8 pole vs 5 pole..I knew this would happen
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I think, still, someone needs to define what a ROOFING
FILTER is. Say for sake of argument - I have a passive or active or crystal filter - and it is to be used as a ROOFING FILTER. Why is it called this? Why is the filter itself, called a ROOFING FILTER? And where does the adjective, ROOFING, come into play? ...... I'm sure I'm dumb on this one - but would like to learn. Not until the K3 came on the Elecraft scene - did anyone mention or get concerned about the need for ROOFING FILTERS. Now they're all the rage? Fred, N3CSY __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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The term "roofing filter" has been around a long time, at least 20 years.
Usually used in the context of up-converting receivers, where the first IF is 40.455 MHz, or 45.000 MHz or even higher. The term means the first selective filter in the receiver. If the first IF is > 30 MHz, the roofing filter is generally wider than one normally needs for SSB or even AM, and the receiver's ultimate selectivity is provided in a later IF stage. As to why it is called a "roofing" filter, I imagine it derives from the fact that it puts a "roof" over the receiver's selectivity. Jack K8ZOA Fred (FL) wrote: > I think, still, someone needs to define what a ROOFING > FILTER is. Say for sake of argument - I have a > passive or active or crystal filter - and it is to > be used as a ROOFING FILTER. Why is it called this? > > Why is the filter itself, called a ROOFING FILTER? > And where does the adjective, ROOFING, come into > play? > > ...... I'm sure I'm dumb on this one - but would > like to learn. Not until the K3 came on the > Elecraft scene - did anyone mention or get > concerned about the need for ROOFING FILTERS. > Now they're all the rage? > > Fred, N3CSY > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by Fred (FL)
Roofing filters - I think the term has more to do with marketing than
engineering. Other companies have made a big deal over having them and people have come to think of them as something special. They are little more than filters placed early in the RX signal path to limit bandwidth ASAP. They were added to correct issues / problems that have crept into modern synth-based mulit-mode radios and they really do make the receivers work better. I have no idea where the term Roofing comes and I certainly don't try to make sense of it. It is just a term applied to a filter that is very worth having in a rig. What is sweet about the K2 is that the filters in the K2 are positioned early in the signal path so they in effect operate similar to the roofing filters that other manufactures put in their rigs. Check out the K2's RX performance and you'll see it is great. Early filtering is partly why. - Keith N1AS - - K2 5411.ssb.100 - -----Original Message----- I think, still, someone needs to define what a ROOFING FILTER is. Say for sake of argument - I have a passive or active or crystal filter - and it is to be used as a ROOFING FILTER. Why is it called this? Why is the filter itself, called a ROOFING FILTER? And where does the adjective, ROOFING, come into play? ...... I'm sure I'm dumb on this one - but would like to learn. Not until the K3 came on the Elecraft scene - did anyone mention or get concerned about the need for ROOFING FILTERS. Now they're all the rage? Fred, N3CSY _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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A lack of understanding is also shown in the FT-2000 Yahoo! group. A fine
document which explains traditional roofing filters is here: http://www.qth.com/inrad/roofing-filters.pdf . The FT-2000 is an up-conversion receiver (unless I've lost the plot again). Elecraft's design is more subtle and has been explained several times in this list. Simon Brown, HB9DRV ----- Original Message ----- From: "Darwin, Keith" <[hidden email]> Roofing filters - I think the term has more to do with marketing than engineering. Other companies have made a big deal over having them and people have come to think of them as something special. _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by Jack Smith-6
Just cannot resist saying this Jack, the term "roofing filter" has certainly
been around for a long time - close to 50 years I believe, possibly longer. I think that I first ran across the term being used to identify the first IF filter in an Independent Sideband Receiver which the company for whom I worked manufactured for HF Point-to-Point applications in the very late 1950's, along with companion high power ISB transmitters. Perhaps some other term might be less confusing and prevent any misuse of the term , but don't let us change from "roofing filter" now!! 73, Geoff GM4ESD Jack Smith wrote: > The term "roofing filter" has been around a long time, at least 20 years. > > Usually used in the context of up-converting receivers, where the first > IF is 40.455 MHz, or 45.000 MHz or even higher. The term means the first > selective filter in the receiver. If the first IF is > 30 MHz, the roofing > filter is generally wider than one normally needs for SSB or even AM, and > the receiver's ultimate selectivity is provided in a later IF stage. > > As to why it is called a "roofing" filter, I imagine it derives from the > fact that it puts a "roof" over the receiver's selectivity. _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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It's an interesting question when the term "roofing filter" entered
amateur radio circles. My Drake R7 has the classic up-conversion design with a 48 MHz IF with a crystal filter immediately following the first mixer, but it is not described as a "roofing" filter. Here's how Drake describes its function in the 1979 Service Manual: ...This stage [the first mixer] followed by a four-pole monolithic 48.05 MHz crystal filter. The purpose of this filter is to attenuate signals removed more than +/- 4 KHz from 48.05 MHz, thus protecting the remaining stages of the receiver from strong interfering signals. In this manner, optimum receiver dynamic range is preserved while providing excellent sensitivity. Just checked Racal's RA6790/GM manual (1985), which employs a 40.455 MHz first IF / 20 KHz bandwidth crystal filter and I don't see the word "roofing filter" used. Rather, it's called simply "bandpass filter" in both the block diagram and accompanying text. Jack K8ZOA Geoffrey Mackenzie-Kennedy wrote: > Just cannot resist saying this Jack, the term "roofing filter" has > certainly been around for a long time - close to 50 years I believe, > possibly longer. I think that I first ran across the term being used > to identify the first IF filter in an Independent Sideband Receiver > which the company for whom I worked manufactured for HF Point-to-Point > applications in the very late 1950's, along with companion high power > ISB transmitters. > > Perhaps some other term might be less confusing and prevent any misuse > of the term , but don't let us change from "roofing filter" now!! > > 73, > Geoff > GM4ESD > > Jack Smith wrote: > > >> The term "roofing filter" has been around a long time, at least 20 >> years. >> >> Usually used in the context of up-converting receivers, where the >> first IF is 40.455 MHz, or 45.000 MHz or even higher. The term means >> the first selective filter in the receiver. If the first IF is > 30 >> MHz, the roofing filter is generally wider than one normally needs >> for SSB or even AM, and the receiver's ultimate selectivity is >> provided in a later IF stage. >> >> As to why it is called a "roofing" filter, I imagine it derives from >> the fact that it puts a "roof" over the receiver's selectivity. > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by Geoffrey Mackenzie-Kennedy-2
One more data point on the term "roofing filter."
I have a copy of the June 1981 RSGB Radio Communications magazine that reviewed Drake's TR7. It describes the design as follows: "A low-noise, wide-dynamic range amplifier is used at 48.05 MHz to precede the 10-KHz wide roofing filter." Leaving aside the RSGB's odd use of hyphens, it describes the filter as a "roofing filter" although Drake does not use the term in its technical manual. Is it the case that "roofing filter" is UK terminology that has made its way to the US side of the pond only recently? Jack Geoffrey Mackenzie-Kennedy wrote: > Just cannot resist saying this Jack, the term "roofing filter" has > certainly been around for a long time - close to 50 years I believe, > possibly longer. I think that I first ran across the term being used > to identify the first IF filter in an Independent Sideband Receiver > which the company for whom I worked manufactured for HF Point-to-Point > applications in the very late 1950's, along with companion high power > ISB transmitters. > > Perhaps some other term might be less confusing and prevent any misuse > of the term , but don't let us change from "roofing filter" now!! > > 73, > Geoff > GM4ESD > > Jack Smith wrote: > > >> The term "roofing filter" has been around a long time, at least 20 >> years. >> >> Usually used in the context of up-converting receivers, where the >> first IF is 40.455 MHz, or 45.000 MHz or even higher. The term means >> the first selective filter in the receiver. If the first IF is > 30 >> MHz, the roofing filter is generally wider than one normally needs >> for SSB or even AM, and the receiver's ultimate selectivity is >> provided in a later IF stage. >> >> As to why it is called a "roofing" filter, I imagine it derives from >> the fact that it puts a "roof" over the receiver's selectivity. > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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Marketing term, I tell ya, pushed extra hard by the sales folks at YaeComWood. :-) -----Original Message----- ... it describes the filter as a "roofing filter" although Drake does not use the term in its technical manual. _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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Irrespective of the original source of the term "roofing filter", it seems
clear enough that whoever made it up wanted to imply the idea of protection, which is the word used in the RSGB document. A ROOF is a first line of protection against having nearby high-energy stuff from the outside world (rain, hail, falling rocks and trees) hit you in the head. :-) A ROOFING FILTER is likewise a first line of protection for the stage that follows it against nearby high-energy signals hitting it in the head. (Er, the base, or the gate, or whatever.) Whether it was first used in some marketing brochure or in an engineering paper, the term nonetheless is aptly descriptive. Since the concept involved really has to be understood in order for the term to make sense, however, I tend to lean toward the idea that it was made up by an engineer. Most marketing guys aren't that smart. Uh, no offense intended. :-) Bill / W5WVO Darwin, Keith wrote: > Marketing term, I tell ya, pushed extra hard by the sales folks at > YaeComWood. :-) > > -----Original Message----- > > ... it describes the filter as a "roofing filter" although Drake does > not use the term in its technical manual. > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by Jack Smith-6
I do not know where or when the term "roofing filter" first appeared, when I
first came across it in the late 1950s I was working in Canada. I suspect that the term originated in N.America, most probably in connection with the type of equipment which I mentioned, most of which was purchased by Common Carriers for use on long haul international circuits. 73, Geoff GM4ESD Jack Smith wrote: > One more data point on the term "roofing filter." > > I have a copy of the June 1981 RSGB Radio Communications magazine that > reviewed Drake's TR7. > > It describes the design as follows: > > "A low-noise, wide-dynamic range amplifier is used at 48.05 MHz to > precede the 10-KHz wide roofing filter." > > > Leaving aside the RSGB's odd use of hyphens, it describes the filter as a > "roofing filter" although Drake does not use the term in its technical > manual. > > Is it the case that "roofing filter" is UK terminology that has made its > way to the US side of the pond only recently? > > > Jack _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Jack Smith-6
I think the term "roofing filter" is misleading. A narrow filter at the
first IF protects a receiver even better than a "roofing filter", so there is nothing inherently distortion reducing in using a wider filter at the first IF and then a narrower one later. The ideal situation for IMD would be a pair of matched narrow filters at both IFs. The real reason for a "roofing filter" it seems to me, is to allow passband or slope tuning. This compromises IMD and AGC performance for the sake of a feature... which may or may not be valuable to the user. Therefore, the "roofing filter" should be termed the "passband tuning enabling filter", or "PBTE" filter ;-) Thankfully, I think Elecraft has done a brilliant job of giving us the options we want without compromises. By tying the DSP bandwidths and PBT functions to the "roofing filters", we have the ability to have the combination of 1st and 2nd IF BW we want,,, and with the variable "roofing filters", I think we will be able to almost set the relative BWs between the two... allowing a window for PBT or not as we choose. This is an exciting development, and will be copied by many companies over the next year. Kudos to the design team on this. 73, Larry N8LP Jack Smith wrote: > One more data point on the term "roofing filter." > > I have a copy of the June 1981 RSGB Radio Communications magazine > that reviewed Drake's TR7. > > It describes the design as follows: > > "A low-noise, wide-dynamic range amplifier is used at 48.05 MHz to > precede the 10-KHz wide roofing filter." > > > Leaving aside the RSGB's odd use of hyphens, it describes the filter > as a "roofing filter" although Drake does not use the term in its > technical manual. > > Is it the case that "roofing filter" is UK terminology that has made > its way to the US side of the pond only recently? > > > Jack > > > > Geoffrey Mackenzie-Kennedy wrote: >> Just cannot resist saying this Jack, the term "roofing filter" has >> certainly been around for a long time - close to 50 years I believe, >> possibly longer. I think that I first ran across the term being used >> to identify the first IF filter in an Independent Sideband Receiver >> which the company for whom I worked manufactured for HF >> Point-to-Point applications in the very late 1950's, along with >> companion high power ISB transmitters. >> >> Perhaps some other term might be less confusing and prevent any >> misuse of the term , but don't let us change from "roofing filter" now!! >> >> 73, >> Geoff >> GM4ESD >> >> Jack Smith wrote: >> >> >>> The term "roofing filter" has been around a long time, at least 20 >>> years. >>> >>> Usually used in the context of up-converting receivers, where the >>> first IF is 40.455 MHz, or 45.000 MHz or even higher. The term means >>> the first selective filter in the receiver. If the first IF is > 30 >>> MHz, the roofing filter is generally wider than one normally needs >>> for SSB or even AM, and the receiver's ultimate selectivity is >>> provided in a later IF stage. >>> >>> As to why it is called a "roofing" filter, I imagine it derives from >>> the fact that it puts a "roof" over the receiver's selectivity. >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> 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: [hidden email] > 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: [hidden email] 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 |
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Hello Larry!
> ...Therefore, the "roofing filter" should be termed the "passband > tuning enabling filter", or "PBTE" filter ;-) > > Thankfully, I think Elecraft has done a brilliant job of giving us the > options we want without compromises. By tying the DSP bandwidths and PBT > functions to the "roofing filters", we have the ability to have the > combination of 1st and 2nd IF BW we want,,, and with the variable > "roofing filters", I think we will be able to almost set the relative > BWs between the two... allowing a window for PBT or not as we choose. In the olden days, analog radios would use two IF filters and slide them back and forth against each other to form variable bandwidth filters. This may be some of the PBT you were referring to. In the K3, you can set the IF selectivity almost anywhere you like. The conversion oscillator and the DSP's internal software BFO will be moved around to ensure that the narrowest available 8.215 MHz IF filter is selected. The edges of the DSP IF filters and the crystal filter aren't worked against each other. In general, we try to keep the passband of interest centered in the IF filters. The variable-width crystal filters will make this matchup fairly precise :-) Thus we can offer passband tuning without opening up the crystal filter bandwidth wider than required for the ultimate passband chosen by the operator of the radio. Oh, and did I mention we also shape the audio passband according to the filter selection? And that is overlaid with the 8-band Rx EQ? 73, Lyle KK7P _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Yes, that is exactly the point I was trying to make! You can have it as
you like it (I am speculating a bit about the control options in the firmware, of course). Some people like a wider width at the first IF to hear signals approaching, even if it opens the window for AGC blocking or desense. Others would want the two passbands to be exactly aligned and as narrow as possible, which would provide the best IMD and AGC performance, but then the signals will drop off the cliff as you tune. What you appear to have done is allow nuance in these adjustments, which I think is quite clever and well thought out. I can't wait to play with it. I didn't mention the audio passband shaping, but that makes it just that much better. Well done. Look forward to seeing you at FDIM. 73, Larry N8LP Lyle Johnson wrote: > Hello Larry! > >> ...Therefore, the "roofing filter" should be termed the "passband >> tuning enabling filter", or "PBTE" filter ;-) >> >> Thankfully, I think Elecraft has done a brilliant job of giving us >> the options we want without compromises. By tying the DSP bandwidths >> and PBT functions to the "roofing filters", we have the ability to >> have the combination of 1st and 2nd IF BW we want,,, and with the >> variable "roofing filters", I think we will be able to almost set the >> relative BWs between the two... allowing a window for PBT or not as >> we choose. > > In the olden days, analog radios would use two IF filters and slide > them back and forth against each other to form variable bandwidth > filters. This may be some of the PBT you were referring to. > > In the K3, you can set the IF selectivity almost anywhere you like. > The conversion oscillator and the DSP's internal software BFO will be > moved around to ensure that the narrowest available 8.215 MHz IF > filter is selected. The edges of the DSP IF filters and the crystal > filter aren't worked against each other. In general, we try to keep > the passband of interest centered in the IF filters. The > variable-width crystal filters will make this matchup fairly precise :-) > > Thus we can offer passband tuning without opening up the crystal > filter bandwidth wider than required for the ultimate passband chosen > by the operator of the radio. > > Oh, and did I mention we also shape the audio passband according to > the filter selection? And that is overlaid with the 8-band Rx EQ? > > 73, > > Lyle KK7P > > > Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by N8LP
I thought some rigs also passed the transmit signal
out past the filter, and to save money just fit say an FM sized filter there. FM and AM are 'features' also I guess... The K3 is going to relay switch filters in for FM, AM, SSB, and CW. Since they are working at a lower frequency, they will really work well, and that is the main trick going on in the K3. Then you get all those DSP extra goodies... Brett N2DTS > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Larry Phipps > Sent: Thursday, May 03, 2007 9:12 PM > To: Jack Smith > Cc: Elecraft Discussion List > Subject: Re: [Elecraft] 8 pole vs 5 pole..I knew this would happen > > I think the term "roofing filter" is misleading. A narrow > filter at the > first IF protects a receiver even better than a "roofing filter", so > there is nothing inherently distortion reducing in using a > wider filter > at the first IF and then a narrower one later. The ideal > situation for > IMD would be a pair of matched narrow filters at both IFs. The real > reason for a "roofing filter" it seems to me, is to allow passband or > slope tuning. This compromises IMD and AGC performance for > the sake of a > feature... which may or may not be valuable to the user. > > Therefore, the "roofing filter" should be termed the "passband tuning > enabling filter", or "PBTE" filter ;-) > > Thankfully, I think Elecraft has done a brilliant job of > giving us the > options we want without compromises. By tying the DSP > bandwidths and PBT > functions to the "roofing filters", we have the ability to have the > combination of 1st and 2nd IF BW we want,,, and with the variable > "roofing filters", I think we will be able to almost set the relative > BWs between the two... allowing a window for PBT or not as we choose. > This is an exciting development, and will be copied by many companies > over the next year. Kudos to the design team on this. > > 73, > Larry N8LP > > _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by Fred (FL)
What is the first thing rain hits when coming down from the sky ?
What is the first thing a signal hits after the first mixer coming down from the sky ? What is a leaky roofing filter ? It's what is in the K-3 <G> since it lets the signal from SOMEBODY through to your ears! Walt K8CV Royal Oak, MI. ----- Original Message ----- From: "Fred (FL)" <[hidden email]> To: <[hidden email]> Sent: Thursday, May 03, 2007 12:55 PM Subject: [Elecraft] 8 pole vs 5 pole..I knew this would happen >I think, still, someone needs to define what a ROOFING > FILTER is. Say for sake of argument - I have a > passive or active or crystal filter - and it is to > be used as a ROOFING FILTER. Why is it called this? > > Why is the filter itself, called a ROOFING FILTER? > And where does the adjective, ROOFING, come into > play? > > ...... I'm sure I'm dumb on this one - but would > like to learn. Not until the K3 came on the > Elecraft scene - did anyone mention or get > concerned about the need for ROOFING FILTERS. > Now they're all the rage? > > Fred, N3CSY > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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 |
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In reply to this post by KK7P
Hi!
I'm wondering; if order my K3 today (paying half down) will I receive it by Christmas '07? ;=) I seem to recall seeing the question posed, but missed seeing the answer; how many K3s does Elecraft expect to be producing/delivering each month? - Paul __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: So, How Many K3 Orders?
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I ordered mine yesterday, and am likely
number 1000 or something. I did the deposit thing, but it does not show up on the order confirmation, so maybe I missed out... With Elecraft, you know its got to be good, so I imagine loads of people ordered one the first day! I sure hope they plan on a truckload in the first batch! And when is the band scope coming out? Do they ever take a vacation? The 756 pro is GONE! Brett N2DTS > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Paul Clay > Sent: Thursday, May 03, 2007 10:39 PM > To: Lyle Johnson > Cc: [hidden email] > Subject: [Elecraft] So, How Many K3 Orders? > > Hi! > > I'm wondering; if order my K3 today (paying half down) > will I receive it by Christmas '07? ;=) I seem to > recall seeing the question posed, but missed seeing > the answer; how many K3s does Elecraft expect to be > producing/delivering each month? > > - Paul > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by KK7P
On Thu, 3 May 2007, Lyle Johnson wrote:
> In the olden days, analog radios would use two IF filters and slide them back > and forth against each other to form variable bandwidth filters. This may be > some of the PBT you were referring to. Being as technically adroit as your average cow pie, all of this is over my head. I have a TR7 sitting here that has something called PassBand tuning. I recall that I used it, with one of those ancient, non-digital, I didn't build it Autek filters. I have memories of twisting many knobs to get rid of the crud, and either notching out noise or peaking the signals that were down in the mud, even lower than the bottom dwellers and scum suckers. Given that I hardly ever, but maybe now and then operate SSB, and would like to try other digital modes, what would suggest as a reasonable approach to filters? Thanks Thom, who finds ordering from a Chineese Menu easier than this filter stuff...and only has first hand knowledge of leaky roofs, which he doesn't believe is an official option for a K3. Thom www.baltimorehon.com/ Home of the Baltimore Lexicon www.tlchost.net/hosting/ Web Hosting as low as 3.49/month _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: 8 pole vs 5 pole..I knew this would happen
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In reply to this post by KK7P
On Thursday 03 May 2007 21:29:00 Lyle Johnson wrote:
> In the olden days, analog radios would use two IF filters and slide them > back and forth against each other to form variable bandwidth filters. Yes indeed. My Eddystone EA12 receiver that I bought from Tom Roberts, G3YTO (SK 1985) is a dual conversion with a tunable first IF from 1.1 Mc/s to 1.7 Mc/s and crystal controlled converters changing the bands to the tunable IF. The second IF is 100 kc/s with a slot filter and continuously variable selectivity: this is accomplished by varying, mechanically the coupling between the coils - it's like flying by the seat .. rather than by wire. At the narrow end of the filter, a 100 kc/s crystal kicks in and I can feel the switch that does it. With up to volts input to the linear ECC189 to the ECH81 first mixer, I think modern radios are building ever more complex sandcastles rather than pyramids. ( Mc/s and kc/s as in the EA12 manual) Ian, G4ICV, PP-ASEL, AB2GR, K2 #4962 -- _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by N8LP
> Yes, that is exactly the point I was trying to make! You can have it as
> you like it (I am speculating a bit about the control options in the > firmware, of course). Some people like a wider width at the first IF to > hear signals approaching, even if it opens the window for AGC blocking > or desense. Others would want the two passbands to be exactly aligned > and as narrow as possible, which would provide the best IMD and AGC > performance, but then the signals will drop off the cliff as you tune. > What you appear to have done is allow nuance in these adjustments, which > I think is quite clever and well thought out. I can't wait to play with it. One other feature you're sure to like, then, is the CW "context" or "PB2" filter. Set this one as wide as you like -the crystal filter selection will be driven by this. Then set a "suppression level" maybe down 10 or 20 or 30 dB. Overlay this with the narrow filter you want and presto! You can hear the context from nearby stations, but at reduced amplitude, while the signals in the narrow filter you are working (or trying to work :-) are emphasized and drive the AGC level. 73, Lyle KK7P _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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