RE: [Elecraft] Tuner efficiency question
I still don't know what to think. I came home from Hamvention today with the tiny T1 tuner for my K2, based more on convenience of installation and ability to use it with other rigs and portability. If I eventually want an auto tuner for higher power, I'll go through all this again, I guess. Meanwhile, I'll keep the Hallicrafters connected to the Palstar tuner. Hey, it was worth the price of the tuner, just to meet Don at the Elecraft booth! Parker -Original Message- From: Bill Coleman [mailto:[EMAIL PROTECTED] Sent: Friday, May 20, 2005 2:24 PM To: John, KI6WX Cc: Don; Parker Buckley; elecraft@mailman.qth.net Subject: Re: [Elecraft] Tuner efficiency question On May 13, 2005, at 12:40 AM, John, KI6WX wrote: > At high power, an inefficient tuner can generate significant > amounts of heat, which can destroy components. A 1kW transmitter > into a 70% efficient tuner will generate 300 watts of heat in the > tuner. This is why I tend to disbelieve tuner efficiency figures. From the QST tests, there seem to be a lot of tuners than have losses greater than 10% -- yet there is no evidence that any of these tuners heat up appreciably! At 1 kW, a 10% loss is 100 watts -- imagine how hot a tuner enclosure would get if you had a 100 watt light bulb inside it. Even at 100 watts, 10% loss is 10 watts. That's still enough to induce a few degree change in a small enclosure. Bill Coleman, AA4LR, PP-ASELMail: [EMAIL PROTECTED] Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
On May 13, 2005, at 9:32 AM, Stephen W. Kercel wrote: Comment on baluns: If you drive a ferrite core to saturation, it will overheat. True. Once the core overheats, the inductance changes and you lose your match (quite severely, in my experience). In order to change the inductance permanently, it must reach the Curie temperature. The inductance will change much at a much lower temperature than this, but the effects aren't lasting. It doesn't really take much to do it; a few minutes of normal CW operating with 100 watts into a 5:1 SWR on 20 meters will do the trick for me. You are much more likely to drive a balun core into saturation on the high SWR output of a tuner than on the low SWR input of the tuner. Note that a normal current-type balun feeding a non-pathological antenna (one that has made a reasonable attempt to be balanced) will show little or no flux on the core. The object of the current-type balun is to discourage current from flowing by creating a high- impedance path -- if there's high impedance there's little current and therefore less chance of heating. Bill Coleman, AA4LR, PP-ASELMail: [EMAIL PROTECTED] Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
On May 13, 2005, at 12:40 AM, John, KI6WX wrote: At high power, an inefficient tuner can generate significant amounts of heat, which can destroy components. A 1kW transmitter into a 70% efficient tuner will generate 300 watts of heat in the tuner. This is why I tend to disbelieve tuner efficiency figures. From the QST tests, there seem to be a lot of tuners than have losses greater than 10% -- yet there is no evidence that any of these tuners heat up appreciably! At 1 kW, a 10% loss is 100 watts -- imagine how hot a tuner enclosure would get if you had a 100 watt light bulb inside it. Even at 100 watts, 10% loss is 10 watts. That's still enough to induce a few degree change in a small enclosure. Bill Coleman, AA4LR, PP-ASELMail: [EMAIL PROTECTED] Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
In a message dated 5/13/05 12:51:01 PM Eastern Daylight Time, [EMAIL PROTECTED] writes: > Many QRP operators assume that a tuner used for QRP can > be small because one doesn't need the power-handling capability of a larger > tuner. However, if a tuner has x db loss, then that loss will reduce the > strength of a received signal by x db whether the signal is transmitted at 5 > or > 500 watts! > > That's true but it doesn't mean good tuners must be big. The lossiest element in most tuners is the inductor. If an inductor has high Q, then by definition it has low loss. Power-handling capability is a related but different thing.It involves the ability to withstand high voltage if necessary, and to dissipate a certain amount of power. A high Q coil doesn't necessarily have a high power handling capacity, and vice versa. 73 de Jim, N2EY ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Tuner efficiency question
I like the "QRP Balanced Antenna Tuner" rated at only 500W. Eric KE6US -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim W7RY Sent: Friday, May 13, 2005 4:32 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Tuner efficiency question Wow... This chap has quite a setup! And he's very talented! Take a look at some of those construction projects! Very nice indeed! 73 Jim W7RY At 01:21 PM 5/13/2005, Stephen W. Kercel wrote: >Stuart > >It was a year or two back that I saw them. It may well be the case that >they are discontinued. They were way out of the price range of the typical ham. > >However, these Web pages still work. > >http://www.hewezi.com/bal_tuner.html > >http://www.dj2hz.de/ > >If you're really curious, get in touch with DJ2HZ > >73, > >Steve >AA4AK > >At 01:59 PM 5/13/2005 -0500, you wrote: >>My understanding, from L. B. Cebik, was the German balanced tuners >>were discontinued. I could not find them by Google search. >>-Stuart >>K5KVH > > >___ >Elecraft mailing list >Post to: Elecraft@mailman.qth.net >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): >http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Tuner efficiency question
There is a fellow here in the NW that builds link coupled tuners. Pat Buller, W7RQT. They are quite well made and look great. His email is shown on www.qrz.com 73 Jim W7RY ConAt 09:30 AM 5/13/2005, [EMAIL PROTECTED] wrote: > ... > Contrary to popular belief, balun loss is not the largest > contributing factor, and if properly designed, makes > little difference whether it is placed on the input or the > output. Charles Green W1CG has done a lot of work > on balun loss and reports that the loss is actually > quite low (even when their design impedance is > severly mismatched). > > My bottom line conclusion here is that we pay a price > in efficiency for the convenience of compactness and > a large matching range. Yes, we most certainly do. Too many of us care only about the automatic aspect of these compact tuners, and we give up really efficient tuner operation. Tuners have to be really large to be really good. The components have to be large and the enclosures have to be large. But because many people don't like large boxes on their operating tables, and because they would rather not twiddle knobs, they go to these small, sometimes lossy autotuners. As long as they understand what they are giving up by doing this, it's cool. However, balun loss isn't the only important factor and may not even be the most important factor. The balun's primary purpose is to convert to a balanced two-wire system, and in order to preserve the antenna pattern and keep the feedline from radiating, it has to provide equal currents in each leg of the feedline. In order to be effective at this, the balun's impedance has to be large compared to the antenna's input impedance. When baluns in tuners have to look into very high impedances, they stop acting as baluns. You may be happy that a particular balun doesn't have a lot of loss, but you would be very unhappy to learn that that same balun isn't doing it's job as a balun anymore. Under these conditions, who knows what the antenna pattern is. Using a balanced tuner gets you part of the way to a highly efficient antenna system; the other half of the journey is to use a balun-less design that attains true balance no matter what the antenna/feedline conditions are. I have found this possible only by homebrewing such a tuner. I don't know if you've ever seen the Annecke tuner on L. B. Cebik's web site: http://www.cebik.com/link/link.html . It was the best hope we've had to seeing a link-coupled tuner like the old Johnson Matchbox, and many folks were expecting it to go back into production, but the person who bought the rights to the design has decided not to pursue the manufacture of the tuner at this time. Too bad. We'll just have to keep building them ourselves. Al W6LX ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Wow... This chap has quite a setup! And he's very talented! Take a look at some of those construction projects! Very nice indeed! 73 Jim W7RY At 01:21 PM 5/13/2005, Stephen W. Kercel wrote: Stuart It was a year or two back that I saw them. It may well be the case that they are discontinued. They were way out of the price range of the typical ham. However, these Web pages still work. http://www.hewezi.com/bal_tuner.html http://www.dj2hz.de/ If you're really curious, get in touch with DJ2HZ 73, Steve AA4AK At 01:59 PM 5/13/2005 -0500, you wrote: My understanding, from L. B. Cebik, was the German balanced tuners were discontinued. I could not find them by Google search. -Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Stuart: The Johnson differs from modern balanced tuners in that it used link coupling (a tuned transformer with inductive coupling) rather than a matching network. It also had the advantage over home brew link couplers that you tuned it with knobs instead of moving little clips around on the big coil. 73, Steve AA4AK At 02:14 PM 5/13/2005 -0500, you wrote: The MFJ balanced tuner has a double tee network to give the most range of adjustment. Note even the vaunted Johnson Matchbox did not cover all of today's bands and impedances. -Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Stuart It was a year or two back that I saw them. It may well be the case that they are discontinued. They were way out of the price range of the typical ham. However, these Web pages still work. http://www.hewezi.com/bal_tuner.html http://www.dj2hz.de/ If you're really curious, get in touch with DJ2HZ 73, Steve AA4AK At 01:59 PM 5/13/2005 -0500, you wrote: My understanding, from L. B. Cebik, was the German balanced tuners were discontinued. I could not find them by Google search. -Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: Re: [Elecraft] Tuner efficiency question
You are correct, Stuart. But, while lacking 160m, it did cover 80 to 10m. Okay, so the bandswitch was discrete in the bands available at the time, but it I have used it on the other bands we have now and it still worked there, at least with my 340' double extended Zepp. I didn't measure the efficiency though. Again, from my rambling comments last night, possibly the correct solution for one person is a tuner that covers the widest range of impedances while another that may not be the case. Maybe one person has no need for balanced lines and is only interested in coaxial fed antennas and a tuner that does well with those (and that person has probably deleted all of these emails). Like many topics, this one has many possible "correct" answers. As somebody else said "It depends" is the right answer. Mark, NK8Q >The MFJ balanced tuner has a double tee network to give the most range of >adjustment. > >Note even the vaunted Johnson Matchbox did not cover all of today's bands >and impedances. > >-Stuart >K5KVH > > ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
The MFJ balanced tuner has a double tee network to give the most range of adjustment. Note even the vaunted Johnson Matchbox did not cover all of today's bands and impedances. -Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
My understanding, from L. B. Cebik, was the German balanced tuners were discontinued. I could not find them by Google search. -Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Google the name Frank Witt, and you will find the tuner studies he did. Also in archives of QRP-L reflector where he posted them, and maybe on www.arrl.org technical topics links. 72, Stuart K5KVH ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
>> Is there a modern tuner out there for balanced lines that >> doesn't use a balun? >I don't know of any. There is nothing wrong with using a balun >as long as the balun is looking into a relatively low SWR . Even the MFJ-974, 974H, and 976 balanced line tuners use a 1:1 current balun on the input (http://www.mfjenterprises.com/man/pdf/MFJ-974.pdf ). I don't suppose that's all that bad a design compromise, though when these MFJ tuners were first announced I had hoped that we would see a modernized Matchbox design. There are plenty of the Johnson Matchboxes to be found at hamfests and on ebay. I found mine (the version rated for about 300 watts) at a small local hamfest a few years ago for $50. I wouldn't even consider trading or selling it. 73, Mike / KK5F ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
[EMAIL PROTECTED] wrote: Yes, we most certainly do. Too many of us care only about the automatic aspect of these compact tuners, and we give up really efficient tuner operation. Tuners have to be really large to be really good. The components have to be large and the enclosures have to be large. This is a good point. Many QRP operators assume that a tuner used for QRP can be small because one doesn't need the power-handling capability of a larger tuner. However, if a tuner has x db loss, then that loss will reduce the strength of a received signal by x db whether the signal is transmitted at 5 or 500 watts! So if I were building a QRP-only tuner, I would use a big silver-plated inductor in a big box (although the capacitors could be smaller, since the voltage requirement would be less). -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
I haven't had lots of different tuners to compare myself, but I do have a Johnson KW Matchbox tuner. It does a great job on Balanced lines. I didn't really know about the Palastar but just checked it out on the website. Looked like an interesting tuner. But to me the downside of it was that there is a balun on the output, which of course as Don stated is a dominating factor in losses in a tuner (at least maybe that is what I took away from his comments as well as other discussions on this subject in the past). Is there a modern tuner out there for balanced lines that doesn't use a balun? I don't know of any. There is nothing wrong with using a balun as long as the balun is looking into a relatively low SWR . The baluns we are all familiar with only work well when feeding a balanced load that is fairly flat. In other words the balun ought to be at the INPUT of the tuner instead of the OUTPUT. This makes the tuner electrically and mechanically much more complex and expensive and that is why you don't see it done very often. As John said .. half a db or so does not matter as far as signal strength at the receiving station is concerned. The only problem is that the power dissipation could damage the tuner or balun itself at the transmitting station. As a purist with lots of time on my hands I am trying for the best of all worlds by building a true balanced L-C-L tuner with a balun at the input. It is an auto tuner with all of the bells and whistles and will (probably .. I think) handle up to 500 watts into my big wire antenna (but probably not into shorter antennas). I am going to put it into a K2 case with matching button switches and a similar LCD. It is working now on the benchtop at low power levels but it remains to be seen if, when packed tightly into a small case, I can keep the PIC controller circuits sufficiently free of rf interference at high power levels. Don K7FJ ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Tuner efficiency question
> ... > Contrary to popular belief, balun loss is not the largest > contributing factor, and if properly designed, makes > little difference whether it is placed on the input or the > output. Charles Green W1CG has done a lot of work > on balun loss and reports that the loss is actually > quite low (even when their design impedance is > severly mismatched). > > My bottom line conclusion here is that we pay a price > in efficiency for the convenience of compactness and > a large matching range. Yes, we most certainly do. Too many of us care only about the automatic aspect of these compact tuners, and we give up really efficient tuner operation. Tuners have to be really large to be really good. The components have to be large and the enclosures have to be large. But because many people don't like large boxes on their operating tables, and because they would rather not twiddle knobs, they go to these small, sometimes lossy autotuners. As long as they understand what they are giving up by doing this, it's cool. However, balun loss isn't the only important factor and may not even be the most important factor. The balun's primary purpose is to convert to a balanced two-wire system, and in order to preserve the antenna pattern and keep the feedline from radiating, it has to provide equal currents in each leg of the feedline. In order to be effective at this, the balun's impedance has to be large compared to the antenna's input impedance. When baluns in tuners have to look into very high impedances, they stop acting as baluns. You may be happy that a particular balun doesn't have a lot of loss, but you would be very unhappy to learn that that same balun isn't doing it's job as a balun anymore. Under these conditions, who knows what the antenna pattern is. Using a balanced tuner gets you part of the way to a highly efficient antenna system; the other half of the journey is to use a balun-less design that attains true balance no matter what the antenna/feedline conditions are. I have found this possible only by homebrewing such a tuner. I don't know if you've ever seen the Annecke tuner on L. B. Cebik's web site: http://www.cebik.com/link/link.html . It was the best hope we've had to seeing a link-coupled tuner like the old Johnson Matchbox, and many folks were expecting it to go back into production, but the person who bought the rights to the design has decided not to pursue the manufacture of the tuner at this time. Too bad. We'll just have to keep building them ourselves. Al W6LX ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Dave: Personally, I've always thought that balanced was cool. I was using balanced lines 20+ years ago. The sense that I had from my fellow hams at the time was that practically everybody else thought that they were decidedly uncool. It is only in the last year or so that I've noticed them becoming rediscovered. 73, Steve AA4AK At 09:41 AM 5/13/2005 -0400, you wrote: Side note: I dimly recall that there is an outfit in Germany that has been making balanced tuners since before balanced became cool. Balanced didn't become cool; balanced always was cool. Balanced is only being rediscovered by the generation (or two (or three)) that thought that coax was the only means for feeding a wire. best wishes, dave belsley, w1euy ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Side note: I dimly recall that there is an outfit in Germany that has been making balanced tuners since before balanced became cool. Balanced didn't become cool; balanced always was cool. Balanced is only being rediscovered by the generation (or two (or three)) that thought that coax was the only means for feeding a wire. best wishes, dave belsley, w1euy ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Tuner efficiency question
The comparison of balanced tuners is in the September 2004 QST. It is worth mentioning that there is a strong correlation between tuner efficiency and money. According to the ARRL lab data, a $900 Palstar is substantially more efficient (Surprised?) than a $200 MFJ. Side note: I dimly recall that there is an outfit in Germany that has been making balanced tuners since before balanced became cool. They are very expensive ($1.5 K - $2K), but I suspect that they are much more efficient than the specimens tested in the ARRL lab. A comparison of unbalanced tuners is in the February 2003 QST. Again, it is worth mentioning that there is a strong correlation between tuner efficiency and cost. According to the ARRL lab data, a $600 Ameritron is substantially more efficient than a $330 MFJ. (All the more remarkable, seeing that apparently the same people make both.) Comparing the two different reviews reveals another detail. Commercially available balanced tuners, as a class appear to be lossier than unbalanced tuners. (Speculation: Since both the loss and cost are dominated by the inductor quality, and the balanced tuner needs two of them, I expect that the manufacturers are tempted to cut corners on the inductor quality for the balanced tuner.) Other point worth noting: Losses are much more severe when the load resistance is substantially lower than 50 ohms. All the tuners show their worst performance at R = 6.25. With R = 400 all the tuners do much better, despite the fact that the SWR is 8:1 in both cases. (Almost certainly this is caused by the resistive voltage divider effect. The resistance in the tuner inductor is in series with the load impedance.) Comment on baluns: If you drive a ferrite core to saturation, it will overheat. It doesn't really take much to do it; a few minutes of normal CW operating with 100 watts into a 5:1 SWR on 20 meters will do the trick for me. Once the core overheats, the inductance changes and you lose your match (quite severely, in my experience). You are much more likely to drive a balun core into saturation on the high SWR output of a tuner than on the low SWR input of the tuner. 73, Steve Kercel AA4AK ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Tuner efficiency question
Folks, I recall comparisons and analysis of different tuner types done several years ago by ARRL. The conclusion was that the inductor Q was the major determining factor for tuner efficiency of any one type of tuner. The T match circuit can match a large range but at some settings can produce high circulating currents leading to very high losses, the PI network is generally low loss but at the expense of failing to match very low impedance loads with reasonable value capacitors, the L network is quite efficient, but the lowest loss is a link coupled tuned tank circuit type tuner with a high Q inductor (i.e. Johnson Matchbox type). IMHO, compact designs have produced more tuner losses than any other contributing factor - Hi-Q inductors are generally large airwound fixed coils spaced far away from conducting surfaces. I look at my Johnsom Matchbox and see an air-wound coil supported in the center of a large box (the coil has lots of surrounding empty space), quite in contrast to my MFJ T match circuit tuner with the roller inductor placed less than an inch from the side, bottom and top of the enclosure - the front panel appearance of that tuner was judged more important than minimizing the inductor loss - and we call it progress!!! Contrary to popular belief, balun loss is not the largest contributing factor, and if properly designed, makes little difference whether it is placed on the input or the output. Charles Green W1CG has done a lot of work on balun loss and reports that the loss is actually quite low (even when their design impedance is severly mismatched). My bottom line conclusion here is that we pay a price in efficiency for the convenience of compactness and a large matching range. While I have not seen efficiency tests of the Elecraft tuners, I would venture to guess that their L network design with switched toroid inductors would show a relatively low loss compared to many other designs. 73, Don W3FPR > -Original Message- > > I haven't had lots of different tuners to compare myself, but I do have > a Johnson KW Matchbox tuner. It does a great job on Balanced lines. I > didn't really know about the Palastar but just checked it out on the > website. Looked like an interesting tuner. But to me the downside of > it was that there is a balun on the output, which of course as Don > stated is a dominating factor in losses in a tuner (at least maybe that > is what I took away from his comments as well as other discussions on > this subject in the past). Is there a modern tuner out there for > balanced lines that doesn't use a balun? > > Maybe the proper comparison for more apples to apples comparison should > be made for tuners that are designed for type of feedline output or > maybe Hi-Z vs Lo-Z, as most today, including the Elecraft, are likely > ... -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.11.9 - Release Date: 5/12/2005 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Tuner efficiency question
Hi guys. I certainly appreciate your quick responses. Like everything else, I guess the answer to a certain extent is "It depends". I probably should have sidestepped the balanced tuner vs tuner/balun part of the question. I've tried all kinds of combinations along those lines, probably guided more by practicality for the particular installation than efficiency. So maybe I should have started with "Assuming a coax-fed antenna.." It sounds like the decision still comes back to (given a reasonably efficient design), what's most practical for the need. The KAT2 integrates directly into the K2 and the T1 offers flexibility for use with other rigs. Looking forward to Dayton! 73, Parker WD8JOL ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Palstar BT1500A is fully balanced tuner with balun in INPUT, and tuning elements work balanced. Here balun works properly. The same applies to e.g. MFJ976. World seems to wake up again for lattice feeders. Most welcome. -- Benny AUMALA OH9NB ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
I haven't had lots of different tuners to compare myself, but I do have a Johnson KW Matchbox tuner. It does a great job on Balanced lines. I didn't really know about the Palastar but just checked it out on the website. Looked like an interesting tuner. But to me the downside of it was that there is a balun on the output, which of course as Don stated is a dominating factor in losses in a tuner (at least maybe that is what I took away from his comments as well as other discussions on this subject in the past). Is there a modern tuner out there for balanced lines that doesn't use a balun? Maybe the proper comparison for more apples to apples comparison should be made for tuners that are designed for type of feedline output or maybe Hi-Z vs Lo-Z, as most today, including the Elecraft, are likely moreso designed not for balanced line output and Hi-Z but coaxial output and Lo-Z. Sure, many tuners may also have a balanced line output option, but that is likely there as a convenience or for marketing or whatever but is really just added on as compared to the overall tuner being designed for Hi-Z and balanced output. While I like my Johnson KW tuner for certain antennas I may opt for some other tuner for other types of antennas. The type of tuner should be considered as a whole in the antenna system, not as a one size fits all solution (unless there is a tuner out there that really can do both ends of the spectrum equally well). When I first started getting back into QRP just over one year ago I had my RockMite-40 sitting on top of the Johnson KW Matchbox. It was going to a resonant antenna and didn't go through the tuner. Even though the Matchbox is supposedly a low loss antenna tuner it did seem like there was something just wrong about using it with a QRP rig, maybe like some sort of sacralidge in its own way, but maybe that is just me. Maybe the purist would say that only resonant antennas should be used so a tuner is not needed. Okay, that makes some sense, but maybe I can get an antenna with better overall performance than the extra losses involved when using a tuner. Again, the whole systems needs to be evaluated an not just individual parts of a system. If individual parts are selected because they are the best but when put together they don't work so well collectively it doesn't seem like a good solution. Maybe a tuner with more versatility even if it has slightly higher losses is a better solution for the next ham who doesn't use just one antenna at a fixed location all the time. Certainly as QRPers we are all aware that antenna systems are quite important and band conditions really dominate how well we can communicate. But really, given good band conditions and being able to somehow get some signal to something to radiate things will result in being able to communicate. I just installed the KAT2 in my K2 and am amazed at how fast it tunes. I haven't tried it with a variety of different antenna configurations, so I can't comment much on its verstatility. Unfortunately I'm not currently using my balanced feedline antenna anymore due to a change in QTH and a temporary hamshack setup, but the KAT2 seems to suit my needs for now. If anything, at this time the Matchbox at least still looks quite respectable sitting on the bench (farther away from the K2 than when I had the RockMite sitting on top of the Matchbox, HI! HI!). I hope my late night ramblings make some sense. Sorry if they don't. Mark, NK8Q K2 4876 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Parker & Don; I haven't tried to measure the efficiency of the Elecraft tuners. It is a fairly difficult measurement to make correctly when the input and output impedance are significantly different. However, there are two effects to consider in tuner efficiency. At high power, an inefficient tuner can generate significant amounts of heat, which can destroy components. A 1kW transmitter into a 70% efficient tuner will generate 300 watts of heat in the tuner. The second effect is the loss of signal at the receive station. A 90% efficient tuner will lose 0.5 dB; a 70% efficient tuner will lose 1.5 dB. The 1 dB difference will not have any noticeable effect on the ability to receive CW. Even on digital modes, it will only have a minor effect on the received error rate. Other factors, such as QSB, QRM, or QRN, will have a bigger effect. As long as the Elecraft tuners are reasonably efficient, they shouldn't have any significant effect on your ability to communicate. -John KI6WX Parker et al, QST did a review and test of a bunch of balanced tuners a year or so back. I don't remember too much of it now but remember being shocked at how high the losses typically were. As I recall efficiency ran in the 65 to 75 percent range for many of them. The Johnson matchbox was the most efficient by far (90% or more??) but did not cover all bands. I have not really studied this issue but have always been interested. My gut feel is that often much of the loss in these tuners (when driving a balanced line) is in the internal balun which is at the output of typical tuners and is driving a balanced line to the antenna which often has a horrendous SWR. The high SWR on the balanced line is not itself a problem because balanced twin line or ladder line feeders can easily handle the high currents and voltages with low losses but the poor balun can quickly get too hot to touch because of the high circulating currents within the balun. Don K7FJ K2 4438 I've been using my QRP K2 for the last 2-3 years with a "full sized" Palstar tuner. I use a variety of antennas from 160 to 10 meters, fed with coax, ladder line, choke baluns, the Elecraft balun, etc. I'm thinking about going to an auto tuner (Dayton Hamvention coming). Has anyone compared the efficiencies of the very small tuner like the T1, the KAT2, and larger tuners like the Palstar? (I've been the Johnson KW Matchbox route as well.) Intuition tells me there is something lost when going to very small components packed into a tiny space compared to large air variables, big roller inductors, etc., but I don't have anything to back up that gut feel. Anyone make any measurements? Parker K2 2636 WD8JOL ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Tuner efficiency question
Parker et al, QST did a review and test of a bunch of balanced tuners a year or so back. I don't remember too much of it now but remember being shocked at how high the losses typically were. As I recall efficiency ran in the 65 to 75 percent range for many of them. The Johnson matchbox was the most efficient by far (90% or more??) but did not cover all bands. I have not really studied this issue but have always been interested. My gut feel is that often much of the loss in these tuners (when driving a balanced line) is in the internal balun which is at the output of typical tuners and is driving a balanced line to the antenna which often has a horrendous SWR. The high SWR on the balanced line is not itself a problem because balanced twin line or ladder line feeders can easily handle the high currents and voltages with low losses but the poor balun can quickly get too hot to touch because of the high circulating currents within the balun. Don K7FJ K2 4438 I've been using my QRP K2 for the last 2-3 years with a "full sized" Palstar tuner. I use a variety of antennas from 160 to 10 meters, fed with coax, ladder line, choke baluns, the Elecraft balun, etc. I'm thinking about going to an auto tuner (Dayton Hamvention coming). Has anyone compared the efficiencies of the very small tuner like the T1, the KAT2, and larger tuners like the Palstar? (I've been the Johnson KW Matchbox route as well.) Intuition tells me there is something lost when going to very small components packed into a tiny space compared to large air variables, big roller inductors, etc., but I don't have anything to back up that gut feel. Anyone make any measurements? Parker K2 2636 WD8JOL ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
