Re: [Elecraft] high-power tuner
There seems to have been no answer as to how to accurately measure the loss in a tuner. Here is a solution but requires two tuners or at least one calibrated one that could be used to measure others. Take first tuner and tune it into the mismatch, say 600 ohms. Use an antenna analyzer. Then remove the load, and connect another tuner to the output of the first (back- to-back - antenna port on first to antenna port on second tuner.) Then put a 50 ohm load on the second tuner where the transceiver would be connected, and tune the second tuner to a match. It will have the same settings as the first tuner, complete symmetry. Then measure the power in the 50 ohm load to get the loss. Since both tuners are matching the same load, and the system is symmetrical the loss contribution by each tuner is half. Repeat for other types of loads, and now you have a calibrated tuner to use with any tuner you want to test. Rick K2XT __ 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
Re: [Elecraft] high-power tuner
Hi All, What you really need to do is to put the whole tuner inside a calorimeter and measure the rate of temperature change to determine the the dissipated wattage. Tim gm4lmh __ 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
Re: [Elecraft] high-power tuner
I was investigating tuner losses a few years ago and ran into many of these same questions. A physicist buddy pointed out to me that the normal approach to measure loss in something like a tuner is to put it in a well-insulated chamber and measure the rise in temperature over time while transmitting. From there on can calculate the energy required to cause the temperature rise which can be used to calculate the number of watts of RF that never make it through the box. 73, Ron AC7AC -Original Message- There seems to have been no answer as to how to accurately measure the loss in a tuner. Here is a solution but requires two tuners or at least one calibrated one that could be used to measure others. Take first tuner and tune it into the mismatch, say 600 ohms. Use an antenna analyzer. Then remove the load, and connect another tuner to the output of the first (back- to-back - antenna port on first to antenna port on second tuner.) Then put a 50 ohm load on the second tuner where the transceiver would be connected, and tune the second tuner to a match. It will have the same settings as the first tuner, complete symmetry. Then measure the power in the 50 ohm load to get the loss. Since both tuners are matching the same load, and the system is symmetrical the loss contribution by each tuner is half. Repeat for other types of loads, and now you have a calibrated tuner to use with any tuner you want to test. Rick K2XT __ 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
Re: [Elecraft] high-power tuner
As has been clearly demonstrated in this thread, there are multiple methods of measurement. The one that gets my vote for elegance is the one with two tuners back-to-back. With respect to the method that measures temperature rise, taking into account the mass of the tuner, one also needs to take into account the specific heat capacity of the tuner. One kilo of material x doesn't heat up at the same rate as one kilo of material y when the same heating power is applied. The tuner will of course be a mix of materials, so one would have to measure the rate at which the tuner heats up when heat is applied through a know heating source rather than TX power. If it is done that way, one needs to know neither the mass nor the specific heat capacity, since what one is measuring is essentially the mass times the specific heat capacity. 73, Erik K7TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ron D'Eau Claire Sent: Saturday, March 10, 2012 11:47 AM To: 'Rick Stealey'; elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner I was investigating tuner losses a few years ago and ran into many of these same questions. A physicist buddy pointed out to me that the normal approach to measure loss in something like a tuner is to put it in a well-insulated chamber and measure the rise in temperature over time while transmitting. From there on can calculate the energy required to cause the temperature rise which can be used to calculate the number of watts of RF that never make it through the box. 73, Ron AC7AC -Original Message- There seems to have been no answer as to how to accurately measure the loss in a tuner. Here is a solution but requires two tuners or at least one calibrated one that could be used to measure others. Take first tuner and tune it into the mismatch, say 600 ohms. Use an antenna analyzer. Then remove the load, and connect another tuner to the output of the first (back- to-back - antenna port on first to antenna port on second tuner.) Then put a 50 ohm load on the second tuner where the transceiver would be connected, and tune the second tuner to a match. It will have the same settings as the first tuner, complete symmetry. Then measure the power in the 50 ohm load to get the loss. Since both tuners are matching the same load, and the system is symmetrical the loss contribution by each tuner is half. Repeat for other types of loads, and now you have a calibrated tuner to use with any tuner you want to test. Rick K2XT __ 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 __ 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
Re: [Elecraft] high-power tuner
I haven't dug it up , but QST April 1995 pp. 30-34 and QST May 1995 pp. 33-37 describes how the QST lab does it. Dave AB7E On 3/10/2012 6:17 AM, Rick Stealey wrote: There seems to have been no answer as to how to accurately measure the loss in a tuner. __ 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
Re: [Elecraft] high-power tuner
I've recently been experimenting with tuners. I have a 275 watt Johnson Matchbox (which is actually good for more than a kW on CW in most cases) and a huge T network that I just built with a massive edge-wound rotary inductor and capacitors with air gaps of about 3/8 (near 10mm). The T network has a DX Engineering 5 kW rated 1:1 balun on the output. The antenna is an 88-foot dipole fed with 500 ohm open-wire line and some 450-ohm ladder line. I can switch between these tuners instantly. On 40 meter received signals I can detect absolutely no difference in signal strength. The T network is adjusted for the least possible inductance that gives a 1:1 SWR, and the output capacitor is at maximum (300 pf air plus 300 pf ceramic padder).. There is also no difference in noise level. If one of the tuners provided better balance, one would expect that there would be less noise pickup on the feedline. But I don't see this. One anomalous result: there is a weak unstable carrier that I can hear on the Matchbox but not on the T network. I have verified that this is not a birdie, but an actual signal. It could be attributed to feedline pickup -- but wouldn't you expect the matchbox to be better in this regard? I'm investigating further. On 3/10/2012 12:31 PM, Erik Basilier wrote: As has been clearly demonstrated in this thread, there are multiple methods of measurement. The one that gets my vote for elegance is the one with two tuners back-to-back. With respect to the method that measures temperature rise, taking into account the mass of the tuner, one also needs to take into account the specific heat capacity of the tuner. One kilo of material x doesn't heat up at the same rate as one kilo of material y when the same heating power is applied. The tuner will of course be a mix of materials, so one would have to measure the rate at which the tuner heats up when heat is applied through a know heating source rather than TX power. If it is done that way, one needs to know neither the mass nor the specific heat capacity, since what one is measuring is essentially the mass times the specific heat capacity. 73, Erik K7TV l -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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
Re: [Elecraft] high-power tuner
I just did the following experiment: I coupled a grid-dip oscillator to my feed line far from the tuners and switching relays. I put it a few inches from the feedline equidistant from the conductors. I found that the T network plus DXE balun reduced the signal pickup by about 15 dB over the Matchbox! That means that both radiation and noise pickup on the feedline are much less with the T than with the Matchbox. At the same time I verified that there was no detectable difference between the strength of received signals coming from the antenna. This is amazing! It means that the T network and balun is significantly better than the Matchbox in this important respect. So much for mythology. On 3/10/2012 1:11 PM, Vic K2VCO wrote: I've recently been experimenting with tuners. I have a 275 watt Johnson Matchbox (which is actually good for more than a kW on CW in most cases) and a huge T network that I just built with a massive edge-wound rotary inductor and capacitors with air gaps of about 3/8 (near 10mm). The T network has a DX Engineering 5 kW rated 1:1 balun on the output. The antenna is an 88-foot dipole fed with 500 ohm open-wire line and some 450-ohm ladder line. I can switch between these tuners instantly. On 40 meter received signals I can detect absolutely no difference in signal strength. The T network is adjusted for the least possible inductance that gives a 1:1 SWR, and the output capacitor is at maximum (300 pf air plus 300 pf ceramic padder).. There is also no difference in noise level. If one of the tuners provided better balance, one would expect that there would be less noise pickup on the feedline. But I don't see this. One anomalous result: there is a weak unstable carrier that I can hear on the Matchbox but not on the T network. I have verified that this is not a birdie, but an actual signal. It could be attributed to feedline pickup -- but wouldn't you expect the matchbox to be better in this regard? I'm investigating further. -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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
Re: [Elecraft] high-power tuner
Vic, Be aware that loss in the tuner can reduce the signal pickup - I would not be so quick to pass judgement that the Matchbox is less efficient than the T-network tuner - I know the link coupled tuner (properly used) is more efficient. You may want to double check your test conditions and instrumentation. 73, Don W3FPR. On 3/10/2012 4:38 PM, Vic K2VCO wrote: I just did the following experiment: I coupled a grid-dip oscillator to my feed line far from the tuners and switching relays. I put it a few inches from the feedline equidistant from the conductors. I found that the T network plus DXE balun reduced the signal pickup by about 15 dB over the Matchbox! That means that both radiation and noise pickup on the feedline are much less with the T than with the Matchbox. At the same time I verified that there was no detectable difference between the strength of received signals coming from the antenna. This is amazing! It means that the T network and balun is significantly better than the Matchbox in this important respect. So much for mythology. On 3/10/2012 1:11 PM, Vic K2VCO wrote: I've recently been experimenting with tuners. I have a 275 watt Johnson Matchbox (which is actually good for more than a kW on CW in most cases) and a huge T network that I just built with a massive edge-wound rotary inductor and capacitors with air gaps of about 3/8 (near 10mm). The T network has a DX Engineering 5 kW rated 1:1 balun on the output. The antenna is an 88-foot dipole fed with 500 ohm open-wire line and some 450-ohm ladder line. I can switch between these tuners instantly. On 40 meter received signals I can detect absolutely no difference in signal strength. The T network is adjusted for the least possible inductance that gives a 1:1 SWR, and the output capacitor is at maximum (300 pf air plus 300 pf ceramic padder).. There is also no difference in noise level. If one of the tuners provided better balance, one would expect that there would be less noise pickup on the feedline. But I don't see this. One anomalous result: there is a weak unstable carrier that I can hear on the Matchbox but not on the T network. I have verified that this is not a birdie, but an actual signal. It could be attributed to feedline pickup -- but wouldn't you expect the matchbox to be better in this regard? I'm investigating further. -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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 __ 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
Re: [Elecraft] high-power tuner
Ron, Rick, Erik: There are many reasons why temperature measurements are a poor way of evaluating a tuner. There is a method of power measure based on temperature rise. It's called a bolometer. It only works well if the mass involved is small. Wiki bolometers if you want the details. I think there is an even more important reason not to use this approach. Let's consider the case where the transmitter has a very strong second harmonic say -10db. If the tuner is doing its job, tuning, not just matching, the 2nd harmonic will be tuned or filtered out. 10% of the energy will be lost. What becomes of that energy? In an ideal world that energy would be reflected into a dummy load, like when you use a circulator. Since most tuners don't have circulators, part of the energy will be dissipated in the tuner and part will be reflected back to the transmitter. That energy that is dissipated in the tuner is a measure of how well, not how poorly, the tuner is working. BTW in this case measuring SWR at the transmitter will also suggest the tuner is not doing its job well when it is. Now we know good rigs don't have strong harmonics but I think I have illustrated why measuring heat is not a good measure of performance. 73, Fred, AE6QL -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Erik Basilier Sent: Saturday, March 10, 2012 12:31 PM To: 'Ron D'Eau Claire'; 'Rick Stealey'; elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner As has been clearly demonstrated in this thread, there are multiple methods of measurement. The one that gets my vote for elegance is the one with two tuners back-to-back. With respect to the method that measures temperature rise, taking into account the mass of the tuner, one also needs to take into account the specific heat capacity of the tuner. One kilo of material x doesn't heat up at the same rate as one kilo of material y when the same heating power is applied. The tuner will of course be a mix of materials, so one would have to measure the rate at which the tuner heats up when heat is applied through a know heating source rather than TX power. If it is done that way, one needs to know neither the mass nor the specific heat capacity, since what one is measuring is essentially the mass times the specific heat capacity. 73, Erik K7TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ron D'Eau Claire Sent: Saturday, March 10, 2012 11:47 AM To: 'Rick Stealey'; elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner I was investigating tuner losses a few years ago and ran into many of these same questions. A physicist buddy pointed out to me that the normal approach to measure loss in something like a tuner is to put it in a well-insulated chamber and measure the rise in temperature over time while transmitting. From there on can calculate the energy required to cause the temperature rise which can be used to calculate the number of watts of RF that never make it through the box. 73, Ron AC7AC -Original Message- There seems to have been no answer as to how to accurately measure the loss in a tuner. Here is a solution but requires two tuners or at least one calibrated one that could be used to measure others. Take first tuner and tune it into the mismatch, say 600 ohms. Use an antenna analyzer. Then remove the load, and connect another tuner to the output of the first (back- to-back - antenna port on first to antenna port on second tuner.) Then put a 50 ohm load on the second tuner where the transceiver would be connected, and tune the second tuner to a match. It will have the same settings as the first tuner, complete symmetry. Then measure the power in the 50 ohm load to get the loss. Since both tuners are matching the same load, and the system is symmetrical the loss contribution by each tuner is half. Repeat for other types of loads, and now you have a calibrated tuner to use with any tuner you want to test. Rick K2XT __ 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 __ 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 __ 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
Re: [Elecraft] high-power tuner
This is why I checked that real signals received through the antenna were not attenuated to a detectable degree. I could not tell the difference between the tuners with weak signals from distant stations. Reasons that the T network may be as efficient as the Matchbox for this test: 1) In this case the T output capacitor is maximum, which makes it an L network. 2) No switches in the path. 3) Very high-Q inductor in the T network. On 3/10/2012 4:06 PM, Don Wilhelm wrote: Vic, Be aware that loss in the tuner can reduce the signal pickup - I would not be so quick to pass judgement that the Matchbox is less efficient than the T-network tuner - I know the link coupled tuner (properly used) is more efficient. You may want to double check your test conditions and instrumentation. 73, Don W3FPR. On 3/10/2012 4:38 PM, Vic K2VCO wrote: I just did the following experiment: I coupled a grid-dip oscillator to my feed line far from the tuners and switching relays. I put it a few inches from the feedline equidistant from the conductors. I found that the T network plus DXE balun reduced the signal pickup by about 15 dB over the Matchbox! That means that both radiation and noise pickup on the feedline are much less with the T than with the Matchbox. At the same time I verified that there was no detectable difference between the strength of received signals coming from the antenna. This is amazing! It means that the T network and balun is significantly better than the Matchbox in this important respect. So much for mythology. On 3/10/2012 1:11 PM, Vic K2VCO wrote: I've recently been experimenting with tuners. I have a 275 watt Johnson Matchbox (which is actually good for more than a kW on CW in most cases) and a huge T network that I just built with a massive edge-wound rotary inductor and capacitors with air gaps of about 3/8 (near 10mm). The T network has a DX Engineering 5 kW rated 1:1 balun on the output. The antenna is an 88-foot dipole fed with 500 ohm open-wire line and some 450-ohm ladder line. I can switch between these tuners instantly. On 40 meter received signals I can detect absolutely no difference in signal strength. The T network is adjusted for the least possible inductance that gives a 1:1 SWR, and the output capacitor is at maximum (300 pf air plus 300 pf ceramic padder).. There is also no difference in noise level. If one of the tuners provided better balance, one would expect that there would be less noise pickup on the feedline. But I don't see this. One anomalous result: there is a weak unstable carrier that I can hear on the Matchbox but not on the T network. I have verified that this is not a birdie, but an actual signal. It could be attributed to feedline pickup -- but wouldn't you expect the matchbox to be better in this regard? I'm investigating further. -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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 -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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
Re: [Elecraft] high-power tuner
Bolometers work at pretty low (milliwatt) power levels and you would need to use an attenuator, which could add some error to the measurement. Hewlett Packard made the HP434A Calorimetric Power Meter, which could measure up to 10 watts by matching the temperature in a load with that caused by DC power (which can be accurately measured). I often used one in the early 1960s (this was at work--they were a bit pricey for ham use). Bob, N7XY On Mar 10, 2012, at 4:56 PM, Fred Townsend wrote: Ron, Rick, Erik: There are many reasons why temperature measurements are a poor way of evaluating a tuner. There is a method of power measure based on temperature rise. It's called a bolometer. It only works well if the mass involved is small. Wiki bolometers if you want the details. I think there is an even more important reason not to use this approach. Let's consider the case where the transmitter has a very strong second harmonic say -10db. If the tuner is doing its job, tuning, not just matching, the 2nd harmonic will be tuned or filtered out. 10% of the energy will be lost. What becomes of that energy? In an ideal world that energy would be reflected into a dummy load, like when you use a circulator. Since most tuners don't have circulators, part of the energy will be dissipated in the tuner and part will be reflected back to the transmitter. That energy that is dissipated in the tuner is a measure of how well, not how poorly, the tuner is working. BTW in this case measuring SWR at the transmitter will also suggest the tuner is not doing its job well when it is. Now we know good rigs don't have strong harmonics but I think I have illustrated why measuring heat is not a good measure of performance. 73, Fred, AE6QL -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Erik Basilier Sent: Saturday, March 10, 2012 12:31 PM To: 'Ron D'Eau Claire'; 'Rick Stealey'; elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner As has been clearly demonstrated in this thread, there are multiple methods of measurement. The one that gets my vote for elegance is the one with two tuners back-to-back. With respect to the method that measures temperature rise, taking into account the mass of the tuner, one also needs to take into account the specific heat capacity of the tuner. One kilo of material x doesn't heat up at the same rate as one kilo of material y when the same heating power is applied. The tuner will of course be a mix of materials, so one would have to measure the rate at which the tuner heats up when heat is applied through a know heating source rather than TX power. If it is done that way, one needs to know neither the mass nor the specific heat capacity, since what one is measuring is essentially the mass times the specific heat capacity. 73, Erik K7TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ron D'Eau Claire Sent: Saturday, March 10, 2012 11:47 AM To: 'Rick Stealey'; elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner I was investigating tuner losses a few years ago and ran into many of these same questions. A physicist buddy pointed out to me that the normal approach to measure loss in something like a tuner is to put it in a well-insulated chamber and measure the rise in temperature over time while transmitting. From there on can calculate the energy required to cause the temperature rise which can be used to calculate the number of watts of RF that never make it through the box. 73, Ron AC7AC -Original Message- There seems to have been no answer as to how to accurately measure the loss in a tuner. Here is a solution but requires two tuners or at least one calibrated one that could be used to measure others. Take first tuner and tune it into the mismatch, say 600 ohms. Use an antenna analyzer. Then remove the load, and connect another tuner to the output of the first (back- to-back - antenna port on first to antenna port on second tuner.) Then put a 50 ohm load on the second tuner where the transceiver would be connected, and tune the second tuner to a match. It will have the same settings as the first tuner, complete symmetry. Then measure the power in the 50 ohm load to get the loss. Since both tuners are matching the same load, and the system is symmetrical the loss contribution by each tuner is half. Repeat for other types of loads, and now you have a calibrated tuner to use with any tuner you want to test. Rick K2XT __ 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
Re: [Elecraft] high-power tuner
So, the Calorimetric HP meter uses the same principle as my suggested measurement, with the only difference being that HP performs the reference measurement simultaneously with the target measurement rather than sequentially. Erik K7TV Hewlett Packard made the HP434A Calorimetric Power Meter, which could measure up to 10 watts by matching the temperature in a load with that caused by DC power (which can be accurately measured). I often used one in the early 1960s (this was at work--they were a bit pricey for ham use). Bob, N7XY ... The tuner will of course be a mix of materials, so one would have to measure the rate at which the tuner heats up when heat is applied through a know heating source rather than TX power. If it is done that way, one needs to know neither the mass nor the specific heat capacity, since what one is measuring is essentially the mass times the specific heat capacity. 73, Erik K7TV __ 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
Re: [Elecraft] high-power tuner
OK folks, I am really truly sorry I started this tuner-efficiency-by-measuring-its-heat thread. I apologize. It was sort of an e-nerd joke and I really miscalculated the laugh-factor in it, it seems there was none, an unfortunate failing for me ... but too common. Boltzmann's Constant is in my HP48GX calculator, not that I actually know or care what to do with it at this point in my life. It would be hugely difficult to get any sort of accuracy in a measurement of the heat lost in a tuner to find its efficiency, I never meant it to be real or even close to reality. Again, I'm sorry to have been joking around on a serious list. Won't do it again. Please, everyone, use what works, have fun, enjoy the hobby with the great E-gear. My KPA500 is heating the room far more than my MFJ989C. If you can make QSO's, it works. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org On 3/10/2012 4:56 PM, Fred Townsend wrote: Ron, Rick, Erik: There are many reasons why temperature measurements are a poor way of evaluating a tuner. There is a method of power measure based on temperature rise. It's called a bolometer. It only works well if the mass involved is small. Wiki bolometers if you want the details. __ 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
Re: [Elecraft] high-power tuner
Fred, I would not apologize. I have enjoyed the thread which is about dead anyway. 73, Bill K9YEQ -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred Jensen Sent: Saturday, March 10, 2012 8:17 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner OK folks, I am really truly sorry I started this tuner-efficiency-by-measuring-its-heat thread. I apologize. It was sort of an e-nerd joke and I really miscalculated the laugh-factor in it, it seems there was none, an unfortunate failing for me ... but too common. Boltzmann's Constant is in my HP48GX calculator, not that I actually know or care what to do with it at this point in my life. It would be hugely difficult to get any sort of accuracy in a measurement of the heat lost in a tuner to find its efficiency, I never meant it to be real or even close to reality. Again, I'm sorry to have been joking around on a serious list. Won't do it again. Please, everyone, use what works, have fun, enjoy the hobby with the great E-gear. My KPA500 is heating the room far more than my MFJ989C. If you can make QSO's, it works. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org On 3/10/2012 4:56 PM, Fred Townsend wrote: Ron, Rick, Erik: There are many reasons why temperature measurements are a poor way of evaluating a tuner. There is a method of power measure based on temperature rise. It's called a bolometer. It only works well if the mass involved is small. Wiki bolometers if you want the details. __ 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 __ 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
Re: [Elecraft] high-power tuner
As one Fred to another it was funny in the heat of the battle so to speak. It fooled me and perhaps the case hardened too. Well done. 73 Fred, AE6QL -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred Jensen Sent: Saturday, March 10, 2012 6:17 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner OK folks, I am really truly sorry I started this tuner-efficiency-by-measuring-its-heat thread. I apologize. It was sort of an e-nerd joke and I really miscalculated the laugh-factor in it, it seems there was none, an unfortunate failing for me ... but too common. Boltzmann's Constant is in my HP48GX calculator, not that I actually know or care what to do with it at this point in my life. It would be hugely difficult to get any sort of accuracy in a measurement of the heat lost in a tuner to find its efficiency, I never meant it to be real or even close to reality. Again, I'm sorry to have been joking around on a serious list. Won't do it again. Please, everyone, use what works, have fun, enjoy the hobby with the great E-gear. My KPA500 is heating the room far more than my MFJ989C. If you can make QSO's, it works. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org On 3/10/2012 4:56 PM, Fred Townsend wrote: Ron, Rick, Erik: There are many reasons why temperature measurements are a poor way of evaluating a tuner. There is a method of power measure based on temperature rise. It's called a bolometer. It only works well if the mass involved is small. Wiki bolometers if you want the details. __ 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 __ 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
Re: [Elecraft] high-power tuner
Very interesting discussions about tuners/loss I didn't understand most of what was discussed anyway, hihi. I have a little tuner history if anyone is interested. In a letter from Don Wallace W6AM, years ago, he told me he swore by the Johnson Viking Kilowatt tuner. He had one connected between each of his Collins 75A4 receivers and his rhombics. Not for matching, he had the rhombics dialed in very well, he said the big KW Johnson Matchbox was a good preselector, said he could peak up a weak signal in the noise enough to get improved copy. He said only the big Johnson KW tuner with the big coils would work as a preselector, the smaller Johnson Matchbox didn't work as a preselector. With our radios today I doubt if the big Johnson would help any. Bob K6UJ On Mar 10, 2012, at 8:50 PM, Fred Townsend wrote: As one Fred to another it was funny in the heat of the battle so to speak. It fooled me and perhaps the case hardened too. Well done. 73 Fred, AE6QL -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred Jensen Sent: Saturday, March 10, 2012 6:17 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner OK folks, I am really truly sorry I started this tuner-efficiency-by-measuring-its-heat thread. I apologize. It was sort of an e-nerd joke and I really miscalculated the laugh-factor in it, it seems there was none, an unfortunate failing for me ... but too common. Boltzmann's Constant is in my HP48GX calculator, not that I actually know or care what to do with it at this point in my life. It would be hugely difficult to get any sort of accuracy in a measurement of the heat lost in a tuner to find its efficiency, I never meant it to be real or even close to reality. Again, I'm sorry to have been joking around on a serious list. Won't do it again. Please, everyone, use what works, have fun, enjoy the hobby with the great E-gear. My KPA500 is heating the room far more than my MFJ989C. If you can make QSO's, it works. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org On 3/10/2012 4:56 PM, Fred Townsend wrote: Ron, Rick, Erik: There are many reasons why temperature measurements are a poor way of evaluating a tuner. There is a method of power measure based on temperature rise. It's called a bolometer. It only works well if the mass involved is small. Wiki bolometers if you want the details. __ 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 __ 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 __ 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
Re: [Elecraft] high-power tuner
Never had any reason to wonder if my MFJ-998 has more than normal loss. It hasn't let any smoke out of the cabinet yet! I use to run a Drake L-7 thru it, but now use the KPA500 all the time and have retired the Drake. /Most of the MFJ tuners tend to rank pretty low in that respect./ Dave, I'd be interested in reading about the info you have on the MFJ tuner loss. - Roger W5RDW -- View this message in context: http://elecraft.365791.n2.nabble.com/high-power-tuner-tp7314904p7359740.html Sent from the Elecraft mailing list archive at Nabble.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
Re: [Elecraft] high-power tuner
I wonder how those that claim a certain efficiency for a MFJ-998 or any other antenna matching device are measuring the output power. No watt meter that I know including the famous and antique Bird can measure power with any degree of accuracy unless the load is very near the nominal value (usually 50 ohms). If you need a tuner, your antenna does not meet this criteria so, what are you using to form your opinion? I suppose that you could compare two tuners for a relative efficiency by using the same transmitter and antenna and a field strength meter. Of course, if you are running near the rated power, you can watch for smoke and get a one time opinion that the device was not efficient enough to survive. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart From: W5RDW rwhitete...@verizon.net To: elecraft@mailman.qth.net Sent: Friday, March 9, 2012 4:10 PM Subject: Re: [Elecraft] high-power tuner Never had any reason to wonder if my MFJ-998 has more than normal loss. It hasn't let any smoke out of the cabinet yet! I use to run a Drake L-7 thru it, but now use the KPA500 all the time and have retired the Drake. /Most of the MFJ tuners tend to rank pretty low in that respect./ Dave, I'd be interested in reading about the info you have on the MFJ tuner loss. - Roger W5RDW -- View this message in context: http://elecraft.365791.n2.nabble.com/high-power-tuner-tp7314904p7359740.html Sent from the Elecraft mailing list archive at Nabble.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 __ 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
Re: [Elecraft] high-power tuner
On Fri, Mar 9, 2012 at 4:24 PM, WILLIS COOKE wrco...@yahoo.com wrote: I wonder how those that claim a certain efficiency for a MFJ-998 or any other antenna matching device are measuring the output power Cookie, the ARRL labs have some way of doing this, but in their reviews of tuners they don't explain how they do it. I suppose they have some scheme for measuring what goes in and what comes out, but they don't say. However, as I mentioned in a previous post, the MFJ 994 tuner they tested (August 2006) had somewhat lower losses than the other similar tuners in the review. I could not find any published data to support the assertion that MFJ tuners have high losses. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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
Re: [Elecraft] high-power tuner
I can think of a few ways to investigate a tuner's efficiency. Google searching can probably give more. You can read the inductor and capacitor values selected by the 998 and then do a circuit simulation of the L network and determine current through the inductors to find their ohmic losses. Second, you can connect known non-inductive resistors (of different values, throw in some inductance or capacitance too) as the output load and then with an RF voltmeter determine the voltage across the load and then calculate the power out. You will have to calculate the phase angle of your load as well if its not purely resistive. This method could be done using low power so its easier to build the output loads. You could probably also measure the temperature rise of the tuner in operation (put it in an insulated box). Granted, there may not be a simple off the self instrument to do it, but it can be done! 73 - Mike WA8BXN ---Original Message--- From: WILLIS COOKE Date: 3/9/2012 5:31:30 PM To: W5RDW; elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner I wonder how those that claim a certain efficiency for a MFJ-998 or any other antenna matching device are measuring the output power. No watt meter that I know including the famous and antique Bird can measure power with any degree of accuracy unless the load is very near the nominal value (usually 50 ohms). If you need a tuner, your antenna does not meet this criteria so, what are you using to form your opinion? I suppose that you could compare two tuners for a relative efficiency by using the same transmitter and antenna and a field strength meter. Of course, if you are running near the rated power, you can watch for smoke and get a one time opinion that the device was not efficient enough to survive. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart __ 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
Re: [Elecraft] high-power tuner
On 3/9/2012 2:24 PM, WILLIS COOKE wrote: If you need a tuner, your antenna does not meet this criteria so, what are you using to form your opinion? Weigh the tuner, then transmit continuously, measure the temperature rise, and when it's stable, calculate the heat loss [something to do with Boltzman's Constant -- the tuner *is* painted black]. What doesn't leave as heat must leave as RF. Did it years ago on a 10 KW FM broadcast transmitter [4 ea 4-1000's], and it came within one percent of the efficiency measured with the water-cooled dummy load. YMMV however. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ 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
Re: [Elecraft] high-power tuner
This probably shows my gross lack of knowledge of the physics involved here, but what does the weight of the tuner have to do with its efficiency? 73, --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/9/2012 6:14 PM, Fred Jensen wrote: On 3/9/2012 2:24 PM, WILLIS COOKE wrote: If you need a tuner, your antenna does not meet this criteria so, what are you using to form your opinion? Weigh the tuner, then transmit continuously, measure the temperature rise, and when it's stable, calculate the heat loss [something to do with Boltzman's Constant -- the tuner *is* painted black]. What doesn't leave as heat must leave as RF. Did it years ago on a 10 KW FM broadcast transmitter [4 ea 4-1000's], and it came within one percent of the efficiency measured with the water-cooled dummy load. YMMV however. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ 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 __ 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
Re: [Elecraft] high-power tuner
I'll take a guess... You have to know the mass to find the amount of energy converted into heat. Like Ohm's law, given two values, you can figure out the third. If you know the mass and know the temperature change, you can calculate the energy. Ok Fred, am I close? Rick wa6nhc -Original Message- From: Ian Kahn - Ham This probably shows my gross lack of knowledge of the physics involved here, but what does the weight of the tuner have to do with its efficiency? 73, --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/9/2012 6:14 PM, Fred Jensen wrote: On 3/9/2012 2:24 PM, WILLIS COOKE wrote: If you need a tuner, your antenna does not meet this criteria so, what are you using to form your opinion? Weigh the tuner, then transmit continuously, measure the temperature rise, and when it's stable, calculate the heat loss [something to do with Boltzman's Constant -- the tuner *is* painted black]. What doesn't leave as heat must leave as RF. Did it years ago on a 10 KW FM broadcast transmitter [4 ea 4-1000's], and it came within one percent of the efficiency measured with the water-cooled dummy load. YMMV however. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ 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 __ 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 __ 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
Re: [Elecraft] high-power tuner
Ian, Weight comes into play in two ways. A heavier tuner will likely have less loss due to less resistive loss by using larger diameter wire etc. But that s not the issue in measuring the loss. As Fred mentions below, power fed into a tuner goes two places. One is out to the load (antenna) and the other is heating the tuner (not a good thing). One can measure how much a tuner warms up during use, that's due to loss in the tuner. Just knowing the temperature change doesn't give the full answer though. Lets say we measure an increased temperature of 10 degrees. Now if we have a very heavy tuner, that would be more power lost in the tuner than in a tuner that has the same 10 degree increase but is very small. Look at it this way. It would take a lot more power to heat a gallon of water 10 degrees than to head a drop of water 10 degrees. To calculate the actual power loss in the tuner you would have to use the right degree units, the right weight (mass) units and constants. You would also have to heat insulate the tuner from the room so it doesn't cool off during your measurement period. 73 - Mike WA8BXN ---Original Message--- From: Ian Kahn - Ham Date: 3/9/2012 6:31:37 PM To: k6...@foothill.net Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner This probably shows my gross lack of knowledge of the physics involved Here, but what does the weight of the tuner have to do with its efficiency? 73, --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/9/2012 6:14 PM, Fred Jensen wrote: On 3/9/2012 2:24 PM, WILLIS COOKE wrote: If you need a tuner, your antenna does not meet this criteria so, what are you using to form your opinion? Weigh the tuner, then transmit continuously, measure the temperature rise, and when it's stable, calculate the heat loss [something to do with Boltzman's Constant -- the tuner *is* painted black]. What doesn't leave as heat must leave as RF. Did it years ago on a 10 KW FM broadcast transmitter [4 ea 4-1000's], and it came within one percent of the efficiency measured with the water-cooled dummy load. YMMV however. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ 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
Re: [Elecraft] high-power tuner
QST had an article a while back comparing tuners, MFJ, Palomar, Drake and several others if I remember correctly. They had a chart showing the loss per band per each tuner. They included the old Johnson Viking matchbox in their ranking too. The old Johnson was right up there in the top rankings, with very low loss. I wish I still had my old Johnson, sigh... Anyway a search on the ARRL webpage for QST articles about tuners should show the article. Bob K6UJ On Mar 9, 2012, at 2:10 PM, W5RDW wrote: Never had any reason to wonder if my MFJ-998 has more than normal loss. It hasn't let any smoke out of the cabinet yet! I use to run a Drake L-7 thru it, but now use the KPA500 all the time and have retired the Drake. /Most of the MFJ tuners tend to rank pretty low in that respect./ Dave, I'd be interested in reading about the info you have on the MFJ tuner loss. - Roger W5RDW -- View this message in context: http://elecraft.365791.n2.nabble.com/high-power-tuner-tp7314904p7359740.html Sent from the Elecraft mailing list archive at Nabble.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 __ 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
Re: [Elecraft] high-power tuner
The only thing that shows gross lack of knowledge is not asking the question for which you need the answer. [Cal Poly Physics Professor whose name escapes me but whose class I remember as a personal struggle]. To know the net rate of heat input [i.e. generation within the tuner] from the temperature change, you need to know the mass of the tuner. Weigh it and a little arithmetic and you have the mass. The RF that doesn't heat the tuner must go up the coax. Weighing has nothing to do with the efficiency itself, it is part of the not-exactly-precise-measurement-method I suggested but don't recommend. For the FM transmitter, we had temperature sensors in the grid compartment on the bottom where the refrigerated air entered, and just far enough above the chimneys where it came out hot. There was a water manometer to measure the pressure difference between the air inlet and the vent that took the hot air outside. The pressure differential was very low so I assumed that the air got hot at a constant pressure. This was an important assumption because at that time I didn't know enough calculus for the alternative. I probably don't remember now either. I got up very early one morning [was 17 and living at the TX], and turned on the filaments. When the temperatures had stabilized, and knowing the filaments were turning 600W of electricity into almost 600W of heat, I could calculate the mass rate of the air flowing through the chimneys. Sign on came, I let the temps stabilize at 5.3 KV and 3.5A plate current, and calculated the heat input to give those temps. That power blew out the vent, the rest went up the 3 1/8 rigid coax to the antenna, I assumed. Turned out we were a little overpower, almost 12KW for about 70% efficiency and the 4-1000 plates were fairly bright. OK, really bright. For the case of the tuner, it's not so simple and I skillfully tried to skate past the effect of radiation from the black body [i.e. the black tuner which, while black, probably isn't a real black body] as the RF heats it. While I know the first six digits of Boltzmann's Constant [138065 -- it used to be the master unlock password for a UHF repeater I maintain], I've forgotten some of the physics and math I used to know and it's guaranteed that, were I to attempt that calculation on this list, a countable infinity of people would correct me and then each other ... likely forever or until Eric stepped in. It was a e-nerd semi-joke, which I've found are not often funny except to other e-nerds. Undaunted however, I continued. Cookie's comment about measuring the efficiency of tuners being hard is very true, and you can't do it with a Micronta SWR meter from Radio Shack. It will involve some math, maybe even calculus, and quite a bit of expensive test equipment. I would trust ARRL's numbers, and those of a few others like Sherwood, I'll remain a little skeptical of the Mfr's numbers, if they even publish them. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org On 3/9/2012 3:30 PM, Ian Kahn - Ham wrote: This probably shows my gross lack of knowledge of the physics involved here, but what does the weight of the tuner have to do with its efficiency? __ 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
Re: [Elecraft] high-power tuner
On Fri, Mar 9, 2012 at 5:30 PM, Ian Kahn - Ham km4ik@gmail.com wrote: This probably shows my gross lack of knowledge of the physics involved here, but what does the weight of the tuner have to do with its efficiency... = Ian, the idea was to measure the power soaked up by the tuner by measuring how fast it heats up. To turn degrees/second into a measure of power, you gotta know how much mass was getting heated. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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
Re: [Elecraft] high-power tuner
I've been making tuner loss measurements for an upcoming QST review of some remote autotuners. My set-up is similar to the ARRL lab, but I've made a few changes. I have two different load boxes. One is a resistive load box that lets me measure loss with loads from 12-800 ohms. The second load box simulates different types of electrically short end-fed antennas - like a 43 footer on lower frequency bands, or an 8-footer like you might have mobile, and other combinations. I use Caddock thick-film 30-watt resistors for the resistive portion of both test boxes. For the short antenna simulator, I use series silver mica capacitors with shunt Caddock resistors. Basically, I feed the 40 watt output of my test transceiver through a high power 6dB pad, through an Array Solutions PowerMaster, then to the tuner. So my test power is 10 watts. The 6dB pad helps keep the power relatively constant, but primarily ensures that any reflected power from a non-perfect tune (the tuners have a target of 1.5:1) is attenuated 12dB more if re-reflected by the transmitter. The output of the tuner feeds the load box. The load box has an output that feeds a 50 ohm attenuator/Minicircuits PWR-6GHS+ power sensor (that output is shunted or seriesed with Caddock resistors to give the required test impedance). So I start with no tuner in-line and adjust the Minicircuits offset so it and the PowerMaster read the same at 10 watts. They are both NIST-traceable cal'd, and were within 3% of each other, but I adjusted the offset so they are within 1%. Then I insert the autotuner, hit it with RF and let it tune. When tuning is complete I adjust the input drive so it is exactly 10 watts, read the output on the PWR-6GHS+, and compare that to the expected power under lossless conditions. Phil - AD5X __ 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
Re: [Elecraft] high-power tuner
All, As I said, question shows my lack of knowledge of physics. :-) Thanks, everyone, for the explanations! 73, --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/9/2012 6:30 PM, Ian Kahn - Ham wrote: This probably shows my gross lack of knowledge of the physics involved here, but what does the weight of the tuner have to do with its efficiency? 73, --Ian Ian Kahn, KM4IK Roswell, GA km4ik@gmail.com K3 #281, P3 #688 On 3/9/2012 6:14 PM, Fred Jensen wrote: On 3/9/2012 2:24 PM, WILLIS COOKE wrote: If you need a tuner, your antenna does not meet this criteria so, what are you using to form your opinion? Weigh the tuner, then transmit continuously, measure the temperature rise, and when it's stable, calculate the heat loss [something to do with Boltzman's Constant -- the tuner *is* painted black]. What doesn't leave as heat must leave as RF. Did it years ago on a 10 KW FM broadcast transmitter [4 ea 4-1000's], and it came within one percent of the efficiency measured with the water-cooled dummy load. YMMV however. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ 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 __ 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
Re: [Elecraft] high-power tuner
Bob, One can construct a link coupled tuner that will have even greater efficiency than the venerable Johnson Matchbox. It will have plug-in coils, and the antenna will connect to taps on the coil rather than using a differential capacitor - that tuner will have a greater matching range than the Matchbox as well as having less loss. The drawback is that it does not lend itself well to bandswitching. OTOH, it does not need to be in an enclosure, can be built on a piece of wood (yes, mine is built on a wooden board), so the plug-in coil is easily accessed and changed to whatever band one wants ot operate on. Once the settings for any one antenna have been established and recorded, changing bands takes less than 30 seconds. As L.B.Cebik has stated many times, link coupled balanced tuners are the most efficient. Their loss is close to zero. 73, Don W3FPR On 3/9/2012 7:56 PM, Bob K6UJ wrote: QST had an article a while back comparing tuners, MFJ, Palomar, Drake and several others if I remember correctly. They had a chart showing the loss per band per each tuner. They included the old Johnson Viking matchbox in their ranking too. The old Johnson was right up there in the top rankings, with very low loss. I wish I still had my old Johnson, sigh... Anyway a search on the ARRL webpage for QST articles about tuners should show the article. Bob K6UJ On Mar 9, 2012, at 2:10 PM, W5RDW wrote: Never had any reason to wonder if my MFJ-998 has more than normal loss. It hasn't let any smoke out of the cabinet yet! I use to run a Drake L-7 thru it, but now use the KPA500 all the time and have retired the Drake. /Most of the MFJ tuners tend to rank pretty low in that respect./ Dave, I'd be interested in reading about the info you have on the MFJ tuner loss. - Roger W5RDW -- View this message in context: http://elecraft.365791.n2.nabble.com/high-power-tuner-tp7314904p7359740.html Sent from the Elecraft mailing list archive at Nabble.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 __ 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 __ 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
Re: [Elecraft] high-power tuner
OK Guys, I have a Physics Degree too, but realistically, if the tuner uses real coils and air capacitors like the Matchbox it is really efficient. If it uses link coupling like we did in olden days it is probably a scotch (technical term meaning a little bit) better than the more common T network. If it uses toroids, small fixed capacitors and relay switching, it probably has even more loss. So, maybe the answer is to buy a tuner that is the same size as your amplifier. If you elect to run a KTA-500 you probably are not terribly concerned whether you get 475 watts to the antenna or 450 watts. If you need an Alpha 9500 to be sure that you get through then you need the Alpha 4040 so it will look great near your 9500 and the 3 grand price will seem cheap after paying 8 grand for the amp. You can always brag on your 75 meter net that of the 1499.9 watts out of the 9500 1499.8 watts get through the 4040 to melt the RG8X that feeds your Buddy Pole. But, if the KTA-500 is your thing then a tuner that costs more than your amp and is the biggest thing in your shack (unless you have a left over BC-610) will look pretty silly. If you must measure your temperatures to figure your efficiency down to the milliwatt, be sure and use RTDs for measurement because thermocouples are not nearly accurate enough for precision measurements. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart From: Tony Estep estept...@gmail.com To: Elecraft elecraft@mailman.qth.net Sent: Friday, March 9, 2012 7:01 PM Subject: Re: [Elecraft] high-power tuner On Fri, Mar 9, 2012 at 5:30 PM, Ian Kahn - Ham km4ik@gmail.com wrote: This probably shows my gross lack of knowledge of the physics involved here, but what does the weight of the tuner have to do with its efficiency... = Ian, the idea was to measure the power soaked up by the tuner by measuring how fast it heats up. To turn degrees/second into a measure of power, you gotta know how much mass was getting heated. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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 __ 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
Re: [Elecraft] high-power tuner
Phil, My lab simulated antenna consists of a dummy load and a Johnson Matchbox. I can connect a dummy load to the Matchbox and twist the dials to create just about any reasonable impedance that you want. I set it up using my MFJ259B if I am looking for something specific. The helpful parameter is that it is frequency sensitive (just like an antenna), while a resistive dummy load is not sensitive to frequency. I do normally use Caddock Thick Film resistors to create dummy loads. I have several 50 ohm loads, but also have a 25 ohm (2 50 ohm resistors in parallel) and a 100 ohm (2 50 ohm resistors in series) that I use for setting the 2:1 SWR point while I am calibrating wattmeters. These are 1% tolerance loads, and if mounted to the connector (and heat sink) with short leads present a flat response up to 500 MHz. Note well that the Caddock literature says only that the 50 ohm resistors are non-reactive - that may be true for other values, but I have taken that information at face value and use only the 50 om resistors for dummy loads. 73, Don W3FPR On 3/9/2012 8:42 PM, Phil Debbie Salas wrote: I've been making tuner loss measurements for an upcoming QST review of some remote autotuners. My set-up is similar to the ARRL lab, but I've made a few changes. I have two different load boxes. One is a resistive load box that lets me measure loss with loads from 12-800 ohms. The second load box simulates different types of electrically short end-fed antennas - like a 43 footer on lower frequency bands, or an 8-footer like you might have mobile, and other combinations. I use Caddock thick-film 30-watt resistors for the resistive portion of both test boxes. For the short antenna simulator, I use series silver mica capacitors with shunt Caddock resistors. Basically, I feed the 40 watt output of my test transceiver through a high power 6dB pad, through an Array Solutions PowerMaster, then to the tuner. So my test power is 10 watts. The 6dB pad helps keep the power relatively constant, but primarily ensures that any reflected power from a non-perfect tune (the tuners have a target of 1.5:1) is attenuated 12dB more if re-reflected by the transmitter. The output of the tuner feeds the load box. The load box has an output that feeds a 50 ohm attenuator/Minicircuits PWR-6GHS+ power sensor (that output is shunted or seriesed with Caddock resistors to give the required test impedance). So I start with no tuner in-line and adjust the Minicircuits offset so it and the PowerMaster read the same at 10 watts. They are both NIST-traceable cal'd, and were within 3% of each other, but I adjusted the offset so they are within 1%. Then I insert the autotuner, hit it with RF and let it tune. When tuning is complete I adjust the input drive so it is exactly 10 watts, read the output on the PWR-6GHS+, and compare that to the expected power under lossless conditions. Phil - AD5X __ 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 __ 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
Re: [Elecraft] high-power tuner
I'm not convinced that toroids are inferior to air wound coils. There will be some core loss but there will be less ohmic loss as well. I'm also not sure that just getting a tuner rated at the same power level as an amplifier is always going to be most efficient. If the marketing agency is doing the tuner rating the rating may be suspect. There are some tuners that can just about match anything for an antenna. If it won't melt at a particular power level, is it the best tuner for that power level? Matching a given load usually means giving the transmitter near a 50 ohm load. If you have a tuner that does that with no antenna attached it means the tuner must dissipate all the power. Manual tuners often have some hints on how to get the best efficiency at a good match, like try to find a match using maximum or minimum value for control X. With automatic tuners, we often just let the tuner do its thing and use the match it finds. Some tuners will have better algorithms than others in picking the best match. The difference from one tuner to another can be a lot more than milliwatts. So it can be a good idea to get good evaluations of available tuners. 73 - Mike WA8BXN ---Original Message--- From: WILLIS COOKE Date: 3/9/2012 9:47:31 PM To: Elecraft Subject: Re: [Elecraft] high-power tuner OK Guys, I have a Physics Degree too, but realistically, if the tuner uses real coils and air capacitors like the Matchbox it is really efficient. If it uses link coupling like we did in olden days it is probably a scotch (technical term meaning a little bit) better than the more common T network. If it uses toroids, small fixed capacitors and relay switching, it probably has even more loss. So, maybe the answer is to buy a tuner that is the same size as your amplifier. If you elect to run a KTA-500 you probably are not terribly concerned whether you get 475 watts to the antenna or 450 watts. If you need an Alpha 9500 to be sure that you get through then you need the Alpha 4040 so it will look great near your 9500 and the 3 grand price will seem cheap after paying 8 grand for the amp. You can always brag on your 75 meter net that of the 1499.9 watts out of the 9500 1499.8 watts get through the 4040 to melt the RG8X that feeds your Buddy Pole. But, if the KTA-500 is your thing then a tuner that costs more than your amp and is the biggest thing in your shack (unless you have a left over BC-610) will look pretty silly. If you must measure your temperatures to figure your efficiency down to the milliwatt, be sure and use RTDs for measurement because thermocouples are not nearly accurate enough for precision measurements. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart __ 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
Re: [Elecraft] high-power tuner
Mike and all, The T-Network tuners are problematic even though they can be quite wide-range - they may show multiple tuning condition for any given antenna/matching situation. They should always be adjusted for the largest value of capacity that will tune properly. Most automatic tuners are of the L network type which avoids the ambiguous tuning spots of the T-network tuners. 73, Don W3FPR On 3/9/2012 10:22 PM, Mike WA8BXN wrote: I'm not convinced that toroids are inferior to air wound coils. There will be some core loss but there will be less ohmic loss as well. I'm also not sure that just getting a tuner rated at the same power level as an amplifier is always going to be most efficient. If the marketing agency is doing the tuner rating the rating may be suspect. There are some tuners that can just about match anything for an antenna. If it won't melt at a particular power level, is it the best tuner for that power level? Matching a given load usually means giving the transmitter near a 50 ohm load. If you have a tuner that does that with no antenna attached it means the tuner must dissipate all the power. Manual tuners often have some hints on how to get the best efficiency at a good match, like try to find a match using maximum or minimum value for control X. With automatic tuners, we often just let the tuner do its thing and use the match it finds. Some tuners will have better algorithms than others in picking the best match. The difference from one tuner to another can be a lot more than milliwatts. So it can be a good idea to get good evaluations of available tuners. 73 - Mike WA8BXN ---Original Message--- From: WILLIS COOKE Date: 3/9/2012 9:47:31 PM To: Elecraft Subject: Re: [Elecraft] high-power tuner OK Guys, I have a Physics Degree too, but realistically, if the tuner uses real coils and air capacitors like the Matchbox it is really efficient. If it uses link coupling like we did in olden days it is probably a scotch (technical term meaning a little bit) better than the more common T network. If it uses toroids, small fixed capacitors and relay switching, it probably has even more loss. So, maybe the answer is to buy a tuner that is the same size as your amplifier. If you elect to run a KTA-500 you probably are not terribly concerned whether you get 475 watts to the antenna or 450 watts. If you need an Alpha 9500 to be sure that you get through then you need the Alpha 4040 so it will look great near your 9500 and the 3 grand price will seem cheap after paying 8 grand for the amp. You can always brag on your 75 meter net that of the 1499.9 watts out of the 9500 1499.8 watts get through the 4040 to melt the RG8X that feeds your Buddy Pole. But, if the KTA-500 is your thing then a tuner that costs more than your amp and is the biggest thing in your shack (unless you have a left over BC-610) will look pretty silly. If you must measure your temperatures to figure your efficiency down to the milliwatt, be sure and use RTDs for measurement because thermocouples are not nearly accurate enough for precision measurements. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart __ 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 __ 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
Re: [Elecraft] high-power tuner
A T-Network tuner with a large enough capacitor in one leg set to full capacity is essentially an L-network tuner. 73, Dave AB7E On 3/9/2012 9:55 PM, Don Wilhelm wrote: Mike and all, The T-Network tuners are problematic even though they can be quite wide-range - they may show multiple tuning condition for any given antenna/matching situation. They should always be adjusted for the largest value of capacity that will tune properly. Most automatic tuners are of the L network type which avoids the ambiguous tuning spots of the T-network tuners. 73, Don W3FPR On 3/9/2012 10:22 PM, Mike WA8BXN wrote: I'm not convinced that toroids are inferior to air wound coils. There will be some core loss but there will be less ohmic loss as well. I'm also not sure that just getting a tuner rated at the same power level as an amplifier is always going to be most efficient. If the marketing agency is doing the tuner rating the rating may be suspect. There are some tuners that can just about match anything for an antenna. If it won't melt at a particular power level, is it the best tuner for that power level? Matching a given load usually means giving the transmitter near a 50 ohm load. If you have a tuner that does that with no antenna attached it means the tuner must dissipate all the power. Manual tuners often have some hints on how to get the best efficiency at a good match, like try to find a match using maximum or minimum value for control X. With automatic tuners, we often just let the tuner do its thing and use the match it finds. Some tuners will have better algorithms than others in picking the best match. The difference from one tuner to another can be a lot more than milliwatts. So it can be a good idea to get good evaluations of available tuners. 73 - Mike WA8BXN ---Original Message--- From: WILLIS COOKE Date: 3/9/2012 9:47:31 PM To: Elecraft Subject: Re: [Elecraft] high-power tuner OK Guys, I have a Physics Degree too, but realistically, if the tuner uses real coils and air capacitors like the Matchbox it is really efficient. If it uses link coupling like we did in olden days it is probably a scotch (technical term meaning a little bit) better than the more common T network. If it uses toroids, small fixed capacitors and relay switching, it probably has even more loss. So, maybe the answer is to buy a tuner that is the same size as your amplifier. If you elect to run a KTA-500 you probably are not terribly concerned whether you get 475 watts to the antenna or 450 watts. If you need an Alpha 9500 to be sure that you get through then you need the Alpha 4040 so it will look great near your 9500 and the 3 grand price will seem cheap after paying 8 grand for the amp. You can always brag on your 75 meter net that of the 1499.9 watts out of the 9500 1499.8 watts get through the 4040 to melt the RG8X that feeds your Buddy Pole. But, if the KTA-500 is your thing then a tuner that costs more than your amp and is the biggest thing in your shack (unless you have a left over BC-610) will look pretty silly. If you must measure your temperatures to figure your efficiency down to the milliwatt, be sure and use RTDs for measurement because thermocouples are not nearly accurate enough for precision measurements. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart __ 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 __ 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 __ 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
Re: [Elecraft] high-power tuner
Ditto on the MFJ-998 autotuner. I have had mine a few years and now use it with the KPA500. It has matched anything I have thrown at it. A little on the noisy side when it gets a hold of a load it has to work on a little, but it has always done what I want it to do. - Roger W5RDW -- View this message in context: http://elecraft.365791.n2.nabble.com/high-power-tuner-tp7314904p7333509.html Sent from the Elecraft mailing list archive at Nabble.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
Re: [Elecraft] high-power tuner
Just curious ... have you ever measured the loss in the tuner? Most of the MFJ tuners tend to rank pretty low in that respect. Presenting a usable load to the amplifier does not in itself make it a good tuner. 73, Dave AB7E On 3/1/2012 11:16 AM, W5RDW wrote: Ditto on the MFJ-998 autotuner. I have had mine a few years and now use it with the KPA500. It has matched anything I have thrown at it. A little on the noisy side when it gets a hold of a load it has to work on a little, but it has always done what I want it to do. - Roger W5RDW __ 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
Re: [Elecraft] high-power tuner
On Thu, Mar 1, 2012 at 1:25 PM, David Gilbert xda...@cis-broadband.com wrote: ...Most of the MFJ tuners tend to rank pretty low ... === QST hasn't reviewed the 998, but they did have a review of the MFJ 994 back in 2006. Tested across all bands and a range of impedances, it generally showed lower losses than the other similar autotuners tested, made by Palstar and LDG. There is a mini-review of the 998 by list member AD5X at: http://www.ad5x.com/images/Presentations/MFJ998%20Review%20RevA.pdf but it doesn't include loss measurements. Other than the loss measurements for the 994 mentioned above, which looked pretty good, I can't find any other measured results for MFJ auto-tuners. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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
[Elecraft] high-power tuner
All, I find myself finally admitting that I need an antenna tuner that supports high power. I run a K3/P3 combo with an Ameritron AL-811H amp. Since we are still waiting on word about pricing and release date for the KAT500, I find myself looking at other alternatives for a 1 - 1.5 KW auto tuner. What are others using? Several people I know have had issues with the LDG AT-1000PRO, so I probably want to stay away from that one. Thanks in advance for the advice. 73, -- Ian Ian Kahn, KM4IK Roswell, GA EM74ua km4ik@gmail.com K3 #281, P3 #688 __ 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
Re: [Elecraft] high-power tuner
Hi Ian, Many of us are in that boat. I don't believe the KTA500 is vaperware. I'm just cooling my heals for the reason you cited, unreliable products from the competition. I want good products and great support from people that care about their customers. That is worth the wait, even if it is until the end of the year. Heck the K3 tuner will load a hairpin, I would expect the KTA500 will as well. If I just couldn't wait any longer ,I think I would find a manual tuner to hold me over (one that had a good resale value). :) 73, Bill AK5X On Feb 24, 2012, at 8:05 AM, Ian Kahn wrote: All, I find myself finally admitting that I need an antenna tuner that supports high power. I run a K3/P3 combo with an Ameritron AL-811H amp. Since we are still waiting on word about pricing and release date for the KAT500, I find myself looking at other alternatives for a 1 - 1.5 KW auto tuner. What are others using? Several people I know have had issues with the LDG AT-1000PRO, so I probably want to stay away from that one. Thanks in advance for the advice. 73, -- Ian Ian Kahn, KM4IK Roswell, GA EM74ua km4ik@gmail.com K3 #281, P3 #688 __ 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 Bill Hammond wham...@aol.com Bill Hammond-AK5X a...@mac.com a...@sbcglobal.net K3 #69 P3 #817 KPA500 # 149 K2/100 #4637 K1 #2033 KX1 #1023 T1 __ 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
Re: [Elecraft] high-power tuner
On 2/24/2012 6:05 AM, Ian Kahn wrote: What are others using? Several people I know have had issues with the LDG AT-1000PRO, so I probably want to stay away from that one. I found the AT-1000 lacking and sold it when LDG could not improve it (and kept it for three months). I strongly recommend the Ten Tec 229 and 238 tuners, which can be bought used for around $275 and $300 respectively. Essentially the same, different appearance. Manual tuner, rated for legal limit. L-section design, so they tend to produce a match with greater bandwidth than T-section tuners. The only PITA about these tuners is the dial cord. 73, Jim K9YC. __ 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
Re: [Elecraft] high-power tuner
We're just making sure performance is as good as possible. (The stakes are even higher in a QRO tuner.) The most recent prototype worked great, in general, but on 6 meters we felt the loss was a fraction of a dB too high. The PCB layout has been changed to cut the RF path length and strays by a factor of two, which should do the trick. We'll receive these boards in a week or so and should have test results a week after that. This suggests that we could have some field test units out in mid/late-March. 73, Wayne N6KR On Feb 24, 2012, at 8:23 AM, Bill Hammond wrote: Hi Ian, Many of us are in that boat. I don't believe the KTA500 is vaperware. I'm just cooling my heals for the reason you cited, unreliable products from the competition. I want good products and great support from people that care about their customers. That is worth the wait, even if it is until the end of the year. Heck the K3 tuner will load a hairpin, I would expect the KTA500 will as well. If I just couldn't wait any longer ,I think I would find a manual tuner to hold me over (one that had a good resale value). :) 73, Bill AK5X On Feb 24, 2012, at 8:05 AM, Ian Kahn wrote: All, I find myself finally admitting that I need an antenna tuner that supports high power. I run a K3/P3 combo with an Ameritron AL-811H amp. Since we are still waiting on word about pricing and release date for the KAT500, I find myself looking at other alternatives for a 1 - 1.5 KW auto tuner. What are others using? Several people I know have had issues with the LDG AT-1000PRO, so I probably want to stay away from that one. Thanks in advance for the advice. 73, -- Ian Ian Kahn, KM4IK Roswell, GA EM74ua km4ik@gmail.com K3 #281, P3 #688 __ 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 Bill Hammond wham...@aol.com Bill Hammond-AK5X a...@mac.com a...@sbcglobal.net K3 #69 P3 #817 KPA500 # 149 K2/100 #4637 K1 #2033 KX1 #1023 T1 __ 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 __ 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
Re: [Elecraft] high-power tuner
Thanks for the update on the KAT500 development, Wayne. In the meantime, I'm using an MFJ-988 satisfactorily. 73, Bruce, N1RX We're just making sure performance is as good as possible. (The stakes are even higher in a QRO tuner.) The most recent prototype worked great, in general, but on 6 meters we felt the loss was a fraction of a dB too high. The PCB layout has been changed to cut the RF path length and strays by a factor of two, which should do the trick. We'll receive these boards in a week or so and should have test results a week after that. This suggests that we could have some field test units out in mid/late-March. 73, Wayne N6KR __ 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
Re: [Elecraft] high-power tuner
Ian, Unfortunately, I'm in the same boat: Looking for an antenna tuner that *truly* supports high power. I was hoping the Palstar balanced tuner BT1500A was it, but I found it less than robust when processing 1500 W. The tuner (fine print) is not spec'd for 1500 continuous, so forget RTTY/etc and beware full power tune-ups. The input balun toasts quite nicely. Also, the relay that switches the large section of the capacitor in/out failed on me, with the inner insulation of that relay bubbling up out of the core. The tuner ought to run relays energized forever. Mine did not. I had left it configured that way (ten meters) overnight. My bad, apparently. YMMV of course. If you ever find one that will tolerate 1.5 kW into various loads, please post it. FYI, I'm using that tuner to match to a 260' dipole, center fed with nominal 600-ohm OWL (constructed using Ladder Snaps). 73 and GL! Gary W2CS All, I find myself finally admitting that I need an antenna tuner that supports high power. I run a K3/P3 combo with an Ameritron AL-811H amp. Since we are still waiting on word about pricing and release date for the KAT500, I find myself looking at other alternatives for a 1 - 1.5 KW auto tuner. What are others using? Several people I know have had issues with the LDG AT-1000PRO, so I probably want to stay away from that one. Thanks in advance for the advice. 73, -- Ian Ian Kahn, KM4IK __ 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
Re: [Elecraft] high-power tuner
On 2/24/2012 8:57 AM, Gary Ferdinand wrote: is not spec'd for 1500 continuous, so forget RTTY/etc and beware full power tune-ups. Few power amps are rated for1.5kW continuous. Yes, there are a few, like some Alpha models. Most are rated for 1.5kW intermittent duty, and should be de-rated by a few dB for keydown modes. The Ten Tec tuners I mentioned fall into that category too -- indeed, there are a few fixed caps that will release smoke when run at 1.5kW into some loads for long periods during a contest, but those caps are easily replaced with parts rated for more current, and the replacements are not expensive. Folks should be more patient with Elecraft -- they are well known for taking enough time with engineering both at the design and manufacturing stage to produce a product we'll be happy to own, as Wayne's recent post in this thread clearly illustrates. 73, Jim K9YC __ 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
Re: [Elecraft] high-power tuner
Ian - I have been watching product developments I this power/automatic operation category: Palstar HF-AUTO http://www.palstar.com/hf-auto.php RF Concepts/Alpha 4040 Automatic Tuner http://www.rfconcepts.com/PRODUCTS/New-Products/Alpha4040 E-Z Tuner - Jim Garland, W8ZR (2002 QST article and ARRL Handbooks) http://www.w8zr.net/eztuner/index.htm I made a suggestion to Steve at RF Concepts, a couple of years ago, when RF Concepts was planning a high-power HF automatic tuner. They needed to incorporate more uProcessor/controller power (since W8ZR Basic Stamp) in their planned offering, since the state-of-art has progressed since 2002. They did, using Linux kernel with the Beagleboard XM The Palstar and RF Concepts/Alpha offerings are INDOOR tuners. I have a preference to have the tuner outdoors at the antennas or feedpoints (like commercial broadcasters). == IF Wayne, N6NR is coming to Dayton - it would be nice to SEE one of the KAT500 prototypes == Greg, w9gb === previous message === Date: Fri, 24 Feb 2012 08:32:58 -0800 From: Wayne Burdick n...@elecraft.com Subject: Re: [Elecraft] high-power tuner To: Bill Hammond wham...@aol.com We're just making sure performance is as good as possible. (The stakes are even higher in a QRO tuner.) The most recent prototype worked great, in general, but on 6 meters we felt the loss was a fraction of a dB too high. The PCB layout has been changed to cut the RF path length and strays by a factor of two, which should do the trick. We'll receive these boards in a week or so and should have test results a week after that. This suggests that we could have some field test units out in mid/late-March. 73,Wayne - N6KR __ 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
Re: [Elecraft] high-power tuner
Wayne, thank you for the update on the KAT500 progress. While I won't be at Dayton, I, too, would love to see at least photos of the prototype posted to the web site. All others - Thank you for the suggestions. Fortuitously, I actually was offered, at no charge, a legal limit manual inductor roller tuner. Since this one is free, I'll take it and bide my time until Wayne, Eric, and Company release the KAT500. 73, --Ian Ian Kahn, KM4IK Roswell, GA EM74ua km4ik@gmail.com K3 #281, P3 #688 On Fri, Feb 24, 2012 at 1:09 PM, Greg Beat gregory.b...@comcast.net wrote: Ian - I have been watching product developments I this power/automatic operation category: Palstar HF-AUTO http://www.palstar.com/hf-auto.php RF Concepts/Alpha 4040 Automatic Tuner http://www.rfconcepts.com/PRODUCTS/New-Products/Alpha4040 E-Z Tuner - Jim Garland, W8ZR (2002 QST article and ARRL Handbooks) http://www.w8zr.net/eztuner/index.htm I made a suggestion to Steve at RF Concepts, a couple of years ago, when RF Concepts was planning a high-power HF automatic tuner. They needed to incorporate more uProcessor/controller power (since W8ZR Basic Stamp) in their planned offering, since the state-of-art has progressed since 2002. They did, using Linux kernel with the Beagleboard XM The Palstar and RF Concepts/Alpha offerings are INDOOR tuners. I have a preference to have the tuner outdoors at the antennas or feedpoints (like commercial broadcasters). == IF Wayne, N6NR is coming to Dayton - it would be nice to SEE one of the KAT500 prototypes == Greg, w9gb === previous message === Date: Fri, 24 Feb 2012 08:32:58 -0800 From: Wayne Burdick n...@elecraft.com Subject: Re: [Elecraft] high-power tuner To: Bill Hammond wham...@aol.com We're just making sure performance is as good as possible. (The stakes are even higher in a QRO tuner.) The most recent prototype worked great, in general, but on 6 meters we felt the loss was a fraction of a dB too high. The PCB layout has been changed to cut the RF path length and strays by a factor of two, which should do the trick. We'll receive these boards in a week or so and should have test results a week after that. This suggests that we could have some field test units out in mid/late-March. 73,Wayne - N6KR __ 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 -- __ 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
Re: [Elecraft] high-power tuner
-Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft- boun...@mailman.qth.net] On Behalf Of Jim Brown Sent: Friday, February 24, 2012 12:59 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner On 2/24/2012 8:57 AM, Gary Ferdinand wrote: [The Palstar BT1500A] is not spec'd for 1500 continuous, so forget RTTY/etc and beware full power tune-ups. Few power amps are rated for1.5kW continuous. Yes, there are a few, like some Alpha models. Most are rated for 1.5kW intermittent duty, and should be de-rated by a few dB for keydown modes. My mistake, I guess. I run an Alpha 9500. A true 1.5 kW tuner is important to me at least. The Ten Tec tuners I mentioned fall into that category too -- indeed, there are a few fixed caps that will release smoke when run at 1.5kW into some loads for long periods during a contest, but those caps are easily replaced with parts rated for more current, and the replacements are not expensive. Good to hear. But if a tuner is advertised to handle 1500 W, it should do so without user mods. Folks should be more patient with Elecraft -- they are well known for taking enough time with engineering both at the design and manufacturing stage to produce a product we'll be happy to own, as Wayne's recent post in this thread clearly illustrates. The original poster talked about 1500 W. Is Elecraft considering such a tuner? That would be new (and great!) news to me. For some reason I was under the assumption it would handle around 500 W. __ 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
Re: [Elecraft] high-power tuner
10:1 SWR at 500w equals the same internal antenna current and voltage in the tuner for about a 3:1 SWR at 1500W :-) 73, Eric --- www.elecraft.com On 2/24/2012 11:59 AM, Gary Ferdinand wrote: -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft- boun...@mailman.qth.net] On Behalf Of Jim Brown Sent: Friday, February 24, 2012 12:59 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] high-power tuner On 2/24/2012 8:57 AM, Gary Ferdinand wrote: [The Palstar BT1500A] is not spec'd for 1500 continuous, so forget RTTY/etc and beware full power tune-ups. Few power amps are rated for1.5kW continuous. Yes, there are a few, like some Alpha models. Most are rated for 1.5kW intermittent duty, and should be de-rated by a few dB for keydown modes. My mistake, I guess. I run an Alpha 9500. A true 1.5 kW tuner is important to me at least. The Ten Tec tuners I mentioned fall into that category too -- indeed, there are a few fixed caps that will release smoke when run at 1.5kW into some loads for long periods during a contest, but those caps are easily replaced with parts rated for more current, and the replacements are not expensive. Good to hear. But if a tuner is advertised to handle 1500 W, it should do so without user mods. Folks should be more patient with Elecraft -- they are well known for taking enough time with engineering both at the design and manufacturing stage to produce a product we'll be happy to own, as Wayne's recent post in this thread clearly illustrates. The original poster talked about 1500 W. Is Elecraft considering such a tuner? That would be new (and great!) news to me. For some reason I was under the assumption it would handle around 500 W. __ 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 __ 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
Re: [Elecraft] high-power tuner
I've had a MFJ-998 autotuner for about 3.5 years now. It works great, and it is easy to upgrade its software (a new upgrade just became available). The most power I've put through it is 1200 watts feeding my 43-foot vertical, though now I'm only using it with my KPA500. I have a review on my website at www.ad5x.com, as well as a mod whereby it feeds the amp-disable input on my KPA500 when it tunes. Phil - AD5X __ 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
Re: [Elecraft] High Power Tuner
The Ten Tec tuners have already been mentioned by Jim, K9YC. I've found that the old Dentron MT-3000As will tune almost anything. I have a pair of them that I use on a regular basis with a long wire and pair of 65' almost vertical wires on the low bands, 160 up to 40. They work very well and seem to hold there value based on asking prices I see on various sites. These would be a good choice for someone looking for an interim tuner while waiting for the KAT500. The MT-3000A uses a tapped inductor while another model has a roller inductor. (MT-3000RA may be the model number) I tried a Palstar AT1500CV a few years ago and it would not tune my antenna on 160. I put the Dentron on it and it tuned right up. I plan on getting the KAT500 when Wayne says it's ready for prime time. Until then, I'll wait and leave the Dentrons set for the low bands. 73, Dave N8AG __ 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
Re: [Elecraft] High power tuner
You misunderstand me. I never said that being published by the ARRL made it a good design, and in fact I think that the ARRL has a horrible track record for technical integrity on many of their published articles (particularly those in QST). Much of what we read there is just flat out wrong. I merely pointed out that Alpha seemed to think that being published in ARRL gave the tuner design credibility ... an unwarranted association from my perspective. Dave AB7E On 11/26/2011 8:44 PM, Don Wilhelm wrote: Just because it was published by the ARRL does not make it a good design, although it might help to sell a few. Zack Lau published a QRP version of that tuner some years back and later retracted it, and it has not been mentioned much since, but Dean Straw published his high power version of about the same design and that seems to be the best thing since sliced bread despite counterclaims by noted authorities on balun and RF designs - W8JI, W7El and others. Bottom line, it just does not work well, although there will be many who will say that Alpha makes good stuff, that still makes it a stretch of the laws of physics - using an unbalanced network floating (although not really isolated from a common reference (ground)) will still not make everything balanced. I know there are those who will claim that an off center fed dipole has a balanced feedpoint, but I am not convinced. I put the balun at the input tuners in the same category. Take a balanced signal (output of a balun) and feed it through an unbalanced network, and claim that the output of that unbalanced network is balanced just does not make much sense to me. Maybe with ideal components it *might* be possible, but if one would plot the reactance and phase delay around that unbalanced network using good scientific methods, it would become obvious that the output would not be of equal and opposite currents with 180 degrees phase difference. If the schematic does not look balanced, it is not really balanced. Follow the leading current and lagging current around the circuit to convince yourself. 73, Don W3FPR On 11/26/2011 10:10 PM, David Gilbert wrote: If I remember correctly, the announcement for the Alpha tuner even stated that they drew heavily (or words to that effect) from the ARRL Antenna Book for the design. 73, Dave AB7E On 11/26/2011 6:37 PM, Paul Christensen wrote: I was surprised to see this from Alpha, whom I would have expected to know better. The identical design (less automated functions) can seen in recent issues of the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and titled High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines. Even output C is the same at 800 pF max. Paul, W9AC __ __ 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 __ 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 __ 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
[Elecraft] High power tuner
newslet...@rfconcepts.com An example of how the price of a tuner can grow astronomically with power level. At what point does it make more sense to spend the same $$ for antennas which don't require a tuner? 73 de Brian/K3KO __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] high power tuner (link correction)
http://campaign.r20.constantcontact.com/render?llr=eka89lcabv=001fTAmhMmZbVL5AqOm6mDmdnjCbcFXbog1_4JXCmhhFWFkXvic-XnZgqpJGIqwKpQIsWSuSUHswh3dwX-zMfl96No5OXzGlWuH4TlKnoUfb7dRQV01LLAuHqatOeLxNH16NFSeDLbWslXs0meT-edifw%3D%3D __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] High power tuner
No-tune antennas such as the BW all-band no-tune folded dipole generally waste half the power fed them in the termination resistor. However, you can get a good all-band high-power memory tuner for much, much less than what I would imagine that Alpha tuner will cost, and feed an all-band antenna like a G5RV with good results. Van W1WCG newslet...@rfconcepts.com An example of how the price of a tuner can grow astronomically with power level. At what point does it make more sense to spend the same $$ for antennas which don't require a tuner? __ 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
Re: [Elecraft] High power tuner
An example of how the price of a tuner can grow astronomically with power level. At what point does it make more sense to spend the same $$ for antennas which don't require a tuner? For some of us where only one HF antenna is feasible, it may make sense to put all the money in the tuner and *not* the antenna. For example, I've gotten away with an 80m dipole at 60-ft in my gated community, only due to the natural antenna supports: pine trees. For me, the optimal solution for 80m-10m coverage, consists of a remote-controlled, symmetrical tuner built in a WX-proof enclosure and located at the base of an open feeder line. This offers me minimum system loss, minimum RFI leakage to my transmission line, and all band coverage. Sure, I have no control over maximum lobes and minimum nulls at higher frequencies, but given the QTH constrains, it made sense to put all the money into a truly balanced tuner and nearly zero cost in the antenna. Through 4Nec2 modeling and TLD, my antenna system losses are very low and in all cases, exceeds the performance of resonant mono-band dipoles fed with LMR-400. My 600-ohm line length is optimized for all bands using an N2PK VNA. The new RF Concepts tuner would not work well for me. It's an unbalanced C-L-C design with a CM choke input, similar in design with several Palstar tuners, only with much more rugged components than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a C-L-C tuner and have concluded that placement at the input is not as effective for maintaining line balance as a balun placed at the tuner's output. The exception being if the CM choke is placed at the input of a symmetrical, balanced tuner (e.g., AG6K type). My tuner is of this type and can be seen on my QRZ.com page. Read through the eHam reviews and see just how gullible we are when it comes to tuner evaluation. Nearly all accolades are based on: (1) the ability of the tuner to achieve an input VSWR of 1:1; (2) pretty layout; and (3) component size. None of these factors tell us about the tuner's efficiency. When a tuner needs it own cooling and ventilation system to function, that should throw up red warning flags. The new RF Concepts tuner has switched, 8pF to 800 pF output C. Although better than most commercial tuners, it would have been even better to at least double that amount so long as minimum C is maintained through high isolation switched C. The real *big* unknown with the new tuner is coil Q over its entire range. I would like to see a Q plot of the coil mounted in the metal enclosure. That's a critical piece of evidence in order to evaluate the tuner's efficiency, especially with low-Z line terminations. With both input and out C being vacuum types, I would expect high-Q for the C components. I'm not too concerned about a tuner's ability to tune and match low-Z loads. For base station operation, there are few combinations of full size wire antennas that place a low-Z at the line input, no matter the line length. If I'm dealing with low-Z transmission line inputs, then its an antenna I probably don't want in the first place. For portable and mobile installations, that a wholly different matter. Finally, the new RF Concepts tuner has a slick Smith chart display on the front panel. Only, the charting shows the Z at the input of the tuner which is of very limited value. Since the input is always tuned and matched for 50+j0, even the simple Monimatch circuit is sufficient for that purpose. So, it's nice eye candy but I see nearly no value in the display. Paul, W9AC __ 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
Re: [Elecraft] High power tuner
The new RF Concepts tuner would not work well for me. It's an unbalanced C-L-C design with a CM choke input, similar in design with several Palstar tuners, only with much more rugged components than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a C-L-C tuner and have concluded that placement at the input is not as effective for maintaining line balance as a balun placed at the tuner's output. The common mode choke in the Alpha tuner will be completely ineffective with any of the coaxial fed antenna outputs in any case! Since it is *inside* a metal box and the input as well as output connectors are all connected to the case, any common mode current will simply bypass the the choke on the case! The *only way* to make a common mode choke effective with an unbalanced tuner is to connect the case of the tuner to a low impedance ground and place the choke in the feedline between the rig/amplifier and the tuner - external to the tuner. 73, ... Joe, W4TV On 11/26/2011 11:04 AM, Paul Christensen wrote: An example of how the price of a tuner can grow astronomically with power level. At what point does it make more sense to spend the same $$ for antennas which don't require a tuner? For some of us where only one HF antenna is feasible, it may make sense to put all the money in the tuner and *not* the antenna. For example, I've gotten away with an 80m dipole at 60-ft in my gated community, only due to the natural antenna supports: pine trees. For me, the optimal solution for 80m-10m coverage, consists of a remote-controlled, symmetrical tuner built in a WX-proof enclosure and located at the base of an open feeder line. This offers me minimum system loss, minimum RFI leakage to my transmission line, and all band coverage. Sure, I have no control over maximum lobes and minimum nulls at higher frequencies, but given the QTH constrains, it made sense to put all the money into a truly balanced tuner and nearly zero cost in the antenna. Through 4Nec2 modeling and TLD, my antenna system losses are very low and in all cases, exceeds the performance of resonant mono-band dipoles fed with LMR-400. My 600-ohm line length is optimized for all bands using an N2PK VNA. The new RF Concepts tuner would not work well for me. It's an unbalanced C-L-C design with a CM choke input, similar in design with several Palstar tuners, only with much more rugged components than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a C-L-C tuner and have concluded that placement at the input is not as effective for maintaining line balance as a balun placed at the tuner's output. The exception being if the CM choke is placed at the input of a symmetrical, balanced tuner (e.g., AG6K type). My tuner is of this type and can be seen on my QRZ.com page. Read through the eHam reviews and see just how gullible we are when it comes to tuner evaluation. Nearly all accolades are based on: (1) the ability of the tuner to achieve an input VSWR of 1:1; (2) pretty layout; and (3) component size. None of these factors tell us about the tuner's efficiency. When a tuner needs it own cooling and ventilation system to function, that should throw up red warning flags. The new RF Concepts tuner has switched, 8pF to 800 pF output C. Although better than most commercial tuners, it would have been even better to at least double that amount so long as minimum C is maintained through high isolation switched C. The real *big* unknown with the new tuner is coil Q over its entire range. I would like to see a Q plot of the coil mounted in the metal enclosure. That's a critical piece of evidence in order to evaluate the tuner's efficiency, especially with low-Z line terminations. With both input and out C being vacuum types, I would expect high-Q for the C components. I'm not too concerned about a tuner's ability to tune and match low-Z loads. For base station operation, there are few combinations of full size wire antennas that place a low-Z at the line input, no matter the line length. If I'm dealing with low-Z transmission line inputs, then its an antenna I probably don't want in the first place. For portable and mobile installations, that a wholly different matter. Finally, the new RF Concepts tuner has a slick Smith chart display on the front panel. Only, the charting shows the Z at the input of the tuner which is of very limited value. Since the input is always tuned and matched for 50+j0, even the simple Monimatch circuit is sufficient for that purpose. So, it's nice eye candy but I see nearly no value in the display. Paul, W9AC __ 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:
Re: [Elecraft] High power tuner
Looking at the RF Concepts simplified schematic diagram, the directional coupler appears to remain active when the tuner is in bypass. So, as long as the Smith chart feature works in bypass, it would definitely provide some useful information about the line input Z within the limits of the directional coupler accuracy. Paul, W9AC - Original Message - From: Paul Christensen w...@arrl.net To: elecraft@mailman.qth.net Sent: Saturday, November 26, 2011 11:04 AM Subject: Re: [Elecraft] High power tuner An example of how the price of a tuner can grow astronomically with power level. At what point does it make more sense to spend the same $$ for antennas which don't require a tuner? For some of us where only one HF antenna is feasible, it may make sense to put all the money in the tuner and *not* the antenna. For example, I've gotten away with an 80m dipole at 60-ft in my gated community, only due to the natural antenna supports: pine trees. For me, the optimal solution for 80m-10m coverage, consists of a remote-controlled, symmetrical tuner built in a WX-proof enclosure and located at the base of an open feeder line. This offers me minimum system loss, minimum RFI leakage to my transmission line, and all band coverage. Sure, I have no control over maximum lobes and minimum nulls at higher frequencies, but given the QTH constrains, it made sense to put all the money into a truly balanced tuner and nearly zero cost in the antenna. Through 4Nec2 modeling and TLD, my antenna system losses are very low and in all cases, exceeds the performance of resonant mono-band dipoles fed with LMR-400. My 600-ohm line length is optimized for all bands using an N2PK VNA. The new RF Concepts tuner would not work well for me. It's an unbalanced C-L-C design with a CM choke input, similar in design with several Palstar tuners, only with much more rugged components than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a C-L-C tuner and have concluded that placement at the input is not as effective for maintaining line balance as a balun placed at the tuner's output. The exception being if the CM choke is placed at the input of a symmetrical, balanced tuner (e.g., AG6K type). My tuner is of this type and can be seen on my QRZ.com page. Read through the eHam reviews and see just how gullible we are when it comes to tuner evaluation. Nearly all accolades are based on: (1) the ability of the tuner to achieve an input VSWR of 1:1; (2) pretty layout; and (3) component size. None of these factors tell us about the tuner's efficiency. When a tuner needs it own cooling and ventilation system to function, that should throw up red warning flags. The new RF Concepts tuner has switched, 8pF to 800 pF output C. Although better than most commercial tuners, it would have been even better to at least double that amount so long as minimum C is maintained through high isolation switched C. The real *big* unknown with the new tuner is coil Q over its entire range. I would like to see a Q plot of the coil mounted in the metal enclosure. That's a critical piece of evidence in order to evaluate the tuner's efficiency, especially with low-Z line terminations. With both input and out C being vacuum types, I would expect high-Q for the C components. I'm not too concerned about a tuner's ability to tune and match low-Z loads. For base station operation, there are few combinations of full size wire antennas that place a low-Z at the line input, no matter the line length. If I'm dealing with low-Z transmission line inputs, then its an antenna I probably don't want in the first place. For portable and mobile installations, that a wholly different matter. Finally, the new RF Concepts tuner has a slick Smith chart display on the front panel. Only, the charting shows the Z at the input of the tuner which is of very limited value. Since the input is always tuned and matched for 50+j0, even the simple Monimatch circuit is sufficient for that purpose. So, it's nice eye candy but I see nearly no value in the display. Paul, W9AC __ 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 __ 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
Re: [Elecraft] High power tuner
The balanced output is not referenced to the case. So the balun is functional when feeding a balanced line, not shorted as you suggest. However, you are correct that it will not serve as a common mode choke with unbalanced output. And Paul's comments about the placement of the balun are correct. I was surprised to see this from Alpha, whom I would have expected to know better. I suppose I'll have to wait for the KAT1500 (no, no such product has been announced or hinted at as far as I know!) On 11/26/2011 8:55 AM, Joe Subich, W4TV wrote: The new RF Concepts tuner would not work well for me. It's an unbalanced C-L-C design with a CM choke input, similar in design with several Palstar tuners, only with much more rugged components than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a C-L-C tuner and have concluded that placement at the input is not as effective for maintaining line balance as a balun placed at the tuner's output. The common mode choke in the Alpha tuner will be completely ineffective with any of the coaxial fed antenna outputs in any case! Since it is *inside* a metal box and the input as well as output connectors are all connected to the case, any common mode current will simply bypass the the choke on the case! The *only way* to make a common mode choke effective with an unbalanced tuner is to connect the case of the tuner to a low impedance ground and place the choke in the feedline between the rig/amplifier and the tuner - external to the tuner. 73, ... Joe, W4TV -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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
Re: [Elecraft] High power tuner
Vic, I'm waiting for a KPA-1500 with the inbuilt auto-tuner.oops, gotta run, the nice young man in the white coat is calling me again Gary VK4FD - Motorhome Mobile Elecraft Equipment K3 #679, KPA-500 #018 Living the dream!!! - Original Message - From: Vic K2VCO To: elecraft@mailman.qth.net Sent: Sunday, November 27, 2011 9:00 AM Subject: Re: [Elecraft] High power tuner The balanced output is not referenced to the case. So the balun is functional when feeding a balanced line, not shorted as you suggest. However, you are correct that it will not serve as a common mode choke with unbalanced output. And Paul's comments about the placement of the balun are correct. I was surprised to see this from Alpha, whom I would have expected to know better. I suppose I'll have to wait for the KAT1500 (no, no such product has been announced or hinted at as far as I know!) On 11/26/2011 8:55 AM, Joe Subich, W4TV wrote: The new RF Concepts tuner would not work well for me. It's an unbalanced C-L-C design with a CM choke input, similar in design with several Palstar tuners, only with much more rugged components than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a C-L-C tuner and have concluded that placement at the input is not as effective for maintaining line balance as a balun placed at the tuner's output. The common mode choke in the Alpha tuner will be completely ineffective with any of the coaxial fed antenna outputs in any case! Since it is *inside* a metal box and the input as well as output connectors are all connected to the case, any common mode current will simply bypass the the choke on the case! The *only way* to make a common mode choke effective with an unbalanced tuner is to connect the case of the tuner to a low impedance ground and place the choke in the feedline between the rig/amplifier and the tuner - external to the tuner. 73, ... Joe, W4TV -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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 __ 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
Re: [Elecraft] High power tuner
On 11/26/2011 6:00 PM, Vic K2VCO wrote: The balanced output is not referenced to the case. So the balun is functional when feeding a balanced line, not shorted as you suggest. You are correct, that the balun is not shorted when feeding a balanced antenna. However, in that configuration it will *only* function as a common mode choke (if it is not constructed as a voltage balun). Any antenna connected to the balanced terminals will still not be truly balanced as it is not possible to generate a balanced output at the output of an unbalanced network by forcing balance at the input of that network. It is quite likely that a balun at the input of an unbalanced network will only increase circulating currents (and losses) in the network. 73, ... Joe, W4TV On 11/26/2011 6:00 PM, Vic K2VCO wrote: The balanced output is not referenced to the case. So the balun is functional when feeding a balanced line, not shorted as you suggest. However, you are correct that it will not serve as a common mode choke with unbalanced output. And Paul's comments about the placement of the balun are correct. I was surprised to see this from Alpha, whom I would have expected to know better. I suppose I'll have to wait for the KAT1500 (no, no such product has been announced or hinted at as far as I know!) On 11/26/2011 8:55 AM, Joe Subich, W4TV wrote: The new RF Concepts tuner would not work well for me. It's an unbalanced C-L-C design with a CM choke input, similar in design with several Palstar tuners, only with much more rugged components than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a C-L-C tuner and have concluded that placement at the input is not as effective for maintaining line balance as a balun placed at the tuner's output. The common mode choke in the Alpha tuner will be completely ineffective with any of the coaxial fed antenna outputs in any case! Since it is *inside* a metal box and the input as well as output connectors are all connected to the case, any common mode current will simply bypass the the choke on the case! The *only way* to make a common mode choke effective with an unbalanced tuner is to connect the case of the tuner to a low impedance ground and place the choke in the feedline between the rig/amplifier and the tuner - external to the tuner. 73, ... Joe, W4TV __ 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
Re: [Elecraft] High power tuner
The same is true of the antenna itself. Few balanced antennas -- center fed wires, loops, etc.-- actually present a balanced load due to the proximity of other objects in the near field of the radiator. The feed lines to those antennas often will *not* be well balanced even when connected to the most balanced tuner. Fortunately, a reasonable amount of radiation from a somewhat unbalanced feed line will not be a problem in most installations. 73, Ron AC7AC -Original Message- Any antenna connected to the balanced terminals will still not be truly balanced as it is not possible to generate a balanced output at the output of an unbalanced network by forcing balance at the input of that network. It is quite likely that a balun at the input of an unbalanced network will only increase circulating currents (and losses) in the network. 73, ... Joe, W4TV __ 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
Re: [Elecraft] High power tuner
I was surprised to see this from Alpha, whom I would have expected to know better. The identical design (less automated functions) can seen in recent issues of the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and titled High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines. Even output C is the same at 800 pF max. Paul, W9AC __ 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
Re: [Elecraft] High power tuner
I know. I expected better of them, too. On 11/26/2011 5:37 PM, Paul Christensen wrote: I was surprised to see this from Alpha, whom I would have expected to know better. The identical design (less automated functions) can seen in recent issues of the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and titled High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines. Even output C is the same at 800 pF max. Paul, W9AC __ 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 -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ 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
Re: [Elecraft] High power tuner
Google W9CF for an explanation of why a choke balun works and why is matters not if it's on the input or output of a tuner except for convience. Also provides math showing needed CM choke impedence. Google K9YC for a set of measurements of real life CM chokes and suggestions for full legal limit recipes that meet the needed impedences. jim ab3cv __ 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
Re: [Elecraft] High power tuner
Google W9CF for an explanation of why a choke balun works and why is matters not if it's on the input or output of a tuner except for convience. What W9CF said was this: As noted by Roy Lewallen, W7EL,[2] putting a choke balun on the input of an unbalanced tuner to drive a balanced line is useless. It introduces a ``hot'' tuner case which must be isolated with no benefit over putting the balun on the output. Introducing a hot chassis full of CM current isn't trivial. Paul, W9AC __ 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
Re: [Elecraft] High power tuner
A balanced version of the T network is a physical monstrosity requiring that both ends of the capacitors float, but is possible. The T network has the greatest matching range, but suffers from false matches resulting on high circulating currents in the tuner. A balanced L network should not be difficult to produce, but if I may, I would like to put in a plug for my favorite balanced tuner which is IMHO is the old fashoined parallel (or series) resonant tank circuit using a link coupler. No balun required, but it does not lend itself easily to band switching. As a single band tuner, it is the ultimate IMHO, and the venerable Johnson Matchbox was an attempt to make that basic circuit bandswitchable. The Matchbox has some limitations in the matching range it can handle. My Johnson Matchbox will only be pried from my hands over my cold dead body - I do not use it much, but it really is handy for creating artificial antennas with SWR in the workshop, and it works quite well as a bandpass filter when that is needed. 73, Don W3FPR On 11/26/2011 6:48 PM, Joe Subich, W4TV wrote: On 11/26/2011 6:00 PM, Vic K2VCO wrote: The balanced output is not referenced to the case. So the balun is functional when feeding a balanced line, not shorted as you suggest. You are correct, that the balun is not shorted when feeding a balanced antenna. However, in that configuration it will *only* function as a common mode choke (if it is not constructed as a voltage balun). Any antenna connected to the balanced terminals will still not be truly balanced as it is not possible to generate a balanced output at the output of an unbalanced network by forcing balance at the input of that network. It is quite likely that a balun at the input of an unbalanced network will only increase circulating currents (and losses) in the network. 73, ... Joe, W4TV __ 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
Re: [Elecraft] High power tuner
If I remember correctly, the announcement for the Alpha tuner even stated that they drew heavily (or words to that effect) from the ARRL Antenna Book for the design. 73, Dave AB7E On 11/26/2011 6:37 PM, Paul Christensen wrote: I was surprised to see this from Alpha, whom I would have expected to know better. The identical design (less automated functions) can seen in recent issues of the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and titled High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines. Even output C is the same at 800 pF max. Paul, W9AC __ __ 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
Re: [Elecraft] High power tuner
Just because it was published by the ARRL does not make it a good design, although it might help to sell a few. Zack Lau published a QRP version of that tuner some years back and later retracted it, and it has not been mentioned much since, but Dean Straw published his high power version of about the same design and that seems to be the best thing since sliced bread despite counterclaims by noted authorities on balun and RF designs - W8JI, W7El and others. Bottom line, it just does not work well, although there will be many who will say that Alpha makes good stuff, that still makes it a stretch of the laws of physics - using an unbalanced network floating (although not really isolated from a common reference (ground)) will still not make everything balanced. I know there are those who will claim that an off center fed dipole has a balanced feedpoint, but I am not convinced. I put the balun at the input tuners in the same category. Take a balanced signal (output of a balun) and feed it through an unbalanced network, and claim that the output of that unbalanced network is balanced just does not make much sense to me. Maybe with ideal components it *might* be possible, but if one would plot the reactance and phase delay around that unbalanced network using good scientific methods, it would become obvious that the output would not be of equal and opposite currents with 180 degrees phase difference. If the schematic does not look balanced, it is not really balanced. Follow the leading current and lagging current around the circuit to convince yourself. 73, Don W3FPR On 11/26/2011 10:10 PM, David Gilbert wrote: If I remember correctly, the announcement for the Alpha tuner even stated that they drew heavily (or words to that effect) from the ARRL Antenna Book for the design. 73, Dave AB7E On 11/26/2011 6:37 PM, Paul Christensen wrote: I was surprised to see this from Alpha, whom I would have expected to know better. The identical design (less automated functions) can seen in recent issues of the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and titled High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines. Even output C is the same at 800 pF max. Paul, W9AC __ __ 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 __ 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
