[Elecraft] [K3] KRX3 question
I received my KRX3 earlier this year (I think), but I am just now installing it. I have a question about the TMP cable sockets on the KRX3 board. When the sheilded enclosure is installed it touches these connectors. Is this ok, or should these connectors be isolated from the shield? Thanks, Stan Rife W5EWA __ 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] KRX3 question
Stan, All those shields should be grounded, so it is OK if they touch the shields. 73, Don W3FPR sr...@swbell.net wrote: I received my KRX3 earlier this year (I think), but I am just now installing it. I have a question about the TMP cable sockets on the KRX3 board. When the sheilded enclosure is installed it touches these connectors. Is this ok, or should these connectors be isolated from the shield? __ 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 - KRX3 question
I have been chasing Midway Isl (K4M) and using my sub-RX to follow the pack. When K4M was not real loud I would turn the Sub off to get the audio in both ears then back on. After doing that several times (perhaps 10 - 15) the Sub-RX turns on (according to the front panel icon) but there is no audio. The only way I can get the audio back is to turn the K3 off and on. Then it is fine for another 'unknown' number of Sub off/on transitions. This has occurred with several versions of the u-code. I am running the 3.44. Has anyone else experienced this? 73, Bruce-N1LN __ 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 - KRX3 question
I do have the smae thing haping Bruce running version 3.27 also happend with older version, although more often wtih the older versions 73 de Dick PA3FQA - Original Message - From: Bruce Meier beme...@bellsouth.net To: elecraft@mailman.qth.net Sent: Sunday, October 18, 2009 11:24 AM Subject: [Elecraft] K3 - KRX3 question I have been chasing Midway Isl (K4M) and using my sub-RX to follow the pack. When K4M was not real loud I would turn the Sub off to get the audio in both ears then back on. After doing that several times (perhaps 10 - 15) the Sub-RX turns on (according to the front panel icon) but there is no audio. The only way I can get the audio back is to turn the K3 off and on. Then it is fine for another 'unknown' number of Sub off/on transitions. This has occurred with several versions of the u-code. I am running the 3.44. Has anyone else experienced this? 73, Bruce-N1LN __ 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 - KRX3 question
Bruce Meier wrote: I have been chasing Midway Isl (K4M) and using my sub-RX to follow the pack. When K4M was not real loud I would turn the Sub off to get the audio in both ears then back on. After doing that several times (perhaps 10 - 15) the Sub-RX turns on (according to the front panel icon) but there is no audio. The only way I can get the audio back is to turn the K3 off and on. Then it is fine for another 'unknown' number of Sub off/on transitions. This has occurred with several versions of the u-code. I am running the 3.44. Has anyone else experienced this? Yes - same problem, same firmware, same station. -- 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
Re: [Elecraft] K3 - KRX3 question
Just tried it for about at least 50 times in a row, always get the sub-receiver audio without a problem. I'm also using. 3.44. 73 de Roland, DC1RS - K3/100 #1243, KFL3A-2.8K, KFL3A-2.1K, KFL3A-400, KRX3, KFL3A-2.8K, KFL3A-400, KAT3 -- View this message in context: http://n2.nabble.com/K3-KRX3-question-tp3843747p3844124.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 - KRX3 question
Same hear. 73 Stewart G3RXQ On Sun, 18 Oct 2009 05:14:56 -0700 (PDT), DC1RS wrote: Just tried it for about at least 50 times in a row, always get the sub-receiver audio without a problem. I'm also using. 3.44. 73 de Roland, DC1RS - K3/100 #1243, KFL3A-2.8K, KFL3A-2.1K, KFL3A-400, KRX3, KFL3A-2.8K, KFL3A-400, KAT3 __ 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 - KRX3 question
Hi Bruce: I have been using the same procedure as you on CW with the last bunch of DXpeditions and I haven't had the exact problem you described. But I have noticed that sometimes it takes a second for the SUB to come alive. I get a squeaky sound in the right ear as if the SUB is squeezing out the signals. 73, Mike K2MK Bruce Meier Sun, 18 Oct 2009 02:24:02 -0700 I have been chasing Midway Isl (K4M) and using my sub-RX to follow the pack. When K4M was not real loud I would turn the Sub off to get the audio in both ears then back on. After doing that several times (perhaps 10 - 15) the Sub-RX turns on (according to the front panel icon) but there is no audio. The only way I can get the audio back is to turn the K3 off and on. Then it is fine for another 'unknown' number of Sub off/on transitions. This has occurred with several versions of the u-code. I am running the 3.44. Has anyone else experienced this? 73, Bruce-N1LN __ 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: KRX3 question
Joe Subich, W4TV-3 wrote: This is not the case based on careful measurements. The problem is 'skirt sharpening' when multiple filters are cascaded. Where a single filter might have a 6dB bandwidth of 225 Hz (200 Hz roofing fitter), when combined with the 200 Hz DSP filter the effective -6dB bandwidth of the 200 Hz DSP filter and the 200 Hz roofing filter in cascade is 150 Hz! I decided to make my own measurements using an XG1 at 50 uV and the internal dBV meter in the K3 (for 0.1 dB and 1 Hz resolution). These could have some errors due to not being swept narrowband measurements, but they should be consistent which is sufficient for comparison purposes: 1. My 200 XFIL 6 dB BW is actually 203 Hz (measured by disabling all other XFILs and setting DSP = 500 so there is no cascading effect). 2. My 200 DSP 6 dB BW measures 187 Hz (measured by enabling only the 500 XFIL so there is no cascading effect). 3. My 250 DSP measures 210 Hz 4. My 300 DSP measures 272 Hz. 5. 1 and 2 cascaded measure 157 Hz (i.e. close to the 150 Hz Joe calculated). 6. 1 and 3 cascaded measure 175 Hz. 7. 1 and 4 cascaded measure 190 Hz. Ed W0YK said: What can make a difference in large RTTY pileups is running the DSP down as low as 200 Hz which rolls off the outer edges of the tones, but eliminates enough of the pileup to sometimes be a net advantage. Ed reported this using DSP = 200 and XFIL = 370 (his 250). The BW of this combination should effectively be the 187 Hz of the 200 DSP alone since the 370 Hz filter should contribute little attenuation in its center. Using Lyle's formula for DSP shape factor, that's ~487/187 or 2.6. If I select 1 and 4 above, that cascaded combination is 190 Hz BW with a wider shape factor than what Ed used, since it's mainly the XFIL in effect (Elecraft says SF = 4.0 for the 200). I would expect I could copy the same RTTY signal Ed does using the same bandwidth and an even wider shape factor, and it might actually be better for two reasons: 1. It should be to tune because it's shape factor is wider (4.0 for my XFIL alone versus 2.6 for Ed's 200 DSP alone). 2. It has better close-in rejection between the 190 BW edges and the point where the 200 XFIL crosses the 370 XFIL's skirts (which must be well over 400 Hz BW). Incidentally, if my XFIL were 224 Hz as Elecraft measured, all of the above BWs would be about 20 Hz wider (but I'm happy mine is 203 instead of 224!). I'm not sure how critical RTTY tuning is but I believe this demonstrates it's possible to fit a 170 Hz signal inside a 200 XFIL with 6 dB attenuation. It probably requires that you carefully center your 200 XFIL and it may be on the hairy edge of copy (as I believe Ed said) but if RTTY contests are like CW contests, that's what you sometimes need when you want a really narrow filter. I think the bottom line is that I might want both the 200 and 250 if I were a serious RTTY contester, and I would use a set point of 300 for toggling between the two. The latter reminds me...to set a wider DSP BW than the XFIL in my cascaded measurements above, I simply changed my XFIL set point (to 250 or 300 instead of 200). I normally have both my 500 and 200 filter set points a little higher than their actual BW anyway (e.g. 600 and 250). For the 500, this keeps you in that filter when using DUAL PB (which automatically selects whatever XFIL you have set for 600 Hz). One final comment. For those who think the 8-pole filters have zero offsets, that may not be a good assumption, especially for the narrow filters. I was told by someone who has multiple 400 filters that they are actually offset by ~100 Hz. 100 Hz is not a big issue for wider filters but that's significant in a 435 or 370 Hz filter, so you might want to check your narrow filter centers and tweak accordingly (0.01 increment in the menu for each 10 Hz of offset). 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18340909.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3: KRX3 question
Ed Muns wrote: What DSP bandwidths were you using and where did you have your crystal filters engaging? There is only a 65 Hz bandwidth difference between the 400 and 250 crystal filters and both are wider than the what is needed for 170 Hz shift RTTY. The crystal filter function is to protect the DSP For clarity, 170Hz is less than the minimum required bandwidth for RTTY. That needs to be extended by some multiple ( 1.0) of the baud rate, to avoid excessive truncation of significant sidebands. I would suggest that a filter that was significantly down at 250 Hz would be introducing significant distortion. -- David Woolley The Elecraft list is a forum for the discussion of topics related to Elecraft products and more general topics related ham radio List Guidelines http://www.elecraft.com/elecraft_list_guidelines.htm ___ 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: KRX3 question
David Woolley (E.L) wrote: Ed Muns wrote: What DSP bandwidths were you using and where did you have your crystal filters engaging? There is only a 65 Hz bandwidth difference between the 400 and 250 crystal filters and both are wider than the what is needed for 170 Hz shift RTTY. The crystal filter function is to protect the DSP For clarity, 170Hz is less than the minimum required bandwidth for RTTY. That needs to be extended by some multiple ( 1.0) of the baud rate, to avoid excessive truncation of significant sidebands. I would suggest that a filter that was significantly down at 250 Hz would be introducing significant distortion. David you may be suggesting that in theory but I would pay *close attention* to what W0YK says. Ed wins many RTTY contests including several current world records from P49X, and results sometimes speak louder to me than theory (and I'm an engineer if that means anything). http://www.radio-sport.net/wpxrtty08_post1.htm FYI, the DSP filter in the K3 follows the following formula for shape factor according to Lyle KK7P: Shape Factor = (6 dB BW) / (6 dB BW + 300 Hz) At 200 Hz BW, the DSP shape factor computes to 2.5. The 200 Hz crystal filter was measured by Elecraft to be 224 Hz wide with a shape factor of 4.0, so whether you use a 400, 250, or 200 Hz roofing filter, that has little bearing on the final BW when WIDTH is set to 200 as Ed suggested (since all XFILs are wider than the DSP's BW). Many folks seem to have problems confusing the role of roofing filters for determining the final bandwidth in the K3. That is simply not the case. The purpose of the roofing filter is mainly to reduce strong (approximately S9+30) signals from over-driving the ADC in the DSP. If they do that, then the DSP determines the final selectivity over its ~100 dB dynamic range. 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18314270.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3: KRX3 question
FYI, the DSP filter in the K3 follows the following formula for shape factor according to Lyle KK7P: Shape Factor = (6 dB BW) / (6 dB BW + 300 Hz) Oops...no coffee yet. Make that Shape Factor = (6 dB BW + 300 Hz) / (6 dB BW) 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18314324.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: Re: [Elecraft] K3: KRX3 question
Bill I can't recall seeing that figure published before; where would I look for that figure? David G3UNA snip The purpose of the roofing filter is mainly to reduce strong (approximately S9+30) signals from over-driving the ADC in the DSP. If they do that, then the DSP determines the final selectivity over its ~100 dB dynamic range. 73, Bill -- - Email sent from www.virginmedia.com/email Virus-checked using McAfee(R) Software and scanned for spam ___ 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: Re: [Elecraft] K3: KRX3 question
David Cutter wrote: Bill I can't recall seeing that figure published before; where would I look for that figure? David G3UNA snip The purpose of the roofing filter is mainly to reduce strong (approximately S9+30) signals from over-driving the ADC in the DSP. If they do that, then the DSP determines the final selectivity over its ~100 dB dynamic range. 73, Bill David I'm not sure which figure you meant, so I'll try to cover all bases: 1. S9+30 limit for over-driving ADC. This can be deduced by the setpoint of the Hardware AGC Mod quoted from Elecraft's mod page below: This modification raises the hardware AGC threshold from about S9+5 to about S9+25 to +30. The new threshold still protects the DSP's analog-to-digital converter, while providing better receive performance when wider crystal filters are used. 2. 100 dB dynamic range of DSP. I'm not going to search for the exact source but this is often quoted by manufacturers as the practical limit of current DSPs using 24-bit ADCs. Theoretically it should be higher based only on 24-bit ADC resolution but practically it's limited by other factors. All hybird heterodyne/DSP rigs such as Orion, K3, FT-2000/9000 and IC-7700/7800 have about the same limit. I suppose if we get 32-bit ADCs this limit could increase. 3. DSP Shape Factor formula from KK7P: http://www.mail-archive.com/elecraft@mailman.qth.net/msg53271.html Hopefully I covered the figure you were questioning. 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18315394.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: Re: [Elecraft] K3: KRX3 question
Thanks Bill, it was the first 2 that were of interest. David G3UNA David Cutter wrote: Bill I can't recall seeing that figure published before; where would I look for that figure? David G3UNA snip The purpose of the roofing filter is mainly to reduce strong (approximately S9+30) signals from over-driving the ADC in the DSP. If they do that, then the DSP determines the final selectivity over its ~100 dB dynamic range. 73, Bill David I'm not sure which figure you meant, so I'll try to cover all bases: 1. S9+30 limit for over-driving ADC. This can be deduced by the setpoint of the Hardware AGC Mod quoted from Elecraft's mod page below: This modification raises the hardware AGC threshold from about S9+5 to about S9+25 to +30. The new threshold still protects the DSP's analog-to-digital converter, while providing better receive performance when wider crystal filters are used. 2. 100 dB dynamic range of DSP. I'm not going to search for the exact source but this is often quoted by manufacturers as the practical limit of current DSPs using 24-bit ADCs. Theoretically it should be higher based only on 24-bit ADC resolution but practically it's limited by other factors. All hybird heterodyne/DSP rigs such as Orion, K3, FT-2000/9000 and IC-7700/7800 have about the same limit. I suppose if we get 32-bit ADCs this limit could increase. 3. DSP Shape Factor formula from KK7P: http://www.mail-archive.com/elecraft@mailman.qth.net/msg53271.html Hopefully I covered the figure you were questioning. 73, Bill - Email sent from www.virginmedia.com/email Virus-checked using McAfee(R) Software and scanned for spam ___ 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: KRX3 question
2. 100 dB dynamic range of DSP. I'm not going to search for the exact source but this is often quoted by manufacturers as the practical limit of current DSPs using 24-bit ADCs. Theoretically it should be higher based only on 24-bit ADC resolution but practically it's limited by other factors. All hybird heterodyne/DSP rigs such as Orion, K3, FT-2000/9000 and IC-7700/7800 have about the same limit. I suppose if we get 32-bit ADCs this limit could increase. We get about 6 dB per bit of ADC resolution in a perfect ADC. So a 24-bit ADC should give us 144 dB of dynamic range, 144 dB S/N, etc. In practice, we have non-linearity, jitter and other forms of noise that reduce the obtainable accuracy. Pro-audio ADCs work the best. At the time the K3 was designed, the best ADCs provided about 103 to 118 dB of S/N under laboratory conditions. The device we chose is rated at 112 dB. To achieve this requires careful design of all the circuitry that interfaces the ADC to the analog signals. Some ADCs now get S/N in the mid 120-dB range. Use of such devices entails significant additional cost to the radio, but with *very* little benefit. Why? Other important ADC characteristics -- distortion, dynamic range -- limit even these to something in the range of 102 to 108 dB. This is exactly the same as the ADC we use in the K3. Note that these limits are of the ADC itself, not limits of the radio passed on to the ADC. Thanks to its modular construction, the K3 is designed to be able to take advantage of advances in ADC technology. 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
Re: [Elecraft] K3: KRX3 question
Bill, I find the diversity option interesting and I imagine that it will be a very useful feature on topband. In what other situations do you find it useful? I have never tried diversity myself, what would the difference be between a filter matched to the specs provided Elecraft and a set of un-matched filters? 73 de Björn /SM0MDG ___ 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: KRX3 question
With regard to diversity reception on bands other than 160m -- When 6-meter sporadic-E is very intense and present over a fairly large area between two stations, a phenomenon occurs where the signal will come in alternately at a higher angle and at a lower angle, fading back and forth, on average, every second or two. I've confirmed this by switching back and forth between my high/low yagi with the StackMatch while receiving such a signal. I look forward to that someday when I acquire a KRX3 and can try diversity reception on 6 meters. The configuration would be my vertically-stacked 6m yagis each feeding a separate receiver directly. (And of course driven through the StackMatch on transmit, as they are now.) The exact physical model of sporadic-E propagation that is causing this phenomenon is open to some debate, but it is clearly happening -- when the Es is active and complex enough to support multiple-angle paths. Using diversity reception from a two-stack of identical yagis sounds very intriguing, and would certainly work just as well as feedline-combining even when this Es phenomenon isn't occurring strongly. Bill W5VWO DM65 - Original Message - From: Björn Mohr [EMAIL PROTECTED] To: Elecraft Reflector elecraft@mailman.qth.net Sent: Monday, July 07, 2008 9:10 AM Subject: Re: [Elecraft] K3: KRX3 question Bill, I find the diversity option interesting and I imagine that it will be a very useful feature on topband. In what other situations do you find it useful? I have never tried diversity myself, what would the difference be between a filter matched to the specs provided Elecraft and a set of un-matched filters? 73 de Björn /SM0MDG ___ 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: KRX3 question
Björn Mohr SM0MDG wrote: I find the diversity option interesting and I imagine that it will be a very useful feature on topband. In what other situations do you find it useful? I have never tried diversity myself, what would the difference be between a filter matched to the specs provided Elecraft and a set of un-matched filters? Orion had quasi diversity which I've used but it had 2 major problems: 1. There was a constand 2-6 Hz beat between the two signals (which was constant in a given rig but varied from unit to unit) which was very annoying. In true diversity the two RXs are supposed to be phase-locked to exactly the same frequency. 2. Orion's Sub-RX had terrible RF performance, rendering it useless in any sort of large signal environment like contests, large pileups, etc. I've actually never used *true* diversity but am looking forward to it in the K3. The uses I see are: 1. Improvement in weak signal DX copy by feeding two different antennas to the two RXs. 2. Contests where you might want to listen in multiple directions (either azimuth or elevation) simultaneously (i.e. hear signals calling from 2 different geographic directions, copy signals with both high and low angle antennas, or copy signals with both horizontal and vertical polarization antennas). What would be the effect of unmatched filters? You would have a beat frequency, such as I mentioned with Orion above, which would be the difference in the two offsets. Even with identical offsets, you could also have interesting effects if you used different bandwidth filters. This might not necessarily be bad since you could use both a wide bandwidth and a narrow bandwidth simultaneously (somewhat like DUAL PB presently in the K3 but with much more flexibility). It will be fun to experiment with some of these things! 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18319922.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3: KRX3 question
Bill I don't follow how filter offsets degrade oscillator tracking, ie to make a beat frequency. Sorry if I'm being thick. David G3UNA What would be the effect of unmatched filters? You would have a beat frequency, such as I mentioned with Orion above, which would be the difference in the two offsets. Even with identical offsets, you could also have interesting effects if you used different bandwidth filters. This might not necessarily be bad since you could use both a wide bandwidth and a narrow bandwidth simultaneously (somewhat like DUAL PB presently in the K3 but with much more flexibility). It will be fun to experiment with some of these things! 73, Bill ___ 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: KRX3 question
With two synthesizers, our software must calculate the proper PLL divider and reference frequencies for each one. When setting the sub and main to the same RX frequency, if the filter offsets set in the menu are different this can cause small rounding errors in the synthesizer frequency calculation math to place them a couple of Hz apart. (But -not- by the difference in offsets between the filters. We calculate most of that out.) 73, Eric WA6HHQ --- David Cutter wrote: Bill I don't follow how filter offsets degrade oscillator tracking, ie to make a beat frequency. Sorry if I'm being thick. David G3UNA What would be the effect of unmatched filters? You would have a beat frequency, such as I mentioned with Orion above, which would be the difference in the two offsets. Even with identical offsets, you could also have interesting effects if you used different bandwidth filters. This might not necessarily be bad since you could use both a wide bandwidth and a narrow bandwidth simultaneously (somewhat like DUAL PB presently in the K3 but with much more flexibility). It will be fun to experiment with some of these things! 73, Bill ___ 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: KRX3 question
Thanks for the input, this is really interesting! On 2008-07-07 19.23, Eric Swartz - WA6HHQ, Elecraft [EMAIL PROTECTED] wrote: With two synthesizers, our software must calculate the proper PLL divider and reference frequencies for each one. When setting the sub and main to the same RX frequency, if the filter offsets set in the menu are different this can cause small rounding errors in the synthesizer frequency calculation math to place them a couple of Hz apart. So basically I could set the compensation value exactly the same for both filters and accept the difference in passband frequency response... whatever effect that will produce. I agree will Bill W4ZV, it will be interesting to play around with diversity. I can already visualize another coax from a second RX antenna entering the building. I though I had that figured out last season with the new antenna switch... the game never ends :) 73 de Björn /SM0MDG ___ 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: KRX3 question
Bill, David you may be suggesting that in theory but I would pay *close attention* to what W0YK says. Ed wins many RTTY contests including several current world records from P49X, and results sometimes speak louder to me than theory (and I'm an engineer if that means anything). Ed and I had an extensive off-line discussion concerning the K3 filter options and RTTY. We both made multiple measurements of the composite bandwidth (roofing filter, DSP and dual passband filter) with several settings. The consensus is that the 200 Hz DSP settings work as long as the roofing filter is more than 250 Hz wide. The 200 Hz crystal filter was measured by Elecraft to be 224 Hz wide with a shape factor of 4.0, so whether you use a 400, 250, or 200 Hz roofing filter, that has little bearing on the final BW when WIDTH is set to 200 as Ed suggested (since all XFILs are wider than the DSP's BW). This is not the case based on careful measurements. The problem is 'skirt sharpening' when multiple filters are cascaded. Where a single filter might have a 6dB bandwidth of 225 Hz (200 Hz roofing fitter), when combined with the 200 Hz DSP filter the effective -6dB bandwidth of the 200 Hz DSP filter and the 200 Hz roofing filter in cascade is 150 Hz! Much of the narrowing is due to the very humped (Gaussian) nature of the narrow crystal filters but the best responses for RTTY seem to be with a roofing filter wider than 300 Hz (the 250 Hz/8-pole) and/or keeping the DSP filter wider than 250 Hz with or without the dual passband filter. Note: Ed uses the 250 Hz filter with his 200 Hz DSP setting. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bill W4ZV Sent: Monday, July 07, 2008 7:05 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3: KRX3 question David Woolley (E.L) wrote: Ed Muns wrote: What DSP bandwidths were you using and where did you have your crystal filters engaging? There is only a 65 Hz bandwidth difference between the 400 and 250 crystal filters and both are wider than the what is needed for 170 Hz shift RTTY. The crystal filter function is to protect the DSP For clarity, 170Hz is less than the minimum required bandwidth for RTTY. That needs to be extended by some multiple ( 1.0) of the baud rate, to avoid excessive truncation of significant sidebands. I would suggest that a filter that was significantly down at 250 Hz would be introducing significant distortion. David you may be suggesting that in theory but I would pay *close attention* to what W0YK says. Ed wins many RTTY contests including several current world records from P49X, and results sometimes speak louder to me than theory (and I'm an engineer if that means anything). http://www.radio-sport.net/wpxrtty08_post1.htm FYI, the DSP filter in the K3 follows the following formula for shape factor according to Lyle KK7P: Shape Factor = (6 dB BW) / (6 dB BW + 300 Hz) At 200 Hz BW, the DSP shape factor computes to 2.5. The 200 Hz crystal filter was measured by Elecraft to be 224 Hz wide with a shape factor of 4.0, so whether you use a 400, 250, or 200 Hz roofing filter, that has little bearing on the final BW when WIDTH is set to 200 as Ed suggested (since all XFILs are wider than the DSP's BW). Many folks seem to have problems confusing the role of roofing filters for determining the final bandwidth in the K3. That is simply not the case. The purpose of the roofing filter is mainly to reduce strong (approximately S9+30) signals from over-driving the ADC in the DSP. If they do that, then the DSP determines the final selectivity over its ~100 dB dynamic range. 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18314270.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ 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: KRX3 question
Joe Subich, W4TV-3 wrote: Bill, David you may be suggesting that in theory but I would pay *close attention* to what W0YK says. Ed wins many RTTY contests including several current world records from P49X, and results sometimes speak louder to me than theory (and I'm an engineer if that means anything). Ed and I had an extensive off-line discussion concerning the K3 filter options and RTTY. We both made multiple measurements of the composite bandwidth (roofing filter, DSP and dual passband filter) with several settings. The consensus is that the 200 Hz DSP settings work as long as the roofing filter is more than 250 Hz wide. That's interesting since there isn't a 250 Hz roofing filter. There's a 370 Hz and a 224 Hz, but no 250 Hz. What did you use for the 250 measurement above or is that a calculated result? At any rate, I'll defer to Ed since he's forgotten more about RTTY than I'll ever know, as his contest results demonstrate. ;-) 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18328080.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] K3: KRX3 question
Being tha t it was mentioned that best responses seem to be with a roofing filter wider than 300Hz and then he mentioned the 250Hz filter wouldn't you deduce that he meant the 370Hz filter which Elecraft calls 250Hz? I mean maybe I'm jumping to conclusions here but that was pretty clear to me. On Mon, 2008-07-07 at 15:27 -0700, Bill W4ZV wrote: Joe Subich, W4TV-3 wrote: Bill, David you may be suggesting that in theory but I would pay *close attention* to what W0YK says. Ed wins many RTTY contests including several current world records from P49X, and results sometimes speak louder to me than theory (and I'm an engineer if that means anything). Ed and I had an extensive off-line discussion concerning the K3 filter options and RTTY. We both made multiple measurements of the composite bandwidth (roofing filter, DSP and dual passband filter) with several settings. The consensus is that the 200 Hz DSP settings work as long as the roofing filter is more than 250 Hz wide. That's interesting since there isn't a 250 Hz roofing filter. There's a 370 Hz and a 224 Hz, but no 250 Hz. What did you use for the 250 measurement above or is that a calculated result? At any rate, I'll defer to Ed since he's forgotten more about RTTY than I'll ever know, as his contest results demonstrate. ;-) 73, Bill ___ 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: KRX3 question
KFL3A-250 K3 250 Hz, 8 pole filter - Original Message - From: Bill W4ZV [EMAIL PROTECTED] That's interesting since there isn't a 250 Hz roofing filter. There's a 370 Hz and a 224 Hz, but no 250 Hz. What did you use for the 250 measurement above or is that a calculated result? At any rate, I'll defer to Ed since he's forgotten more about RTTY than I'll ever know, as his contest results demonstrate. ;-) ___ 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: KRX3 question
Brett Howard wrote: Being tha t it was mentioned that best responses seem to be with a roofing filter wider than 300Hz and then he mentioned the 250Hz filter wouldn't you deduce that he meant the 370Hz filter which Elecraft calls 250Hz? I mean maybe I'm jumping to conclusions here but that was pretty clear to me. That's a good assumption but not what he said. In other areas of his message, Joe was careful to say 250 (meaning Elecraft's nomenclature) or 370, but the what he actually wrote is: The consensus is that the 200 Hz DSP settings work as long as the roofing filter is more than 250 Hz wide. I suspect much of this is academic anyway. If you have an extremely strong signal 250 Hz from your center frequency, NO filtering is going to solve issues like the other guy's TX noise, although a narrower XFIL may sometimes help with desense. At least on CW that's the advantage I see with the 200, but also remember that we also have a 50 Hz DSP in our ears which helps on CW (but not on RTTY). 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18329092.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] K3: KRX3 question
Direct quote from the message: Much of the narrowing is due to the very humped (Gaussian) nature of the narrow crystal filters but the best responses for RTTY seem to be with a roofing filter wider than 300 Hz (the 250 Hz/8-pole) and/or keeping the DSP filter wider than 250 Hz with or without the dual passband filter. Note: Ed uses the 250 Hz filter with his 200 Hz DSP setting. He says that the roofing filter needs to be wider than 300 and he thus used the 250Hz filter with a 200Hz DSP filter setting. Its simply put that the roofing filter needs to be wider than 300 and he therefore uses the 8-pole 250 Hz filter which it seems clear you know is 370Hz and therefore fits the build of what is required. Then behind that he has a 200Hz filter at the DSP IF. On Mon, 2008-07-07 at 16:35 -0700, Bill W4ZV wrote: Brett Howard wrote: Being tha t it was mentioned that best responses seem to be with a roofing filter wider than 300Hz and then he mentioned the 250Hz filter wouldn't you deduce that he meant the 370Hz filter which Elecraft calls 250Hz? I mean maybe I'm jumping to conclusions here but that was pretty clear to me. That's a good assumption but not what he said. In other areas of his message, Joe was careful to say 250 (meaning Elecraft's nomenclature) or 370, but the what he actually wrote is: The consensus is that the 200 Hz DSP settings work as long as the roofing filter is more than 250 Hz wide. I suspect much of this is academic anyway. If you have an extremely strong signal 250 Hz from your center frequency, NO filtering is going to solve issues like the other guy's TX noise, although a narrower XFIL may sometimes help with desense. At least on CW that's the advantage I see with the 200, but also remember that we also have a 50 Hz DSP in our ears which helps on CW (but not on RTTY). 73, Bill ___ 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: KRX3 question
Brett Howard wrote: So am I to assume that the 8-pole filters are not going to need to worry about this as they are all at 0 anyway? What is the advantage of getting two matched pairs of 5-pole filters when you can get two 8-poles for only 10 bucks a filter more? I'm assuming that its 100 + 100 + 30 for matched 5-pole filters or 125 + 125 for the 8-pole filters. I can see there being a great advantage if you already have a 5-pole and want to match it in your sub RX. But if you're just getting 2 at the same time it seems like the 8-pole makes for a good option too.. At least I hope so cause diversity receive was the main reason I figured I'd go for the 8-poles... :) You're correct that 8-poles have no offsets and avoid this problem. When I ordered my 5-poles there was a $40 per filter discount to 8-poles and nobody (including Elecraft) understood that the Sub RX filters needed to matched if using 5-poles. EI6IZ on the Field Test team discovered this in December when he saw slight frequency offsets as the WIDTH control toggled different filters. But the real reason I ordered my 500 and 200 combination is purely bandwidth. Here are Elecraft's measurements: Filter BW(-6dB) Shape Factor 200 224 4.0 250 370 2.1 400 435 2.1 500 565 3.1 For weak CW signals or in contests I prefer a wider bandwidth. For weak signals the additional bandwidth gives my ears a better context in which to apply my ear/brain's internal 50 Hz filter. In contests, I also want to be able to hear stations calling me off-frequency as well as hear what's going on around my run frequency (so I can chase off those folks who send ? once and then start CQ-ing 250 Hz above me). I would actually prefer 8-pole filters for rejection reasons, but the bandwidth choices above are simply wrong for my use. The 400 is too narrow and the 250 is too wide (and only 65 Hz between the two!). When I need a narrow filter, I want a *truly* narrow filter. The main use I have for the 200 is in nearly simplex pileups with lots of S9+++ signals (think 160m DX pileups). Another reason one might want 8-poles is when using N8LP's LP-PAN and SDR software for a panadaptor/waterfall display. The 5-pole offsets can cause a similar problem here as you rotate WIDTH through different filters. However, with the recent addition of Elecraft's programming commands to read the internal filter offsets, N8LP says WU2X can correct for the offsets in his PowerSDR-IF software. The bottom line to me is that I choose filters primarily for their bandwidth and I prefer the 500/200 combination even with their offset warts. If Elecraft offered different BW choices in the 8-poles, I might prefer them. Quite frankly, given the current $25 price differential, I don't see why Elecraft doesn't go to all 8-pole filters and make some better bandwidth choices (e.g. at least octave differences at the low end...say 600 and a *true* 250...not the one above which is actually 370). I wouldn't be surprised to see Inrad eventually do this even if Elecraft doesn't. 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18301358.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3: KRX3 question
Hi Bill, If you worked RTTY you would find out that the 250Hz filter is ideal for recovering weak ones and for 20M during RTTY contests. The dual passband filter fits very nicely within it. I don't care what bandwidth you call it. Don't eliminate it as a choice. I was astounded the difference it made during yesterdays DL RTTY contest. Fine tuning + the selectivitiy made the 20 KHz RTTY band seem like 100KHz wide while doing search and pounce. A/B comparisons between it and the 400Hz filter did indeed show significant benefit. Spectrogram spectra, with a band loaded with signals, strengthen this A/B comparions conclusion. Some offending signals simply fell off the edge of the 250 Hz filter slope. Part of this benefit is undoubtedly due to the capture effect of FM like modes. Strongest wins. 73 de Brian/K3KO Bill W4ZV wrote: Brett Howard wrote: So am I to assume that the 8-pole filters are not going to need to worry about this as they are all at 0 anyway? What is the advantage of getting two matched pairs of 5-pole filters when you can get two 8-poles for only 10 bucks a filter more? I'm assuming that its 100 + 100 + 30 for matched 5-pole filters or 125 + 125 for the 8-pole filters. I can see there being a great advantage if you already have a 5-pole and want to match it in your sub RX. But if you're just getting 2 at the same time it seems like the 8-pole makes for a good option too.. At least I hope so cause diversity receive was the main reason I figured I'd go for the 8-poles... :) You're correct that 8-poles have no offsets and avoid this problem. When I ordered my 5-poles there was a $40 per filter discount to 8-poles and nobody (including Elecraft) understood that the Sub RX filters needed to matched if using 5-poles. EI6IZ on the Field Test team discovered this in December when he saw slight frequency offsets as the WIDTH control toggled different filters. But the real reason I ordered my 500 and 200 combination is purely bandwidth. Here are Elecraft's measurements: Filter BW(-6dB) Shape Factor 200 224 4.0 250 370 2.1 400 435 2.1 500 565 3.1 For weak CW signals or in contests I prefer a wider bandwidth. For weak signals the additional bandwidth gives my ears a better context in which to apply my ear/brain's internal 50 Hz filter. In contests, I also want to be able to hear stations calling me off-frequency as well as hear what's going on around my run frequency (so I can chase off those folks who send ? once and then start CQ-ing 250 Hz above me). I would actually prefer 8-pole filters for rejection reasons, but the bandwidth choices above are simply wrong for my use. The 400 is too narrow and the 250 is too wide (and only 65 Hz between the two!). When I need a narrow filter, I want a *truly* narrow filter. The main use I have for the 200 is in nearly simplex pileups with lots of S9+++ signals (think 160m DX pileups). Another reason one might want 8-poles is when using N8LP's LP-PAN and SDR software for a panadaptor/waterfall display. The 5-pole offsets can cause a similar problem here as you rotate WIDTH through different filters. However, with the recent addition of Elecraft's programming commands to read the internal filter offsets, N8LP says WU2X can correct for the offsets in his PowerSDR-IF software. The bottom line to me is that I choose filters primarily for their bandwidth and I prefer the 500/200 combination even with their offset warts. If Elecraft offered different BW choices in the 8-poles, I might prefer them. Quite frankly, given the current $25 price differential, I don't see why Elecraft doesn't go to all 8-pole filters and make some better bandwidth choices (e.g. at least octave differences at the low end...say 600 and a *true* 250...not the one above which is actually 370). I wouldn't be surprised to see Inrad eventually do this even if Elecraft doesn't. 73, Bill ___ 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: KRX3 question
I think I must be missing something. As I understand it, the additional crystal filters are only really necessary when operating with very strong adjacent signals in the passband. So, if you don't have a need for rejection of such strong signals, let's say 40 over S9 (somebody correct this figure please) then you don't need these extra filters, the DSP will cope with these large signals. The filters are only there to prevent overload of the DSP. Therefore, to perform the very best diversity reception in 40 over S9 conditions, turn off those extra filters in configuration menu. Having turned off the filters, I can engage the attenuator to avoid DSP overload if needed. Yes, I know it also reduces the signal I'm trying to hear, but that sacrifice may be what is needed. For diversity reception using low gain loop, pennant, flag, Beverage, loaded whip antennas, the signal input is very much lower than from the tx antenna, so, crystal filters are probably not be needed at all. Or do I have it all completely wrong? David G3UNA ___ 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: KRX3 question
David, In most instances, you are correct. My K3 has only the stock 2.7 filter, but then I am not into heavy contesting nor intense DX chasing - I do some contesting and work DX for fun only. When it gets to the point where I really need narrow roofing filters, it is time for me to go listen to some relaxing music, so you will not find me using diversity reception to pull out some obscure weak signal. One related point - the Hardware AGC should prevent overload of the DSP, so the K3 will handle those strong signals nicely. The problem is that the AGC action when a strong unwanted signal is within the roofing filter passband, the AGC will reduce the sensitivity of the entire receiver, so your wanted signal gets weaker too - and you may not even know the offending signal is there if you have the DSP bandwidth at a narrow width - it will behave as though there is QSB on the signal you are listening to. Of course using diversity reception with one antenna having lower gain, that QSB effect may be minimized. 73, Don W3FPR David Cutter wrote: I think I must be missing something. As I understand it, the additional crystal filters are only really necessary when operating with very strong adjacent signals in the passband. So, if you don't have a need for rejection of such strong signals, let's say 40 over S9 (somebody correct this figure please) then you don't need these extra filters, the DSP will cope with these large signals. The filters are only there to prevent overload of the DSP. Therefore, to perform the very best diversity reception in 40 over S9 conditions, turn off those extra filters in configuration menu. Having turned off the filters, I can engage the attenuator to avoid DSP overload if needed. Yes, I know it also reduces the signal I'm trying to hear, but that sacrifice may be what is needed. For diversity reception using low gain loop, pennant, flag, Beverage, loaded whip antennas, the signal input is very much lower than from the tx antenna, so, crystal filters are probably not be needed at all. Or do I have it all completely wrong? ___ 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: KRX3 question
If you worked RTTY you would find out that the 250Hz filter is ideal for recovering weak ones and for 20M during RTTY contests. The dual passband filter fits very nicely within it. I don't care what bandwidth you call it. Don't eliminate it as a choice. I was astounded the difference it made during yesterdays DL RTTY contest. Fine tuning + the selectivitiy made the 20 KHz RTTY band seem like 100KHz wide while doing search and pounce. A/B comparisons between it and the 400Hz filter did indeed show significant benefit. Spectrogram spectra, with a band loaded with signals, strengthen this A/B comparions conclusion. Some offending signals simply fell off the edge of the 250 Hz filter slope. Part of this benefit is undoubtedly due to the capture effect of FM like modes. Strongest wins. What DSP bandwidths were you using and where did you have your crystal filters engaging? There is only a 65 Hz bandwidth difference between the 400 and 250 crystal filters and both are wider than the what is needed for 170 Hz shift RTTY. The crystal filter function is to protect the DSP from strong nearby signals and a 65 Hz delta is irrelevant at 400 Hz. So there will NOT be any discernible benefit on RTTY or any other mode if you do the A/B comparison with the same DSP bandwidth (with or without the DTF). For example, if your 400 Hz filter engages at DSP bandwidth of 400 Hz and your 250 Hz filter engages at 250 Hz, then you are really A/B comparing DSP bandwidths of 400 and 250 Hz, not the crystal filter differences. What can make a difference in large RTTY pileups is running the DSP down as low as 200 Hz which rolls off the outer edges of the tones, but eliminates enough of the pileup to sometimes be a net advantage. In general, running the DSP at 300 Hz with the DTF engaged is ideal for 170 Hz shift RTTY because there is little roll off of the desired passband. Of course, the 250 Hz DSP bandwidth is a step between these two settings and also a viable alternative in some situations. The 250 Hz crystal filter at an actual -6 dB bandwidth of 370 Hz is a good roofer for these three DSP bandwidths, but the 400 Hz crystal filter at an actual BW of 435 Hz is essentially the same as far as protecting the DSP from nearby strong signals. 73, Ed - W0YK ___ 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: KRX3 question
I sense that a fair amount of folks view K3 crystal filters in the traditional sense, for example the need for a 500hz filter on if one is going to operate CW. This ia a long way from the truth with K3. Same thing for the 1.8khz filter, unless you're having antennas that bring in contest strength signals, not necessary at all. Buck can probably comment on this, I never owned Orion, but it seems they never had the ability for a roofing filter on the second receiver and if you put K3's receiver or subreceiver head to head without a roofing filter (DSP only), the Orion receiver would suffer AGC pumping terribly since it's default roofing filter is at more than 10 khz and K3 is at 2.7khz. That's what my Argo V did. The point is, the stock K3 setup is majorly robust for either the main receiver or the subRx in stock form. [Elecraft] K3: KRX3 question Don Wilhelm w3fpr at embarqmail.com Sun Jul 6 09:24:31 EDT 2008 Previous message: [Elecraft] K3: KRX3 question Next message: [Elecraft] K3: KRX3 question David, In most instances, you are correct. My K3 has only the stock 2.7 filter, but then I am not into heavy contesting nor intense DX chasing - I do some contesting and work DX for fun only. When it gets to the point where I really need narrow roofing filters, it is time for me to go listen to some relaxing music, so you will not find me using diversity reception to pull out some obscure weak signal. One related point - the Hardware AGC should prevent overload of the DSP, so the K3 will handle those strong signals nicely. The problem is that the AGC action when a strong unwanted signal is within the roofing filter passband, the AGC will reduce the sensitivity of the entire receiver, so your wanted signal gets weaker too - and you may not even know the offending signal is there if you have the DSP bandwidth at a narrow width - it will behave as though there is QSB on the signal you are listening to. Of course using diversity reception with one antenna having lower gain, that QSB effect may be minimized. 73, Don W3FPR ___ 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: KRX3 question
I find that the narrower filters take out a lot of the noise before it hits the DSP and it can even make just rag chew conditions nicer in my very electrically noisy area. Actually I'm quite excited that once I get my K3 back that I can set the 250Hz filter to be able to use it up at 350. I even am adding the 1Khz filter as the step in the noise when switching from my 250Hz to my 1.8Khz was pretty large. Honestly I'm not so sure that the 1.8 is really all that much of a help over the 2.7 but the 250 is a big help over the 2.7 and the 1.8. Plus I just like having the radio do all the intelligent rock switching. Makes it a very nice combination and mixing of the old way of doing things and the new way of doing things. On Sun, 2008-07-06 at 13:56 +0100, David Cutter wrote: I think I must be missing something. As I understand it, the additional crystal filters are only really necessary when operating with very strong adjacent signals in the passband. So, if you don't have a need for rejection of such strong signals, let's say 40 over S9 (somebody correct this figure please) then you don't need these extra filters, the DSP will cope with these large signals. The filters are only there to prevent overload of the DSP. Therefore, to perform the very best diversity reception in 40 over S9 conditions, turn off those extra filters in configuration menu. Having turned off the filters, I can engage the attenuator to avoid DSP overload if needed. Yes, I know it also reduces the signal I'm trying to hear, but that sacrifice may be what is needed. For diversity reception using low gain loop, pennant, flag, Beverage, loaded whip antennas, the signal input is very much lower than from the tx antenna, so, crystal filters are probably not be needed at all. Or do I have it all completely wrong? David G3UNA ___ 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] K3: KRX3 question
I note in the new KRX3 manual the comment that diversity reception may be enhanced by using filters with matched offsets for the main and sub-receivers. I'm a 160M nut and this is certainly an important point to me... I have these filterson backorder: KFL3A-2002 K3 200 Hz, 5 pole filter KFL3A-5002 K3 500 Hz, 5 pole filter I'm wondering if Elecraft has plans for shipping these as matched sets or if I should scramble to change my order for 8 pole filters which should not need the offset.Heads up and anyone know the answer? Tom N5TW ___ 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: KRX3 question
Tom Whiteside wrote: I note in the new KRX3 manual the comment that diversity reception may be enhanced by using filters with matched offsets for the main and sub-receivers.I'm a 160M nut and this is certainly an important point to me... I have these filterson backorder: KFL3A-2002 K3 200 Hz, 5 pole filter KFL3A-5002 K3 500 Hz, 5 pole filter I'm wondering if Elecraft has plans for shipping these as matched sets or if I should scramble to change my order for 8 pole filters which should not need the offset.Heads up and anyone know the answer? Yes Elecraft is *supposed* to match these...but I would certainly remind them via an email to Lisa. They are also *supposed* to have a process to match existing filters already in the field (i.e. matching the Sub filters to Main filters already installed). I would think this could be as simple as sending them the offsets for existing filters so they could choose units with identical offsets one from production. But only Eric or Wayne can truly answer your question, which is a very timely one! 73, Bill -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18281256.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3: KRX3 question
H Tom, We will match the 5 pole filters (to within 40 Hz) on request. If your filters are already that close you are in good shape. We can't guarantee a good enough yield on filter offsets to get closer than that, though most will be closer. Fortunately 40 Hz is more than adequate as you can set the K3 menu offsets for the two filters the same at the mean between them and both will be within 20 Hz or less of their ideal center. The $30 option is per matched set (not per filter) and will be on the web order form next week. (We're officially on national holiday today :-) We just put it into the in-house ordering system yesterday. This applies to either matching two of the same bandwidth filter at time of shipment or matching a second same b/w filter to one you already have in your radio. For everyone else, if you are not planning on doing 2 receiver, 2 antenna, diversity reception where the frequency of the sub needs to be matched to withing a Hz of the main, this is not necessary. 73, Eric WA6HHQ _..._ Tom Whiteside wrote: I note in the new KRX3 manual the comment that diversity reception may be enhanced by using filters with matched offsets for the main and sub-receivers. I'm a 160M nut and this is certainly an important point to me... I have these filterson backorder: KFL3A-2002 K3 200 Hz, 5 pole filter KFL3A-5002 K3 500 Hz, 5 pole filter I'm wondering if Elecraft has plans for shipping these as matched sets or if I should scramble to change my order for 8 pole filters which should not need the offset.Heads up and anyone know the answer? Tom N5TW ___ 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: KRX3 question
Eric - WA6HHQ wrote: H Tom, We will match the 5 pole filters (to within 40 Hz) on request. If your filters are already that close you are in good shape. We can't guarantee a good enough yield on filter offsets to get closer than that, though most will be closer. Fortunately 40 Hz is more than adequate as you can set the K3 menu offsets for the two filters the same at the mean between them and both will be within 20 Hz or less of their ideal center. The $30 option is per matched set (not per filter) and will be on the web order form next week. (We're officially on national holiday today :-) We just put it into the in-house ordering system yesterday. This applies to either matching two of the same bandwidth filter at time of shipment or matching a second same b/w filter to one you already have in your radio. For everyone else, if you are not planning on doing 2 receiver, 2 antenna, diversity reception where the frequency of the sub needs to be matched to withing a Hz of the main, this is not necessary. 73, Eric WA6HHQ _..._ Tom Whiteside wrote: I note in the new KRX3 manual the comment that diversity reception may be enhanced by using filters with matched offsets for the main and sub-receivers.I'm a 160M nut and this is certainly an important point to me... I have these filterson backorder: KFL3A-2002 K3 200 Hz, 5 pole filter KFL3A-5002 K3 500 Hz, 5 pole filter I'm wondering if Elecraft has plans for shipping these as matched sets or if I should scramble to change my order for 8 pole filters which should not need the offset.Heads up and anyone know the answer? Tom N5TW Tom (and others planning to use diversity), this means you have the following options using the current filter prices: 1. Dual 5-pole filters (matched by Elecraft). 2 X $100 plus $30 = $230 per BW. 2. Dual 8-pole filters (no match needed). 2 X $125 = $250 per BW. This tilts your decision toward 8-pole filters, however there is still an issue of bandwidth. Since the 400 8-pole is actually 435 Hz and the 250 8-pole is actually 370 Hz, I would definitely not order both. I'm faced with the same issue but will probably order one matched 500 since my order was at the original price of $80 for a 5-pole...plus I like the wider BW for contests. I was never planning to use the 200 in diversity mode (you can still use a 500 down to DSP = 250). BTW having used my 200 awhile in a few 160 contests, I would absolutely NOT be without it for huge simplex pileups. So another option for you might be two 400s for diversity, and at least one 200 for the extreme situations we sometimes have on 160. 73, Bill W4ZV -- View this message in context: http://www.nabble.com/K3%3A-KRX3-question-tp18280281p18285112.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3: KRX3 question
Thanks Bill.I like the 5 poles for the reasons you stated recommending them way back when.I ordered the ones you spec'd based on the idea of covering the octaves... I agree that the narrow ones are for more extreme situations but figured for $30 I'd get the narrow ones matched as well. To Jim's question - I mainly use diversity to switch listen to the transmit antenna in one ear and to a Beverage receive antenna in the other ear. Sometimes this is an experience that defies description except you find yourself copying in very tough SNR conditions that you could not otherwise do. Tom N5TW Tom (and others planning to use diversity), this means you have the following options using the current filter prices: 1. Dual 5-pole filters (matched by Elecraft). 2 X $100 plus $30 = $230 per BW. 2. Dual 8-pole filters (no match needed). 2 X $125 = $250 per BW. This tilts your decision toward 8-pole filters, however there is still an issue of bandwidth. Since the 400 8-pole is actually 435 Hz and the 250 8-pole is actually 370 Hz, I would definitely not order both. I'm faced with the same issue but will probably order one matched 500 since my order was at the original price of $80 for a 5-pole...plus I like the wider BW for contests. I was never planning to use the 200 in diversity mode (you can still use a 500 down to DSP = 250). BTW having used my 200 awhile in a few 160 contests, I would absolutely NOT be without it for huge simplex pileups. So another option for you might be two 400s for diversity, and at least one 200 for the extreme situations we sometimes have on 160. 73, Bill W4ZV ___ 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: KRX3 question
So am I to assume that the 8-pole filters are not going to need to worry about this as they are all at 0 anyway? What is the advantage of getting two matched pairs of 5-pole filters when you can get two 8-poles for only 10 bucks a filter more? I'm assuming that its 100 + 100 + 30 for matched 5-pole filters or 125 + 125 for the 8-pole filters. I can see there being a great advantage if you already have a 5-pole and want to match it in your sub RX. But if you're just getting 2 at the same time it seems like the 8-pole makes for a good option too.. At least I hope so cause diversity receive was the main reason I figured I'd go for the 8-poles... :) ~Brett(KC7OTG) ___ 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: KRX3 question
Thanks, Eric, for the update. This is exactly the kind of info I was hoping for from Elecraft on the diversity filter issue. Now I can complete the process of finalizing my RX3 and filter order to complement my existing 5 pole filters. The $30 fee for matching to the offsets I already have is reasonable enough. ... Craig AC0DS ___ 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
