Fwd: New Sherwood report
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Not sure how I missed that. I just did a side by side comparison of the ARRL CW spectral plots for both the K3 and the FTdx-5000, and there is certainly a difference. 30db down from the peak appears to be +/- 350 Hz for the FTdx-5000, and about +/- 125 Hz for the K3 as best I could determine from expanded views of the plots. 60 db down (still probably about S2 for a S9+20 signal) appears to be about +/- 1.35 Khz for the FTdx-5000 and about +/- 350 Hz for the K3. Here's a thought ... if everyone owned a Yaesu the company wouldn't have to worry about designing receivers with close-in BDR because nobody could operate that close to each other anyway. Dave AB7E On 12/1/2010 6:43 PM, Eric Swartz - WA6HHQ, Elecraft wrote: > They already have - See the keying bandwidth spectral plots in the > ARRL reviews. The FT-5000 is considerably wider than the K3. > > 73, Eric WA6HHQ > --- > > On 12/1/2010 3:37 PM, David Gilbert wrote: >> >> A good start would be for someone ... hello ARRL? ... to document key >> clicks. A lot of good it does for me to have a rig with excellent 2 KHz >> BDR only to have everything ruined by key clicks from some Yaesu rig >> that neither the manufacturer nor the operator will fix. >> >> Dave AB7E > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Barry N1EU
On Dec 1, 2010, at 5:59 PM, Barry N1EU wrote: > It's absolutely amazing, after years of Yaesu being called out and doing nothing about key clicks in their rigs, that they would bring out a radio > (FT-5000) and provide the user the ability to reduce the cw rise-time to 1 msec (menu mode, cw group, 063 A1A Shape). Just incredible. The rise time by itself is not the important factor -- what is much more important are first and second order discontinuities, and even higher order discontinuities. If you were to generate a keyed signal that turns on with a constant slope (thus has a large second order discontinuity), you are going to generate very wide keying sidebands even if that "risetime" lasts for 10 msec. For a modern view at CW keying, take a look at Alex VE3NEA's article in the May/June 2006 issue of QEX that is titled "CW Shaping in DSP Software." Alex is of course the author of the CW Skimmer, among other things. This is not just theoretical stuff. cocoaModem on Mac OS X is one program that generates a CW signal using the J2A Emission mode by using a Blackman window whose keying sidebands you can see in Figure 5 here http://homepage.mac.com/chen/w7ay/cocoaModem/UsersManual/cwManual/index.html#filter A Blackman window is initially wider than say, a Hamming window (and certainly much wider than an unshaped pulse), but then it plunges down towards -100 dB with a very steep fall off. There is nothing like it in the analog world :-). In his article, Alex had compared the Blackman-Harris window with Gaussian, raised Cosine, and other windows. Wikipedia has a very nice page on filter windows (many people use the windowed method to design FIR filters) here http://en.wikipedia.org/wiki/Window_function and this plot from Wiki is especially useful if you want to homebrew your own "CW shaper": http://en.wikipedia.org/wiki/File:Window_function_(comparsion).png Notice the asymptotic slopes of the curves towards the right of that plot. The steeper it is, the less you will QRM stations that are far away. The shape towards the left tells you how much close-in bandwidth you are using. For example, the unshaped pulse (black line) has the narrowest close-in bandwidth, but it is also the worst when it comes to far away bandwidth. At 100 times the normalized bandwidth of the filter, pulses that are waveshaped by the Blackman and Blackman-Harris windows are a whopping 80 dB quieter than un-waveshaped pulses. You can think of the normalized bandwidth as what is needed to pass the fundamental N-words-per-minute keying sequence without sounding too soft. For what its worth, cocoaModem lets you dial in an equivalent risetime of 2 msec all the way to 10 msec (for QRS slowpokes like myself who want to cause even less QRM). You need a reasonably good transmit IMD to take the most advantage of good waveshaping. All said and done, it is not the DSP part that is the limiting factor of what you can do with waveshaping CW pulses today, but the transmit IMD. 73 Chen, W7AY ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Fwd: New Sherwood report
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> The rise time by itself is not the important factor -- what is much more
> important are first and second order discontinuities, and even higher > order discontinuities. Evidence of this comes from our K3s. Some time back around F/W version 3.0, the CW rise/fall time was accelerated. My K3 reaches full envelope power in just 2 ms and yet it produces very little bandwidth due to: (1) the DSP shape function; and (2) very well controlled ALC. The best DSP based functions (e.g., raised cosine or Blackman-Harris), can be completely destroyed by aggressive ALC action. One of the best waveform controlled CW transmitters is the Ten Tec Omni VI. One of the worst controlled CW transmitters is the Omni VI+. What happened? In the upgrade process, the ALC time constants changed to the point where a sharp, discontinuous waveform edge was produced. All the DSP shaping one could try would not have helped. The ALC circuit took control of the waveform and generated, among other anomalies, severe key clicks from the abruptly fast leading edge of the CW waveform. Regarding the FTdx-5000, my first suspicion is the ALC system as the culprit and not the DSP generated waveform. When the ARRL tested the IC-7800, it showed an aggressively fast rise time. However, the '7800 has a user adjustable "Drive" control. With only slight ALC action, the '7800 produces an excellent waveform and little keying bandwidth. If the FTdx-5000 has a Drive control active in CW mode, it may be possible to reign-in bandwidth. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Ed Schuller
Tables like this one mean almost nothing to me. Dynamic range is so good across
the board that it's now overrated. When you're talking about differences of a few dB other details start to matter much more. For instance, the chief factor that pushed me off the fence toward a K3 was it's diversity reception scheme; you don't see that listed anywhere in the table. What about how the radio *sounds*? Where in the table is that? How about it's macro and programming capability? Is that in the table? Or its effect on your psyche after 24 hours of a contest? These things are much harder to measure. (Another pet peeve is the dozens of videos on YouTube with two radios set up side by side as the camera operator switches the antenna between them, while the built-in mic on the camera picks up all of the room noise. What in the world are these videos supposed to prove?) To paraphrase what Wynton Marsalis said about technique-- that all it does is get you "in the door"-- about all these numbers prove is that a particular rig is worthy of closer scrutiny. By no means is it a stamp of approval. This goes for the K3 as well as any other rig. Al W6LX ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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I agree with Al -- the Sherwood Engineering tables are mostly lost to me. I understand that the K3 is a very good radio compared to others as pointed out by this information but I couldn't tell you if that information was useful to me. For example, way down on the list is the Icom 756 Pro III but I happen to like my Pro III and only a few times have I noticed differences with the K3 in that the K3 is definitely superior.
The big thing that convinced me in the K3 is Wayne and Eric and this list. The fact that there are dozens, hundreds, of very technical and knowledgable hams on this list who all agree that the K3 is a good radio and are willing to help others, such as myself, learn just a little bit more of this stuff. But, I am learning...I too will someday know why I am setting particular controls one way or another on the K3. It is now my everyday radio and it works great -- my P3 works great too and in a few days my KX1 will work great when I finish it up. 73, phil, K7PEH On Dec 1, 2010, at 9:38 PM, Al Lorona wrote: > Tables like this one mean almost nothing to me. Dynamic range is so good across > the board that it's now overrated. When you're talking about differences of a > few dB other details start to matter much more. For instance, the chief factor > that pushed me off the fence toward a K3 was it's diversity reception scheme; > you don't see that listed anywhere in the table. > > What about how the radio *sounds*? Where in the table is that? How about it's > macro and programming capability? Is that in the table? Or its effect on your > psyche after 24 hours of a contest? These things are much harder to measure. > > (Another pet peeve is the dozens of videos on YouTube with two radios set up > side by side as the camera operator switches the antenna between them, while the > built-in mic on the camera picks up all of the room noise. What in the world are > these videos supposed to prove?) > > To paraphrase what Wynton Marsalis said about technique-- that all it does is > get you "in the door"-- about all these numbers prove is that a particular rig > is worthy of closer scrutiny. By no means is it a stamp of approval. This goes > for the K3 as well as any other rig. > > Al W6LX > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Fwd: New Sherwood report
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In reply to this post by Kok Chen
Kok Chen provides some good references for CW transmit shaping, but cocoaModem source isn't available for hams to look at.
fldigi also offers a choice between raised cosine and Blackman window for CW TX, and the source is in the fldigi distribution at src/cw_rtty/cw.cxx available from http://w1hkj.com/Fldigi.html If you want to experiment with your own shaping code, you can compile fldigi for Windows, Mac, or Linux. I believe the shaping code is by Dave W1HKJ as it wasn't present in earlier programs. Leigh/WA5ZNU |
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On Dec 1, 2010, at 10:37 PM, Leigh L. Klotz Jr WA5ZNU wrote:
> Kok Chen provides some good references for CW transmit shaping, but > cocoaModem source isn't available for hams to look at. Sure it is. cocoaModem sources has been public from the time cocoaModem was written in the days Mac OS X 10.2 (Jaguar). Just go to my iDisk by following this link : http://homepage.mac.com/chen/w7ay/Projects/index.html The above URL can also be found in the Links page of the Yahoo cocoaModem group http://groups.yahoo.com/group/cocoamodem/ Many windows are already built into cocoaModem (in the module CMDSPWindow.c) and it should be easy to add new windows by modifying an existing window routine. Pretty much all Xcode projects of my publicly released programs are on my public iDisk, including cocoaModem, cocoaNEC (GUI preprocessor and postprocessor for NEC-2 and NEC-4), cocoaPath (HF Channel Simulator that include built-in CW, RTTY and PSK31 generators), µH Router (allows multiple apps to share a microHAM keyer on Mac OS X), Serial Tools (terminal and serial port protocol analyzer a.k.a. port sniffer, and USB-serial port diagnostic tool), QST Browser (search and display QST/QEX/NCJ/CommQuarterly/ham radio Magazine CD ROMs), cocoaPTT (AppleScriptable serial port PTT control), cocoaFilter (software APF). cocoaFilter is specifically written to make it easy for a Mac user to go code their favorite Audio Peak Filter parameters and not have to learn Core Audio or Cocoa graphics in Mac OS X. It was written after I saw all the moaning and groaning on this reflector about what Elecraft had done wrong or right. cocoaFilter already has a built-in audio limiter (both soft and hard), adjustable Q is built into the GUI, etc etc. Changing the filters should not take more than a page of code. I have a thick skin, so the code for all of my public apps has always been free and the sources are available for scrutiny. None of it contains GPL material and can be used freely, no strings attached, no need to publish your sources in case you want to share your program. As I have told some people for a few years now, I no longer code for money -- writing code has become "Amateur Software" in my twilight years :-). 73 Chen, W7AY ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Kok Chen
Are you saying that wide sidebands measured with the rig at 4msec rise-time are probably not going to be even wider with the rig at 1 msec rise-time?
Barry N1EU
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Barry, What is being said is that the *shape* of the rise and fall times is important, not the absolute timing of the rise of fall time. In other words, the transitions of the waveshape are the important parameters - if the transitions are smooth rather than angular, they are less likely to generate sidebands. Of course there are practical limits, but the CW sidebands cannot be judged on risetime alone. Most likely, if the shaping with a 4 ms. rise time is such that excessive sidebands are produced, then at 1 ms, the sidebands will be at least as wide, if not wider unless the keying waveshape is changed. But -- while I suspect that, I could not claim it unless it were measured. 73, Don W3FPR On 12/2/2010 7:32 AM, Barry N1EU wrote: > Are you saying that wide sidebands measured with the rig at 4msec rise-time > are probably not going to be even wider with the rig at 1 msec rise-time? > > Barry N1EU > > > Kok Chen wrote: >> On Dec 1, 2010, at 5:59 PM, Barry N1EU wrote: >> >>> It's absolutely amazing, after years of Yaesu being called out and doing >>> nothing about key clicks in their rigs, that they would bring out a radio >>> (FT-5000) and provide the user the ability to reduce the cw rise-time to >>> 1 msec (menu mode, cw group, 063 A1A Shape). Just incredible. >> The rise time by itself is not the important factor -- what is much more >> important are first and second order discontinuities, and even higher >> order discontinuities. > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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WOW, I have not see this much fur flying in a long time.
It was simply a matter of time before a radio showed better numbers than the K3, it had to happen. Now that it has, good for Yeasu. But it does not mean my two K3's do not work anymore or I am not able to use them, Heck No. The fact that the K3 numbers were bettered means now we need to wait for the K4, a larger radio with even better specifications. It will be all that much better when it arrives to claim the top spot. Enjoy what you have, Best 73 Dave Anderson, K4SV Tryon, NC 828 777-5088 www.K4SV.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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On the Ten Tec Eagle list, Rob Sherwood just posted a very interesting
response to the 2 kHz DR rankings being discussed here. Apparently, there's a measurable amount of IMD difference not only between roofing filter production samples, but the manner in which they're inserted. For example, on the Orion II, he gets variations of several dB on close-spaced DR just by unplugging a filter and reversing it -- something not possible with the K3 since the pin-out isn't symmetrical. He goes on to discuss why. Sounds like we could probably take handful of INRAD filters and choose the best ones that may likely be equal to the FTdx-5K under most, if not all narrow filter positions in the K3. On multiple occasions, Rob has stated that once you get up anywhere near these numbers, a prospective purchaser should be looking at other performance factors and features. Probably if you're within the top ten or so on his list, you would be pretty hard-pressed to notice any differences when other factors (e.g., the other guy's bandwidth) will mask incremental improvements to close-spaced DR. For me, those "other factors" that Rob discusses include low distortion, low noise AF sections, low TX IMD, and super fast, click-free T/R times. Right now, those are the most important factors to me now that basic receiver performance has advanced so much in the past decade. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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I haven't (yet) seen Rob's comments, cited by Paul. The designers across the pond are well-aware of the IMD effects in crystal filters, for example here:
http://www.xs4all.nl/~martein/pa3ake/hmode/roofer_intro.html I have searched for, but have not found, remarks that I recall being made by Wayne that said that Elecraft screens its filters for IMD. (I wish they also screened for bandpass symmetry, my 2.8 KHz is very disappointing in that regard) So considering the potential effects of asymmetry in the build of the filter(s) it doesn't surprise that reversing the filter might make a difference, *if* filter IMD is the dominate factor. --- On Thu, 12/2/10, Paul Christensen <[hidden email]> wrote: On the Ten Tec Eagle list, Rob Sherwood just posted a very interesting response to the 2 kHz DR rankings being discussed here. Apparently, there's a measurable amount of IMD difference not only between roofing filter production samples, but the manner in which they're inserted. For example, on the Orion II, he gets variations of several dB on close-spaced DR just by unplugging a filter and reversing it -- something not possible with the K3 since the pin-out isn't symmetrical. He goes on to discuss why. Sounds like we could probably take handful of INRAD filters and choose the best ones that may likely be equal to the FTdx-5K under most, if not all narrow filter positions in the K3. On multiple occasions, Rob has stated that once you get up anywhere near these numbers, a prospective purchaser should be looking at other performance factors and features. Probably if you're within the top ten or so on his list, you would be pretty hard-pressed to notice any differences when other factors (e.g., the other guy's bandwidth) will mask incremental improvements to close-spaced DR. For me, those "other factors" that Rob discusses include low distortion, low noise AF sections, low TX IMD, and super fast, click-free T/R times. Right now, those are the most important factors to me now that basic receiver performance has advanced so much in the past decade. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Ed Schuller
Compare to results shown here;
http://www.remeeus.eu/hamradio/pa1hr/productreview.htm Adrian ... vk4tux ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Barry N1EU
On Dec 2, 2010, at 12/2 4:32 AM, Barry N1EU wrote:
> Are you saying that wide sidebands measured with the rig at 4msec > rise-time are probably not going to be even wider with the rig at 1 > msec rise-time? Not that much, since the really far off keyclicks are mostly from higher order discontinuities. Remember that the RF spectrum for CW is approximated by a rectangular pulse that is convolved by the impulse response of the waveshaping filter if the filter is linear (i.e., none of the silly diodes and so on used to attempt to tame keyclicks). The short way of saying it is that the pulse is filtered in the time domain by the waveshaping filter. The "convolution theorem" thus states that the Fourier of the resultant filtered signal is just the *product* of the Fourier transform of the CW pulse train with the Fourier transform of the waveshaping filter. If you assume that the unfiltered pulse train is completely unfiltered (i.e., perfectly sharp edges and so on), a pulse train of dits will have a Fourier transform that is a sinc(f) (i.e., sine of f divided by f) function in the frequency domain. The spectrum of the waveshaping filter is simply the stuff you can see at the Wikipedia page. Multiply the two to get the RF spectrum of a waveshaped CW, and you will find that the sinc(f) is predominated by the waveshaping filter for far off frequencies. Since the power of the unfiltered CW keying signal (i.e., sinc(f)*sinc(f)) dies down very slowly, all the far off spectrum is determined by the "tail" of the spectrum of the waveshaping filter. Without waveshaping, the power of CW keying pulses die down asymptotically as 1/( f*f), since the spectral envelope of sinc(f) dies down as 1/f . The same scenario holds true for RTTY. You can think of an FSK signal as two pulse trains, when one is on, the other is off (i.e., really no different from a CW signal :-). With randomly generated FSK, you have the same sin(x)/x spectral envelope. If you now make sure that the mark-space phase transition of FSK is smooth -- what many people call "phase continuous FSK"," RTTY improves a lot (this is what the K3 and many other rigs and software do). "Phase continuity" is basically saying there is no first order discontinuity of the temporal waveform, but if the Mark and space frequencies are different (of course), there will be second order and higher order discontinuities unless all mark/space switching are done when their carriers are right at zero -- not very practical). Just like CW, you can also make your RTTY signal friendlier to your spectrum neighbors by waveshaping the FSK signal some more. You can see this process here (those are actual recorded AFSK signals): http://homepage.mac.com/chen/Technical/FSK/Sidebands/sidebands.html Instead of two peaks of the FSK signal, you can visualize in your mind a single peak for a CW signal that is represented by the one sided spectrum, and the spectrum for first oder discontinuitity, second order discontinuities, and waveshaped FSK (I had used a simple Blackman in the Web page above) pretty much holds for the CW case also. I don't know of a single FSK rig today that is as friendly to neighbors as the last two spectra shown in the web page. The Omni V and VI does a little of waveshaping of the keying signal that is applied to the varicaps to generate the FSK signal. I also don't know of any software that applies RTTY waveshaping, although it is easy to do for all AFSK software. You need to be careful, of course. Since any waveshaping will cause a slight overlap between the mark and space carriers, too much waveshaping and you again run into that pesky transmit IMD problem that John (juergen) mentioned. For that reason (and also not to degrade SNR at the end of the matched filter that is discussed in the above web page), cocoaModem doesn't go too far off the deep end when wave shaping. It actually survives pretty well through the K3's transmit IMD. You can see that in the last two spectra on this page: http://homepage.mac.com/chen/Technical/K3/Digital/digital.html The K3 native (i.e., using a paddle) FSK signal (measure by a separate receiver) is in the second last image, and cocoaModem's waveshaped RTTY (using K3 DATA-A) is the last image on that page. You can actually see IMD spikes dues to the intermodulation between the now overlapping mark and space signal. But overall, the QRM is still below the spectrum from the K3's FSK signal. But if the K3 transmit IMD can be improved, you can squeeze more RTTY stations in during a contest. The FSK ops will then get the same reputation as the FT-1000D CW ops :-) :-). The RTTY spectra in the second web page has random (well, LTRS Baudot characters) bit modulation and I had apply a pretty per-bin filtering of the spectra to remove the noise from the receiver and sound card, so it appears smoother and less serrated. But you can see the difference between something that has first order discontinuities, something that has no first order discontinuities, and something that also try to suppress higher order discontinuities. Not much happens in the nearby spectrum. But as you go further away from the keyed carrier, the difference between a "good" waveshape and a "very good" waveshape is quite large. And, at some point (as seen by the IMD spikes in that last plot), the transmit IMD becomes the "weakest link." 73 Chen, W7AY ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by n7ws
> So considering the potential effects of asymmetry in the build of > the filter(s) it doesn't surprise that reversing the filter might > make a difference, *if* filter IMD is the dominate factor. Reversing the filter in the mounting does not effect bandpass symmetry. However, if the filter skirts are asymmetrical, measured IMD will most certainly be different in CW and CW-R - e.g., with the interfering tones above vs. below the filter passband. 73, ... Joe, W4TV On 12/2/2010 1:46 PM, Wes Stewart wrote: > I haven't (yet) seen Rob's comments, cited by Paul. The designers across the pond are well-aware of the IMD effects in crystal filters, for example here: > > http://www.xs4all.nl/~martein/pa3ake/hmode/roofer_intro.html > > I have searched for, but have not found, remarks that I recall being made by Wayne that said that Elecraft screens its filters for IMD. > > (I wish they also screened for bandpass symmetry, my 2.8 KHz is very disappointing in that regard) > > So considering the potential effects of asymmetry in the build of the filter(s) it doesn't surprise that reversing the filter might make a difference, *if* filter IMD is the dominate factor. > > --- On Thu, 12/2/10, Paul Christensen<[hidden email]> wrote: > > > > On the Ten Tec Eagle list, Rob Sherwood just posted a very interesting > response to the 2 kHz DR rankings being discussed here. Apparently, there's > a measurable amount of IMD difference not only between roofing filter > production samples, but the manner in which they're inserted. For example, > on the Orion II, he gets variations of several dB on close-spaced DR just by > unplugging a filter and reversing it -- something not possible with the K3 > since the pin-out isn't symmetrical. He goes on to discuss why. > > Sounds like we could probably take handful of INRAD filters and choose the > best ones that may likely be equal to the FTdx-5K under most, if not all > narrow filter positions in the K3. > > On multiple occasions, Rob has stated that once you get up anywhere near > these numbers, a prospective purchaser should be looking at other > performance factors and features. Probably if you're within the top ten or > so on his list, you would be pretty hard-pressed to notice any differences > when other factors (e.g., the other guy's bandwidth) will mask incremental > improvements to close-spaced DR. > > For me, those "other factors" that Rob discusses include low distortion, low > noise AF sections, low TX IMD, and super fast, click-free T/R times. Right > now, those are the most important factors to me now that basic receiver > performance has advanced so much in the past decade. > > Paul, W9AC > > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Nate Bargmann
* On 2010 01 Dec 16:57 -0600, Nate Bargmann wrote:
> * On 2010 01 Dec 16:19 -0600, Ed Schuller wrote: > > > > > > > > http://www.sherweng.com/table.html > > I understand that Sherwood places a lot of emphasis on 2 kHz BDR. While > that is a worthwhile measurement, I am concerned more about the Filter > Ultimate (dB) column. Not only being 15 dB poorer than than the K3, note > also that the FT-5000 is phase limited in this regard. It will take > someone more educated than I to tell us what that means in practical > terms. No educated guesses on what impact the ultimate filter rejection being phase limited in the FT-5000 has on practical operation? I'd really like to know. 73, de Nate N0NB >> -- "The optimist proclaims that we live in the best of all possible worlds. The pessimist fears this is true." Ham radio, Linux, bikes, and more: http://n0nb.us/index.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Dave Anderson, K4SV
An unfortunate choice of terms on my part has caused some confusion.
While my particular filter's passband is asymmetrical, something mentioned in passing, the asymmetry I was really referring to is a difference between something on one end of the filter from the other. It could be either a crystal or a transformer (if used). Wes N7WS -- On Thu, 12/2/10, Joe Subich, W4TV <[hidden email]> wrote: > From: Joe Subich, W4TV <[hidden email]> > > > So considering the potential effects of asymmetry in > the build of > > the filter(s) it doesn't surprise that reversing > the filter might > > make a difference, *if* filter IMD is the dominate > factor. > > Reversing the filter in the mounting does not effect > bandpass symmetry. > However, if the filter skirts are asymmetrical, measured > IMD will most > certainly be different in CW and CW-R - e.g., with the > interfering > tones above vs. below the filter passband. > > 73, > > ... Joe, W4TV > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Eric Swartz - WA6HHQ
Yes but to what rise/fall time was the radio set? AFAIK in
the FT5000 it can be changed. /Jim SM2EKM --------------- On 2010-12-02 02:43, Eric Swartz - WA6HHQ, Elecraft wrote: > They already have - See the keying bandwidth spectral plots in the ARRL > reviews. The FT-5000 is considerably wider than the K3. > > 73, Eric WA6HHQ > --- > > On 12/1/2010 3:37 PM, David Gilbert wrote: >> >> A good start would be for someone ... hello ARRL? ... to document key >> clicks. A lot of good it does for me to have a rig with excellent 2 KHz >> BDR only to have everything ruined by key clicks from some Yaesu rig >> that neither the manufacturer nor the operator will fix. >> >> Dave AB7E Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Steve Ellington
Yes absolutely
/SM2EKM ------------ On 2010-12-02 02:58, Steve Ellington wrote: > Wouldn't having bad key clicks be an advantage in a contest? > > Steve N4LQ > > > > ----- Original Message ----- > From: "Eric Swartz - WA6HHQ, Elecraft"<[hidden email]> > To: "David Gilbert"<[hidden email]> > Cc:<[hidden email]> > Sent: Wednesday, December 01, 2010 8:43 PM > Subject: Re: [Elecraft] Fwd: New Sherwood report > > >> They already have - See the keying bandwidth spectral plots in the ARRL >> reviews. The FT-5000 is considerably wider than the K3. >> >> 73, Eric WA6HHQ >> --- Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Jan Erik Holm
It was most likely set to the default 4 msec. It can be set to 1, 2, 4, 6 msec. Barry N1EU |
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