Strange SWR change on 20 at
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I recently started using my horizontal loop that is about a full wavelength
on 80, for 20 meters. I took down my yagi as we are moving; drat! My Horizontal Loop is at 40 ft. height and fed with 450 window line into a 4:1 voltage balun with about 15 ft. of coax to rig. I am running 100 watts through my KXPA100. I tune a frequency in the CW portion of 20 to about 1.2 :1 and start sending CQ. After about 3 to 4 3x3 CQ's,, the SWR goes off the charts and power drops to zero. I can retune the antenna and the process repeats itself. 20 meters is the only band affected. I am wondering if I am having RF problems in that part of the 20 meter bands This only occurs on 20 meters. The Amp is grounded, but the KX3 is not bonded to the Amp. I would appreciate any advice. Thanks and 73's, Terry de N7TB ______________________________________________________________ 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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Hmmm... I am having the exact same issue... My SWR changes after a few
transmissions, then returns... Up until now, I have been suspecting my antenna... Time to add an external SWR bridge between the tuner and antenna as a permanent thing... 73s and thanks, Dave NK7Z http://www.nk7z.net On 05/13/2017 09:07 AM, Terry Brown wrote: > I recently started using my horizontal loop that is about a full wavelength > on 80, for 20 meters. I took down my yagi as we are moving; drat! My > Horizontal Loop is at 40 ft. height and fed with 450 window line into a 4:1 > voltage balun with about 15 ft. of coax to rig. > > > > I am running 100 watts through my KXPA100. I tune a frequency in the CW > portion of 20 to about 1.2 :1 and start sending CQ. After about 3 to 4 3x3 > CQ's,, the SWR goes off the charts and power drops to zero. I can retune > the antenna and the process repeats itself. 20 meters is the only band > affected. > > > > I am wondering if I am having RF problems in that part of the 20 meter bands > This only occurs on 20 meters. The Amp is grounded, but the KX3 is not > bonded to the Amp. > > > > I would appreciate any advice. > > > > Thanks and 73's, > > > > Terry de N7TB > > ______________________________________________________________ > 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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In reply to this post by Terry
What's the antenna impedance before the ATU is activated? You may be heating up the BALUN due to big mis-match.
Sent from my iPhone ...nr4c. bill > On May 13, 2017, at 12:07 PM, Terry Brown <[hidden email]> wrote: > > I recently started using my horizontal loop that is about a full wavelength > on 80, for 20 meters. I took down my yagi as we are moving; drat! My > Horizontal Loop is at 40 ft. height and fed with 450 window line into a 4:1 > voltage balun with about 15 ft. of coax to rig. > > > > I am running 100 watts through my KXPA100. I tune a frequency in the CW > portion of 20 to about 1.2 :1 and start sending CQ. After about 3 to 4 3x3 > CQ's,, the SWR goes off the charts and power drops to zero. I can retune > the antenna and the process repeats itself. 20 meters is the only band > affected. > > > > I am wondering if I am having RF problems in that part of the 20 meter bands > This only occurs on 20 meters. The Amp is grounded, but the KX3 is not > bonded to the Amp. > > > > I would appreciate any advice. > > > > Thanks and 73's, > > > > Terry de N7TB > > ______________________________________________________________ > 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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In reply to this post by Terry
Terry,
I would be suspicious of the voltage balun, or connections in the feedline/antenna that are breaking down with increased power. Change the voltage balun to a good common mode choke. A 1:1 choke may work as well or better than a 4:1. You might also have a lot of common mode current on the 450 ohm feedline. A common mode choke on each side of the feedline (at the antenna) will help if that is the case. 73, Don W3FPR On 5/13/2017 12:07 PM, Terry Brown wrote: > I recently started using my horizontal loop that is about a full wavelength > on 80, for 20 meters. I took down my yagi as we are moving; drat! My > Horizontal Loop is at 40 ft. height and fed with 450 window line into a 4:1 > voltage balun with about 15 ft. of coax to rig. > > > > I am running 100 watts through my KXPA100. I tune a frequency in the CW > portion of 20 to about 1.2 :1 and start sending CQ. After about 3 to 4 3x3 > CQ's,, the SWR goes off the charts and power drops to zero. I can retune > the antenna and the process repeats itself. 20 meters is the only band > affected. > > > > I am wondering if I am having RF problems in that part of the 20 meter bands > This only occurs on 20 meters. The Amp is grounded, but the KX3 is not > bonded to the Amp. 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 NK7Z
I added the SWR meter... My actual SWR jumps instantly up about1 SWR
unit... I believe it is a bad connection on the Challenger where the main antenna connects to the 20 meter tuning stub... Just sort of surprised me to see a second person with the exact same issue is all... SWR change is instant, so it is not heating... Happens at 30 watts, or 1 KW... Time for a rebuild. 73s and thanks, Dave NK7Z http://www.nk7z.net On 05/13/2017 10:07 AM, Dave Cole wrote: > Hmmm... I am having the exact same issue... My SWR changes after a few > transmissions, then returns... Up until now, I have been suspecting my > antenna... Time to add an external SWR bridge between the tuner and > antenna as a permanent thing... > > 73s and thanks, > Dave > NK7Z > http://www.nk7z.net > > On 05/13/2017 09:07 AM, Terry Brown wrote: >> I recently started using my horizontal loop that is about a full >> wavelength >> on 80, for 20 meters. I took down my yagi as we are moving; drat! My >> Horizontal Loop is at 40 ft. height and fed with 450 window line into >> a 4:1 >> voltage balun with about 15 ft. of coax to rig. >> >> >> >> I am running 100 watts through my KXPA100. I tune a frequency in the CW >> portion of 20 to about 1.2 :1 and start sending CQ. After about 3 to >> 4 3x3 >> CQ's,, the SWR goes off the charts and power drops to zero. I can >> retune >> the antenna and the process repeats itself. 20 meters is the only band >> affected. >> >> >> >> I am wondering if I am having RF problems in that part of the 20 meter >> bands >> This only occurs on 20 meters. The Amp is grounded, but the KX3 is not >> bonded to the Amp. >> >> >> >> I would appreciate any advice. >> >> >> >> Thanks and 73's, >> >> >> >> Terry de N7TB >> >> ______________________________________________________________ >> 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] |
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In reply to this post by Terry
I have ALMOST the same setup.... horiz loop at approx. 40 ft cut for
80m, fed with 45 feet or so of 300 Ohm (18 GA) foam core, twin-lead to a Balun Designs 6:1, to TMW 240-DB coax (18-20 feet) to the K3s. Never experienced anything like what you are.... sounds like something is heating up... balun maybe?... almost like something heating up and opening... ______________________ Clay Autery, KY5G On 5/13/2017 11:07 AM, Terry Brown wrote: > I recently started using my horizontal loop that is about a full wavelength > on 80, for 20 meters. I took down my yagi as we are moving; drat! My > Horizontal Loop is at 40 ft. height and fed with 450 window line into a 4:1 > voltage balun with about 15 ft. of coax to rig. > > > > I am running 100 watts through my KXPA100. I tune a frequency in the CW > portion of 20 to about 1.2 :1 and start sending CQ. After about 3 to 4 3x3 > CQ's,, the SWR goes off the charts and power drops to zero. I can retune > the antenna and the process repeats itself. 20 meters is the only band > affected. > > > > I am wondering if I am having RF problems in that part of the 20 meter bands > This only occurs on 20 meters. The Amp is grounded, but the KX3 is not > bonded to the Amp. > > > > I would appreciate any advice. > > > > Thanks and 73's, > > > > Terry de N7TB 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 NK7Z
I have had similar problems with swr trips on my KPA500, only after several
transmissions on some bands. By a process of elimination it was traced to a toroidal voltage heating up in an external coupler. It came on suddenly after about 5 minutes of transmissions, and came good after a few minutes to cool. Replacing the toroid with a larger one cured the problem. "Ron D'Eau Claire" <[hidden email]> wrote: > Hi Dave: I thought you said it happened after you sent CQ+Call a few > times. When a core heats to its Curie temp, the inductance change happens > "instantly". You are right - if it happens instantly when you hit the key > it is not heating. Something is breaking down. > > 73, Ron AC7AC > > -----Original Message----- From: Elecraft > [mailto:[hidden email]] On Behalf Of Dave Cole Sent: > Saturday, May 13, 2017 10:39 AM To: [hidden email] Subject: Re: > [Elecraft] Strange SWR change on 20 at > > I added the SWR meter... My actual SWR jumps instantly up about1 SWR > unit... I believe it is a bad connection on the Challenger where the main > antenna connects to the 20 meter tuning stub... > > Just sort of surprised me to see a second person with the exact same issue > is all... SWR change is instant, so it is not heating... Happens at 30 > watts, or 1 KW... Time for a rebuild. > > 73s and thanks, Dave NK7Z http://www.nk7z.net > > On 05/13/2017 10:07 AM, Dave Cole wrote: > > Hmmm... I am having the exact same issue... My SWR changes after a few > > transmissions, then returns... Up until now, I have been suspecting my > > antenna... Time to add an external SWR bridge between the tuner and > > antenna as a permanent thing... > > > > 73s and thanks, Dave NK7Z http://www.nk7z.net > > > > On 05/13/2017 09:07 AM, Terry Brown wrote: > > > I recently started using my horizontal loop that is about a full > > > wavelength on 80, for 20 meters. I took down my yagi as we are > > > moving; drat! My Horizontal Loop is at 40 ft. height and fed with > > > 450 window line into a 4:1 voltage balun with about 15 ft. of coax to > > > rig. > >> > >> > >> > > > I am running 100 watts through my KXPA100. I tune a frequency in the > > > CW portion of 20 to about 1.2 :1 and start sending CQ. After about 3 > > > to 4 3x3 CQ's,, the SWR goes off the charts and power drops to zero. > > > I can retune the antenna and the process repeats itself. 20 meters > > > is the only band affected. > >> > >> > >> > > > I am wondering if I am having RF problems in that part of the 20 meter > > > bands This only occurs on 20 meters. The Amp is grounded, but the KX3 > > > is not bonded to the Amp. > >> > >> > >> > > > I would appreciate any advice. > >> > >> > >> > > > Thanks and 73's, > >> > >> > >> > > > Terry de N7TB > >> > > > ______________________________________________________________ > > > 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] > > -- Brian Duffell Yarm England ______________________________________________________________ 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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Diddn't proof read enoough, meant voltage transformer.
Brian D <[hidden email]> wrote: > I have had similar problems with swr trips on my KPA500, only after > several transmissions on some bands. By a process of elimination it was > traced to a toroidal voltage transformer > heating up in an external coupler. It came on > suddenly after about 5 minutes of transmissions, and came good after a few > minutes to cool. Replacing the toroid with a larger one cured the problem. > > > > "Ron D'Eau Claire" <[hidden email]> wrote: > > > Hi Dave: I thought you said it happened after you sent CQ+Call a few > > times. When a core heats to its Curie temp, the inductance change > > happens "instantly". You are right - if it happens instantly when you > > hit the key it is not heating. Something is breaking down. > > > > 73, Ron AC7AC > > > > -----Original Message----- From: Elecraft > > [mailto:[hidden email]] On Behalf Of Dave Cole Sent: > > Saturday, May 13, 2017 10:39 AM To: [hidden email] Subject: > > Re: [Elecraft] Strange SWR change on 20 at > > > > I added the SWR meter... My actual SWR jumps instantly up about1 SWR > > unit... I believe it is a bad connection on the Challenger where the > > main antenna connects to the 20 meter tuning stub... > > > > Just sort of surprised me to see a second person with the exact same > > issue is all... SWR change is instant, so it is not heating... Happens > > at 30 watts, or 1 KW... Time for a rebuild. > > > > 73s and thanks, Dave NK7Z http://www.nk7z.net > > > > On 05/13/2017 10:07 AM, Dave Cole wrote: > > > Hmmm... I am having the exact same issue... My SWR changes after a > > > few transmissions, then returns... Up until now, I have been > > > suspecting my antenna... Time to add an external SWR bridge between > > > the tuner and antenna as a permanent thing... > > > > > > 73s and thanks, Dave NK7Z http://www.nk7z.net > > > > > > On 05/13/2017 09:07 AM, Terry Brown wrote: > > > > I recently started using my horizontal loop that is about a full > > > > wavelength on 80, for 20 meters. I took down my yagi as we are > > > > moving; drat! My Horizontal Loop is at 40 ft. height and fed with > > > > 450 window line into a 4:1 voltage balun with about 15 ft. of coax > > > > to rig. > > >> > > >> > > >> > > > > I am running 100 watts through my KXPA100. I tune a frequency in > > > > the CW portion of 20 to about 1.2 :1 and start sending CQ. After > > > > about 3 to 4 3x3 CQ's,, the SWR goes off the charts and power drops > > > > to zero. I can retune the antenna and the process repeats itself. > > > > 20 meters is the only band affected. > > >> > > >> > > >> > > > > I am wondering if I am having RF problems in that part of the 20 > > > > meter bands This only occurs on 20 meters. The Amp is grounded, but > > > > the KX3 is not bonded to the Amp. > > >> > > >> > > >> > > > > I would appreciate any advice. > > >> > > >> > > >> > > > > Thanks and 73's, > > >> > > >> > > >> > > > > Terry de N7TB > > >> > > > > ______________________________________________________________ > > > > 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] > > > > > > -- Brian Duffell Yarm England ______________________________________________________________ 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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