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fun with loading
How would you guys who are stuck in an endless thread of loading coils like
to take on 'linear loading'?? are the currents the same at each end of the loading line?? do they cancel completely along the length of the loading line? does the loading line replace so many degrees of the length of the elements or cause some kind of delay??? the antenna i am working on is an m-squared 40m4lldd where, for example, the reflector is 50' tip to tip, about 10' out from the boom there is an insulator, a rod about 9' long connects with a metal bracket on each side of the insulator and folds back toward the boom where they are connected with an aluminum shorting bar that then uses a piece of phillystrand that goes to an element truss support bracket. then of course beyond the insulator is another 15' or so of element, the tips are adjusted to tune the elements. |
fun with loading
"John - KD5YI" wrote in message news:uP70g.270$_s5.47@trnddc04... Dave wrote: How would you guys who are stuck in an endless thread of loading coils like to take on 'linear loading'?? are the currents the same at each end of the loading line?? do they cancel completely along the length of the loading line? does the loading line replace so many degrees of the length of the elements or cause some kind of delay??? the antenna i am working on is an m-squared 40m4lldd where, for example, the reflector is 50' tip to tip, about 10' out from the boom there is an insulator, a rod about 9' long connects with a metal bracket on each side of the insulator and folds back toward the boom where they are connected with an aluminum shorting bar that then uses a piece of phillystrand that goes to an element truss support bracket. then of course beyond the insulator is another 15' or so of element, the tips are adjusted to tune the elements. What's "linear loading"? What's a "loading line"? i probably didn't do a very good job of describing it, but basically you take a shorter than 1/4 wave element and cut it in the middle somewhere and put in an insulator. instead of putting in a loading coil as you would normally expect you use a shorted piece of parallel wire line to tune it. in the case of the 40m4lldd the parallel wire line is made of aluminum rod and is folded back to use it as a truss for the element. |
fun with loading
"Dave" wrote in message ... "John - KD5YI" wrote in message news:uP70g.270$_s5.47@trnddc04... Dave wrote: How would you guys who are stuck in an endless thread of loading coils like to take on 'linear loading'?? are the currents the same at each end of the loading line?? do they cancel completely along the length of the loading line? does the loading line replace so many degrees of the length of the elements or cause some kind of delay??? As far as acting as loading element, it is another form of (real life) loading inductance, so it is similar to loading coil, but worse performer in the loaded Yagi situation. Have look at the end of my article http://www.k3bu.us/loadingcoils.htm where EZNEC plot shows current distribution along the loaded Yagi element, using loading stubs. the antenna i am working on is an m-squared 40m4lldd where, for example, the reflector is 50' tip to tip, about 10' out from the boom there is an insulator, a rod about 9' long connects with a metal bracket on each side of the insulator and folds back toward the boom where they are connected with an aluminum shorting bar that then uses a piece of phillystrand that goes to an element truss support bracket. then of course beyond the insulator is another 15' or so of element, the tips are adjusted to tune the elements. What's "linear loading"? What's a "loading line"? i probably didn't do a very good job of describing it, but basically you take a shorter than 1/4 wave element and cut it in the middle somewhere and put in an insulator. instead of putting in a loading coil as you would normally expect you use a shorted piece of parallel wire line to tune it. in the case of the 40m4lldd the parallel wire line is made of aluminum rod and is folded back to use it as a truss for the element. It has been found and published in articles in CQ magazine, where loading stubs were replaced by the loading coils and the performance of the antenna like KLM 80m 3 el. loaded Yagi was improved significantly. Better gain and better and cleaner F/B and pattern. Real modeling and measurements confirmed that, regardless what the "flat earth - same current" believers claim and try to "prove". Folding the loading stubs along the elements seems to distort the current distribution along the element and deteriorate its' performance. So you are better off replacing loading stubs with loading coils, and that's what the whole debate about the current distribution, reality and understanding it is about. 73 and GL Yuri, K3BU.us |
fun with loading
On Sat, 15 Apr 2006 12:06:45 -0400, "Yuri Blanarovich"
wrote: it is similar to loading coil, but worse performer in the loaded Yagi situation. Have look at the end of my article http://www.k3bu.us/loadingcoils.htm Hi Yuri, As usual, your statement has nothing to do with your link. What is worse, this EZNEC model is from a third party who is not available to comment as to the accuracy of your statements about performance. Even more is the compounding of error at the link: "G5RV antenna using inductors in the form of loading stubs" Clearly, then, it is NOT a G5RV. When we continue with the commentary we find: "When simple inductance in Eznec is inserted in place of the stubs, the current erroneously is shown as the same at the both ends of the inductor." Clearly, then, the model designer who expected something other does not know how to design the model. It would seem after several years of corrections to this error you continue to publish, that you would have updated your page by now. It is easy to offer broken solutions. This group sees many of them that are then used to discredit either the tool or the theory. What these broken models reveals are the bankrupt designer. Perhaps you should vet the material from your contributors more closely. 73's Richard Clark, KB7QHC |
fun with loading
Hi Richard,
I thank you for posting such revealing evaluation of my deficient, misleading knowledge. Yes, my web site is full of old no good stuff. Even my C6AYB picture is too many pounds old. Anyone with spec of antenna knowledge can see that "G5RV" is operated as dipole, judging by the standing wave current distribution, and it is not cardinal sin to call it G5RV dipole or vice versa. If I can get away from deflecting mumbo-jumbo and over holidays, I will start working on the project. Looks like audience here is looking for sticking needles rather than providing answers and suggestions to questions. The main thrust of question posted here was, should he stay with loading stubs or do something better. I described what was done, and stubs suck, coils are MUCH better and that current distribution is what it is and illustrated in that "butchered" drawing by W5DXP. I humbly bow in view of your much better, educational posting. I am sure the questioner is fully satisfied with your answers and solutions. Happy Easter from bankrupt designer 73 Yuri, K3BU "Richard Clark" wrote in message ... On Sat, 15 Apr 2006 12:06:45 -0400, "Yuri Blanarovich" wrote: it is similar to loading coil, but worse performer in the loaded Yagi situation. Have look at the end of my article http://www.k3bu.us/loadingcoils.htm Hi Yuri, As usual, your statement has nothing to do with your link. What is worse, this EZNEC model is from a third party who is not available to comment as to the accuracy of your statements about performance. Even more is the compounding of error at the link: "G5RV antenna using inductors in the form of loading stubs" Clearly, then, it is NOT a G5RV. When we continue with the commentary we find: "When simple inductance in Eznec is inserted in place of the stubs, the current erroneously is shown as the same at the both ends of the inductor." Clearly, then, the model designer who expected something other does not know how to design the model. It would seem after several years of corrections to this error you continue to publish, that you would have updated your page by now. It is easy to offer broken solutions. This group sees many of them that are then used to discredit either the tool or the theory. What these broken models reveals are the bankrupt designer. Perhaps you should vet the material from your contributors more closely. 73's Richard Clark, KB7QHC |
fun with loading
On Sat, 15 Apr 2006 21:44:55 -0400, "Yuri Blanarovich"
wrote: Hi Richard, I thank you for posting such revealing evaluation of my deficient, misleading knowledge. Hi Yuri, Your appreciation is well placed. Anyone with spec of antenna knowledge can see that "G5RV" is operated as dipole, judging by the standing wave current distribution, and it is not cardinal sin to call it G5RV dipole or vice versa. Anyone? No, this is embracing a crowd to insulate you from sloppiness. You rail about accuracy, bewail efficiency, demand perfection, and this is your defense? It works better in a teenager's diary - not here. If I can get away from deflecting mumbo-jumbo and over holidays, I will start working on the project. Looks like audience here is looking for sticking needles rather than providing answers and suggestions to questions. More sobbing. Yuri, if "doing" this had anything to offer you, you would have done it by now. Others, including myself, have already posted results, answers and suggestions. We merely wait for you to either catch up, or pass us. In light of the many promises of more horsepower, faster acceleration, and better gas mileage, that has been a long wait. The main thrust of question posted here was, should he stay with loading stubs or do something better. I described what was done, and stubs suck, Suck goes right up there with BS that is sold for a dime a truck full. coils are MUCH better How much better? This sounds like a fractal sales pitch. and that current distribution is what it is Zen and BS depress the price to a nickel a truck load. and illustrated in that "butchered" drawing by W5DXP. This confirms my comment that you should vet your references closer. I humbly bow in view of your much better, educational posting. I am sure the questioner is fully satisfied with your answers and solutions. Not something I would take for granted. You have to careful about being humble, I whip peasants for fun too. 73's Richard Clark, KB7QHC protecting the world against fractal salesmen for 10 years. |
fun with loading
"Richard Clark" wrote How much better? This sounds like a fractal sales pitch. Your HOW MUCH is getting a bit TOO MUCH! Comparing this to fractal sales pitch??? That is TOO MUCH! Go read the article in CQ magazine if you like to find out details. Geeez! Guy asked question, I gave some answer, better than nothing that you gave or anyone else. If you expect me to write a book, than wait! Looks like you got TOO MUCH time and enjoy sticking needles. Sorry I don't write exactly as you would wish. Get a life! 73 Yuri |
fun with loading
On Sun, 16 Apr 2006 01:33:10 -0400, "Yuri Blanarovich"
wrote: How much better? This sounds like a fractal sales pitch. Your HOW MUCH is getting a bit TOO MUCH! Comparing this to fractal sales pitch??? That is TOO MUCH! Would it touch a raw nerve to ask how much too much is? Go read the article in CQ magazine if you like to find out details. Geeez! Hi Yuri, A vanity rag? When you can't remember what you read, that has to be the hallmark of a grand article. I bet GQ will give me better details, I would learn to dress better too - if that mattered. Get a life! OK, so this is about the style of men's fashions. Do the lash marks show through your hair shirt? 73's Richard Clark, KB7QHC |
fun with loading
On Sat, 15 Apr 2006 12:06:45 -0400, "Yuri Blanarovich"
wrote: As far as acting as loading element, it is another form of (real life) loading inductance, so it is similar to loading coil, but worse performer in the loaded Yagi situation. Have look at the end of my article http://www.k3bu.us/loadingcoils.htm Hi Yuri, Now, when we actually "look" at the design at your link, we find we don't know much about: 1. How tall the antenna is (never said); 2. How long the radials are (never said); 3. How many turns in the coil (have to squint and count and hope); 4. How long the coil is (you gotta guess); 5. What frequency this resonates at (well, actually it doesn't say it resonates anywhere); 6. What the drive point Z is (as if that mattered) But we do know that some one can find 7. The current into the coil and; 8. The current out of the coil; 9. which according to breathless reports makes all the difference in the world, until 10. I threw away that trash coil, replaced it with a distributed load (aka shorted transmission line) and boosted the performance. 73's Richard Clark, KB7QHC |
fun with loading
Dave wrote: How would you guys who are stuck in an endless thread of loading coils like to take on 'linear loading'?? are the currents the same at each end of the loading line?? do they cancel completely along the length of the loading line? does the loading line replace so many degrees of the length of the elements or cause some kind of delay??? All of the petty arguing and self-promotion aside, linear loading is just a very poor form of a loading coil. Like any poorly designed system, the ill effects of design shortfalls can range from very small to very large. As a general rule, linear loading reduces efficiency over a lumped coil of good design. Again the exact amount and the overall effect varies with where the loading is placed in the antenna, how it is constructed, and where and how the loading coil compared to it is constructed and placed. A transmission line, even a very good one, generally has a Q of someplace around 20-75. The definition of Q I am using is reactance over ESR. Say you need a reactance of 400 ohms to resonate an antenna. Linear or stub loading would add a series resistance of 5 to 20 ohms as loss resistance at that point in the system. It would take a very poor coil to have that Q, but it can be done. Depending on where in the antenna you insert that loss resistance, the effects can be large or small. Myself, I avoid linear loading. I'm not a person who likes to gamble. We have now all seen first hand how a fascination with destroying others really just destroys the ability to learn anything ourselves and to help others learn. This loading coil thing has become a mental illness, like uncontrolled shoplifting. One fellow wrote a nice book on transmission lines and a long argument about amplifiers and a long argument about reflected waves on amplifiers did the same thing. This stuff is more a demonstration of emotional problems or mental illness than science and education. It's one step below someone going postal and just shooting everyone else in the world who is responsible for his failures and unpopularity! I hope this post gives insight into how arguing or fixations ruin the educational process, and also sheds light on linear loading. Something for everyone. 73 Tom |
fun with loading
OK, I gotta take issue with the part that says,
" A transmission line, even a very good one, generally has a Q of someplace around 20-75. The definition of Q I am using is reactance over ESR. Say you need a reactance of 400 ohms to resonate an antenna. Linear or stub loading would add a series resistance of 5 to 20 ohms as loss resistance at that point in the system. " I know that transmission line Q varies all over the place: it's much more reasonable to use it in a resonator at high frequencies than low, and line construction makes a big difference too. To back this up with numbers, I just ran some calcs (actually put together a little Scilab program to run them for me) on four different lines: (a) is RG-8/RG-213 type line with solid poly dielectric, (b) is 75 ohm air insulated coax in an 0.5" ID copper tube, (c) is balanced two-wire line made with 12AWG (~2mm) wire spaced 2" (~5cm) on centers), and (d) is two 0.625" OD copper tubes spaced 3" on center. For a 1/8 wave section of line shorted at the far end, the calculated impedances and Qs a line a, 10MHz: 0.622+j50, Q=80 line a, 100MHz: 0.197+j50, Q=254 line a, 1000MHz: 0.0622+j50, Q=800 line b, 10MHz: 0.35+j75, Q=215 100MHz: 0.110+j75, Q=679 1GHz: 0.035+j75, Q=2147 line c, 10MHz: 0.972+j469, Q=482 100MHz: 0.307+j469, Q=1526 1GHz * : 0.097+j469, Q=4826 line d, 10MHz: 0.124+j270, Q=2170 100MHz: 0.039+j270, Q=6864 1GHz * : 0.012+j270, Q=21.7k * -- the open wire lines will likely not work in practice quite this well at UHF... With luck, I got all the calcs right; but in any event, I do expect the Q to go up for a given stub as the sqrt(f), and the Q of open-wire lines to be considerably higher than that of coax with similar conductor diameter, just because the impedance is higher. The Q of an RG-8-type stub at 10MHz isn't wonderful, but at higher frequencies and with different construction, stubs can work better than coils. There is a range of frequencies where it can be a matter of construction preference: the stub may be easier to integrate into a design, or the coil may be, depending. At high enough frequencies, the stub often is easier. Also, I want to point out that in a collinear -- a half-wave dipole, center fed, in the center, and an additional half-wave element on either end, coupled through a two-wire-line stub perpendicular to the antenna performs distinctly better than the same antenna in which the stubs are replaced by self-resonant coils, or by a coaxial stub which is made to be collinear with the antenna. That's because the perpendicular stub interacts with the antenna field to excite the right mode on the line to get substantial current in the outboard collinear half-waves. See King for further explanation. Cheers, Tom wrote: Dave wrote: How would you guys who are stuck in an endless thread of loading coils like to take on 'linear loading'?? are the currents the same at each end of the loading line?? do they cancel completely along the length of the loading line? does the loading line replace so many degrees of the length of the elements or cause some kind of delay??? All of the petty arguing and self-promotion aside, linear loading is just a very poor form of a loading coil. Like any poorly designed system, the ill effects of design shortfalls can range from very small to very large. As a general rule, linear loading reduces efficiency over a lumped coil of good design. Again the exact amount and the overall effect varies with where the loading is placed in the antenna, how it is constructed, and where and how the loading coil compared to it is constructed and placed. A transmission line, even a very good one, generally has a Q of someplace around 20-75. The definition of Q I am using is reactance over ESR. Say you need a reactance of 400 ohms to resonate an antenna. Linear or stub loading would add a series resistance of 5 to 20 ohms as loss resistance at that point in the system. It would take a very poor coil to have that Q, but it can be done. Depending on where in the antenna you insert that loss resistance, the effects can be large or small. Myself, I avoid linear loading. I'm not a person who likes to gamble. We have now all seen first hand how a fascination with destroying others really just destroys the ability to learn anything ourselves and to help others learn. This loading coil thing has become a mental illness, like uncontrolled shoplifting. One fellow wrote a nice book on transmission lines and a long argument about amplifiers and a long argument about reflected waves on amplifiers did the same thing. This stuff is more a demonstration of emotional problems or mental illness than science and education. It's one step below someone going postal and just shooting everyone else in the world who is responsible for his failures and unpopularity! I hope this post gives insight into how arguing or fixations ruin the educational process, and also sheds light on linear loading. Something for everyone. 73 Tom |
fun with loading
Chrystos Voskres! Christ has risen!
May he nelighten those confused and enlighten them! Nice going Tom, W8JI! 73 Yuri, K3BU.us |
fun with loading
On 16 Apr 2006 15:44:06 -0700, "K7ITM" wrote:
OK, I gotta take issue with the part that says, " A transmission line, even a very good one, generally has a Q of someplace around 20-75. The definition of Q I am using is reactance over ESR. Say you need a reactance of 400 ohms to resonate an antenna. Linear or stub loading would add a series resistance of 5 to 20 ohms as loss resistance at that point in the system. " I know that transmission line Q varies all over the place: it's much more reasonable to use it in a resonator at high frequencies than low, and line construction makes a big difference too. To back this up with numbers, I just ran some calcs (actually put together a little Scilab program to run them for me) on four different lines: (a) is RG-8/RG-213 type line with solid poly dielectric, (b) is 75 ohm air insulated coax in an 0.5" ID copper tube, (c) is balanced two-wire line made with 12AWG (~2mm) wire spaced 2" (~5cm) on centers), and (d) is two 0.625" OD copper tubes spaced 3" on center. For a 1/8 wave section of line shorted at the far end, the calculated impedances and Qs a line a, 10MHz: 0.622+j50, Q=80 line a, 100MHz: 0.197+j50, Q=254 line a, 1000MHz: 0.0622+j50, Q=800 I tried these numbers in the line loss calculator at http://www.vk1od.net/tl/tllce.php using Belden 8267 of 2.475m length for 0.125 wavelengths and Zload=0.0000000001. The input Z I got was a little higher at 0.88+j50 (probably slightly different approximation of Zo used in the calcs), yeilding a Q of 57. The Q is quite dependent on line length, decreasing as length increases towards a quarter wave. I suspect this is not a good method of analysing behaviour when the line elements are field coupled to other radiator elements, the currents in each leg are not necessarily equal and opposite. Owen -- |
fun with loading
Yes, the Q as determined by simply taking X/R decreases as you approach
1/4 wavelength, but what you really need to do is resonate it with a capacitance and look at the Z as a function of frequency when you do that. I mean, it IS a resonator if it's 1/4 wave long: it would look like Q=0 there if you take X/R, but of course it's not. If you simply want _inductance_ (i.e. a loading coil), do NOT make the stub close to 1/4 wave long. It's just the same as trying to use a coil for inductance up near its self-resonance. Also, a point that was in my mind when I originally posted, but failed to put well into writing then, is that as frequency increases, the Q of a solenoid coil will increase about as the square root of frequency...and the size stays the same. But the stub's Q also increases as the square root of frequency, while it's size (length) is directly proportional to 1/freq, and it's shrinking in size. And thanks for the cross-check on my numbers, Owen. I hacked it pretty quickly, and may have missed a cog somewhere, though I think the numbers are reasonably close. I suppose one of Reg's programs will give you stub impedance, too. -- I think I see why my numbers may be a bit different than what you got; I'll check on it as I have time, though the difference isn't enough to worry me--the trends are still the same. Cheers, Tom Owen Duffy wrote: On 16 Apr 2006 15:44:06 -0700, "K7ITM" wrote: OK, I gotta take issue with the part that says, " A transmission line, even a very good one, generally has a Q of someplace around 20-75. The definition of Q I am using is reactance over ESR. Say you need a reactance of 400 ohms to resonate an antenna. Linear or stub loading would add a series resistance of 5 to 20 ohms as loss resistance at that point in the system. " I know that transmission line Q varies all over the place: it's much more reasonable to use it in a resonator at high frequencies than low, and line construction makes a big difference too. To back this up with numbers, I just ran some calcs (actually put together a little Scilab program to run them for me) on four different lines: (a) is RG-8/RG-213 type line with solid poly dielectric, (b) is 75 ohm air insulated coax in an 0.5" ID copper tube, (c) is balanced two-wire line made with 12AWG (~2mm) wire spaced 2" (~5cm) on centers), and (d) is two 0.625" OD copper tubes spaced 3" on center. For a 1/8 wave section of line shorted at the far end, the calculated impedances and Qs a line a, 10MHz: 0.622+j50, Q=80 line a, 100MHz: 0.197+j50, Q=254 line a, 1000MHz: 0.0622+j50, Q=800 I tried these numbers in the line loss calculator at http://www.vk1od.net/tl/tllce.php using Belden 8267 of 2.475m length for 0.125 wavelengths and Zload=0.0000000001. The input Z I got was a little higher at 0.88+j50 (probably slightly different approximation of Zo used in the calcs), yeilding a Q of 57. The Q is quite dependent on line length, decreasing as length increases towards a quarter wave. I suspect this is not a good method of analysing behaviour when the line elements are field coupled to other radiator elements, the currents in each leg are not necessarily equal and opposite. Owen -- |
fun with loading
You dim witts are calculating Q incorrectly.
Q = X / R where R is the RF resistance of the conductor and X is the reactance of the conductor's inductance. You first have to calculate inductance. You get a high Q at resonance. ---- Reg, G4FGQ |
fun with loading
On Mon, 17 Apr 2006 08:41:36 +0100, "Reg Edwards"
wrote: You dim witts are calculating Q incorrectly. Reg, that is just so polite! Q = X / R where R is the RF resistance of the conductor and X is the reactance of the conductor's inductance. You first have to calculate inductance. So, you state that the ratio X/R is an acceptable way to express the Q of an inductor, why is it unacceptable to express the Q of a two terminal device with an equivalent series impedance of 0.88+j50 (where 0.88 is the RF series resistance of the network and 50 is the series inductive reactance of the element) as 50/0.88 or 57? Aren't the effiency implications (for that was the context) for a 50 ohm reactance created with a TL stub as described just the same as for a coil with 50 ohms of inductive reactance and 0.88 ohms of series (RF) resistance, ie a coil with the same Q factor? Owen -- |
fun with loading
"Owen Duffy" wrote in message ... On Mon, 17 Apr 2006 08:41:36 +0100, "Reg Edwards" wrote: You dim witts are calculating Q incorrectly. Reg, that is just so polite! Q = X / R where R is the RF resistance of the conductor and X is the reactance of the conductor's inductance. You first have to calculate inductance. So, you state that the ratio X/R is an acceptable way to express the Q of an inductor, why is it unacceptable to express the Q of a two terminal device with an equivalent series impedance of 0.88+j50 (where 0.88 is the RF series resistance of the network and 50 is the series inductive reactance of the element) as 50/0.88 or 57? Aren't the effiency implications (for that was the context) for a 50 ohm reactance created with a TL stub as described just the same as for a coil with 50 ohms of inductive reactance and 0.88 ohms of series (RF) resistance, ie a coil with the same Q factor? Owen ---------------------------------------------------------------------- --- Owen, Please excuse my mild scold. There is only ONE way to calculate Q of a coil or a wire and that is the way I have described. It is the ratio of inductive reactance to resistance of the wire, in series with other. They cannot be measured in combination with each other. To do so results in something altogether different like measuring the input impedance of an antenna at or near resonance where the inductive reactance is tuned out by the capacitance and is therefore NOT measured. It is elementary my dear Watson. ---- Reg. |
fun with loading
Reg, old sot, you need to either quit drinking so much or go back to
the fundamental definition of Q. The Q of a coil or capacitor is always an abstraction from the definition. In any event, trying to use a coil or a stub at or near its self (anti)resonance to get an inductive reactance is a really bad plan. You can't separate the self-capacitance from the coil or the stub, so assuming only the reactance from the wire's inductance does you no good at all in that case. As a resonator, it's fine. As an inductive loading component (which is the topic of this thread), it sucks. Cheers, Tom |
fun with loading
Just an afterthought.
Q is dimensionless quantity. Therefore it cannot be measured directly. It is always obtained as the CALCULATED ratio of TWO independent measurements or previous calculations. Its only use is to predict, by further calculation, other properties of a circuit such as bandwith or voltage magnification. It is just a convenient intermediary which can frequently be bypassed or done without. It can seldom be determined accurately which is a measure of its true worth. Your guess is as good as mine at high frequencies. The common or garden Q meter indicates only the resistance of a coil relative to a standard of some sort. The coil's inductive reactance is already known, or is related to the capacitor and frequency, or can otherwise be calculated. Here you still have a pair of independent measurable quantities. I'd better stop here. The subject has been over-complicated quite enough. Here in the Black Country, the weather is beautifully fresh. Spring is well on its way. ---- Reg. |
fun with loading
That (your afterthought) is much more like it. Thanks.
After all, this is NOT a thread about Q, it's a thread about the effectiveness of different two-terminal devices for use in inductively loading a linear radiator. In that case, the measured impedance, that is, the measured X and R, of the two-terminal device is indeed what matters. Given that we need a particular X, a high ratio of measured X to measured R is advantageous, since the R term represents dissipation. Maybe we should invent a new term and define it thus: Xiddle = X(measured)/R(measured) where Xiddle is to be pronounced "Ziddle," and rhymes with "piddle." Or, we could just use the shorthand that W8JI elected to use AND DEFINE in his posting: Q=X(meas)/R(meas). Just as you say, Q is only an intermediate on the path to something more interesting. It works for me if someone wants to offer a slightly non-standard definition, so long as the definition is clear, as it was to me from W8JI's post. Thanks for mentioning the Black Country. It was an education for me to look it up. Spring is trying to gain a toehold here, but it's a bit tenuous. Got up to a couple feet of new snow in the hills over the weekend. Cheers, Tom (PS--where do you find gardens that grow "Q meters"? Or are they the things that invade the garden to try to eat the qms?) |
fun with loading
now that you guys have had fun with Q... how about trying the practical
aspects of the originally stated problem? how would the described element loading compare with, lets say, a 40-2cd element? bandwidth? coupling between yagi elements?? losses? "K7ITM" wrote in message oups.com... That (your afterthought) is much more like it. Thanks. After all, this is NOT a thread about Q, it's a thread about the effectiveness of different two-terminal devices for use in inductively loading a linear radiator. In that case, the measured impedance, that is, the measured X and R, of the two-terminal device is indeed what matters. Given that we need a particular X, a high ratio of measured X to measured R is advantageous, since the R term represents dissipation. Maybe we should invent a new term and define it thus: Xiddle = X(measured)/R(measured) where Xiddle is to be pronounced "Ziddle," and rhymes with "piddle." Or, we could just use the shorthand that W8JI elected to use AND DEFINE in his posting: Q=X(meas)/R(meas). Just as you say, Q is only an intermediate on the path to something more interesting. It works for me if someone wants to offer a slightly non-standard definition, so long as the definition is clear, as it was to me from W8JI's post. Thanks for mentioning the Black Country. It was an education for me to look it up. Spring is trying to gain a toehold here, but it's a bit tenuous. Got up to a couple feet of new snow in the hills over the weekend. Cheers, Tom (PS--where do you find gardens that grow "Q meters"? Or are they the things that invade the garden to try to eat the qms?) |
fun with loading
Just a second afterthought.
The measured impedance of a 2-terminal device tells you next to nothing about it. It certainly does not tell you the Q. To find anything useful about it, it is necessary to shift frequency and make a SECOND measurement. So we return, yet again, to a pair of independent measurements or calculations in order to obtain a ratio. A ratio has two degrees of freedom. I just love that phrase. I/ve been waiting for years just to mention it. ---- Reg. |
fun with loading
On Mon, 17 Apr 2006 21:07:41 -0000, "Dave" wrote:
how would the described element loading compare Hi Dave, Without some expression of what you might find acceptable, or unacceptable, comparisons are condemned to vagueness, or extreme elaboration. with, lets say, a 40-2cd element? Approx. the same; bandwidth? Approx. the same; coupling between yagi elements?? Greater, forcing a different geometry. losses? Approx. the same. There is nothing in your question that breaks new ground, and substituting equivalent components really only shuffles a few design parameters. Such shuffling may entail considerable tedium in implementation details, but you say nothing of what passes for good or bad. We could equally rend the correspondence bandwidth here into the equivalent tedium of quoting the partial dB differences - that has been good for more than a thousand posts so far. One of our infrequent correspondents here would substitute metal tubing for bamboo wrapped with metalized mylar film. He couldn't expect any gain in this swap, nor could we point out any considerable loss; but let's face it, the market is not rushing to build antennas this way because there is no economic nor technical justification. Thus, the only advantage is one of marketing. If you cannot quote a gain advantage, you can at least argue conservation because you are doing Green DXing with Bamboo elements and recycled weather balloons. So it comes down to a familiar question: What's your point? 73's Richard Clark, KB7QHC |
fun with loading
:-)
How nice it is to have modern instruments which cover a wide range of frequencies in one simple measurement setup, display the results in any of an array of formats, and even store the measurement results for use in a variety of analysis programs. (Sometimes, it's even nicer to just escape from them altogether.) Cheers, Tom |
fun with loading
"Richard Clark" wrote in message ... On Sat, 15 Apr 2006 12:06:45 -0400, "Yuri Blanarovich" wrote: As far as acting as loading element, it is another form of (real life) loading inductance, so it is similar to loading coil, but worse performer in the loaded Yagi situation. Have look at the end of my article http://www.k3bu.us/loadingcoils.htm Hi Yuri, Now, when we actually "look" at the design at your link, we find we don't know much about: Here is the information from my web site as described by Barry, W9UCW: "Here are some actual measurements of current below and above loading coils. 92" mast, using a HI-Q coil (openwound airdux, 2 1/2"d) with small thermocouple type meters mounted on the insulated coil support. First for 40m, moving the coil in the mast from base to center to top (with hat) and reresonating. Base --100ma below & 66ma above Center --100ma below & 45ma above Top --100ma below & 37ma above Then, same test but for 30m Base --100ma below & 75ma above Center --100ma below & 60ma above Top --100ma below & 52ma above On a long, skinny 160 resonator with 25pf of top hat and whip, mounted on an 8' mast, I read 100ma below and 65ma above the coil. Because of the constant claim that this must be due to the fact that the coil is so big compared to a wavelength, I measured the in and out current on a TOROIDAL loading coil used on a 20m mobile antenna. It was a 78" base mast (including spring and mount) with a 38" top whip (including 12" of alum. tubing for adjustment). Below --100ma & Above --79ma When I moved the coil to the top of the mast and made a horizontal "X" top hat to resonate it back on the same freq, I got Below --100ma & Above --47ma So, It happens even in a totally shielded loading coil with miniscule power going thru it! Kirchoff has no laws about current being the same on both ends of inductors. His current law is about one POINT in a circuit and his voltage law is about a closed loop." .... and some significant difference W9UCW in field strength measured between the base and center loading coil: "The actual difference in signal strength between top and base loading of a 9' antenna is about 16 db (measured) on 75m, but Tom calculates 8db on 160. That's because he assumes the same current in the coil. Actually it's worse on 160 than 75." 1. How tall the antenna is (never said); He said - 92" simulating mobile whip. 2. How long the radials are (never said); Radials laid on the ground are non resonant, doesn't matter much, but there were enough of them (I remember him mentioning at least 32) 3. How many turns in the coil (have to squint and count and hope); Coild is of good quality (aka Texas Bugcatcher), what is important that it was adjusted to bring antenna to 90 electr. degrees - RESONANCE. 4. How long the coil is (you gotta guess); Same as 3, in each test, enough to resonante on band of test (40, 30, 80) 5. What frequency this resonates at (well, actually it doesn't say it resonates anywhere); Ham bands 40, 30, 80 and 160 is where they measured the currents. 6. What the drive point Z is (as if that mattered) Not important as long as antenna is resonant on frequency in question. The power was adjusted to show 100 ma full scale on the bottom of the coil and read on the same type of meter on the top. But we do know that some one can find 7. The current into the coil and; 8. The current out of the coil; 9. which according to breathless reports makes all the difference in the world, Picture of REALITY vs. phasors, distributed baloney, pink electrons, bla, bla ... why it "could not be". More appropriate assesment would be "significant", which you can judge by his comment about 16 dB vs. 8 dB "calculated" by W8JI Anyone can duplicate the test and verify the results and claims, instead of displaying their ignorance of reality. until 10. I threw away that trash coil, replaced it with a distributed load (aka shorted transmission line) and boosted the performance. And you did that, and measured it, right? It has been proven in real life and measurements that "trash" coil performs better in the loaded Yagi design that loading stub (distributed load). It has been done, described and measured by at least three happy owners of modified KLM 2 or 3 el. loaded Yagis on 80. Improved gain and pattern, F/B. Interesting that the "problems" with loading coils and same current affcionados "know it" based on their (faulty) theories. W8JI attributes his mental state to others to "prove" his "right" which will end up being big egg in his face. Interesting, that question about loading stubs has "matured" to this also, instead of providing some answers for David. This is my last contribution to this thread. 73's Richard Clark, KB7QHC 73 Yuri, K3BU |
fun with loading
On Mon, 17 Apr 2006 23:03:56 -0400, "Yuri Blanarovich"
wrote: Now, when we actually "look" at the design at your link, we find we don't know much about: Here is the information from my web site as described by Barry, W9UCW: This is still insufficient even for a partial description. "Here are some actual measurements of current below and above loading coils. 92" mast, using a HI-Q coil (openwound airdux, 2 1/2"d) with small 92" does not agree with other numbers offered. snip On a long, skinny 160 resonator The coil shown is no such thing. with 25pf of top hat and whip I frankly don't accept the description of "25pf of top hat and whip" because there is absolutely no supporting discussion, measurements, or modeling. This is "blue sky" reporting. , mounted on an 8' mast, I read 100ma below and 65ma above the coil. An 8' mast equates to 92" mast which leaves no room for a whip, that, or the whip is unspecified. snip a 20m mobile antenna. It was a 78" base mast (including spring and mount) with a 38" top whip (including 12" of alum. tubing for adjustment). Which has absolutely nothing to do with your published page. It is bad enough to fight for details with one obscure design, to then australian tag match for two obscure antennas. snip 1. How tall the antenna is (never said); He said - 92" simulating mobile whip. This is incorrect from the your statements offered above. The ANTENNA is larger, that much is obvious. 2. How long the radials are (never said); Radials laid on the ground are non resonant, doesn't matter much, but there were enough of them (I remember him mentioning at least 32) This does not answer the question. 3. How many turns in the coil (have to squint and count and hope); Coild is of good quality (aka Texas Bugcatcher), This does not answer the question. what is important that it was adjusted to bring antenna to 90 electr. degrees - RESONANCE. The coil is stock, there was no adjustment made, that is quite obvious. Further, nothing was resonated. This page's material came from a jury-rigged set-up for a kangaroo court proof. The antenna was not resonated the tuning was performed in the shack. Twist enough knobs to jimmy a current was the name of the game here. 4. How long the coil is (you gotta guess); Same as 3, in each test, This does not answer the question. enough to resonante on band of test (40, 30, 80) Yuri, you are ****ing on our legs and telling us it is raining. One coil, one mast, one whip, does not resonate on three bands. You guys were twisting knobs, not resonating a radiator with a load. 5. What frequency this resonates at (well, actually it doesn't say it resonates anywhere); Ham bands 40, 30, 80 and 160 is where they measured the currents. Impossible, the coil is much to small for such a small radiator to resonate in 160M band, the rest of these claims are equally invalid by the simple observation of the content at your page and the poor responses to technical questions above. 6. What the drive point Z is (as if that mattered) Not important as long as antenna is resonant on frequency in question. This is simply your way of saying you don't know and you couldn't find out. Further, nothing was resonant - it would take far more details that you don't have to make it happen. Again, you just don't know. until 10. I threw away that trash coil, replaced it with a distributed load (aka shorted transmission line) and boosted the performance. And you did that, and measured it, right? Yes. It has been proven in real life and measurements that "trash" coil performs better in the loaded Yagi design that loading stub (distributed load). It has been done, described and measured by at least three happy owners of modified KLM 2 or 3 el. loaded Yagis on 80. Improved gain and pattern, F/B. And they aren't here are they? Tell us the found the missing WMD and that would make them real heroes. This is my last contribution to this thread. You over-rate it considerably. No doubt we will hear more on this, but that won't be contribution either. 73's Richard Clark, KB7QHC |
fun with loading
Yuri Blanarovich wrote:
Kirchoff has no laws about current being the same on both ends of inductors. His current law is about one POINT in a circuit ... But Yuri, a lumped circuit inductance is a point so it must have the same current on each side of that point. :-) It is interesting that, although any coil can be positioned in the standing wave environment such that the current at each end of the coil has the same magnitude, only *ONE* of the many measurements showed the same current at both ends. -- 73, Cecil http://www.qsl.net/w5dxp |
fun with loading
OK one more time.
We had argument about current in antenna loading coils, one bunch says it is different, another bunch says it is, has to be the same, no way can it be different. Instead of trying to verify the reality on real antennas, with real, typical hardware and measure it or show that there is something wrong with what we so far presented, we see "theoretical reasons" why it can't be and nitpicking on tangents leading to la-la land, instead of hitting the "meat" of the argument. Suit yourself. No one said that W9UCW did all the different band experiments with the same setup in the picture. He showed one picture, proof that current CAN be different at two ends of a loading coil, which W8JI and his worshippers claim it CAN NOT BE. Show us your setup, description and details showing that in all cases current IS ALWAYS (or almost) the SAME! There is really no point of arguing any more here. I will do the tests and with help of "our campers" we will present comprehensive article on the subject. I would like to thank you all, including "current nonbelievers" for their opposition, because they highlighted how much misinformation (50 years) and false "science" is out there and helped us to understand the depth and reasons for the current in the loading coil behavior, and especially for the need to set the record straight and help to improve the modeling of loaded antennas. The rest will be reported on my web site, which I will consolidate and bring up to date in the next few days at www.K3BU.us Then you can nitpick or provide critique. There is no point in arguing, when Cecil asks why is there higher current at the top of the coil and "unbelievers" are mum or keep rattling off their but, but, but... IT IS STANDING WAVE CURRENT and VOLTAGE along the resonator, get it? What's next? Denying that there is a daylight, when the sun is out? 73 + Yuri, K3BU |
fun with loading
K7ITM wrote:
:-) How nice it is to have modern instruments which cover a wide range of frequencies in one simple measurement setup, display the results in any of an array of formats, and even store the measurement results for use in a variety of analysis programs. (Sometimes, it's even nicer to just escape from them altogether.) Cheers, Tom It's not quite so nice, though, when you develop a psychotic addiction to measuring which sends you to the poorhouse for buying expensive equipment, and to the therapist for treatment of your obsession. 73, Tom Donaly, KA6RUH |
fun with loading
Yuri Blanarovich wrote:
IT IS STANDING WAVE CURRENT and VOLTAGE along the resonator, get it? What's next? Denying that there is a daylight, when the sun is out? The problem as I see it is that the lumped circuit folk have no way of knowing when their model has failed them and it is known to have a failure range. The only way I know of verifying their model's results is to compare it to the distributed network model results (or Maxwell's equations) to see if it agrees. That is something they have proven unwilling to do so they are really shooting in the dark. In particular, using a signal containing no phase information to try to measure the phase shift through a coil and then continuing to report it as a valid result is really strange. They apparently atill haven't realized that superposition doesn't preserve all of the information in the two original waves. -- 73, Cecil http://www.qsl.net/w5dxp |
fun with loading
On Tue, 18 Apr 2006 10:24:07 -0400, "Yuri Blanarovich"
wrote: OK one more time. Hi Yuri, Of all things, "one more time" is boringly trivial. Put it in your sweetheart diary, lock that sucker up, and put it back under your pillow. You have not adequately specified anything, and your comments about efficiency, performance and the rest (if in fact there was anything else) are castles in the air. There is really no point of arguing any more here. And yet this is the entire point of your having posted anything, isn't it? I will do the tests and with help of "our campers" we will present comprehensive article on the subject. Why would anyone believe in a future of full disclosure when you obviously have such difficulty with simpler topics now? I offered very simple questions, all about very specific characteristics of ONE antenna. This antenna was YOUR choice to introduce the topic. This antenna was YOUR source of data for all comments that flowed for 10000 postings ever after. You have had more than 2 years to fill in the gaps about ONE antenna. The minimum among these ANTENNA questions was: 1. How high? 2. What drive point Z? 3. What frequency for the combination of all elements? Now as to the particulars of loading: 1. How long a coil? 2. How many turns in that coil? 3. How long are the radials? Now as to your efficiency/performance claims: 1. What is the efficiency of a bare radiator without loading? 2. What is the efficiency of the loaded antenna you presented at your page? 3. What is the performance criteria of a bare radiator? 4. What was the performance response of the loaded radiator you presented at your page? We roll on to test proclamations about linear loading: 1. Let's simply skip this as being obviously tainted by so much missing information as to be irresolvable from more old wives' tales. Everyone of these questions is easily answered with a simple number. Everyone of these questions is commonplace discussion for technical examination. You have answered NONE of these questions. Or was it just one, 92 inches tall? You couldn't even get that one right because the picture ON YOUR PAGE obviously showed a bigger one! You apparently think you can treat us like fools and that this is enough to prove: What's next? Denying that there is a daylight, when the sun is out? Yuri, you don't have the horsepower to win the race of wits. 73's Richard Clark, KB7QHC |
fun with loading
OK,
standby for our tests, measurements and data. Appears that you distrust anything we have argued, but W8JI and equal current believers need not to present similar data for your microscope. I will chronicle my experiments and provide data that you question. I am already washing up my 72 Buick LeSabre and cleaning antenna contacts, sharpening my instruments and hopefully have enough accurate numbers and answers for your questions. Helloooo! We are arguing current distribution in antenna loading coil. Is it always equal or can it vary? The rest is nitpicking and obfuscating the question in question. now really, really SK! 73 Yuri "Richard Clark" wrote in message ... On Tue, 18 Apr 2006 10:24:07 -0400, "Yuri Blanarovich" wrote: OK one more time. Hi Yuri, Of all things, "one more time" is boringly trivial. Put it in your sweetheart diary, lock that sucker up, and put it back under your pillow. You have not adequately specified anything, and your comments about efficiency, performance and the rest (if in fact there was anything else) are castles in the air. There is really no point of arguing any more here. And yet this is the entire point of your having posted anything, isn't it? I will do the tests and with help of "our campers" we will present comprehensive article on the subject. Why would anyone believe in a future of full disclosure when you obviously have such difficulty with simpler topics now? I offered very simple questions, all about very specific characteristics of ONE antenna. This antenna was YOUR choice to introduce the topic. This antenna was YOUR source of data for all comments that flowed for 10000 postings ever after. You have had more than 2 years to fill in the gaps about ONE antenna. The minimum among these ANTENNA questions was: 1. How high? 2. What drive point Z? 3. What frequency for the combination of all elements? Now as to the particulars of loading: 1. How long a coil? 2. How many turns in that coil? 3. How long are the radials? Now as to your efficiency/performance claims: 1. What is the efficiency of a bare radiator without loading? 2. What is the efficiency of the loaded antenna you presented at your page? 3. What is the performance criteria of a bare radiator? 4. What was the performance response of the loaded radiator you presented at your page? We roll on to test proclamations about linear loading: 1. Let's simply skip this as being obviously tainted by so much missing information as to be irresolvable from more old wives' tales. Everyone of these questions is easily answered with a simple number. Everyone of these questions is commonplace discussion for technical examination. You have answered NONE of these questions. Or was it just one, 92 inches tall? You couldn't even get that one right because the picture ON YOUR PAGE obviously showed a bigger one! You apparently think you can treat us like fools and that this is enough to prove: What's next? Denying that there is a daylight, when the sun is out? Yuri, you don't have the horsepower to win the race of wits. 73's Richard Clark, KB7QHC |
fun with loading
On Tue, 18 Apr 2006 12:56:58 -0400, "Yuri Blanarovich"
wrote: Appears that you distrust anything we have argued, Yuri, Arguing is only hot air suitable for inflating the sagged esteem of guru-bashers. If you cannot present the simple characteristics of YOUR choice of antenna, then you don't have enough wind to toot a penny whistle. but W8JI and equal current believers need not to present similar data for your microscope. Yuri, I don't need you spoon feeding me bull**** and telling me its steak. Frankly, I can get the full specifications and details of an antenna from anyone faster than you. Except Cecil perhaps, he would have us believe it's BBQ steaks cooked by standing waves. In the past 4 or 5 calls for this simple data, you have offered nothing but excuses and put-offs like: I will chronicle my experiments and provide data that you question. "We will see," in response would seem to be an answer only Rumsfeld could love. Helloooo! We are arguing.... blah blah blah It is a pathetic corpse you are trying to prove that it still laughs and cries; and whispers the solution to Fermat's last problem to the nurse at night. 73's Richard Clark, KB7QHC |
fun with loading
Yuri Blanarovich wrote:
standby for our tests, measurements and data. Yuri, I don't know what you are going to prove. W8JI's and W7EL's own measurements prove beyond any doubt that the current at each end of the coil is NOT equal. And the error they made in trying to measure phase using a signal with unchanging phase is more than obvious. What you are going to find is that the coil warps the current profile away from a pure cosine wave as is shown in Figure 3 at: http://www.k6mhe.com/n7ws/Loaded%20antennas.htm The delay through that coil is obviously NOT zero and the currents at the ends are obviously NOT equal. -- 73, Cecil http://www.qsl.net/w5dxp |
fun with loading
Cecil Moore wrote:
Yuri Blanarovich wrote: standby for our tests, measurements and data. Yuri, I don't know what you are going to prove. W8JI's and W7EL's own measurements prove beyond any doubt that the current at each end of the coil is NOT equal. And the error they made in trying to measure phase using a signal with unchanging phase is more than obvious. What you are going to find is that the coil warps the current profile away from a pure cosine wave as is shown in Figure 3 at: http://www.k6mhe.com/n7ws/Loaded%20antennas.htm The delay through that coil is obviously NOT zero and the currents at the ends are obviously NOT equal. How do you know it's a "pure cosine wave," Cecil? 73, Tom Donaly, KA6RUH |
fun with loading
Richard Clark wrote:
You have answered NONE of these questions. Or was it just one, 92 inches tall? You couldn't even get that one right because the picture ON YOUR PAGE obviously showed a bigger one! You apparently think you can treat us like fools and that this is enough to prove: What's next? Denying that there is a daylight, when the sun is out? Yuri, you don't have the horsepower to win the race of wits. 73's Richard Clark, KB7QHC If he will just post the plans to duplicate the antenna, it would give the rest of us something to test. That would be way too easy, I guess. tom K0TAR |
fun with loading
Tom Donaly wrote:
Cecil Moore wrote: What you are going to find is that the coil warps the current profile away from a pure cosine wave ... How do you know it's a "pure cosine wave," Cecil? Because Kraus says so? -- 73, Cecil http://www.qsl.net/w5dxp |
fun with loading
On Tue, 18 Apr 2006 18:59:47 -0500, Tom Ring
wrote: Richard Clark wrote: You have answered NONE of these questions. Or was it just one, 92 inches tall? You couldn't even get that one right because the picture ON YOUR PAGE obviously showed a bigger one! You apparently think you can treat us like fools and that this is enough to prove: What's next? Denying that there is a daylight, when the sun is out? Yuri, you don't have the horsepower to win the race of wits. 73's Richard Clark, KB7QHC If he will just post the plans to duplicate the antenna, it would give the rest of us something to test. That would be way too easy, I guess. Hi Tom, If the mood strikes me, I will see how much effort it takes to blow away his "efficient" antenna. Seeing how he has no answers for its construction, I can easily impose my own choices like an high E piano string radiator mid loaded with a squirrel cage over a radial field of rusting springs from a burnt-out mattress. There should be room for improvement over that using a coat hanger with distributed loads of barn nails over the roof of a 1948 Hudson. Hi Dave, You never answered: "What's your point?" but are you having fun with loading yet? 73's Richard Clark, KB7QHC |
fun with loading
Cecil Moore wrote:
Tom Donaly wrote: Cecil Moore wrote: What you are going to find is that the coil warps the current profile away from a pure cosine wave ... How do you know it's a "pure cosine wave," Cecil? Because Kraus says so? That's interesting. It means we don't need to use NEC any more. 73, Tom Donaly, KA6RUH |
fun with loading
Richard Clark wrote:
Hi Tom, If the mood strikes me, I will see how much effort it takes to blow away his "efficient" antenna. Seeing how he has no answers for its construction, I can easily impose my own choices like an high E piano string radiator mid loaded with a squirrel cage over a radial field of rusting springs from a burnt-out mattress. There should be room for improvement over that using a coat hanger with distributed loads of barn nails over the roof of a 1948 Hudson. 73's Richard Clark, KB7QHC I would prefer a radiator made from half inch PVC filled with a dilute sodium chloride solution. If you put a valve at the bottom, it's a snap to adjust resonance. tom K0TAR |
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