and Explanations
I acquired the 250 Hz filter primarily because a very good RTTY specialist friend (W0YK) recommended it for contest RTTY. I haven't used it much. But I haven't often used the 250 Hz bandwidth on any radio. My other radios had uncompensated high filter loss with very narrow filters and I got into the habit of getting narrow enough to remove the strongest interfering stations and have tried to develop my aural discrimination capability for the rest. In CW contest run situations 250 Hz is much too narrow. In CW contest SP situations I want to move quickly about and a narrow filter isn't well suited to that. Since most of my operation is CW contests, the 250 Hz filter doesn't get much use. Fortunately with DSP filtering I can dial in just the width I want for any situation and don't have to guess ahead of time exactly the final selectivity I will want. The DSP does most of the work, and having a corresponding width roofing filter (greatly) increases the capability of the radio to deal with strong interference that is nearby. If the interfering signal is within reasonable limits, the DSP alone can knock it down quite well. Roofing filters show their value in situations where nearby interfering signals are much stronger than the desired signal. The bands during contests don't seem to be quite as full of thumps and crud with my K3 as they do with other, less capable equipment. During SP, I find myself tuning more slowly as I pass already-worked strong CQing stations, because weaker nearby desired stations are now more audible. If I sequenced the filters I currently have in the order of perceived need, I'd have this order: 2.8 KHz because you must use a 2.7 or 2.8 KHz filter for CW and SSB transmission; it's the general purpose SSB filter and wide CW filter. 400 Hz for tight CW or data modes. 1 KHz because I do much more CW than SSB, and this is about my general CW width (most of my operation is during CW contests) 1.8 KHz because having this narrow capability makes phone contesting much more pleasant and I can stay longer with less fatigue. I also like this filter for opened up CW contest run situations. When I dial 1.2 KHz bandwidth for CW running, this is the roofing filter I get. 250 Hz for rarely-encountered severe CW conditions or as-yet-unexperienced data mode needs. Although I haven't seen this explored publicly too much, you can configure the roofing filter crossover points at bandwidths that differ slightly from the bandwidth printed on the filter. If you study the available bandwidth curves (or make curves of the filters you actually have), you can choose the points at which the filters kick in. If you think your 400 Hz filter is really a 430 Hz filter, you might try configuring the K3 as if it had a 450 Hz filter, for example. You'll need to configure the 2.7 or 2.8 KHz filter as 2.70, 2.75, or 2.80, and don't fiddle with the widths of the AM or FM filters, but the rest are fair game. Dick, K6KR -Original Message- From: David Yarnes [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 01, 2008 6:16 AM To: [EMAIL PROTECTED]; 'Jim Miller'; 'Elecraft Reflector' Subject: Re: [Elecraft] K3 Filter Configurations and Explanations I think Dick has put together an excellent summary regarding the available filters. I sure don't see much to contradict based on my experience. I would mention one thing, however, and i'm curious if others are experiencing the same anomoly. I opted for both the 400 hz and the 200 hz filters (in addition to the 2.7 khz and 6 khz filters). I am quite happy with the 400 hz filter. Perhaps the 500 hz would have been sufficient, but I do like the 400 hz just fine. My question is about the narrower filters--the 200 hz and the 250 hz. I was almost certain I would use the narrow filter fairly often. With other rigs I frequently found myself trying to 'tighten things down to eliminate QRM. However, I find myself rarely needing to go down that far on the K3. I probably haven't really given it the acid test, like Field Day, but it does surprise me that I tend to not even need something narrower. I can only attribute that to the fact that the roofing filter system on the K3 is superior--that it does such a good job compared to other receivers I don't have to fight QRM as much. I'm not into the digital modes yet on any kind of serious basis, so maybe that will turn out to be where the narrower filter proves to be most useful. I would also be inclined to endorse Dick's suggestion of a 1 khz filter for casual CW use. I don't have one though, so I can't say for sure. But I strongly suspect it would be more pleasant to use. I like not having to go too narrow, but QRM usually forced me to do so. But since these are roofing filters, and not just crystal filters we usually rely on, I think QRM will still be minimized. I am thinking seriously of ordering a 1 khz filter when I get my 2nd receiver. If it works like I think it might, I may do
Re: [Elecraft] K3 Filter Configurations and Explanations
I can vouch that there is no reason to order both the 400 and 250 filters. When I first ordered my K3 on the phone, whomever I spoke with (and I can't remember) convinced me that these two would be the best combination for CW operation. In reality, there is very little difference between the two filters and in actual operation I don't see the need for the 250. A better combination would be the 1000 and 400. When calling CQ, I like to keep the BW set to around 800 to capture those signals that are not zero-beat. Once in a QSO or contest exchange, I can crank the BW down below 400 if needed. At least with the way I operate, the 1000/400 combo makes more sense. So, I plan to order the 1000 filter. Anyone want a 250 filter at a good discount? Contact me offline. 73, John, WA6L Jim Miller-14 wrote: Thanks for bringing up the filter topic - This is one of my main questions now. I finally ordered mine with no optional filters and plan on adding them to the order before ship BUT I do not know which will be the best for me. I suppose the answer to that is that it will be different for everybody. I do expect to add the second reciever board at some point, maybe not before initial ship. Some sub-topics: 1) Is there any point in ordering the 200, 250, 400 and 500? Probably not. Somebody explain how the filters are selected by the radio and recommend a couple of reasonable configurations please. I want to be able to run PSK, RTTY, CW and SSB and mainly I want to not have to deal with nearby signals, I want them GONE. 2) a. Why would you order a 2.8 when you get a 2.7 with the radio? b. Can you order the 2.8 instead of the standard 2.7 and receive some credit for the 2.7 you didn't want? 3) Will the 1.8 make the SSB hard to understand vs possibly the 2.1? I almost ordered the 1.8 but wasn't sure so didn't order anything yet. 4) What would be the best filter for RTTY? 5) Which filter will be best for PSK? A 6K filter or a 2.8 or narrower looking at just part of the band at a time? Pick one (or all) and give me your thoughts, THANKS, de Jim KG0KP (NewBee) ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- View this message in context: http://www.nabble.com/K3%3A--SSB---WPX---Filters---Controls-tp16399464p16418680.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] K3 Filter Configurations and Explanations
Repeating what I've posted here previously, the first thing to get firmly in mind about the K3 crystal filters is what their purpose is. They are not used to determine the bandwidth you are using on any mode. (Yes, you need the 2.7 or 2.8 for transmit on CW, RTTY and SSB. The AM and FM filters for transmit on those modes.) Your receive bandwidth is determined by the DSP filtering which is continually adjustable to any bandwidth you desire. The Icom 756Pro series radios are excellent performers and have a single 15kHz crystal filter. Narrower filtering is provided by the DSP just like the K3. The purpose of the five easily-installable crystal filters in the K3 are to pre-filter strong nearby signals so that the DSP can better do its excellent job of the primary filtering. INRAD makes add-on roofing filter kits for many radios and now has a 4-5kHz roofing filter kit for the Icom 756Pro series for those people who are mostly interested in CW, RTTY and/or SSB. This is a great improvement over the stock 15kHz filter for contesting and situations where there are lots of very strong close-in signals. You don't need any additional crystal filters in the K3 beyond the stock 2.7kHz filter to listen to CW at a 600Hz or 350Hz or 200Hz or whatever bandwidth. Just dial in the width you want with the WIDTH, SHIFT, LO CUT and/or HI CUT controls. You only need to consider additional crystal filters if you operate in conditions where strong signals close to your operating frequency (inside the 2.7kHz filter) may deteriorate the excellent filtering of the DSP with IMD and other interference. Because my primary Ham radio activity is contesting, having crystal filters right at the bandwidths I use for each mode is useful. It is one of many reasons why the K3 is my favorite contest radio. But all these filters are not needed by many K3 users. - For SSB, my default bandwidth is 1.5kHz and that is saved as ALT-1 and as my standard SSB bandwidth on all my band-mode memories. Specifically, the DSP filter is set at 300-1800kHz. I'm currently using the 1.8kHz crystal filter which is actually about 1.9kHz at the -6dB points. - For CW, my default bandwidth is 400Hz although I'd be just as happy at 500Hz. It's just that I'm currently using the 400Hz crystal filters. I seldom go below that, but occasionally on 160 with heavy QRM I might go down to 250 or 200Hz. - For RTTY, my default bandwidth is 200Hz plus the Dual-Tone Filter of additional cascaded 50Hz filters around each tone. In theory, the bandwidth for 170Hz-shift RTTY should be 250-300Hz, but I've found operationally that 200Hz works great in my RTTY contesting. Note that the actual -6dB bandwidths of the 400Hz and 250Hz filters are 435Hz and 370Hz respectively. You definitely don't need both of those filters, although that's exactly what I personally have right now because I failed to consider the actual bandwidths when making my initial selection. Don't make that mistake. Finally, you can set the point at which each crystal filter kicks in as the DSP bandwidth is varied. I set my trigger points per the -6db bandwidths of the various filters, not the product name. Thus, the 250Hz filter switches in at 350Hz because its actual bandwidth is 370Hz. Since I receive RTTY at 200Hz DSP bandwidth, a better crystal filter for me in that mode might be the 200Hz (225Hz actual) for maximum strong signal protection. 73, Ed - W0YK Thanks for bringing up the filter topic - This is one of my main questions now. I finally ordered mine with no optional filters and plan on adding them to the order before ship BUT I do not know which will be the best for me. I suppose the answer to that is that it will be different for everybody. I do expect to add the second reciever board at some point, maybe not before initial ship. Some sub-topics: 1) Is there any point in ordering the 200, 250, 400 and 500? Probably not. Somebody explain how the filters are selected by the radio and recommend a couple of reasonable configurations please. I want to be able to run PSK, RTTY, CW and SSB and mainly I want to not have to deal with nearby signals, I want them GONE. 2) a. Why would you order a 2.8 when you get a 2.7 with the radio? b. Can you order the 2.8 instead of the standard 2.7 and receive some credit for the 2.7 you didn't want? 3) Will the 1.8 make the SSB hard to understand vs possibly the 2.1? I almost ordered the 1.8 but wasn't sure so didn't order anything yet. 4) What would be the best filter for RTTY? 5) Which filter will be best for PSK? A 6K filter or a 2.8 or narrower looking at just part of the band at a time? ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm
RE: [Elecraft] K3 Filter Configurations and Explanations
Thanks to all for the comments. (I am using a 2x 400Hz and 2x 250 Hz Inrad combo in my MP for selectivity at this time, and a wiide roofing filter) The subject is very interesting to me since I expect my K3 sometime in June. How about this one for the K3: 2.7 standard 2.1 8-pole SSB contesting 500 5-pole CW contest running 200 5-pole CW SP especially 160m and 40m The rationale: you don't need 8-pole since: 1. the interfering signals causing IMD don't have to be more than 20dB down to stop the IMD. 2. If I use the DSP filtering, why add 8-pole filters if 1. applies 3. I read that the roofing filters can introduce IMD (because of steep skirts or...? Is there a chance that 5-pole filters have less chance of introducing IMD? Anybody can comment on this?) I sure would like to hear the difference between 400 8-pole and 500 5-pole with fixed DSP bandwidth in a crowded strong signal band. How about that? 73 Arie PA3A ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 Filter Configurations and Explanations
John, I ordered the 500 hz and 250hz filters The 500 will be great for the casual stuff. When it gets tough like the 160 mtr contest with signals 30 and 40 db over S9 all over that 250 will be king. I have 2 TS-850S with inrad 400 hz - they are ok but I assume that when my K3 arrives I won't here the next guy blasting me off to the side that much anymore. the 250 hz will defintely have it's place. Likewise I hope that the 2.1 will work better than the 850S on SSB! This will make my contesting so much more enjoyable! 73, Bill N4ZI --- WA6L [EMAIL PROTECTED] wrote: I can vouch that there is no reason to order both the 400 and 250 filters. When I first ordered my K3 on the phone, whomever I spoke with (and I can't remember) convinced me that these two would be the best combination for CW operation. In reality, there is very little difference between the two filters and in actual operation I don't see the need for the 250. A better combination would be the 1000 and 400. When calling CQ, I like to keep the BW set to around 800 to capture those signals that are not zero-beat. Once in a QSO or contest exchange, I can crank the BW down below 400 if needed. At least with the way I operate, the 1000/400 combo makes more sense. So, I plan to order the 1000 filter. Anyone want a 250 filter at a good discount? Contact me offline. 73, John, WA6L Jim Miller-14 wrote: Thanks for bringing up the filter topic - This is one of my main questions now. I finally ordered mine with no optional filters and plan on adding them to the order before ship BUT I do not know which will be the best for me. I suppose the answer to that is that it will be different for everybody. I do expect to add the second reciever board at some point, maybe not before initial ship. Some sub-topics: 1) Is there any point in ordering the 200, 250, 400 and 500? Probably not. Somebody explain how the filters are selected by the radio and recommend a couple of reasonable configurations please. I want to be able to run PSK, RTTY, CW and SSB and mainly I want to not have to deal with nearby signals, I want them GONE. 2) a. Why would you order a 2.8 when you get a 2.7 with the radio? b. Can you order the 2.8 instead of the standard 2.7 and receive some credit for the 2.7 you didn't want? 3) Will the 1.8 make the SSB hard to understand vs possibly the 2.1? I almost ordered the 1.8 but wasn't sure so didn't order anything yet. 4) What would be the best filter for RTTY? 5) Which filter will be best for PSK? A 6K filter or a 2.8 or narrower looking at just part of the band at a time? Pick one (or all) and give me your thoughts, THANKS, de Jim KG0KP (NewBee) ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- View this message in context: http://www.nabble.com/K3%3A--SSB---WPX---Filters---Controls-tp16399464p16418680.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost. http://tc.deals.yahoo.com/tc/blockbuster/text5.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] K3 Filter Configurations and Explanations
- For RTTY, my default bandwidth is 200Hz plus the Dual-Tone Filter of additional cascaded 50Hz filters around each tone. In theory, the bandwidth for 170Hz-shift RTTY should be 250-300Hz, but I've found operationally that 200Hz works great in my RTTY contesting. The two 50 Hz filters spaced 170 Hz would have a total bandwidth of 230Hz. This is very close to the published value of 224 Hz for the 5-pole filter (I intend to measure mine when it arrives later this week). However, I wonder if it would not be useful to modify the 200 Hz filter - or for Elecraft to offer a real 250 Hz filter using the values shown in the K3 schematic pack (page 7). Based on the published 224 Hz (and reports of 210 Hz) and 4:1 shape factor a 250 Hz 5-pole filter would still offer much better performance between -6dB and - 30 dB than the 250 Hz 8 pole filter but a real 250 Hz wide filter should be just enough wider to eliminate potential sharpening of the dual- tone (DSP) filter. My filter choices - and I'll see if I guessed right in a week or so - were FM, 2.8 KHz, 500 Hz and 200 Hz. I'm leaving the one slot open for 2.1, 1.8 or possibly a variable SSB filter if/when that is available. The FM filter was chosen for general non-critical listening (including AM) as it is still narrower than the front end filter in any of the mid-grade up-conversion receivers. I know I will want something between 2.8 and 500 Hz and suspect the 1.8 will fill the bill for general CW on a quiet band and for click on the waterfall PSK31 operation. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ed Muns Sent: Tuesday, April 01, 2008 2:33 PM To: 'Jim Miller' Cc: 'Elecraft Reflector' Subject: RE: [Elecraft] K3 Filter Configurations and Explanations Repeating what I've posted here previously, the first thing to get firmly in mind about the K3 crystal filters is what their purpose is. They are not used to determine the bandwidth you are using on any mode. (Yes, you need the 2.7 or 2.8 for transmit on CW, RTTY and SSB. The AM and FM filters for transmit on those modes.) Your receive bandwidth is determined by the DSP filtering which is continually adjustable to any bandwidth you desire. The Icom 756Pro series radios are excellent performers and have a single 15kHz crystal filter. Narrower filtering is provided by the DSP just like the K3. The purpose of the five easily-installable crystal filters in the K3 are to pre-filter strong nearby signals so that the DSP can better do its excellent job of the primary filtering. INRAD makes add-on roofing filter kits for many radios and now has a 4-5kHz roofing filter kit for the Icom 756Pro series for those people who are mostly interested in CW, RTTY and/or SSB. This is a great improvement over the stock 15kHz filter for contesting and situations where there are lots of very strong close-in signals. You don't need any additional crystal filters in the K3 beyond the stock 2.7kHz filter to listen to CW at a 600Hz or 350Hz or 200Hz or whatever bandwidth. Just dial in the width you want with the WIDTH, SHIFT, LO CUT and/or HI CUT controls. You only need to consider additional crystal filters if you operate in conditions where strong signals close to your operating frequency (inside the 2.7kHz filter) may deteriorate the excellent filtering of the DSP with IMD and other interference. Because my primary Ham radio activity is contesting, having crystal filters right at the bandwidths I use for each mode is useful. It is one of many reasons why the K3 is my favorite contest radio. But all these filters are not needed by many K3 users. - For SSB, my default bandwidth is 1.5kHz and that is saved as ALT-1 and as my standard SSB bandwidth on all my band-mode memories. Specifically, the DSP filter is set at 300-1800kHz. I'm currently using the 1.8kHz crystal filter which is actually about 1.9kHz at the -6dB points. - For CW, my default bandwidth is 400Hz although I'd be just as happy at 500Hz. It's just that I'm currently using the 400Hz crystal filters. I seldom go below that, but occasionally on 160 with heavy QRM I might go down to 250 or 200Hz. - For RTTY, my default bandwidth is 200Hz plus the Dual-Tone Filter of additional cascaded 50Hz filters around each tone. In theory, the bandwidth for 170Hz-shift RTTY should be 250-300Hz, but I've found operationally that 200Hz works great in my RTTY contesting. Note that the actual -6dB bandwidths of the 400Hz and 250Hz filters are 435Hz and 370Hz respectively. You definitely don't need both of those filters, although that's exactly what I personally have right now because I failed to consider the actual bandwidths when making my initial selection. Don't make that mistake. Finally, you can set the point at which each crystal
RE: [Elecraft] K3 Filter Configurations and Explanations
1. the interfering signals causing IMD don't have to be more than 20dB down to stop the IMD. 2. On the other hand the 2.8 KHz 8 pole filter is actually narrower than the 2.7 KHz 5 pole (2.888 KHz vs. 2910 KHz from previously published data) with significantly sharper skirts so the -30 dB widths are roughly 3.755 KHz for the 2.8 KHz filter vs. 5.675 KHz for the 2.7 KHz filter. If I use the DSP filtering, why add 8-pole filters if 1. applies 3. I read that the roofing filters can introduce IMD (because of steep skirts or...? Is there a chance that 5-pole filters have less chance of introducing IMD? The signal level thorough the roofing filters is quite high. With high signal levels, the crystals need to be exceptionally clean and well behaved. Eric tells me that the 8 pole filters are specially selected by INRAD for low IMD characteristics (the lower grade filters go into FT-1000/FT-1000MPs). Elecraft to a special burn in of their crystals before building the 5 pole filters. Still, the filter IMD (due to non-linearity in the crystals) may be up to 2 dB better with the 8 pole filters than with the 5 pole units. 73, ... Joe, W4TV If I use the DSP filtering, why add 8-pole filters if 1. applies 3. I read that the roofing filters can introduce IMD (because of steep skirts or...? Is there a chance that 5-pole filters have less chance of introducing IMD? Anybody can comment on this?) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Arie Kleingeld PA3A Sent: Tuesday, April 01, 2008 5:32 PM To: 'Elecraft Reflector' Subject: RE: [Elecraft] K3 Filter Configurations and Explanations Thanks to all for the comments. (I am using a 2x 400Hz and 2x 250 Hz Inrad combo in my MP for selectivity at this time, and a wiide roofing filter) The subject is very interesting to me since I expect my K3 sometime in June. How about this one for the K3: 2.7 standard 2.1 8-pole SSB contesting 500 5-pole CW contest running 200 5-pole CW SP especially 160m and 40m The rationale: you don't need 8-pole since: 1. the interfering signals causing IMD don't have to be more than 20dB down to stop the IMD. 2. If I use the DSP filtering, why add 8-pole filters if 1. applies 3. I read that the roofing filters can introduce IMD (because of steep skirts or...? Is there a chance that 5-pole filters have less chance of introducing IMD? Anybody can comment on this?) I sure would like to hear the difference between 400 8-pole and 500 5-pole with fixed DSP bandwidth in a crowded strong signal band. How about that? 73 Arie PA3A ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
