Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
 
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Hi all,
In honor of the FCC's proposed "2200 meter" allocation (137 kHz), we decided to see if we could improve the K3's receive sensitivity in the 100-500 kHz range. This extended coverage is made possible by the new synth (KSYN3A). After a lot of digging, we discovered the cause of the wide-band low-frequency noise. We also found a way to shift the passband of the KBPF3 lower. With a couple of simple modifications, the MDS (minimum discernible signal) can be improved by about 25 dB at the low end (100 kHz). Here are some test results (preamp off, 400-Hz bandwidth): 137 kHz -114 dBm FCC's proposed 2200 meter band 160 kHz -117 dBm low end of the "Low-Fer" band 250 kHz -126 dBm test frequency in the long-wave beacon band 472 kHz -133 dBm 630 meter experimental band This represents an improvement throughout the range, but especially at the low end. I believe -114 dBm MDS should suffice at 137 kHz, given the high band noise in this range. Another indication of how well the mods work: With no antenna connoted, the K3's S-meter now just barely flickers (S1) at 100 kHz. Without the mods, the no-antenna S-meter reading could be as high as S7 due to the noise source we've now identified (a voltage regulator). (By the way, this regulator noise had no impact on frequencies about about 500 kHz.) Here's a summary of the changes required: RF board: Add one leaded capacitor KRX3 (if applicable): Add one leaded capacitor KBPF3: Remove two inductors; parallel three new capacitors If you're interested in this low frequency range, and you'd like to try the mods, please email me directly. Note: To tune this range with the K3, you'll need the new synth (KSYN3A), a KBPF3 module (on the main and/or sub receiver), and a KXV3 module. A KXV3 is required because the antenna for the 100-500 kHz range should be connected to RX ANT IN or XVTR IN. The ANT1/ANT2 path goes through the T/R switch, which has a high-pass filter to protect the K3's fast PIN-diode T/R circuitry. 73, Wayne N6KR ______________________________________________________________ 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 Message delivered to [hidden email] |
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And this is why we like Elecraft so much.
Wayne - will these mods be rolled into production boards (all 3 parts)? Thanks, Mike On 04/29/2015 09:23 PM, Wayne Burdick wrote: > Here's a summary of the changes required: > > RF board: Add one leaded capacitor > KRX3 (if applicable): Add one leaded capacitor > KBPF3: Remove two inductors; parallel three new capacitors -- 73, Mike, KW1ND Knoxville, TN ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by wayne burdick
On Wed, Apr 29, 2015 at 8:23 PM, Wayne Burdick <[hidden email]> wrote:
> ....the changes required: > > RF board: Add one leaded capacitor > KRX3 (if applicable): Add one leaded capacitor > KBPF3: Remove two inductors; parallel three new > capacitors > > > ============= Could these mods have any effect on the BPF performance at higher frequencies? Tony, KT0NY ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by wayne burdick
Outstanding! It is such fun to watch you guys at work.
73, Guy On Wednesday, April 29, 2015, Wayne Burdick <[hidden email]> wrote: > Hi all, > > In honor of the FCC's proposed "2200 meter" allocation (137 kHz), we > decided to see if we could improve the K3's receive sensitivity in the > 100-500 kHz range. This extended coverage is made possible by the new synth > (KSYN3A). > > After a lot of digging, we discovered the cause of the wide-band > low-frequency noise. We also found a way to shift the passband of the KBPF3 > lower. > > With a couple of simple modifications, the MDS (minimum discernible > signal) can be improved by about 25 dB at the low end (100 kHz). Here are > some test results (preamp off, 400-Hz bandwidth): > > 137 kHz -114 dBm FCC's proposed 2200 meter band > 160 kHz -117 dBm low end of the "Low-Fer" band > 250 kHz -126 dBm test frequency in the long-wave beacon band > 472 kHz -133 dBm 630 meter experimental band > > This represents an improvement throughout the range, but especially at the > low end. I believe -114 dBm MDS should suffice at 137 kHz, given the high > band noise in this range. > > Another indication of how well the mods work: With no antenna connoted, > the K3's S-meter now just barely flickers (S1) at 100 kHz. Without the > mods, the no-antenna S-meter reading could be as high as S7 due to the > noise source we've now identified (a voltage regulator). (By the way, this > regulator noise had no impact on frequencies about about 500 kHz.) > > Here's a summary of the changes required: > > RF board: Add one leaded capacitor > KRX3 (if applicable): Add one leaded capacitor > KBPF3: Remove two inductors; parallel three new > capacitors > > If you're interested in this low frequency range, and you'd like to try > the mods, please email me directly. > > Note: To tune this range with the K3, you'll need the new synth (KSYN3A), > a KBPF3 module (on the main and/or sub receiver), and a KXV3 module. A KXV3 > is required because the antenna for the 100-500 kHz range should be > connected to RX ANT IN or XVTR IN. The ANT1/ANT2 path goes through the T/R > switch, which has a high-pass filter to protect the K3's fast PIN-diode T/R > circuitry. > > 73, > Wayne > N6KR > > > -- Sent via Gmail Mobile on my iPhone ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by Tony Estep
On Apr 29, 2015, at 7:22 PM, Tony Estep <[hidden email]> wrote: > On Wed, Apr 29, 2015 at 8:23 PM, Wayne Burdick <[hidden email]> wrote: > >> ....the changes required: >> >> RF board: Add one leaded capacitor >> KRX3 (if applicable): Add one leaded capacitor >> KBPF3: Remove two inductors; parallel three new >> capacitors >> >> >> ============= > Could these mods have any effect on the BPF performance at higher > frequencies? No; this is strictly an issue below 500 kHz. All of the K3's band-pass filters already work exactly as they should. 73, Wayne N6KR ______________________________________________________________ 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 Message delivered to [hidden email] |
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In reply to this post by Tony Estep
IIRC, original statement for the new board was -120 dBm at 475 KHz.
Now saying -133 with the mods. Maybe broadcast band DXers would find it useful on the lower half of the AM band? 73, Drew AF2Z On Wed, 29 Apr 2015 21:22:56 -0500, you wrote: >Could these mods have any effect on the BPF performance at higher >frequencies? > >Tony, KT0NY >______________________________________________________________ ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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On Apr 29, 2015, at 8:30 PM, drewko <[hidden email]> wrote:
> IIRC, original statement for the new board was -120 dBm at 475 KHz. That was conservative. > Now saying -133 with the mods. At least on my lab K3. > Maybe broadcast band DXers would find it useful on the lower half of the AM band? Could be. On my K3, with the mods, the MDS at 1.0 MHz is now -136 dBm, preamp on (400 Hz BW). Just keep in mind that in the lower frequency ranges, you'll want to use RX ANT IN or XVTR IN to avoid the loss of the high-pass filter in the T/R switch. Wayne N6KR ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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Wayne,
I don't think I'd get too spun up over sensitivity of better than -95 DBM below the AM BC band. You are going to run in to a practical limit set by atmospheric and man made noise. If you assume a -147 dbm for a perfect receiver in a 500 Hz BW, used because the math is easier, and then subtract 60 db for expected value of noise on 80 meters, you should find that the K3 sensitivity greatly exceeds what could practically be used. I did not look at the noise figure for the K3 as I assume it is much, much better than the expected value of what the antenna will see. And, the environmental noise gets worse as you decrease frequency. I guess what I'm trying to convey is the idea that you already have a superb design. So, will you have done anything to the radio's characteristics in the higher regions of the spectrum to achieve better MF and down performance? 73, Barry K3NDM On 4/29/2015 11:55 PM, Wayne Burdick wrote: > On Apr 29, 2015, at 8:30 PM, drewko <[hidden email]> wrote: > >> IIRC, original statement for the new board was -120 dBm at 475 KHz. > That was conservative. > > >> Now saying -133 with the mods. > At least on my lab K3. > > >> Maybe broadcast band DXers would find it useful on the lower half of the AM band? > > Could be. On my K3, with the mods, the MDS at 1.0 MHz is now -136 dBm, preamp on (400 Hz BW). > > Just keep in mind that in the lower frequency ranges, you'll want to use RX ANT IN or XVTR IN to avoid the loss of the high-pass filter in the T/R switch. > > Wayne > N6KR > > > > ______________________________________________________________ > 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 > Message delivered to [hidden email] > ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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That excellent sensitivity will allow the use of lossy antennas like small loops, etc. I was tuning around listening to beacons from 200-300 kHz, and the difference with the mods is very apparent.
Wayne N6KR ---- http://www.elecraft.com > On Apr 29, 2015, at 10:53 PM, Barry LaZar <[hidden email]> wrote: > > Wayne, > I don't think I'd get too spun up over sensitivity of better than -95 DBM below the AM BC band. You are going to run in to a practical limit set by atmospheric and man made noise. If you assume a -147 dbm for a perfect receiver in a 500 Hz BW, used because the math is easier, and then subtract 60 db for expected value of noise on 80 meters, you should find that the K3 sensitivity greatly exceeds what could practically be used. I did not look at the noise figure for the K3 as I assume it is much, much better than the expected value of what the antenna will see. And, the environmental noise gets worse as you decrease frequency. I guess what I'm trying to convey is the idea that you already have a superb design. So, will you have done anything to the radio's characteristics in the higher regions of the spectrum to achieve better MF and down performance? > > 73, > Barry > K3NDM > >> On 4/29/2015 11:55 PM, Wayne Burdick wrote: >>> On Apr 29, 2015, at 8:30 PM, drewko <[hidden email]> wrote: >>> >>> IIRC, original statement for the new board was -120 dBm at 475 KHz. >> That was conservative. >> >> >>> Now saying -133 with the mods. >> At least on my lab K3. >> >> >>> Maybe broadcast band DXers would find it useful on the lower half of the AM band? >> >> Could be. On my K3, with the mods, the MDS at 1.0 MHz is now -136 dBm, preamp on (400 Hz BW). >> >> Just keep in mind that in the lower frequency ranges, you'll want to use RX ANT IN or XVTR IN to avoid the loss of the high-pass filter in the T/R switch. >> >> Wayne >> N6KR >> >> >> >> ______________________________________________________________ >> 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 >> Message delivered to [hidden email] > > ______________________________________________________________ > 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 > Message delivered to [hidden email] 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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I agree with both comments. In the real world most of us inhabit,
environmental noise is the killer. To the extent that the loops will help reject some noise, the extra sensitivity can help. 73, Jim K9YC On Wed,4/29/2015 11:42 PM, Wayne Burdick wrote: > That excellent sensitivity will allow the use of lossy antennas like small loops, etc. I was tuning around listening to beacons from 200-300 kHz, and the difference with the mods is very apparent. > > Wayne > N6KR > > ---- > http://www.elecraft.com > >> On Apr 29, 2015, at 10:53 PM, Barry LaZar <[hidden email]> wrote: >> >> Wayne, >> I don't think I'd get too spun up over sensitivity of better than -95 DBM below the AM BC band. You are going to run in to a practical limit set by atmospheric and man made noise. If you assume a -147 dbm for a perfect receiver in a 500 Hz BW, used because the math is easier, and then subtract 60 db for expected value of noise on 80 meters, you should find that the K3 sensitivity greatly exceeds what could practically be used. I did not look at the noise figure for the K3 as I assume it is much, much better than the expected value of what the antenna will see. And, the environmental noise gets worse as you decrease frequency. I guess what I'm trying to convey is the idea that you already have a superb design. So, will you have done anything to the radio's characteristics in the higher regions of the spectrum to achieve better MF and down performance? >> >> 73, >> Barry >> K3NDM >> >>> On 4/29/2015 11:55 PM, Wayne Burdick wrote: >>>> On Apr 29, 2015, at 8:30 PM, drewko <[hidden email]> wrote: >>>> >>>> IIRC, original statement for the new board was -120 dBm at 475 KHz. >>> That was conservative. >>> >>> >>>> Now saying -133 with the mods. >>> At least on my lab K3. >>> >>> >>>> Maybe broadcast band DXers would find it useful on the lower half of the AM band? >>> Could be. On my K3, with the mods, the MDS at 1.0 MHz is now -136 dBm, preamp on (400 Hz BW). >>> >>> Just keep in mind that in the lower frequency ranges, you'll want to use RX ANT IN or XVTR IN to avoid the loss of the high-pass filter in the T/R switch. >>> >>> Wayne >>> N6KR >>> >>> >>> >>> ______________________________________________________________ >>> 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 >>> Message delivered to [hidden email] >> ______________________________________________________________ >> 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 >> Message delivered to [hidden email] > ______________________________________________________________ > 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 > Message delivered to [hidden email] > ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by wayne burdick
So, after this testing is completed, will production KBPF3s be shipped
with the modifications? 73, Ross N4RP On 4/29/2015 9:23 PM, Wayne Burdick wrote: > Hi all, > > In honor of the FCC's proposed "2200 meter" allocation (137 kHz), we decided to see if we could improve the K3's receive sensitivity in the 100-500 kHz range. This extended coverage is made possible by the new synth (KSYN3A). > > After a lot of digging, we discovered the cause of the wide-band low-frequency noise. We also found a way to shift the passband of the KBPF3 lower. > > With a couple of simple modifications, the MDS (minimum discernible signal) can be improved by about 25 dB at the low end (100 kHz). Here are some test results (preamp off, 400-Hz bandwidth): > > 137 kHz -114 dBm FCC's proposed 2200 meter band > 160 kHz -117 dBm low end of the "Low-Fer" band > 250 kHz -126 dBm test frequency in the long-wave beacon band > 472 kHz -133 dBm 630 meter experimental band > > This represents an improvement throughout the range, but especially at the low end. I believe -114 dBm MDS should suffice at 137 kHz, given the high band noise in this range. > > Another indication of how well the mods work: With no antenna connoted, the K3's S-meter now just barely flickers (S1) at 100 kHz. Without the mods, the no-antenna S-meter reading could be as high as S7 due to the noise source we've now identified (a voltage regulator). (By the way, this regulator noise had no impact on frequencies about about 500 kHz.) > > Here's a summary of the changes required: > > RF board: Add one leaded capacitor > KRX3 (if applicable): Add one leaded capacitor > KBPF3: Remove two inductors; parallel three new capacitors > > If you're interested in this low frequency range, and you'd like to try the mods, please email me directly. > > Note: To tune this range with the K3, you'll need the new synth (KSYN3A), a KBPF3 module (on the main and/or sub receiver), and a KXV3 module. A KXV3 is required because the antenna for the 100-500 kHz range should be connected to RX ANT IN or XVTR IN. The ANT1/ANT2 path goes through the T/R switch, which has a high-pass filter to protect the K3's fast PIN-diode T/R circuitry. > > 73, > Wayne > N6KR > > ______________________________________________________________ > 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 > Message delivered to [hidden email] -- FCC Section 97.313(a) “At all times, an amateur station must use the minimum transmitter power necessary to carry out the desired communications.” ______________________________________________________________ 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 Message delivered to [hidden email] |
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I assume there will be a set of notes on the Elecraft website so that we can all retrofit this mod??
Andy G4HUE ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: [Elecraft_K3] Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by Ross Primrose
Maybe. First we need feedback from early testers, which I expect we'll have in a couple of days.
73, Wayne N6KR On Apr 30, 2015, at 7:27 AM, "Ross Primrose [hidden email] [Elecraft_K3]" <[hidden email]> wrote: > So, after this testing is completed, will production KBPF3s be shipped > with the modifications? > > 73, Ross N4RP ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: [Elecraft_K3] Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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I expected there might be several iterations. ;)
73, Ross N4RP On 4/30/2015 10:45 AM, Wayne Burdick [hidden email] [Elecraft_K3] wrote: > Maybe. First we need feedback from early testers, which I expect we'll have in a couple of days. > > 73, > Wayne > N6KR > > > On Apr 30, 2015, at 7:27 AM, "Ross Primrose [hidden email] [Elecraft_K3]" <[hidden email]> wrote: > >> So, after this testing is completed, will production KBPF3s be shipped >> with the modifications? >> >> 73, Ross N4RP > > > > > ------------------------------------ > > ------------------------------------ > > > ------------------------------------ > > Yahoo Groups Links > > <*> To visit your group on the web, go to: > http://groups.yahoo.com/group/Elecraft_K3/ > > <*> Your email settings: > Individual Email | Traditional > > <*> To change settings online go to: > http://groups.yahoo.com/group/Elecraft_K3/join > (Yahoo! ID required) > > <*> To change settings via email: > [hidden email] > [hidden email] > > <*> To unsubscribe from this group, send an email to: > [hidden email] > > <*> Your use of Yahoo Groups is subject to: > https://info.yahoo.com/legal/us/yahoo/utos/terms/ > -- FCC Section 97.313(a) “At all times, an amateur station must use the minimum transmitter power necessary to carry out the desired communications.” ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by wayne burdick
Roger that. I hadn't considered a small loop. I have a small backyard
with fairly big wire antennas. And, of course you are are correct when you add that consideration. Hope to meet you and your partner at Dayton. 73, Barry K3NDM On 4/30/2015 2:42 AM, Wayne Burdick wrote: > That excellent sensitivity will allow the use of lossy antennas like small loops, etc. I was tuning around listening to beacons from 200-300 kHz, and the difference with the mods is very apparent. > > Wayne > N6KR > > ---- > http://www.elecraft.com > >> On Apr 29, 2015, at 10:53 PM, Barry LaZar <[hidden email]> wrote: >> >> Wayne, >> I don't think I'd get too spun up over sensitivity of better than -95 DBM below the AM BC band. You are going to run in to a practical limit set by atmospheric and man made noise. If you assume a -147 dbm for a perfect receiver in a 500 Hz BW, used because the math is easier, and then subtract 60 db for expected value of noise on 80 meters, you should find that the K3 sensitivity greatly exceeds what could practically be used. I did not look at the noise figure for the K3 as I assume it is much, much better than the expected value of what the antenna will see. And, the environmental noise gets worse as you decrease frequency. I guess what I'm trying to convey is the idea that you already have a superb design. So, will you have done anything to the radio's characteristics in the higher regions of the spectrum to achieve better MF and down performance? >> >> 73, >> Barry >> K3NDM >> >>> On 4/29/2015 11:55 PM, Wayne Burdick wrote: >>>> On Apr 29, 2015, at 8:30 PM, drewko <[hidden email]> wrote: >>>> >>>> IIRC, original statement for the new board was -120 dBm at 475 KHz. >>> That was conservative. >>> >>> >>>> Now saying -133 with the mods. >>> At least on my lab K3. >>> >>> >>>> Maybe broadcast band DXers would find it useful on the lower half of the AM band? >>> Could be. On my K3, with the mods, the MDS at 1.0 MHz is now -136 dBm, preamp on (400 Hz BW). >>> >>> Just keep in mind that in the lower frequency ranges, you'll want to use RX ANT IN or XVTR IN to avoid the loss of the high-pass filter in the T/R switch. >>> >>> Wayne >>> N6KR >>> >>> >>> >>> ______________________________________________________________ >>> 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 >>> Message delivered to [hidden email] >> ______________________________________________________________ >> 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 >> Message delivered to [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by wayne burdick
Wayne and all: Sky noise using a 630m inverted-L is -120 dBm at best
and more often -115 dBm so K3 Rx is satisfactory at 630m with stock KBPF3. I also use a SDR-IQ that has a MDS of -132 dBm which measures -115 dBm noise floor from the inverted-L. Use of Beverage antennas or Loop antennas can provide lower noise floors depending on your location (southern latitudes are noisier due to lightening activity). 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: [Elecraft_K3] Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by wayne burdick
Hi Wayne and all,
the most important is to be sure that it will not affect all the other bands mainly BDR etc. by IMD products from strong sigs below 500kHz... ;( Thank You very much Wayne for posting update regarding this improvement / development. 73 - Petr, OK1RP
73 - Petr, OK1RP
"Apple & Elecraft freak" B:http://ok1rp.blogspot.com MeWe: https://bit.ly/2HGPoDx MeWe: https://bit.ly/2FmwvDt |
Re: [Elecraft_K3] Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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Administrator
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Hi Petr,
The modification only affects 500 kHz and lower. We'll have a modification kit ready in a week or two. A few K3s have been modified so far, and all performed very well. 73, Wayne N6KR On May 13, 2015, at 8:27 AM, ok1rp <[hidden email]> wrote: > Hi Wayne and all, > > the most important is to be sure that it will not affect all the other bands > mainly BDR etc. by IMD products from strong sigs below 500kHz... ;( > > Thank You very much Wayne for posting update regarding this improvement / > development. > > 73 - Petr, OK1RP ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: [Elecraft_K3] Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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Good to hear the kit will be ready reasonably
soon, Wayne. Seems like a good change to make, so I will. Phil W7OX On 5/13/15 8:39 AM, Wayne Burdick wrote: > Hi Petr, > > The modification only affects 500 kHz and lower. We'll have a modification kit ready in a week or two. > > A few K3s have been modified so far, and all performed very well. > > 73, > Wayne > N6KR > > > On May 13, 2015, at 8:27 AM, ok1rp <[hidden email]> wrote: > >> Hi Wayne and all, >> >> the most important is to be sure that it will not affect all the other bands >> mainly BDR etc. by IMD products from strong sigs below 500kHz... ;( >> >> Thank You very much Wayne for posting update regarding this improvement / >> development. >> >> 73 - Petr, OK1RP ______________________________________________________________ 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 Message delivered to [hidden email] |
Re: [Elecraft_K3] Re: Dramatic improvement in K3 RX sensitivity below 500 kHz -- looking for testers
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In reply to this post by wayne burdick
There it is from the horse's mouth (keyboard)! It's a *K3s*...
73, Josh W6XU On 5/13/2015 8:39 AM, Wayne Burdick wrote: > A few*K3s* have been modified so far, and all performed very well. > > 73, > Wayne > N6KR ______________________________________________________________ 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 Message delivered to [hidden email] |
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