K3 SWR Question3
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Hello,
My K3 is exhibiting some SWR meter behavior I don’t quite understand. To eliminate any possible effects of antennas or cabling, I hooked a Palstar DL2K dummy load directly to the K3 antenna connector. All bands except 40 meters seem fine, with SWR reading as you would expect with a dummy load. The anomaly I am seeing is that SWR as shown on the K3 meter looks fine at 7.01 MHz (approx. 1.2:1), but as I go up in frequency, the SWR as shown on the K3 meter rises. When I transmit into the dummy load on 7.298 MHz, the K3 meter reads almost 3:1. I can switch in the K3 internal tuner and bring the SWR down to 1:1. I also tried an older Cantenna dummy load with the same puzzling results. Any ideas as to what may be causing this 40 meter only problem? I first noticed this problem during NAQP SSB when using my Steppir, which of course retunes itself as I change frequency. When going from the low part of the phone band to the high part on 40 meters, I noticed SWR increasing on the K3 meter, even though it was not increasing and stayed at 1.2:1 on my inline LP-100A. The K3 also started to fold back power. That prompted me to do the further testing with the dummy load as I discussed above. --Ed— Sent from Mail for Windows 10 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ 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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Hi Ed
I recall having had a similar experience with my K3 some years ago, although it wasn't on 40m. I think it was either 10 or 12m and related to an antenna connected to the ANT 1 socket. Eventually I tracked it down to having previously had an antenna connected to the ANT 2 socket and having used the ATU in the K3 to tune it at that time although I think that there was no antenna on ANT 2 when the problem cropped up. I believe that the feed through between ANT 1 and 2 sockets was sufficient to give a false SWR reading on the K3. It might be worth investigating this and possibly swapping over your antenna/dummy load to the ANT 2 socket to see what happens. I think I eventually just retuned the ATU on ANT 2 with a dummy load in place and the problem went away. Good luck. Barry VK2BJ On Mon, 21 Jan 2019 at 04:17, Ed G <[hidden email]> wrote: > Hello, > My K3 is exhibiting some SWR meter behavior I don’t quite understand. > To eliminate any possible effects of antennas or cabling, I hooked a > Palstar DL2K dummy load directly to the K3 antenna connector. All bands > except 40 meters seem fine, with SWR reading as you would expect with a > dummy load. The anomaly I am seeing is that SWR as shown on the K3 meter > looks fine at 7.01 MHz (approx. 1.2:1), but as I go up in frequency, the > SWR as shown on the K3 meter rises. When I transmit into the dummy load on > 7.298 MHz, the K3 meter reads almost 3:1. I can switch in the K3 internal > tuner and bring the SWR down to 1:1. > I also tried an older Cantenna dummy load with the same puzzling > results. Any ideas as to what may be causing this 40 meter only problem? > I first noticed this problem during NAQP SSB when using my Steppir, which > of course retunes itself as I change frequency. When going from the low > part of the phone band to the high part on 40 meters, I noticed SWR > increasing on the K3 meter, even though it was not increasing and stayed at > 1.2:1 on my inline LP-100A. The K3 also started to fold back power. That > prompted me to do the further testing with the dummy load as I discussed > above. > --Ed— > > > Sent from Mail for Windows 10 > > > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > ______________________________________________________________ > 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] |
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Hi Barry,
I think what I am seeing is related to your experience. I ran through some additional testing. I see perhaps some slight differences between ANT1 and ANT2 positions as far as SWR readings, but nothing significant, at least on 40 meters. I do now see something I’m even more puzzled over. While collecting SWR readings into a dummy load on 10 meters, I initially did see a high (2.0:1) reading on the K3 meter. I switched in the K3 tuner, and brought the SWR down to 1:1. But when I then bypassed the tuner, the low 1:1 SWR remained. This was true for either ANT1 or ANT2. I really don’t understand that. So back to 40 meters, where I first noticed the high SWR anomaly. I thought I would try the tuner again, and then bypass it, to see if SWR would stay low on the K3 meter as it did on 10 meters. It did not. So I still have the anomaly on 40 meters, and it is the same on either ANT1 or ANT2 positions. To summarize: 1. SWR using a dummy load on 40 meters remains constant using an external LP-100A meter, but varies greatly using the K3 meter. As you tune up in frequency on the 40 meter band, the SWR on the K3 meter rises to almost 3:1, and the K3 output power drops back significantly. 2. Antenna tuner settings appear to “stick” on 10 meters, even when the tuner is bypassed. I believe some users, assuming there are others that have K3s which would exhibit this behavior, may not have noticed this anomaly. I do believe it may be responsible for what some users have noticed when using their K3 with an amp such as the KPA1500. That is, power overshoot. I suspect the K3, at least for me on 40 meters, is folding back power in response to a false SWR reading, and this can be seen in how the KPA1500 amp correspondingly drops back in power as the user transmits. That is perhaps why (again, for my situation) I see the power overshoot only on 40 meters when using my KPA1500. --Ed— Sent from Mail for Windows 10 From: Barry Simpson Sent: Monday, January 21, 2019 1:51 AM To: Ed G; Elecraft Mailing List Subject: Re: [Elecraft] K3 SWR Question3 Hi Ed I recall having had a similar experience with my K3 some years ago, although it wasn't on 40m. I think it was either 10 or 12m and related to an antenna connected to the ANT 1 socket. Eventually I tracked it down to having previously had an antenna connected to the ANT 2 socket and having used the ATU in the K3 to tune it at that time although I think that there was no antenna on ANT 2 when the problem cropped up. I believe that the feed through between ANT 1 and 2 sockets was sufficient to give a false SWR reading on the K3. It might be worth investigating this and possibly swapping over your antenna/dummy load to the ANT 2 socket to see what happens. I think I eventually just retuned the ATU on ANT 2 with a dummy load in place and the problem went away. Good luck. Barry VK2BJ On Mon, 21 Jan 2019 at 04:17, Ed G <[hidden email]> wrote: Hello, My K3 is exhibiting some SWR meter behavior I don’t quite understand. To eliminate any possible effects of antennas or cabling, I hooked a Palstar DL2K dummy load directly to the K3 antenna connector. All bands except 40 meters seem fine, with SWR reading as you would expect with a dummy load. The anomaly I am seeing is that SWR as shown on the K3 meter looks fine at 7.01 MHz (approx. 1.2:1), but as I go up in frequency, the SWR as shown on the K3 meter rises. When I transmit into the dummy load on 7.298 MHz, the K3 meter reads almost 3:1. I can switch in the K3 internal tuner and bring the SWR down to 1:1. I also tried an older Cantenna dummy load with the same puzzling results. Any ideas as to what may be causing this 40 meter only problem? I first noticed this problem during NAQP SSB when using my Steppir, which of course retunes itself as I change frequency. When going from the low part of the phone band to the high part on 40 meters, I noticed SWR increasing on the K3 meter, even though it was not increasing and stayed at 1.2:1 on my inline LP-100A. The K3 also started to fold back power. That prompted me to do the further testing with the dummy load as I discussed above. --Ed— Sent from Mail for Windows 10 --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ 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] |
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Have you done a TX GAIN CAL procedure? I have found this often solves
quirky problems that have cropped up with my K3 over the past 10 years. Also, if you are getting power overshoot, check to be sure your MIC or LINE IN is not set higher than 4 bars with the 5th bar flashing on the ALC meter. 73 Eric WD6DBM On Mon, Jan 21, 2019, 5:36 AM Ed G <[hidden email] wrote: > Hi Barry, > I think what I am seeing is related to your experience. I ran through > some additional testing. I see perhaps some slight differences between ANT1 > and ANT2 positions as far as SWR readings, but nothing significant, at > least on 40 meters... > ______________________________________________________________ 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 Ed G
The revised KAT3A has a hard bypass with relays. The KAT3 does a “soft” bypass by placing the tuning network in some kind of neutral position.
I don’t know what the KAT3 actually does to achieve this, but is it possible this is somehow related to the anomaly you are seeing? With the KAT3 in “neutral” (whatever that actually means), since the SWR bridge sits between the KPA3 output and the KAT3 input, maybe that’s something to look at — or at least get more info from Elecraft about how it works and if that might be related. Grant NQ5T K3 #2091 KX3 #8342 > On Jan 21, 2019, at 8:34 AM, Ed G <[hidden email]> wrote: > > Hi Barry, > I think what I am seeing is related to your experience. I ran through some additional testing. I see perhaps some slight differences between ANT1 and ANT2 positions as far as SWR readings, but nothing significant, at least on 40 meters. > I do now see something I’m even more puzzled over. While collecting SWR readings into a dummy load on 10 meters, I initially did see a high (2.0:1) reading on the K3 meter. I switched in the K3 tuner, and brought the SWR down to 1:1. But when I then bypassed the tuner, the low 1:1 SWR remained. This was true for either ANT1 or ANT2. I really don’t understand that. > So back to 40 meters, where I first noticed the high SWR anomaly. I thought I would try the tuner again, and then bypass it, to see if SWR would stay low on the K3 meter as it did on 10 meters. It did not. So I still have the anomaly on 40 meters, and it is the same on either ANT1 or ANT2 positions. > To summarize: > 1. SWR using a dummy load on 40 meters remains constant using an external LP-100A meter, but varies greatly using the K3 meter. As you tune up in frequency on the 40 meter band, the SWR on the K3 meter rises to almost 3:1, and the K3 output power drops back significantly. > 2. Antenna tuner settings appear to “stick” on 10 meters, even when the tuner is bypassed. > > I believe some users, assuming there are others that have K3s which would exhibit this behavior, may not have noticed this anomaly. I do believe it may be responsible for what some users have noticed when using their K3 with an amp such as the KPA1500. That is, power overshoot. I suspect the K3, at least for me on 40 meters, is folding back power in response to a false SWR reading, and this can be seen in how the KPA1500 amp correspondingly drops back in power as the user transmits. That is perhaps why (again, for my situation) I see the power overshoot only on 40 meters when using my KPA1500. > --Ed— > ______________________________________________________________ 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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Looking at the KAT3 schematic indicates that in bypass all the relays
are set such that all the series inductors are individually short circuited and all the capacitors are open circuit. This potentially introduces strays due to the short circuit inductors, relays and pcb tracks still in the RF path. I believe it is mentioned on the Elecraft web site that this is the reason for the KAT3A having a "true bypass" or words to that effect. It was suggested that you could tune out the strays by tuning the ATU into a dummy load rather than simply putting it in bypass. I've just checked my KAT3 action by tuning each band via the Ant1 port into an Oak Hills Research 100W dummy load and comparing the result with simply bypassing it. All the way from 160m to 10m both states "Auto" and "Bypass" read 1.0-1 On 6m both read 1.1-1. I normally have the KAT3 in "bypass" given that much of the time my K3 is looking at the input circuit of an Acom 1000 or the antennas are already an acceptable match. There were clearly some long forgotten tuning solutions still sitting in the atu memory which were tuned out whilst feeding the dummy load. Regards, Mike VP8NO On 21/01/2019 12:40, Grant Youngman wrote: > The revised KAT3A has a hard bypass with relays. The KAT3 does a “soft” bypass by placing the tuning network in some kind of neutral position. > > I don’t know what the KAT3 actually does to achieve this, but is it possible this is somehow related to the anomaly you are seeing? With the KAT3 in “neutral” (whatever that actually means), since the SWR bridge sits between the KPA3 output and the KAT3 input, maybe that’s something to look at — or at least get more info from Elecraft about how it works and if that might be related. > > Grant NQ5T > K3 #2091 KX3 #8342 > >> On Jan 21, 2019, at 8:34 AM, Ed G <[hidden email]> wrote: >> >> Hi Barry, >> I think what I am seeing is related to your experience. I ran through some additional testing. I see perhaps some slight differences between ANT1 and ANT2 positions as far as SWR readings, but nothing significant, at least on 40 meters. >> I do now see something I’m even more puzzled over. While collecting SWR readings into a dummy load on 10 meters, I initially did see a high (2.0:1) reading on the K3 meter. I switched in the K3 tuner, and brought the SWR down to 1:1. But when I then bypassed the tuner, the low 1:1 SWR remained. This was true for either ANT1 or ANT2. I really don’t understand that. >> So back to 40 meters, where I first noticed the high SWR anomaly. I thought I would try the tuner again, and then bypass it, to see if SWR would stay low on the K3 meter as it did on 10 meters. It did not. So I still have the anomaly on 40 meters, and it is the same on either ANT1 or ANT2 positions. >> To summarize: >> 1. SWR using a dummy load on 40 meters remains constant using an external LP-100A meter, but varies greatly using the K3 meter. As you tune up in frequency on the 40 meter band, the SWR on the K3 meter rises to almost 3:1, and the K3 output power drops back significantly. >> 2. Antenna tuner settings appear to “stick” on 10 meters, even when the tuner is bypassed. >> >> I believe some users, assuming there are others that have K3s which would exhibit this behavior, may not have noticed this anomaly. I do believe it may be responsible for what some users have noticed when using their K3 with an amp such as the KPA1500. That is, power overshoot. I suspect the K3, at least for me on 40 meters, is folding back power in response to a false SWR reading, and this can be seen in how the KPA1500 amp correspondingly drops back in power as the user transmits. That is perhaps why (again, for my situation) I see the power overshoot only on 40 meters when using my KPA1500. >> --Ed— 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 Ed G
Hi Mike,
Have not heard from Support yet. But this is an interesting discussion and I am learning some things from the group. I had not kept up with the differences between the KAT3 and the KAT3A, but it would seem that’s at the center of the issue I have. My K3 is S/N 02977, and I have the KAT3 tuner. Apparently the KAT3 is not really bypassed in the BYPASS position. From reading earlier posts, the KAT3 supposedly sets itself for what it thinks is a 50 ohm match when in the BYPASS position. It was suggested by Joe, W4TV, that the user could enable the tuner, tune into a dummy load and then bypass the tuner, and that process would reset the bypass settings. That seems to have worked for me on 10 meters, but not on 40 meters. So part of my original post has been answered, but here’s what remains: 1. With my particular KAT3, I am not sure why the recal of bypass settings per W4TV does not work on 40 meters. 2. If the KAT3 is not truly being bypassed, can there be some unexpected results when using the K3 with the KPA1500, such as power overshoot? 3. Am I ok to enable the KAT3 in my K3 and also use the tuner in the KPA1500? Otherwise I am having to readjust the K3 power out setting as I change frequency on 40 meters, to keep from overdriving the KPA1500. It would appear that I might have some unknown tuner circuit issue when bypassing the tuner on 40 meters due to whatever is still in the RF path, or perhaps even the faulty trap component Mike mentioned. Elecraft – do I need to replace the KAT3 with the KAT3A to get rid of this problem, and eliminate the need to readjust power up when using my KPA1500? I appreciate all the responses so far! --Ed— Sent from Mail for Windows 10 From: Mike Wetzel Sent: Monday, January 21, 2019 1:33 PM To: [hidden email] Subject: K3 SWR Ed, I’m sure you have heard from Elecraft Support on this but just in case. I had a very similar problem on 40 meter a couple of years ago. It turned out to be a faulty trap component on a nearly vacant board near the ant terminals. The trap is not needed I removed a cap and all has been fine ever since. Mike W9RE I think what I am seeing is related to your experience. I ran through some additional testing. I see perhaps some slight differences between ANT1 and ANT2 positions as far as SWR readings, but nothing significant, at least on 40 meters. I do now see something I?m even more puzzled over. While collecting SWR readings into a dummy load on 10 meters, I initially did see a high (2.0:1) reading on the K3 meter. I switched in the K3 tuner, and brought the SWR down to 1:1. But when I then bypassed the tuner, the low 1:1 SWR remained. This was true for either ANT1 or ANT2. I really don?t understand that. So back to 40 meters, where I first noticed the high SWR anomaly. I thought I would try the tuner again, and then bypass it, to see if SWR would stay low on the K3 meter as it did on 10 meters. It did not. So I still have the anomaly on 40 meters, and it is the same on either ANT1 or ANT2 positions. To summarize: 1. SWR using a dummy load on 40 meters remains constant using an external LP-100A meter, but varies greatly using the K3 meter. As you tune up in frequency on the 40 meter band, the SWR on the K3 meter rises to almost 3:1, and the K3 output power drops back significantly. 2. Antenna tuner settings appear to ?stick? on 10 meters, even when the tuner is bypassed. I believe some users, assuming there are others that have K3s which would exhibit this behavior, may not have noticed this anomaly. I do believe it may be responsible for what some users have noticed when using their K3 with an amp such as the KPA1500. That is, power overshoot. I suspect the K3, at least for me on 40 meters, is folding back power in response to a false SWR reading, and this can be seen in how the KPA1500 amp correspondingly drops back in power as the user transmits. That is perhaps why (again, for my situation) I see the power overshoot only on 40 meters when using my KPA1500. --Ed? --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ 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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This may be out of left field, but I seem to recall from the deep recesses of
my memory that there were some issues regarding an IF trap in the output of the K3. It could be that one of the components in the trap has changed and it now affects 40m. I don't know if newer K3s even have this circuit. Just thinking out loud. Larry N8LP -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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