Re: [Elecraft] Question about antenna matching
That doesn't actually answer the question "what are manufacturers measuring when they quote 10:1 matching ability?", and makes a gross and insulting generalization about the quality of equipment produced for the amateur radio market. On Wed, Jul 14, 2021, 01:45 Ray wrote: > The Statement "This tuner will tune an 8:1 mismatch." > Is made in an Armature world, buy an Amateur person, > Not for a Professional Product by Calibrated Test Equipment. > This is Not New, it has happened for Decades. Buyer Beware. > WA6VAB Ray K3 > > > From: Al Lorona > Sent: Tuesday, July 13, 2021 9:32 AM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] Question about antenna matching > > Thanks to Al N1AL, Jack W6FB, and Dave AB7E for great information that > helped me a lot. > > I'm in the circuit simulation business, after all, and I confess that I > was just being lazy, so I ran some simulations that confirmed what Dave, in > particular, had said. > > As suggested by Dave, I chose typical Q values of 100 for the inductor and > 1000 for the capacitor. Then I simulated as many points as I could on the > entire Smith Chart to see 1/ if the tuner could tune each point to 50 ohms, > and 2/ what the power loss was in the tuner at each of those points. Then, > I discovered that K6JCA had already done this on his excellent blog at: > https://k6jca.blogspot.com/2015/03/notes-on-antenna-tuners-l-network-and.html > . The > guy is totally professional and exhaustive in his discussions. I really > admire his work. > > Anyway, it turns out you can make a graph of power lost in the tuner > versus phase angle of the load. As you might suspect, 'easy' loads of 5 or > 500 ohms resistive (SWR = 10:1) don't tax a tuner as much as reactive loads > do. In fact, they're near (but interestingly, not at) the areas of > *minimum* power loss. > > Whenever an antenna tuner is reviewed in QST, resistive mismatched loads > are usually used. I'd like to see tuners tested with reactive loads, but > the number of loads required to do this from 160 to 10 meters would be > enormous. I see why resistive loads are preferred, because you can re-use > the loads on every band. > > I'm frustrated by imprecise statements like, "This tuner will tune an 8:1 > mismatch." What does that mean? There has to be a better way for > manufacturers to spec the exact impedance ranges that their tuners will > tune. I like the method that I used, which shades a Smith Chart in color > based on the two criteria I listed above. One picture would tell you all > about a tuner's effectiveness. No real tuner can tune the entire Smith > Chart, but the more of the chart that is covered, the better the tuner. And > if you can shade the areas of higher tuner loss in red, then that would > also tell you an important piece of information. (However, to generate such > a plot through measurement you'd probably need a very expensive load-pull > setup, which is a totally separate discussion.) > > For the L-network I simulated, a particularly difficult 10:1 load was near > the 7 - j30 ohm point, which is toward the bottom edge of the Smith Chart > at a phase angle of 282 degrees (or -77 degrees), and a similar point near > the top edge. The lower impedances with capacitive reactance were > definitely the most difficult (using power loss as the measure of > 'difficulty') for the tuner to handle, which Dave stated in his post, while > the high impedances with inductive reactance were generally more difficult. > If your antenna must be mismatched, and you're using an L-network tuner, > you want it to be > 50 ohms with a little bit of capacitive reactance, or > below 50 and inductive. > > By the way, K6JCA actually put the Elecraft KAT500 through this simulated > evaluation and it tested so well that he ended up buying one. > > > Al W6LX/4 > > > __ > 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 > Message delivered to wa6...@gmail.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 > Message delivered to ju...@juliatuttle.net __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] Question about antenna matching
The Statement "This tuner will tune an 8:1 mismatch." Is made in an Armature world, buy an Amateur person, Not for a Professional Product by Calibrated Test Equipment. This is Not New, it has happened for Decades. Buyer Beware. WA6VAB Ray K3 From: Al Lorona Sent: Tuesday, July 13, 2021 9:32 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Question about antenna matching Thanks to Al N1AL, Jack W6FB, and Dave AB7E for great information that helped me a lot. I'm in the circuit simulation business, after all, and I confess that I was just being lazy, so I ran some simulations that confirmed what Dave, in particular, had said. As suggested by Dave, I chose typical Q values of 100 for the inductor and 1000 for the capacitor. Then I simulated as many points as I could on the entire Smith Chart to see 1/ if the tuner could tune each point to 50 ohms, and 2/ what the power loss was in the tuner at each of those points. Then, I discovered that K6JCA had already done this on his excellent blog at: https://k6jca.blogspot.com/2015/03/notes-on-antenna-tuners-l-network-and.html . The guy is totally professional and exhaustive in his discussions. I really admire his work. Anyway, it turns out you can make a graph of power lost in the tuner versus phase angle of the load. As you might suspect, 'easy' loads of 5 or 500 ohms resistive (SWR = 10:1) don't tax a tuner as much as reactive loads do. In fact, they're near (but interestingly, not at) the areas of *minimum* power loss. Whenever an antenna tuner is reviewed in QST, resistive mismatched loads are usually used. I'd like to see tuners tested with reactive loads, but the number of loads required to do this from 160 to 10 meters would be enormous. I see why resistive loads are preferred, because you can re-use the loads on every band. I'm frustrated by imprecise statements like, "This tuner will tune an 8:1 mismatch." What does that mean? There has to be a better way for manufacturers to spec the exact impedance ranges that their tuners will tune. I like the method that I used, which shades a Smith Chart in color based on the two criteria I listed above. One picture would tell you all about a tuner's effectiveness. No real tuner can tune the entire Smith Chart, but the more of the chart that is covered, the better the tuner. And if you can shade the areas of higher tuner loss in red, then that would also tell you an important piece of information. (However, to generate such a plot through measurement you'd probably need a very expensive load-pull setup, which is a totally separate discussion.) For the L-network I simulated, a particularly difficult 10:1 load was near the 7 - j30 ohm point, which is toward the bottom edge of the Smith Chart at a phase angle of 282 degrees (or -77 degrees), and a similar point near the top edge. The lower impedances with capacitive reactance were definitely the most difficult (using power loss as the measure of 'difficulty') for the tuner to handle, which Dave stated in his post, while the high impedances with inductive reactance were generally more difficult. If your antenna must be mismatched, and you're using an L-network tuner, you want it to be > 50 ohms with a little bit of capacitive reactance, or below 50 and inductive. By the way, K6JCA actually put the Elecraft KAT500 through this simulated evaluation and it tested so well that he ended up buying one. Al W6LX/4 __ 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 Message delivered to wa6...@gmail.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 Message delivered to arch...@mail-archive.com
[Elecraft] PX3 Panadapter for sale
A PX3 in like new condition with KX3 interconnection cable, power cable, and manual. The current Elecraft price is $730. $525 via Paypal shipped in the US __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] Question about antenna matching
Thanks to Al N1AL, Jack W6FB, and Dave AB7E for great information that helped me a lot. I'm in the circuit simulation business, after all, and I confess that I was just being lazy, so I ran some simulations that confirmed what Dave, in particular, had said. As suggested by Dave, I chose typical Q values of 100 for the inductor and 1000 for the capacitor. Then I simulated as many points as I could on the entire Smith Chart to see 1/ if the tuner could tune each point to 50 ohms, and 2/ what the power loss was in the tuner at each of those points. Then, I discovered that K6JCA had already done this on his excellent blog at: https://k6jca.blogspot.com/2015/03/notes-on-antenna-tuners-l-network-and.html . The guy is totally professional and exhaustive in his discussions. I really admire his work. Anyway, it turns out you can make a graph of power lost in the tuner versus phase angle of the load. As you might suspect, 'easy' loads of 5 or 500 ohms resistive (SWR = 10:1) don't tax a tuner as much as reactive loads do. In fact, they're near (but interestingly, not at) the areas of *minimum* power loss. Whenever an antenna tuner is reviewed in QST, resistive mismatched loads are usually used. I'd like to see tuners tested with reactive loads, but the number of loads required to do this from 160 to 10 meters would be enormous. I see why resistive loads are preferred, because you can re-use the loads on every band. I'm frustrated by imprecise statements like, "This tuner will tune an 8:1 mismatch." What does that mean? There has to be a better way for manufacturers to spec the exact impedance ranges that their tuners will tune. I like the method that I used, which shades a Smith Chart in color based on the two criteria I listed above. One picture would tell you all about a tuner's effectiveness. No real tuner can tune the entire Smith Chart, but the more of the chart that is covered, the better the tuner. And if you can shade the areas of higher tuner loss in red, then that would also tell you an important piece of information. (However, to generate such a plot through measurement you'd probably need a very expensive load-pull setup, which is a totally separate discussion.) For the L-network I simulated, a particularly difficult 10:1 load was near the 7 - j30 ohm point, which is toward the bottom edge of the Smith Chart at a phase angle of 282 degrees (or -77 degrees), and a similar point near the top edge. The lower impedances with capacitive reactance were definitely the most difficult (using power loss as the measure of 'difficulty') for the tuner to handle, which Dave stated in his post, while the high impedances with inductive reactance were generally more difficult. If your antenna must be mismatched, and you're using an L-network tuner, you want it to be > 50 ohms with a little bit of capacitive reactance, or below 50 and inductive. By the way, K6JCA actually put the Elecraft KAT500 through this simulated evaluation and it tested so well that he ended up buying one. Al W6LX/4 __ 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 Message delivered to arch...@mail-archive.com
[Elecraft] Question about antenna matching
It's probably worth noting that KAT500 stores the bypass SWR (VSWRB) for every tuning solution (every bin and every antenna in that bin). The bypass SWR is used to limit the power that can be applied to the tuner without it faulting. e.g. DM BN00;BIN 31;FR 1810-1819;ADDR 10612; AN3;BYPN;SIDET;CE7;L19;VSWRB 2.40; AN3;BYPN;SIDET;CA0;L10;VSWRB 1.93; AN3;BYPN;SIDET;CFC;L1A;VSWRB 3.10; AN3;BYPN;SIDET;CB4;L1A;VSWRB 2.66; AN3;BYPB;VSWRB 1.00; AN3;BYPN;SIDET;CC6;L18;VSWRB 2.37; " Fault 2 Power Above Design Limit for Antenna SWR Transmitter power exceeds the design limit for the unmatched antenna SWR. This power limit varies with the SWR of the antenna: 600 watts at 10:1 SWR, 1000 watts at 3:1 SWR." My notes say: "The permitted power in watts is 7000 / bypass SWR, constrained between 250 and 1800 watts." The power limit implementation does not appear to depend on the L and C required to achieve a match but it could because those values are known. 73, Andy, k3wyc __ 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 Message delivered to arch...@mail-archive.com
