Re: [Elecraft] [K3] Roofing filters are misunderstood
On Mon, May 12, 2014 at 8:47 PM, Bill Turner dez...@outlook.com wrote: I like that! Much more accurate. A roof keeps everything out while a window lets only certain things such as the desired signal in. Much more self-explanatory. Should rename them to skylight filters.. :) Holes in the roof to let stuff through. Frank KG6EYC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
That's a good name. I like it. 73 Jerry KM3K Sent from my NOOK Frank Precissi vad...@gmail.com wrote: On Mon, May 12, 2014 at 8:47 PM, Bill Turner dez...@outlook.com wrote: I like that! Much more accurate. A roof keeps everything out while a window lets only certain things such as the desired signal in. Much more self-explanatory. Should rename them to skylight filters.. :) Holes in the roof to let stuff through. Frank KG6EYC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jso...@comcast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
On Sun, 2014-05-11 at 22:06 -0700, Bill Turner wrote: I have always thought that roofing was a marketing ploy to imbue it with some kind of magical powers. Bill, These aren't the filters you are looking for... Move along... Sorry, I just had too inject that at this point in the discussion! It just seemed too funny not to... To get back on topic, As soon as someone here said they are 1st IF filters, all questions about them were answered... THANK YOU whoever said that. -- Thanks and 73's, For equipment, and software setups and reviews see: www.nk7z.net for MixW support see; http://groups.yahoo.com/neo/groups/mixw/info for Dopplergram information see: http://groups.yahoo.com/neo/groups/dopplergram/info for MM-SSTV see: http://groups.yahoo.com/neo/groups/MM-SSTV/info __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Good point. A true roofing filter would be in the antenna line. Repeaters have roofing filters, typically in the form of an extremely high Q resonant cavity. Chas - Original Message - From: David Cole d...@nk7z.net To: elecraft@mailman.qth.net Sent: Monday, May 12, 2014 8:43 AM Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood On Sun, 2014-05-11 at 22:06 -0700, Bill Turner wrote: I have always thought that roofing was a marketing ploy to imbue it with some kind of magical powers. Bill, These aren't the filters you are looking for... Move along... Sorry, I just had too inject that at this point in the discussion! It just seemed too funny not to... To get back on topic, As soon as someone here said they are 1st IF filters, all questions about them were answered... THANK YOU whoever said that. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Well, You defenitely need those filters in the K3. When signals are strong and the band is busy, signals coming through the roofing filter (line S9+20dB) is said to pump the hardware AGC, even if you have the DSP filtering set to a small BW. Anyway, you can certainly hear that. Try it on CW, on 40m in the evening when there's a contest. You'll love the 400Hz roofing filter. 73 Arie PA3A Al Lorona schreef op 11-5-2014 23:03: What determines the bandwidth you hear at the loudspeaker? It's not your roofing filter, despite a continuing notion that it is. Dave Hachadorian's point in a post a few weeks ago was that you don't need a 1.8 kHz filter to get a 1.8 kHz bandwidth. You're free to set whatever bandwidth you want with any filter. Before rigs had DSP we got used to the idea that your crystal filter sets your bandwidth. That's not true any more. It sets your *maximum* bandwidth. You then have the freedom to narrow and position a bandwidth arbitrarily using the DSP controls [SHIFT and WIDTH or HI and LO]. Here's a true-false quiz: 1. I'm a contester, so I need a 1.8 kHz roofing filter in the K3. 2. I should purchase the 400 Hz filter if I like to operate CW with bandwidths of 300 - 400 Hz. 3. For SSB, the 2.7 and 2.8 kHz filters are 'too wide'. 4. I have the 2.7 kHz filter installed, so for best results I should set my WIDTH control for a passband of 2.7 kHz. 5. I can use my 2.7 kHz filter in CW mode with my LO=0.30 and HI=0.50 (that is, BW=0.20). __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. 73 Jerry KM3K -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill Turner Sent: Monday, May 12, 2014 1:07 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood ORIGINAL MESSAGE: (may be snipped) On 5/11/2014 7:25 PM, Fred Jensen wrote: I too think roofing filters are really not well understood. REPLY: A large part of the misunderstanding is due to the name. Whoever chose the name roofing did a great disservice. A better name would simply be it's function: 1st I.F. filter. That's what it is and that's what it does. I have always thought that roofing was a marketing ploy to imbue it with some kind of magical powers. 73, Bill W6WRT __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jso...@comcast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Jerry, Why do you say it has been corrupted? This is exactly the purpose for the Roofing Filters in the K3. Jack B, W6FB On May 12, 2014, at 9:33 AM, Jerome Sodus jso...@comcast.net wrote: Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. 73 Jerry KM3K -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill Turner Sent: Monday, May 12, 2014 1:07 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood ORIGINAL MESSAGE: (may be snipped) On 5/11/2014 7:25 PM, Fred Jensen wrote: I too think roofing filters are really not well understood. REPLY: A large part of the misunderstanding is due to the name. Whoever chose the name roofing did a great disservice. A better name would simply be it's function: 1st I.F. filter. That's what it is and that's what it does. I have always thought that roofing was a marketing ploy to imbue it with some kind of magical powers. 73, Bill W6WRT __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jso...@comcast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jackbrin...@me.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
http://www.elecraft.com/K3/Roofing_Filters.htm On Mon, May 12, 2014 at 9:45 AM, Jack Brindle jackbrin...@me.com wrote: Jerry, Why do you say it has been corrupted? This is exactly the purpose for the Roofing Filters in the K3. Jack B, W6FB On May 12, 2014, at 9:33 AM, Jerome Sodus jso...@comcast.net wrote: Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. 73 Jerry KM3K -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill Turner Sent: Monday, May 12, 2014 1:07 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood ORIGINAL MESSAGE: (may be snipped) On 5/11/2014 7:25 PM, Fred Jensen wrote: I too think roofing filters are really not well understood. REPLY: A large part of the misunderstanding is due to the name. Whoever chose the name roofing did a great disservice. A better name would simply be it's function: 1st I.F. filter. That's what it is and that's what it does. I have always thought that roofing was a marketing ploy to imbue it with some kind of magical powers. 73, Bill W6WRT __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jso...@comcast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jackbrin...@me.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to a...@cablespeed.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Jerry, Yes, the term has become corrupted and misunderstood over the years. That *is* exactly what the K3 filters do (protect the downstream circuits from strong out of passband signals), but is done using a much more narrow bandwidth at the 1st IF. If the operator never encounters signal levels in excess of S-9+30, there is no need for the roofing filter, but signals stronger than that are encountered commonly in contests and tuning through a DX pileup. If it were not for the Hardware AGC, they would overload the A-D converter causing the entire output to become garbage. With the Hardware AGC present, that is not going to happen, but strong signals within the 1st IF bandpass will cause pumping of the Hardware AGC as those signals come and go. In the K3, *that* condition is what the roofing filters will prevent. Bottom line, if you hear that pumping (and subsequent desensing of the receiver), you would benefit from a more narrow filter. 73, Don W3FPR On 5/12/2014 12:33 PM, Jerome Sodus wrote: Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Thank-you, Greg. Excellent. Jerry KM3K _ From: Greg [mailto:a...@cablespeed.com] Sent: Monday, May 12, 2014 12:52 PM To: Jack Brindle Cc: Jerome Sodus; elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood http://www.elecraft.com/K3/Roofing_Filters.htm On Mon, May 12, 2014 at 9:45 AM, Jack Brindle jackbrin...@me.com wrote: Jerry, Why do you say it has been corrupted? This is exactly the purpose for the Roofing Filters in the K3. Jack B, W6FB On May 12, 2014, at 9:33 AM, Jerome Sodus jso...@comcast.net wrote: Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. 73 Jerry KM3K __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
No problem Jerry. Didn't seem to make much sense hashing out something that was already clarified by the designers. :) 73 Greg On Mon, May 12, 2014 at 9:59 AM, Jerome Sodus jso...@comcast.net wrote: Thank-you, Greg. Excellent. Jerry KM3K -- *From:* Greg [mailto:a...@cablespeed.com] *Sent:* Monday, May 12, 2014 12:52 PM *To:* Jack Brindle *Cc:* Jerome Sodus; elecraft@mailman.qth.net *Subject:* Re: [Elecraft] [K3] Roofing filters are misunderstood http://www.elecraft.com/K3/Roofing_Filters.htm On Mon, May 12, 2014 at 9:45 AM, Jack Brindle jackbrin...@me.com wrote: Jerry, Why do you say it has been corrupted? This is exactly the purpose for the Roofing Filters in the K3. Jack B, W6FB On May 12, 2014, at 9:33 AM, Jerome Sodus jso...@comcast.net wrote: Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. 73 Jerry KM3K __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
I have two big time dxers/contesters near me - on 160 , one is -8 to -9 dBm and the other is -10 to -11dBm . Folks , thats in the 50 to 100 mv area at the poor K3 .(S9+60 to 70 area) Just for fun of it , I can easily see both on my scope hung on my antenna. With the 250 hz 8 pole - I could copy an HS0 at my noise level split 2.2 khz away from the -9 dBm station and not even know he was there except seeing him on the P3. (He is using a K3 exciter and an ALPHA amp. ) Cannot say that for some of the other locals who have phase noise from various and sundry other rigs. 73 Hank K7HP (SNIP) If the operator never encounters signal levels in excess of S-9+30, there is no need for the roofing filter, but signals stronger than that are encountered commonly in contests and tuning through a DX pileup. If it were not for the Hardware AGC, they would overload the A-D converter causing the entire output to become garbage. With the Hardware AGC present, that is not going to happen, but strong signals within the 1st IF bandpass will cause pumping of the Hardware AGC as those signals come and go. In the K3, *that* condition is what the roofing filters will prevent. Bottom line, if you hear that pumping (and subsequent desensing of the receiver), you would benefit from a more narrow filter. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
ORIGINAL MESSAGE: (may be snipped) On 5/12/2014 9:33 AM, Jerome Sodus wrote: Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. 73 Jerry KM3K REPLY: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
At least I do, Arie. Maybe those with fewer local signals do not. Dunno. Phil w7ox On 5/12/14, 9:23 AM, Arie Kleingeld PA3A wrote: Well, You defenitely need those filters in the K3. When signals are strong and the band is busy, signals coming through the roofing filter (line S9+20dB) is said to pump the hardware AGC, even if you have the DSP filtering set to a small BW. Anyway, you can certainly hear that. Try it on CW, on 40m in the evening when there's a contest. You'll love the 400Hz roofing filter. 73 Arie PA3A Al Lorona schreef op 11-5-2014 23:03: What determines the bandwidth you hear at the loudspeaker? It's not your roofing filter, despite a continuing notion that it is. Dave Hachadorian's point in a post a few weeks ago was that you don't need a 1.8 kHz filter to get a 1.8 kHz bandwidth. You're free to set whatever bandwidth you want with any filter. Before rigs had DSP we got used to the idea that your crystal filter sets your bandwidth. That's not true any more. It sets your *maximum* bandwidth. You then have the freedom to narrow and position a bandwidth arbitrarily using the DSP controls [SHIFT and WIDTH or HI and LO]. Here's a true-false quiz: 1. I'm a contester, so I need a 1.8 kHz roofing filter in the K3. 2. I should purchase the 400 Hz filter if I like to operate CW with bandwidths of 300 - 400 Hz. 3. For SSB, the 2.7 and 2.8 kHz filters are 'too wide'. 4. I have the 2.7 kHz filter installed, so for best results I should set my WIDTH control for a passband of 2.7 kHz. 5. I can use my 2.7 kHz filter in CW mode with my LO=0.30 and HI=0.50 (that is, BW=0.20). __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
From an older Inrad writeup (and consistent with Wayne's): The term “roofing” stems from the fact that it protects the rest of the radio following it from out of the passband signals. http://www.qth.com/inrad/roofing-filters.pdf I like the term preselector from my 75S-1, but that doesn't fit well with selectable bandwidths. 73, Josh W6XU On 5/12/2014 12:01 PM, Bill Turner wrote: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
I have imperfect recollections that the source of the term roofing filter came from the idea that the filter put a roof over your receiver to prevent very strong, off-frequency signals from getting in. You'll need to crank up your imagination here ... similar to the roof of your house keeping out things falling from the sky while desired things can still enter through the doors. I did say imagination. :-) I do also agree, it's probably not a particularly descriptive name, but the filters do have a purpose in SDR's like the K3. I think most of the thread was aimed at the differences between the various filters available for the K3. 73, Fred K6DGW - Northern California Contest Club - CU in the 2014 Cal QSO Party 4-5 Oct 2014 - www.cqp.org On 5/12/2014 12:01 PM, Bill Turner wrote: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Bill, Originally the superhet receivers converted from the signal frequency to a lower fixed intermediate frequency in order to obtain sufficient selectivity. IFs went as low as 85kHz until crystal filters became more widespread. As designs changed ( changed not improved) it became usual to convert to a higher frequency, in the order of 70MHz to obtain good image rejection because manufacturers economised on signal frequency filtering and they then down converted to a low IF as before. To protect the second mixer a roofing filter was added and so termed because it was at the high IF ie the roof in terms of frequency. There were good reasons for this in commercial equipment and the amateur equipment followed as a marketing ploy. Hope that helps and please excuse my poor writing. Regards Peter G3SMT I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to peter.to...@talktalk.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Bill, Like a roof protects the contents of a building, a roofing filter protects the electronics that follow it from overload. 73, Don W3FPR On 5/12/2014 3:01 PM, Bill Turner wrote: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
There you go! Well said. 73 Jerry KM3K KX3#6088 Sent from my NOOK Don Wilhelm w3...@embarqmail.com wrote: Bill, Like a roof protects the contents of a building, a roofing filter protects the electronics that follow it from overload. 73, Don W3FPR On 5/12/2014 3:01 PM, Bill Turner wrote: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Roof-upper ... higher ... overhead ... protective ... There are several fairly intuitive possibilities, none of which are worth getting confused about in the first place. Dave AB7E On 5/12/2014 12:01 PM, Bill Turner wrote: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
ORIGINAL MESSAGE: (may be snipped) On 5/12/2014 12:38 PM, Josh Fiden wrote: The term “roofing” stems from the fact that it protects the rest of the radio following it from out of the passband signals. REPLY: A roof keeps what falls on it (rain, snow) out. It doesn't pass it through. Just the opposite of what a so-called roofing filter does. I prefer names that are pretty much self-explanatory. This one isn't. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Wasn't the chicken little sky is falling thing popular back when roofing filter originated? We may be luckier than we know that it became known as a roofing filter. 73 de Dennis KD7CAC Scottsdale, AZ On May 12, 2014, at 3:04 PM, David Gilbert xda...@cis-broadband.com wrote: Roof-upper ... higher ... overhead ... protective ... There are several fairly intuitive possibilities, none of which are worth getting confused about in the first place. Dave AB7E On 5/12/2014 12:01 PM, Bill Turner wrote: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Think of your roof blocking the rain so the ceiling doesn't have to work so hard. It's not used for band-pass, it's to let the DSP work less. Sent from my iPhone ...nr4c. bill On May 12, 2014, at 3:01 PM, Bill Turner dez...@outlook.com wrote: ORIGINAL MESSAGE: (may be snipped) On 5/12/2014 9:33 AM, Jerome Sodus wrote: Hello Bill, The term roofing-filter made sense back in the 1980's when I designed roofing-filters at 70 MHz. Bandwidths would be in tens of KHz. The purpose then was to protect downstream circuitry by rejecting very strong out-of-band signals that could cause overload; selectivity was not the purpose. Selectivity was done further downstream. So the term has become corrupted over the years. 73 Jerry KM3K REPLY: I still don't get it. What does the word roof have to do with bandpass? That's where the confusion comes from. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to n...@widomaker.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
Actually, a roofing filter does exactly what it says. It protects against ... i.e., does not allow to pass ... out-of-passband signals from affecting the ADC or hardware AGC. It's a roof against unwanted energy and a window for desired signals. So would you prefer to call it a window? Have at it, but that doesn't alter the fact that its fundamental purpose is to protect ... protect the ADC and protect the AGC so that they can perform their function properly. And it doesn't mean that anybody will recognize what you're talking about, which is probably more relevant than the semantics involved. Dave AB7E On 5/12/2014 3:38 PM, Bill Turner wrote: ORIGINAL MESSAGE: (may be snipped) On 5/12/2014 12:38 PM, Josh Fiden wrote: The term “roofing” stems from the fact that it protects the rest of the radio following it from out of the passband signals. REPLY: A roof keeps what falls on it (rain, snow) out. It doesn't pass it through. Just the opposite of what a so-called roofing filter does. I prefer names that are pretty much self-explanatory. This one isn't. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
ORIGINAL MESSAGE: (may be snipped) On 5/12/2014 4:15 PM, David Gilbert wrote: So would you prefer to call it a window? REPLY: I like that! Much more accurate. A roof keeps everything out while a window lets only certain things such as the desired signal in. Much more self-explanatory. 73, Bill W6WRT dez...@outlook.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] [K3] Roofing filters are misunderstood
What determines the bandwidth you hear at the loudspeaker? It's not your roofing filter, despite a continuing notion that it is. Dave Hachadorian's point in a post a few weeks ago was that you don't need a 1.8 kHz filter to get a 1.8 kHz bandwidth. You're free to set whatever bandwidth you want with any filter. Before rigs had DSP we got used to the idea that your crystal filter sets your bandwidth. That's not true any more. It sets your *maximum* bandwidth. You then have the freedom to narrow and position a bandwidth arbitrarily using the DSP controls [SHIFT and WIDTH or HI and LO]. Here's a true-false quiz: 1. I'm a contester, so I need a 1.8 kHz roofing filter in the K3. 2. I should purchase the 400 Hz filter if I like to operate CW with bandwidths of 300 - 400 Hz. 3. For SSB, the 2.7 and 2.8 kHz filters are 'too wide'. 4. I have the 2.7 kHz filter installed, so for best results I should set my WIDTH control for a passband of 2.7 kHz. 5. I can use my 2.7 kHz filter in CW mode with my LO=0.30 and HI=0.50 (that is, BW=0.20). The answers are: 1. False. You do not need a 1.8 kHz filter just to set the BW=1.80. A 2.7 kHz filter can serve well during a contest with a much narrower DSP bandwidth. Refer to Dave's original post. 2. False. You can set the CW bandwidth to 400 using any filter whose bandwidth is equal to or greater than 400. 3. False. This was Dave's point. You're free to have a 2.7 or 2.8 installed, yet set the WIDTH to 1.8, 1.5 or anything else you wish. 4. False. You don't need to restrict yourself to only that bandwidth. You can set it to a narrower value if you wish. 5. True. And you'll probably suffer no ill effects under most conditions. Furthermore, the but extremely strong signals will pump my hardware AGC arguments are probably a bit overrated. Most folks, even before a strong station gets close enough to do that, will give up and leave the frequency because of the QRM, especially in the presence of transmitted phase noise or key clicks as has come up in more recent posts. So then why have narrow roofing filters to choose from? To maximize the close-in dynamic range, which is important if you have large antennas in high-RF environments. The vast majority of hams does not absolutely need really narrow roofing filters. It's wonderful that the K3 allows this, but it's certainly not mandatory, especially for casual operating. Finally, note that if you received good training as a Novice with a poor, unselective receiver, you'll be able to copy right through any AGC pumping! It's the operator, more than the filters. Al W6LX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
I completely agree with all of that except for the very last sentence. Clearly you've never used a 756Pro (first version) in a major CW contest. I can remember very loud stations 10 or 15 KHz away completely desensing my receiver to the point that the station I was trying to copy simply disappeared. When I switched to the K3 the difference was astounding. 73, Dave AB7E On 5/11/2014 2:03 PM, Al Lorona wrote: What determines the bandwidth you hear at the loudspeaker? It's not your roofing filter, despite a continuing notion that it is. Dave Hachadorian's point in a post a few weeks ago was that you don't need a 1.8 kHz filter to get a 1.8 kHz bandwidth. You're free to set whatever bandwidth you want with any filter. Before rigs had DSP we got used to the idea that your crystal filter sets your bandwidth. That's not true any more. It sets your *maximum* bandwidth. You then have the freedom to narrow and position a bandwidth arbitrarily using the DSP controls [SHIFT and WIDTH or HI and LO]. Here's a true-false quiz: 1. I'm a contester, so I need a 1.8 kHz roofing filter in the K3. 2. I should purchase the 400 Hz filter if I like to operate CW with bandwidths of 300 - 400 Hz. 3. For SSB, the 2.7 and 2.8 kHz filters are 'too wide'. 4. I have the 2.7 kHz filter installed, so for best results I should set my WIDTH control for a passband of 2.7 kHz. 5. I can use my 2.7 kHz filter in CW mode with my LO=0.30 and HI=0.50 (that is, BW=0.20). The answers are: 1. False. You do not need a 1.8 kHz filter just to set the BW=1.80. A 2.7 kHz filter can serve well during a contest with a much narrower DSP bandwidth. Refer to Dave's original post. 2. False. You can set the CW bandwidth to 400 using any filter whose bandwidth is equal to or greater than 400. 3. False. This was Dave's point. You're free to have a 2.7 or 2.8 installed, yet set the WIDTH to 1.8, 1.5 or anything else you wish. 4. False. You don't need to restrict yourself to only that bandwidth. You can set it to a narrower value if you wish. 5. True. And you'll probably suffer no ill effects under most conditions. Furthermore, the but extremely strong signals will pump my hardware AGC arguments are probably a bit overrated. Most folks, even before a strong station gets close enough to do that, will give up and leave the frequency because of the QRM, especially in the presence of transmitted phase noise or key clicks as has come up in more recent posts. So then why have narrow roofing filters to choose from? To maximize the close-in dynamic range, which is important if you have large antennas in high-RF environments. The vast majority of hams does not absolutely need really narrow roofing filters. It's wonderful that the K3 allows this, but it's certainly not mandatory, especially for casual operating. Finally, note that if you received good training as a Novice with a poor, unselective receiver, you'll be able to copy right through any AGC pumping! It's the operator, more than the filters. Al W6LX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to xda...@cis-broadband.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
I too think roofing filters are really not well understood. For the record, I have the stock SSB [2.7 KHz? I don't actually know] and the 500 Hz CW. In 99% of my operating situations, it doesn't matter which one I use, I set the received BW with the DSP, and I'm a very happy ham. I do have several close HP contesters, WX6V is one. On CW if I were to use the 2.7 roofer, even with a 250 Hz DSP, Jim will desense my K3 -- like maybe 1.5 miles as the electromagnetic waves travel. The roofer makes a difference with strong close in signals. Whether or not you want a 1.8, 2.7, 5-pole, 8-pole, or whatever may be trying to pick fly poop out of the pepper for most of us. If you run a lot of CW in crowded conditions, a more CW-ish filter is likely good for you. My neighbor Jim got a K3 early this year, replacing an ICOMsomething. Still just as strong on frequency, all of the phase noise has disappeared, no clicks -- nothing. Yet again, I'm a happy ham. 73, Fred K6DGW - Northern California Contest Club - CU in the 2014 Cal QSO Party 4-5 Oct 2014 - www.cqp.org On 5/11/2014 7:02 PM, David Gilbert wrote: I completely agree with all of that except for the very last sentence. Clearly you've never used a 756Pro (first version) in a major CW contest. I can remember very loud stations 10 or 15 KHz away completely desensing my receiver to the point that the station I was trying to copy simply disappeared. When I switched to the K3 the difference was astounding. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
I can remember very loud stations 10 or 15 KHz away completely desensing my receiver to the point that the station I was trying to copy simply disappeared. When I switched to the K3 the difference was astounding. That is because the 756Pro is a completely brain dead design ... there is only a single 30 KHz or so roofing filter at VHF and AGC which is based on total signal in that 30 KHz or so window starts at a very low level. The only job of the K3's *hardware AGC* is to protect the analog to digital converter from being driven into saturation so it does not begin to activate until approximately S9+40. The K3's normal AGC is entirely DSP based and is effectively controlled by only the signal which passes through the DSP (it is a shame the AGC control point isn't also after the notch G). 73, ... Joe, W4TV On 5/11/2014 10:02 PM, David Gilbert wrote: I completely agree with all of that except for the very last sentence. Clearly you've never used a 756Pro (first version) in a major CW contest. I can remember very loud stations 10 or 15 KHz away completely desensing my receiver to the point that the station I was trying to copy simply disappeared. When I switched to the K3 the difference was astounding. 73, Dave AB7E __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] [K3] Roofing filters are misunderstood
I would take issue with your answer to #1. It really depends on your situation. For most of the folks on this list your answer very well may be correct. In areas where there is very high station density, it probably is not. Here in Silicon Valley there are a LOT of very strong near-by signals. The 1.8 KHz filter keeps close-in LOUD signals out of my passband so that the DSP filters have a chance to do their job. This is the whole purpose of the filter, to keep other strong signals out of the passband so that the DSP can do the real work. By the way, for contesting (actually my main operating mode), I normally listen to SSB signals with low cut at 500 and high cut in the 1500-1800 range, well inside the 1.8KHz filter’s purview. Interestingly, I use matched 500 Hz 5-pole filters for CW contesting, where I can get within just a few hundred hertz of the local big signals without problem. My normal DSP bandwidth is something less that 500 Hz. It’s sideband contesting where I need the narrow filters. Since most of the local big guns also use K3s, phase noise and other similar problems are not a factor here. I really can get close to these folks and work lots of stations without either one of us being disturbed. I credit all this to the great RF system my friends have created. When I’m not in one of the big contests, or just casual QSOs where the big guns aren’t a factor, the 2.7 KHz filter does an outstanding job on whatever mode I use. I guess there is an exception to everything, and indeed there are times when the narrow filters are needed. Some of us actually do fall in that category. Oh to live back in the south where I definitely didn't have the problem… Jack B, W6FB (ex-WA4FIB) On May 11, 2014, at 2:03 PM, Al Lorona alor...@sbcglobal.net wrote: What determines the bandwidth you hear at the loudspeaker? It's not your roofing filter, despite a continuing notion that it is. Dave Hachadorian's point in a post a few weeks ago was that you don't need a 1.8 kHz filter to get a 1.8 kHz bandwidth. You're free to set whatever bandwidth you want with any filter. Before rigs had DSP we got used to the idea that your crystal filter sets your bandwidth. That's not true any more. It sets your *maximum* bandwidth. You then have the freedom to narrow and position a bandwidth arbitrarily using the DSP controls [SHIFT and WIDTH or HI and LO]. Here's a true-false quiz: 1. I'm a contester, so I need a 1.8 kHz roofing filter in the K3. 2. I should purchase the 400 Hz filter if I like to operate CW with bandwidths of 300 - 400 Hz. 3. For SSB, the 2.7 and 2.8 kHz filters are 'too wide'. 4. I have the 2.7 kHz filter installed, so for best results I should set my WIDTH control for a passband of 2.7 kHz. 5. I can use my 2.7 kHz filter in CW mode with my LO=0.30 and HI=0.50 (that is, BW=0.20). The answers are: 1. False. You do not need a 1.8 kHz filter just to set the BW=1.80. A 2.7 kHz filter can serve well during a contest with a much narrower DSP bandwidth. Refer to Dave's original post. 2. False. You can set the CW bandwidth to 400 using any filter whose bandwidth is equal to or greater than 400. 3. False. This was Dave's point. You're free to have a 2.7 or 2.8 installed, yet set the WIDTH to 1.8, 1.5 or anything else you wish. 4. False. You don't need to restrict yourself to only that bandwidth. You can set it to a narrower value if you wish. 5. True. And you'll probably suffer no ill effects under most conditions. Furthermore, the but extremely strong signals will pump my hardware AGC arguments are probably a bit overrated. Most folks, even before a strong station gets close enough to do that, will give up and leave the frequency because of the QRM, especially in the presence of transmitted phase noise or key clicks as has come up in more recent posts. So then why have narrow roofing filters to choose from? To maximize the close-in dynamic range, which is important if you have large antennas in high-RF environments. The vast majority of hams does not absolutely need really narrow roofing filters. It's wonderful that the K3 allows this, but it's certainly not mandatory, especially for casual operating. Finally, note that if you received good training as a Novice with a poor, unselective receiver, you'll be able to copy right through any AGC pumping! It's the operator, more than the filters. Al W6LX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to jackbrin...@me.com __ Elecraft mailing list Home:
Re: [Elecraft] [K3] Roofing filters are misunderstood
ORIGINAL MESSAGE: (may be snipped) On 5/11/2014 7:25 PM, Fred Jensen wrote: I too think roofing filters are really not well understood. REPLY: A large part of the misunderstanding is due to the name. Whoever chose the name roofing did a great disservice. A better name would simply be it's function: 1st I.F. filter. That's what it is and that's what it does. I have always thought that roofing was a marketing ploy to imbue it with some kind of magical powers. 73, Bill W6WRT __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] K3 Roofing filters
Dear Elecrafters, I've been using my K2 for a dozen years and I'm thinking I might go for a K3. I have a question about RX filtering I'd like to get straight. Is the widest bandwidth available to the receiver the width of the widest roofing filter? I was wondering about getting the general coverage receive filter board, but I wanted to know if I'd be as well to get the AM (6kHz) roofing filter as well - or could I dial out beyond the stock 2.7 kHz? My usual mode is CW, so I know I'd want a narrow filter to help with - although I realise that the DSP does the filtering, the xtal filters provide roofing. 73, Paul EI5KI __ 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 Roofing filters
Paul Barlow-2 wrote Is the widest bandwidth available to the receiver the width of the widest roofing filter? Correct. If you operate mostly CW, you may be wasting money getting wider filters than the stock 2.7 kHz...you definitely need a 500 Hz or lower filter for CW to prevent blocking in the presence of strong (S9+20) signals. 73, Bill W4ZV -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Roofing-filters-tp7579774p7579777.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: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 Roofing filters
Paul, The roofing filters protect the A to D converter input from strong adjacent signals, so choose your CW filter according to your operating habits. If you do CW contesting or DXing in pileup situations, you will want a narrow filter. If you are using the K3 as an SWL receiver, you would want either the 13 kHz or the 6 kHz roofing filter installed. The DSP audio bandpass will go out to about 4 kHz, so if you want full fidelity, choose the 13 kHz filter for that - AM bandwidth is double the audio bandwidth. The DSP width is displayed as the audio passband, the roofing filter is at the IF, so for AM double the audio bandwidth. 73, Don W3FPR On 10/10/2013 6:06 AM, Paul Barlow wrote: Dear Elecrafters, I've been using my K2 for a dozen years and I'm thinking I might go for a K3. I have a question about RX filtering I'd like to get straight. Is the widest bandwidth available to the receiver the width of the widest roofing filter? I was wondering about getting the general coverage receive filter board, but I wanted to know if I'd be as well to get the AM (6kHz) roofing filter as well - or could I dial out beyond the stock 2.7 kHz? My usual mode is CW, so I know I'd want a narrow filter to help with - although I realise that the DSP does the filtering, the xtal filters provide roofing. __ 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 Roofing filters
I think Paul had gotten the information he was asking about from others Bill and Don. I don't see much use for the 6K filter since you can now use the 13K FM filter for AM transmit. If you do a lot of AM transmit you will have a cleaner signal with the 6K filter. If you only do AM receive, you can use the 2.7K or 2.8K filter to receive on only one sideband and get usable performance when conditions need narrower roofing than provided by the 13K filter. Save your filter slots for hard SSB, CW and digital conditions where roofing can be a lifesaver. Cheers - Bill, AE6JV --- Bill Frantz| I don't have high-speed | Periwinkle (408)356-8506 | internet. I have DSL.| 16345 Englewood Ave www.pwpconsult.com | | Los Gatos, CA 95032 __ 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 Roofing filters
If you do a lot of AM transmit you will have a cleaner signal with the 6K filter. Only marginally and only so far as it applies to synthesizer phase noise more than +/- 3 KHz from the carrier. Even then, the K3 will be much cleaner that the typical YaeComWood up-conversion transceiver with their 30 KHz wide 4 pole VHF filters. 73, ... Joe, W4TV On 10/10/2013 1:27 PM, Bill Frantz wrote: I think Paul had gotten the information he was asking about from others Bill and Don. I don't see much use for the 6K filter since you can now use the 13K FM filter for AM transmit. If you do a lot of AM transmit you will have a cleaner signal with the 6K filter. If you only do AM receive, you can use the 2.7K or 2.8K filter to receive on only one sideband and get usable performance when conditions need narrower roofing than provided by the 13K filter. Save your filter slots for hard SSB, CW and digital conditions where roofing can be a lifesaver. Cheers - Bill, AE6JV --- Bill Frantz| I don't have high-speed | Periwinkle (408)356-8506 | internet. I have DSL.| 16345 Englewood Ave www.pwpconsult.com | | Los Gatos, CA 95032 __ 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 Roofing Filters
Ray, short answer: Use the SSB bw filter for JT65. The sw looks at up to 4-KHz bw, if available, and the narrow band feature of this mode is accomplished at the digital level in the sw (inside the computer). Narrowing bw below this just limits the number of signal the sw looks at. JT65 and MAP65 both have sw features to limit the decoding bw window if you are operating in a crowded band. That happens to me a lot as I am the only AK station QRV on 2m eme (if you want eme WAS on 2m you have to work me - KL6M is working on curing IM issues and should be on 2m-eme soon). So I often have several stations calling me on JT65 and may be only spaced 10-20 Hz apart. JT65 provides the ability to narrow the bw which I often set a 20-Hz. If you are running JT65HF I am not familiar enough what the HF environment is like to know if this situation happens much on HF. Narrowing the radio bw does not aid JT65 in decoding. 73, Ed - KL7UW -- Date: Wed, 7 Aug 2013 11:00:33 +0100 From: Ray Coles raycole...@gmail.com To: elecraft@mailman.qth.net Subject: [Elecraft] Reflector: K3 Roofing Filters Since this subject is current (and likely always will be!) I have to ask the learned brethren which filter does experience show to be best for use with JT65 mode. I currently only have the standard issue 2.7KHz filter, which of course works OK for everything (except I suppose DSB and FM). If I used CW I would definitely choose a narrow-band filter, but the waterfall display used for JT65, PSK31 etc. might lead me to rely on a 2-3KHz filter for these modes, even though the signal bandwidths are much narrower. My question is: is anyone using narrower roofing filters and tuning across the waterfall to squeeze the most out of those DX data stations? Or am I being dumb? 73, Ed - KL7UW http://www.kl7uw.com dubus...@gmail.com 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
[Elecraft] K3 Roofing filters
I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. Ivan G3IZD __ 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 Roofing filters
Ivan You'll get as many different views here as there are combinations of different filters ! Roofing filters are quite easy to add at a later date (ease depends somewhat on the options installed), so my suggestion is to go lightly at first and see how you get on with just a couple of filters, and rely on the DSP for filtering - which is pretty good. For SSB, consider either 2.4 or 2.1kHz. Anything narrower is obviously more effective, but also tiring to listen to for long periods. For CW I think the choice is easy - head for the 500Hz filter. Regards John G4ZTR -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of g3...@sky.com Sent: 06 August 2013 10:37 To: elecraft@mailman.qth.net Subject: [Elecraft] K3 Roofing filters I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. Ivan G3IZD __ 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 Roofing filters
Hi Ivan I use Inrad SSB Wide 2.8khz #716 SSB Narrow 1.5Khz #727 CW / Data 400hz #701 I find these filters outstanding in all conditions and I contest in SSB CW RTTY and PSK31 Jim M0CKE On 6 August 2013 10:50, James Balls makid...@gmail.com wrote: Hi Ivan I use Inrad SSB Wide 2.8khz #716 SSB Narrow 1.5Khz #727 CW / Data 400hz #701 I find these filters outstanding in all conditions and I contest in SSB CW RTTY and PSK31 Jim M0CKE On 6 August 2013 10:37, g3...@sky.com g3...@sky.com wrote: I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. Ivan G3IZD __ 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 Roofing filters
On Tuesday August 6, Ivan (G3IZD) wrote ... I am about to purchase a K3 ... what is the general feeling regarding [filter] bandwidth(s) ... -- Hi Ivan, In addition to the choices available from Elecraft and INRAD, WB2ART and I also offer a 700 Hz (wide CW) alternative. IMHO 700 Hz fits really well between the INRAD 1.5 k Hz and 400 Hz filters and it's ideal for scanning. The lead-time for the 700 Hz filter is upwards of 14 weeks, as there's a 12-manufacturing lead-time and we only commission production as demand warrants. The current batch (due to arrive in early October) will probably sell out within a matter of hours. The next batch can be expected sometime between December and February. --- - - - --- Our website http://www.unpcbs.com/ features a unique visual comparison of the five 8-pole filters (1,000, 700, 500, 400, and 250 Hz). This comparison is packaged as both an online slideshow and as a (printable) PDF file. Brief descriptions accompany each slide. As a whole, these descriptions create a concise 8-pole CW filter buyer's guide If you are a serious contester, then 700 and 400 Hz would be an excellent choice. Otherwise (if you're not a serious contester) then the 700 is probably the only CW filter you'll ever need. Oh and it's also ideal for 500 Hz digital formats. --- - - - --- Additional suggestions ... 1) Avoid filters whose widths are too similar. Specifically, IMHO a ratio of less than 1.4 (i.e. the square root of two) is an exercise in diminishing returns. 2) For historic reasons, the filter widths are not always the same as their designations. This is especially true of the INRAD 250 Hz 8-pole filter, which is closer 370 Hz wide. 3) INRAD offers two additional 8-pole filters 1500 Hz and 500 Hz which are not available through Elecraft. 4) If you have the sub-RX, then adding/changing filters is a fairly significant undertaking. (Thus the advice about just getting a bare K3 and adding filters later may not apply to you, if your intention is to get a factory assembled K3 with sub-RX.) Cheers, Gary KI4GGX __ 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 Roofing filters
Ivan, You are right to ask, the filters can drive the cost of the K3 spiraling upward. I will not answer simply, but rather give you some guidelines for selection. Your choice of roofing filters will depend a lot on your operating conditions and preferences. Remember that the roofing filters are present NOT to achieve the final bandwidth - that is done in the DSP processing. The roofing filters are used to protect the input of the DAC from strong adjacent signals - ones that you would not hear because they are outside the DSP passband. There is another mechanism - Hardware AGC - that also protects the DAC from overload. Its response is what you will hear when there are strong signals within the passband of the roofing filter but outside the passband you have set in the DSP - the strong unwanted signal will cause pumping of the AGC and constantly change the receivers sensitivity. The Hardware AGC will begin to operate when the signal strength is greater than S-9+30 dB (If I recall correctly). For weaker signals, it will not activate. So -- if you are an SSB ragchewer, the 2.8 kHz filter will likely be sufficient, you probably seek to operate in a clear area of the band anyway. But -- if you are operating in a crowded band with lots of adjacent strong signals (heavy DXing or serious contesting), you will likely want to add roofing filters. How much tolerance you have to those nearby strong signals will influence your choice of filters. Of course, if you want to operate FM, you will need the 13 kHz filter, and for AM transmit, the 6 kHz filter. 5 pole or 8 pole? - if you have the subRX, *and* want to use diversity receive, the filters in the main and the sub must be matched for the filter offset. The choice of 8 pole filters makes it easy, they have zero offset. If you choose the 5 pole filters, matched offset filters are available. If you decide to purchase without the subRX initially, but plan to add it later, order the 8 pole filters unless diversity receive is not a consideration. If you cannot decide by order time, I would suggest you go with the 2.8 kHz 8 pole filter only, then operate using only the DSP filtering for some period of time to allow you to find out where you are experiencing difficulty, then purchase whatever additional filters you need for your operation. The filters are not difficult to add later (unless the subRX is installed, because it must be removed to get to the main filter area). 73, Don W3FPR On 8/6/2013 5:37 AM, g3...@sky.com wrote: I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. Ivan G3IZD __ 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 Roofing filters
Hi Ivan, I am a CW guy and agree with John's assessment on the number of answers you will receive! Here's mine: I run 250Hz, 400Hz, 1000Hz, and 2.8Khz. I know folks out there will say that the 250 400 are so close in filter shape when you really take a look at things, that they are somewhat redundant. If you want to cut down on initial expenses, I would start with the 400Hz filter, this will serve the double duty for CW and your occasional dabbles in the digital arena. They are somewhat easy to add at a later date, depending on what other options you have added, which also gives you the opportunity to learn a little more on the workings of the K3. As far as SSB, I can't comment, as I do not even own any microphones! One thing for sure, you will be a very happy CW operator once you learn your way around the K3... it is a fantastic radio! 73 de Jim - KE8G John Lemay j...@carltonhouse.eclipse.co.uk wrote: Ivan You'll get as many different views here as there are combinations of different filters ! Roofing filters are quite easy to add at a later date (ease depends somewhat on the options installed), so my suggestion is to go lightly at first and see how you get on with just a couple of filters, and rely on the DSP for filtering - which is pretty good. For SSB, consider either 2.4 or 2.1kHz. Anything narrower is obviously more effective, but also tiring to listen to for long periods. For CW I think the choice is easy - head for the 500Hz filter. Regards John G4ZTR -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of g3...@sky.com Sent: 06 August 2013 10:37 To: elecraft@mailman.qth.net Subject: [Elecraft] K3 Roofing filters I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. Ivan G3IZD __ 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 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 Roofing filters
I know many users are happy with the 700 Hz roofing filter you guys have had custom-made. However, I am wondering just how helpful it actually is, compared to other, more standard roofing filter BWs. If a 700 Hz bandwidth is ideal for scanning, just how is a roofing filter needed when scanning? By definition, when scanning, one is tuning across a band, looking for a signal of interest. Is a medium-narrow roofing filter really helpful in this case? Does it make scanning more productive than say, a 1 KHz filter? I am not trying to be argumentative, just trying to understand how a roofing filter of this width may be (more) useful (than other choices) in a radio like the K3 with continuously variable final DSP filtering. Thanks for any input, Bruce N1RX In addition to the choices available from Elecraft and INRAD, WB2ART and I also offer a 700 Hz (wide CW) alternative. IMHO 700 Hz fits really well between the INRAD 1.5 k Hz and 400 Hz filters and it's ideal for scanning... __ 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 Roofing filters
Hi Ivan, 250 Hz: CW and some data modes 1.8 KHz: Other data modes (MT63, WL2K) and SSB Narrow 2.8 KHz: Normal SSB 6.0 KHz: SWL (AM and DSB) and 80m AM nets 15.0 KHz: FM on 10m and 6m The 250 Hz roofing filter works extremely well in crowded band conditions on CW. It's also just about right for low-bandwidth data modes like PSK, Thor, Olivia, etc. If you only need two, I'd go with 250 Hz and 2.8 KHz. Both are 8-pole. I say this because your main interest is in CW, and either the 2.7 or 2.8 KHz filter is needed no matter what. I've had both 5- and 8-pole filters. The skirts are somewhat steeper with the 8-pole, but both types perform quite well. Just remember that the DSP provides most of the filtering you'll hear. The roofiing filters reduce (or in many cases, eliminate) close-in blocking from adjacent interference. Very handy in crowded contest conditions. 73, matt W6NIA On Tue, 06 Aug 2013 10:37:27 +0100 (BST), you wrote: I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. Ivan G3IZD __ 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 Roofing filters
Unlike many other transceivers, ultimate selectivity in the K3 is not determined by the crystal filter. Ultimate selectivity is determined by the DSP whilst the roofing filter only impacts narrow band dynamic range (the level of close in signals applied to the second mixer and analog to digital converter [ADC]). In this case, the roofing filter sets the maximum bandwidth of the receive chain. See discussions by Elecraft here: http://www.elecraft.com/K3/Roofing_Filters.htm My experience leads me to recommend the standard 2.7 KHz (5 pole) for SSB (based on theexchange price) with the added $130 spent on a 2.1 or 1.8 KHz filter if necessary. For CW and digital I would choose 400 Hz as the primary filter (the 500 Hz INRAD if one uses some of the 500 Hz wide MFSK based modes) and the 200 Hz 5 pole for critical CW (or possibly PSK31 and JT9) in the presence of strong adjacent signals. I don't see the need for a 1000 or 700 Hz filter as when conditions allow wide scanning, one of the SSB filters is generally sufficient in combination with DSP set to 1000/800/700 Hz. 73, ... Joe, W4TV On 8/6/2013 5:37 AM, g3...@sky.com wrote: I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. Ivan G3IZD __ 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 Roofing filters
Ivan, you wrote: I am about to purchase a K3 (k). My main interest is certainly CW with occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included. From the operating you plan, and having operated many different K-3s, for SSB CW I would suggest: 1. The standard 2.7 KHz filter for occasional SSB. As others have mentioned, the roofing filter is to protect the DSP. 2. A 400 Hz, 8-pole (or 500 Hz-8 pole) filter for general CW operation (I find anything narrower too restricting for general operating band awareness) 3. If you are inclined to contest or dig really deep for rare DX, add a 200 Hz or 250 Hz filter, also. (Crank it in--only when needed.) I'll defer to others about the better bandwidths for data modes. 73 de K3YD __ 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 roofing filters
My 2 cents worth: Since you are primarily a cw operator, you may now or in the future want the roofing filter that is the ultimate in protecting the DSP in the toughest possible conditions such as when you are running big antennas in a contest on the lower bands. This would mean a very narrow roofing filter. Under other conditions you may encounter conditions that are less severe, but would still cause the DSP to be overwhelmed if you were to use an ssb roofing filter. It would then make sense to have a moderately wide cw roofing filter. Of course, since it is easy to add filters, for many it makes sense to get the latter filter first and add the sharpest filter later if you find you need it. But plan ahead; if you see a possiblity that you will buy a sharper filter later, don't pick the first filter such that it is too similar to that sharp filter to come later. (This advice is given based on your main focus on the cw mode. If you were not mainly a cw operator, it might make more sense to plan for only one cw roofing filter even in the long run.) So, plan ahead right now and decide what is that ultimate narrow filter to you. In practice, that means either the 200 Hz 5-pole or the 250 Hz (in reality about 325 Hz if I remember correctly) 8-pole filter. In other words, what is more useful: the narrower bandwidth at the peak of the 5-pole or the steeper flanks of the 8-pole? I have not made a practical comparison, but my choice was the 200 Hz filter based on a rather simplified argument about what the roofing filter's job is: Most of the time even an SSB roofing filter is fine for cw operation. The need for a narrower roofing filter appears when there are too many, too strong signals in the gaps between the roofing filter passband and the narrower DSP passband (the portion of the band that you are actually listening to). Things are fine until the combined voltage of those unwanted signals as well as the wanted signals (within the dsp passband) exceeds the input voltage capacity of the analog-to-digital converter (or actually the threshold of the hardware agc that will prevent that from happening). While in most casual operation situations there will be no problem even with an ssb roofing filter, most of those situations that require a cw roofing filter will only need the signals in the gaps to be attenuated by a moderate amount, say 10 or 20 dB, to get the job done. I don't see any direct advantage in picking a roofing filter that provides an ultimate attenuation of, say 80 dB over one that provides just 60 dB. I don't remember the ultimate attenuation numbers for the 5-pole and 8-pole filters, so I am just making a general argument here when I suggest that ultimate attenuation is not a reason to use 8-pole filters for the particular reason of ultimate attenuation in selecting a very narrow cw roofing filter. OTOH, the steeper flanks of an 8-pole filter are obviously helpful. How helpful? That depends in the particular situation on how the offending signals are distributed in the passband gaps. Also, while the flanks of the 5-pole filters are not as steep, they may provide better attenuation on a given signal due to the fact that the curve starts closer to the primary wanted signal. Without the benefit of actual comparison, I simply figure that the competition between the filters w.r.t. gap attenuation may be a wash. But remember that signals within the wanted passband also contribute to potential ADC overload. It is therefore very helpful to crank down the dsp bandwidth as long as the roofing filter bandwidth is correspondingly reduced. If we can go from a 325 Hz (nominal 250 Hz) roofing filter to a 200 Hz one, we are reducing the onslaught on the ADC very substantially, by reducing the wanted passband (I assume that the dsp setting changes in the same way), and this in addition to what may happen in what I have called the gaps. Bottom line: I think the 200 Hz filter (and not the 250 Hz one) is the ultimate narrow cw filter. While other list members may have more experience with practical comparison, I don't remember reading about anyone claiming otherwise, for strict cw operation. Of course if you just can't stand listening to just a 200 Hz slice of the band, even in the toughest contest situations, your choice could still be different. Ditto if you are not so much a cw operator as an RTTY operator. Anyway, my own choice was the 200Hz, and I have not regretted it. Now getting back to that other cw filter, which may be the only one you buy to begin with. As many people have pointed out, it makes sense to have significant differences between the roofing filter bandwidths. If the narrowest is 200 Hz, then I wouldn't consider anything narrower than the 400 Hz for the normal cw roofing filter. You probably want something wide enough that you can hear who is next to you. Many people want a really wide cw listening bandwidth for everyday casual
Re: [Elecraft] K3 Roofing filters
Excellent answer from Don, W3FPR. I fit the mostly SSB type with sub-Rx, so I use diversity reception. I chose for the main Rx: 13-KHz (for AM and FM) 2.8-KHz 400-Hz The sub-Rx has just the 2.8-KHz filter I chose the 8-pole for ease in set up for diversity Rx and for the steeper skirts (which I may not really needed up here in AK, but I figured made the resale value better). The DSP bw control works fine and I often narrow the high split on weak or noisy SSB to improve reception. I keep the low split at 200-Hz. The 400-Hz filter makes CW reception of a single station possible. 400-Hz filter is really amazing. I have not used it on CW eme but expect it will provide some advantages in narrowing the noise bw. Typically, I run 100-Hz for eme CW once I have the signal tuned. Scanning for eme signals I use the wider SSB bw and waterfall displays to detect the signal. Most of my eme on 2m is using digital mode so no filter is used as I export the IF of the K3 to LP-Pan and therefore to a soundcard. Digital eme is watched not heard. I actually have the K3 select an empty filter slot when running DATA-A which eliminates a center frequency gain suck out (black zone on zero freq display). 73, Ed - KL7UW http://www.kl7uw.com dubus...@gmail.com 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
Re: [Elecraft] K3 Roofing filters
From the operating you plan, and having operated many different K-3s, for SSB CW I would suggest: 1. The standard 2.7 KHz filter for occasional SSB. As others have mentioned, the roofing filter is to protect the DSP. 2. A 400 Hz, 8-pole (or 500 Hz-8 pole) filter for general CW operation (I find anything narrower too restricting for general operating band awareness) 3. If you are inclined to contest or dig really deep for rare DX, add a 200 Hz or 250 Hz filter, also. (Crank it in--only when needed.) I'll defer to others about the better bandwidths for data modes. 73 de K3YD Hello Ivan, and welcome to the K3! Knowing your interests, I'd agree with Blair above, and with Joe before that. Coming to the K3 from the FT-1000MP, I already had a particular liking for the Inrad 400Hz filter for general-purpose CW and RTTY because of its comfortable bandwidth and nicely shaped passband. The Elecraft 200Hz 5-pole filter is useful for really tight spots, and you can hear the difference with strong signals very close in (some people may disagree... but they probably aren't in Europe :-) For casual SSB the stock 2.7kHz 5-pole filter performs quite well, using SHIFT and WIDTH to control most of the QRM. However, I also happened to have a 1.8kHz Inrad 8-pole filter from the 1000MP which needed only a change of interface board to make it compatible with the K3, and I find that very good for SSB contesting. 73 from Ian GM3SEK __ 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 roofing filters
_Love this reflector_I have two, K3-8 Pole roofing filters spoken for, so that leaves only two roofing filters left. Still available are the KFL3A-2.1k and the KFL3A-6k filters. $125.00 each shipped to your CONUS qth at my expense. Wayne, Thanks so much for the preliminary KX3 manual...It helps ease the wait. Thanks too, to you and Eric and the Elecraft Family for producing such OUTSTANDING equipment...See you at Dayton !! vy73' Steve W8CRH SEMPER FI __ 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 roofing filters all gone
Greetings, I've just received 2 emails asking for my last 2 roofing filters. So Alas...They are all gone. Thanks for your responses. VY73' Steve W8CRH SEMPER FI __ 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 roofing filters for sale
I have two 8-pole 1.0KHz filters for sale. Both were used in K3 #24 for 1-2 years. $210 for both to same party, or $110 for a single. I'll pay for UPS Ground shipping in CONUS. Email: mzilmer(at)verizon(dot)net Thanks and Happy Thanksgiving! matt W6NIA __ 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 roofing filters for sale
Both filters have been sold. Thanks for all the interest! matt W6NIA On Thu, 25 Nov 2010 10:08:22 -0800, you wrote: I have two 8-pole 1.0KHz filters for sale. Both were used in K3 #24 for 1-2 years. $210 for both to same party, or $110 for a single. I'll pay for UPS Ground shipping in CONUS. Email: mzilmer(at)verizon(dot)net Thanks and Happy Thanksgiving! matt W6NIA __ 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] Roofing Filters
Greetings, One more question on roofing filters, specifically about using identical BW filters in adjacent slots. Lots of roofing filter blurbs on the reflector, but I could not find anything specific to this question. In reading the owners manual, it states that roofing filters are to be placed in decreasing BW order, starting from slot #1, with the option of bypassing slots along the way, with the filter configuration setup taking care of letting the firmware know who is where and for what purpose. The manual also indicates that the firmware relates the DSP BW to the filter setup, and routes the IF to (only) one of the five roofing filter slots, depending on the aforementioned filter configuration/setup. So here's my question. Is it possible, albeit perhaps not terribly beneficial at first glance, to put another 0.40 roofer in the next downstream slot from my current 0.40 roofer? Would the F/W even accept that setup? If it would allow that configuration, would the F/W just select the first 0.40 slot, or would the F/W route the IF through both 0.40 roofers? So the real question is whether there is a way to configure two identical 8 pole roofers (i.e. 0.40 kHz) such that the F/W treats that as 16 poles? I'm guessing the answer is most likely a definite no, per hardware and firmware design, but the remote possibility seemed intriguing nonetheless. I guess this is what happens sometimes when there aren't enough sunspots to keep one productively engaged in this hobby. But hey, if you don't ask, you don't learn. ;-) Thanks. 73 Walter WB2IDK __ 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] Roofing Filters
Walter V. Gilles wrote: Is it possible, albeit perhaps not terribly beneficial at first glance, to put another 0.40 roofer in the next downstream slot from my current 0.40 roofer? Would the F/W even accept that setup? If it would allow that configuration, would the F/W just select the first 0.40 slot, or would the F/W route the IF through both 0.40 roofers? So the real question is whether there is a way to configure two identical 8 pole roofers (i.e. 0.40 kHz) such that the F/W treats that as 16 poles? I'm guessing the answer is most likely a definite no The answer is a definite NO. Only one filter at a time can be selected. 73, Bill -- View this message in context: http://n2.nabble.com/Roofing-Filters-tp3088508p3089163.html Sent from the [K3] 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: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] Roofing Filters
I'm not the definitive source for the answer to this question, but I'll hazard an educated guess. The firmware probably wouldn't mind if you put two identical width filters in adjacent slots. The firmware would pick one or the other as you dialed the bandwidth to the appropriate values. I don't know which one it would choose. You could lie to the configuration tool and say one of the filters was 450 Hz and the other 400 Hz and be able to use one and then the other at those bandwidth settings. I don't think you'll find a way to run the output of one filter into the other. For any given bandwidth the firmware chooses one of up to five filters; there's no provision for routing the output of one filter into the input of another, and making them the same width wouldn't change that. I'll guess that 5 poles is often enough, 8 poles is almost always plenty and the benefit gained by going from 8 to 16 poles wouldn't often be very important. Dick, K6KR -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Walter V. Gilles Sent: Tuesday, June 16, 2009 12:58 PM To: elecraft@mailman.qth.net Subject: [Elecraft] [K3] Roofing Filters Greetings, One more question on roofing filters, specifically about using identical BW filters in adjacent slots. Lots of roofing filter blurbs on the reflector, but I could not find anything specific to this question. In reading the owners manual, it states that roofing filters are to be placed in decreasing BW order, starting from slot #1, with the option of bypassing slots along the way, with the filter configuration setup taking care of letting the firmware know who is where and for what purpose. The manual also indicates that the firmware relates the DSP BW to the filter setup, and routes the IF to (only) one of the five roofing filter slots, depending on the aforementioned filter configuration/setup. So here's my question. Is it possible, albeit perhaps not terribly beneficial at first glance, to put another 0.40 roofer in the next downstream slot from my current 0.40 roofer? Would the F/W even accept that setup? If it would allow that configuration, would the F/W just select the first 0.40 slot, or would the F/W route the IF through both 0.40 roofers? So the real question is whether there is a way to configure two identical 8 pole roofers (i.e. 0.40 kHz) such that the F/W treats that as 16 poles? I'm guessing the answer is most likely a definite no, per hardware and firmware design, but the remote possibility seemed intriguing nonetheless. I guess this is what happens sometimes when there aren't enough sunspots to keep one productively engaged in this hobby. But hey, if you don't ask, you don't learn. ;-) Thanks. 73 Walter WB2IDK __ 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] Roofing Filters
Dick Dievendorff wrote: I'll guess that 5 poles is often enough, 8 poles is almost always plenty and the benefit gained by going from 8 to 16 poles wouldn't often be very important. Don't forget that the roofing filter is cascaded with the DSP filter, which is typically equivalent to an 8-pole crystal filter at a setting of 400 Hz, so the effective selectivity is already ~16 poles. 73, Bill -- View this message in context: http://n2.nabble.com/Roofing-Filters-tp3088508p3089175.html Sent from the [K3] 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: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 Roofing filters
I don't recall anyone answering the original question of why roofing filters The term has been used in the UK for many many years. Imagine you are in a well designed tent and it is capable of keeping you warm and dry in normal weather conditions but during a cloud burst water may start to enter the tent. The solution, as all you happy campers know, is to put a fly sheet over the tent and the problem is over. The tent is the DSP system and the fly sheet is your roofing filter. 73 Max ZL4VV ___ 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] K3 Roofing Filters - Zerobeat
Use the shape factor to predict the 60 db down response or band width. example = the 200 Hz filter has 4 to 1 so ... multiply with a calculator the 6 db response by 4 and that would equal 224 X 4 = 896 Hz and the 8 pole 250 Hz has a 2 X 1 so it is 270 X 2 = 740 ! so the 8 pole is really 156 Hz narrower than the 200 in getting rid of LOUD ADJACENT QRM ! You can do the math for yourself ... http://www.zerobeat.net/mediawiki/index.php/K3_Roofing_Filters#Roofing_Filter_Response ___ 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 Roofing Filters - Zerobeat
[EMAIL PROTECTED] wrote: Use the shape factor to predict the 60 db down response or band width. example = the 200 Hz filter has 4 to 1 so ... multiply with a calculator the 6 db response by 4 and that would equal 224 X 4 = 896 Hz and the 8 pole 250 Hz has a 2 X 1 so it is 270 X 2 = 740 ! so the 8 pole is really 156 Hz narrower than the 200 in getting rid of LOUD ADJACENT QRM ! This is very misleading, because the ultimate selectivity is provided by the DSP. So even though there would a big difference if the selectivity were provided only by the filters, they are only needed to protect the DSP. A signal *within the crystal passband* has to be S9 +30 dB before it will activate the hardware AGC; so if a signal is already on the skirt of the crystal filter, it will have to be even louder before any desensing will take place. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ 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] K3 Roofing Filters - Zerobeat
270 x 2 = 540, so the difference is 356Hz. ;-) 73, Season's Greetings all. DaveL G3TJP ___ 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 Roofing Filters - Zerobeat
270 x 2 = 540, so the difference is 356Hz. ;-) However, the 250 Hz filter is actually 370 Hz at the - 6dB points according to previous e-mail here. With the K3, the point of diminishing returns for IMD (and close in rejection) is perhaps - 30dB instead of -60dB or more in a conventional crystal filter only radio. If we use a straight line (linear slope) from the -6dB to -60dB points the 200 and 250 Hz filters look like this: 200 250 - - 6dB 224 Hz370 Hz -60dB 896 Hz777 Hz slope 6.22 Hz/dB3.77 Hz/dB (one side) -10dB 274 Hz400 Hz -20dB 398 Hz475 Hz -30dB 522 Hz550 Hz -40dB 647 Hz626 Hz -50dB 771 Hz702 Hz By this simple calculation (or by plotting on graph paper) one can see that the 200 Hz filter should do a BETTER job as the most narrow filter. It remains tighter to about -35 dB and the five pole design should result in less pulse stretching (ringing in the presence of static) than the 250 (really 350 Hz) filter. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of David Lankshear Sent: Monday, December 10, 2007 6:24 PM To: elecraft@mailman.qth.net Subject: [Elecraft] K3 Roofing Filters - Zerobeat 270 x 2 = 540, so the difference is 356Hz. ;-) 73, Season's Greetings all. DaveL G3TJP ___ 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 roofing filters
Lyle Johnson wrote: Can I use all 5 available roofing filter slots and also have the KBPF3 General Coverage Rx filter module installed without losing any of the slots for the roofing filters? Yes. The KBPF3 is an array of pre-mixer bandpass filters rather than a post-mixer roofing filter, so it does not count as one of the five crystal roofing filters. 73, Lyle KK7P ___ 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 Oops, it would appear I was incorrect Larry, sorry :) Ian -- Ian J Maude, G0VGS SysOp GB7MBC DX Cluster Member RSGB, GQRP K2 #4044 |K3 #? ___ 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 roofing filters
Can I use all 5 available roofing filter slots and also have the KBPF3 General Coverage Rx filter module installed without losing any of the slots for the roofing filters? Yes. The KBPF3 is an array of pre-mixer bandpass filters rather than a post-mixer roofing filter, so it does not count as one of the five crystal roofing filters. 73, Lyle KK7P ___ 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] K3 roofing filters
I plan to order my K3 probably in January '08. Can I use all 5 available roofing filter slots- in my case the FM, AM, 2.8, 2.1 and 1.0 roofing filters- and also have the KBPF3 General Coverage Rx filter module installed without losing any of the slots for the roofing filters? I will not be ordering the sub-receiver. For what it's worth, I wish I could get a power supply/speaker combo as an option from Elecraft. Larry WD4MBE ___ 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 roofing filters
Larry Maguire wrote: I plan to order my K3 probably in January '08. Can I use all 5 available roofing filter slots- in my case the FM, AM, 2.8, 2.1 and 1.0 roofing filters- and also have the KBPF3 General Coverage Rx filter module installed without losing any of the slots for the roofing filters? I will not be ordering the sub-receiver. For what it's worth, I wish I could get a power supply/speaker combo as an option from Elecraft. Larry WD4MBE ___ 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 There are 5 slots in total Larry, so the answer to your question is no. I cannot imagine that you would need so many filters so close in frequency anyway. As for the PSU/Speaker, Elecraft have mooted that one might eventually be forthcoming. Ian -- Ian J Maude, G0VGS SysOp GB7MBC DX Cluster Member RSGB, GQRP K2 #4044 |K3 #? ___ 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] K3 roofing filters: Important ordering information
If you wish to transmit in wide-band modes (AM, ESSB, FM), you'll need to have the corresponding wide filter bandwidths installed in the main receiver. This is because the transmitter and main receiver share the same circuitry. By wide, I mean: AM or ESSBKFL3A-6.0 (6 kHz) FMKFL3B-FM (approx. 13 kHz) Of course you can also install wide filters on the subreceiver. This information is being added to the order form. My apologies for any inconvenience due to not explaining this sooner. 73, Wayne N6KR --- 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
Re: [Elecraft] K3 roofing filters: Important ordering information
Does that mean that if we substitute the 2.8kHz 8 pole filter for the 2.7kHz 5 pole then we'll get a slightly cleaner transmit signal, too? 73, doug From: wayne burdick [EMAIL PROTECTED] Date: Tue, 1 May 2007 10:21:38 -0700 If you wish to transmit in wide-band modes (AM, ESSB, FM), you'll need to have the corresponding wide filter bandwidths installed in the main receiver. This is because the transmitter and main receiver share the same circuitry. By wide, I mean: AM or ESSBKFL3A-6.0 (6 kHz) FMKFL3B-FM (approx. 13 kHz) Of course you can also install wide filters on the subreceiver. This information is being added to the order form. My apologies for any inconvenience due to not explaining this sooner. 73, Wayne N6KR --- 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 ___ 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 roofing filters: Important ordering information
And could you use the FM filter on AM or SSB? Thanks, Brett -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Doug Faunt N6TQS +1-510-655-8604 Sent: Tuesday, May 01, 2007 1:38 PM To: [EMAIL PROTECTED] Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 roofing filters: Important ordering information Does that mean that if we substitute the 2.8kHz 8 pole filter for the 2.7kHz 5 pole then we'll get a slightly cleaner transmit signal, too? 73, doug From: wayne burdick [EMAIL PROTECTED] Date: Tue, 1 May 2007 10:21:38 -0700 If you wish to transmit in wide-band modes (AM, ESSB, FM), you'll need to have the corresponding wide filter bandwidths installed in the main receiver. This is because the transmitter and main receiver share the same circuitry. By wide, I mean: AM or ESSBKFL3A-6.0 (6 kHz) FMKFL3B-FM (approx. 13 kHz) Of course you can also install wide filters on the subreceiver. This information is being added to the order form. My apologies for any inconvenience due to not explaining this sooner. 73, Wayne N6KR --- 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 ___ 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
