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#242
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Cecil Moore wrote:
Jim Kelley wrote: Cecil Moore wrote: We have been told that lumped inductors have zero phase shift. I think the claim is that there is zero current differential in magnitude across a lumped inductor. It's certainly true of a pure inductor. Presumably, one in which radiation is not a factor, and for which the electrical length is short compared to wavelength. For a lumped inductance, the electrical length is zero. Presumably, that has a zero effect on the current. Assuming that only the voltage is affected, the phase relationship between the voltage and current is blown compared to an unloaded antenna. But the relationship is somehow (magically?) restored by the time the end of the antenna is encountered. Exactly how is that relationship restored? The problem seems to be caused by the assumption that an inductor has no current lag in an antenna circuit. In my experience, lumped circuit elements are just a simplified way of expressing the characteristics of device that has distributed reactances and resistance. You draw the equivalent circuit as inductors, capacitors, and resistors in series and shunt where appropriate, and assign the appropriate values to each. You can do that just as easily with an antenna as with a transformer. In the case of a loading coil, perhaps you could say that a portion of the "lumped" inductance of the antenna is replaced with a coil inductor. From a relative size standpoint, the inductance of the coil is certainly "lumped" compared the inductance of the rest of the antenna. But does size matter? :-) As Richard alluded, an inductor with zero phase shift must have zero inductance. I think it's safe to assume loading coils cause a phase shift. But what of the current differential? Seems difficult to believe that current can go from max to min, and impedance and voltage go from min to max along the 15" of a 40 meter hamstick whip. 73, Jim AC6XG |
#243
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On 06 Nov 2003 19:38:27 GMT, oSaddam (Yuri Blanarovich)
wrote: Hi Yuri, What is the problem with going back to a post and responding to that? Duplicated unnecessarily, but obviously needed: 100mA on an 8 Ampere full scale 3.5 inch meter is slightly more than 1% deflection (less than the width of the needle). The 100W excitation current levels near and through the model's solenoid exhibit values in the 1 Ampere region or at 12% deflection for an instrument that is arguably as accurate as 10%. This does not bode well for a compelling exhibition of any conclusive results. NOW, if I were wrong to presume that 100W is going to be the excitation - is that MY fault? If we jack up the power applied (easily within the means of an amateur so empowered, so to speak) then that region can certainly be forced into readings of vastly improved accuracy relative to the available metering. HOWEVER, this now inhibits doing the full length survey because the lower section would clearly overload the metering. You can't win for losing. Well, you can win if you are accomplished at the bench (a rare talent in this ivory tower where merit is weighed by angel population counts) by modifying your metering through shunts. I will warn you, however, it is incumbent upon you to reveal how that was accomplished, how it was confirmed and the data to support that too. You will also have to measure the surface temperatures and conspire to replicate them to your metering (something that you have not really responded to) to observe the systematic error introduced by these ever growing power applications. This, in a sense, is a turn of "you can't win for losing, but you can get close, but you still might lose anyway." Given your failure to respond/correct/aknowledge forced speculations, I had to cover many angles "implicit" in your vague specifications. You found an error, skipped the correct guess and still did not actually offer a hard specification. I have not done it yet. You have technical questions about W9UCW measurements and setup, ask him You haven't done what? I've asked how large the radiator, how large the coil, what size the radial field. WAS not WILL BE. All of these are fundamental questions for specifications that supposedly are part and parcel to your evidence and you ask ME to confirm the details? Why do you expect this to be compelling evidence that blows Tom out of the water? I did far more with a simple model that anyone could review for completeness' sake. You didn't responded to that! What's the program here? You left me to speculate about the model - NO RESPONSE to that either. What model? Hardware "model" W9UCW used was 60 quarter wave radials on ground (40m - see the picture) shorted radiator tuned to resonance with loading coil (see picture). Normal loaded antenna. Soft model by W5DXP was described by him. GAD! Why do you bother to come here for support? This all started with your avowed problem of Significant impact on modeling software. If the stuff is not accomodated properly, then results (mainly efficiency) are way off. Which had already been answered before you started this thread. You say so in your web page. 3 Days ago I offer my model that disputes Tom, supports you inferentially and you ask "what model?" Boy how lazy. OK, the plain vanilla radiator 93" tall (3/8" stock) in 93 segments surrounded by 60 X 93" radials (#12 wire) ALL elevated 6" above a real, medium ground. SRC DATA @ 7.1MHz = 0.7995 - J 810.9 ohms Current varies from 1A at drive point to 0 at tip The adornment consists of this underspecified coil being decimated and spread across 10 inches of space in the middle of the radiator with lumped values of 30µH each. For the life of me, I don't know what this exercise was to prove given the results: SRC DATA @ 7.1MHz = 1.258 - J 1561 ohms Current varies from 1A at the drive point to 0 at the tip One variation on the first pass design is that when this current hits the decimated inductor, the current drops to 0 a few inches before the first inductor section and quickly develops an 180° shift over those next few inches which persists on out to the tip. At the bottom of the coil sections, the current again picks up to roughly 100mA climbing to roughly 150mA at the top and then declining over the remaining length of radiator. It would seem that anyone could craft any assortment of conditions to support any of a dozen new theories from this kind of legerdemain. If there are ANY details that are wrong, I haven't seen one syllable written by you to the matter. I would point out that nothing about this model quoted above resonates in spite of your assertion that it did for the hardware tested. You never read this did you? I said that W9UCW set the drive level to show 100 mA deflection on the bottom meter, to eliminate errors you worried about, can't get any better than full scale deflection. The objective was to see the how much current decreases from the bottom to the top of the coil. Is it +-0 as Tom camp claims or is it significantly more like around 50% we found and claim. How is that terribly wrong that would prove Toms are right? Have you actually read any of my posts? You describe the enormous heat issues that come with these characteristics that have been UNRESPONDED to. Huh? I mentioned heat effect, where "lousy" Hustler coil demonstrates more heat generation at the bottom than at the top, therefore higher current at the bottom than at the top. What's wrong with that and conclusion that there must be more current flowing in the bottom turns than in top turns? Huh? Can you elaborate? Yuri, it is your statement that begs elaboration. Do you have data that supports nitpicking in the .01 area of significance - obviously not. What has bottom third of the coil heating up from the current (no meters) has to do with caloric based measuring device? You are now removing the frog's legs to prove it is deaf? You stick heat sensitive strip on the coil you will see the rapid change of colors going from the bottom to the top. What is wrong with that? Do you know how that ammeter works? You have here, and repeatedly, offered a description of considerable heat. The RF Ammeter works on the basis of heat (that's why it is called a thermocouple type). It is in close proximity to a source of heat by simple observation of the photos offered and undoubtedly what you anticipate in repeating at elevated power levels (more heat). What more does it take to suggest this heat is a source of error? 88's Yuri Blanarovich, K3BU still waiting for ONE PROPER MEASUREMENT, hellooooo???? otherwise you flat earth (er equal loading coil current) believers are the ones flying in the la-la land. Still waiting for you to 1.) provide a complete specification of the a.) radiator b.) solenoid c.) ground d.) drive applied (not readings) 2.) respond to the model offered; 3.) describe the errors possibly attending all this heat. Do I get real technical specifications OR should I be applauding? Please tell me what form of support you expect. 73's Richard Clark, KB7QHC |
#244
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Richard Clark wrote:
You are now removing the frog's legs to prove it is deaf? Cricket's leg, Richard, cricket's leg. Still waiting for you to 1.) provide a complete specification of the a.) radiator b.) solenoid c.) ground d.) drive applied (not readings) 2.) respond to the model offered; 3.) describe the errors possibly attending all this heat. Too bad you don't hold the other side to the same standards. One wonders why. Others asserted the positive premise. Why is it not up to them to prove their assertions? Why is it up to Yuri to disprove the positive assertions by others that triggered this entire discussion? You're not prejudiced, are you? -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#245
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Jim Kelley wrote:
Seems difficult to believe that current can go from max to min, and impedance and voltage go from min to max along the 15" of a 40 meter hamstick whip. Not difficult at all for True Believers of Old Wives' Tales or hams seduced by the steady-state model. :-) Component energy waves don't matter, don'tcha know? Never mind that standing waves are probably impossible without forward waves and reverse waves. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#246
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The time I am spending arguing here, I will be better off to do my own
measurements and start to write the article. I think this is about what I needed, I have got the picture, explanation for what are we seeing, its time to put it all together. I will just comment on your ending comments, unless I see any serious and measured arguments, further arguments are just running around in circles. Do you know how that ammeter works? You have here, and repeatedly, offered a description of considerable heat. The RF Ammeter works on the basis of heat (that's why it is called a thermocouple type). It is in close proximity to a source of heat by simple observation of the photos offered and undoubtedly what you anticipate in repeating at elevated power levels (more heat). What more does it take to suggest this heat is a source of error? I know how ammeters work. I key the TX, the ammeter almost instantaneously shows the current. W9UCW used good quality coils that would not heat up with 100 mA current. No time for coil to get red hot and fry the meters. You can see that from the pictures. I mentioned Hustler coil, wound with small gage aluminum wire and have experienced heating of the bottom with no meters screwing it up or vice versa. I put 500 W to it and saw that heatshrink tubing fried at the bottom = more current there, no meters to show error. So what's the horrendous heat got to do with what W9UCW measured? Try it, measure it. If I will do measurement I will not use Hustler aluminum coils but 1/4" tubing. Got that? 88's Yuri Blanarovich, K3BU still waiting for ONE PROPER MEASUREMENT, hellooooo???? otherwise you flat earth (er equal loading coil current) believers are the ones flying in the la-la land. Still waiting for you to 1.) provide a complete specification of the a.) radiator b.) solenoid c.) ground d.) drive applied (not readings) You pick typical mobile antenna, mount the coil from half way up, pick pair of radials or any ground, drive with what you have and see what you get. The objective is to prove or disprove that current across the loading is not the same, but more in the order of 50% drop with +/-10% error if you like. 2.) respond to the model offered; 3.) describe the errors possibly attending all this heat. Do I get real technical specifications OR should I be applauding? Please tell me what form of support you expect. 73's Richard Clark, KB7QHC As I said, you want to verify W9UCW measurements, contact him, I don't have ALL the details of his experiment. I will provide that info on my setup, when I get around to do it. What I expected? To see if anyone else measured the current in the coils and what they found, or if we are in error, where did we committed error and show us where we are wrong, if we are. (no one yet) I was looking for explanation of the effect. (thanks Cecil, makes sense) We found that software (EZNEC) does not treat the effect properly. We found that people learned that coil "must" have the same current and they will not accept reality and argue to death that it ain't so, if it is. I am happy to confirm that I was right, I found out about the effect and reasons behind it, opened my eyes wider and got me some ideas to improve loaded and mobile antennas. I corrected my opinion about reflected waves, I don't like them on feedlines, but I appreciate them on the radiators now (thanks Cecil). I found that presently we can approximate loading coil as a loading stub in the soft modeling (thanks Cecil) to get some more meaningful results rather than using imaginary coil. Unless someone shows that 7 points I raised are not valid, I am happy with results of this interesting exercise. Thanks all! Yuri |
#247
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Yuri Blanarovich wrote:
Unless someone shows that 7 points I raised are not valid, I am happy with results of this interesting exercise. Here's an interesting EZNEC result. I took the 102' loaded dipole that was resonant on 3.76 MHz and ran it on 14.3 MHz. I repositioned the loading coils at a current minimum point with a one ohm resistor on each side so there is 0.03 wavelength between resistors. --------------R1--coil1--R2-------FP--------R3--coil2--R4-------------- EZNEC sez: Current through R1 is 0.1618 amps at -156 degrees Current through coil1 0.09643 amps at -130 degrees Current through R2 is 0.08098 amps at -70 degrees In the ten degrees between R1 and R2, the current doubles and shifts phase by 86 degrees. Can we use these results to prove there is a phase shift through a lumped inductor? :-) -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#248
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Cecil Moore wrote:
Yuri Blanarovich wrote: Unless someone shows that 7 points I raised are not valid, I am happy with results of this interesting exercise. Here's an interesting EZNEC result. I took the 102' loaded dipole that was resonant on 3.76 MHz and ran it on 14.3 MHz. I repositioned the loading coils at a current minimum point with a one ohm resistor on each side so there is 0.03 wavelength between resistors. --------------R1--coil1--R2-------FP--------R3--coil2--R4-------------- EZNEC sez: Current through R1 is 0.1618 amps at -156 degrees Current through coil1 0.09643 amps at -130 degrees Current through R2 is 0.08098 amps at -70 degrees In the ten degrees between R1 and R2, the current doubles and shifts phase by 86 degrees. Can we use these results to prove there is a phase shift through a lumped inductor? :-) No. It'll take a lot more than an EZNEC analysis, or back yard measurement for that matter, to disprove theory that's been verified and used successfully for more than a century. Roy Lewallen, W7EL |
#249
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Roy Lewallen, W7EL, wrote: No. It'll take a lot more than an EZNEC analysis, or back yard measurement for that matter, to disprove theory that's been verified and used successfully for more than a century As I followed this topic thread both in this forum and on eHam, I formed my own opinion about the observed disparity between currents entering and leaving an antenna loading coil. My conclusion was that the parasitic capacitances between the coil turns and ground were responsible for shunting a fraction of this current away from the coil terminal that connects to the top part of the antenna (in the present case of a shortened, vertical monopole - the typical HF mobile antenna). To confirm this notion, I created the following EZNEC(tm) model of a 13-foot, inductively loaded monopole fed against a perfect ground: (1) a 3-ft bottom section containing the RF source, (2) a set of four inductors connected in series and occupying a physical length on the antenna of 2 feet, (3) a set of three "gimmick" wires attached to the internal nodes of the inductor assembly and extending horizontally for 2 feet that simulate the parasitic capacitances between the coil turns and ground and (4) an 8-foot whip on the top to complete the antenna. The operating frequency was chosen to be 3900 kHz and the inductors were adjusted in value to resonate the entire antenna at this frequency. The results are shown below as an EZNEC printout of the load data for the four inductors (Inductor 1 is the one closest to the bottom): EZNEC ver. 3.0 Yuri's Mobile #1 11/7/2003 6:05:04 AM --------------- LOAD DATA --------------- Frequency = 3.9 MHz Load 1 Voltage = 4280 V. at 89.99 deg. -- Current = 10.24 A. at -0.01 deg. Impedance = 0 + J 418 ohms Power = 0 watts Load 2 Voltage = 4144 V. at 89.98 deg. -- Current = 9.914 A. at -0.02 deg. Impedance = 0 + J 418 ohms Power = 0 watts Load 3 Voltage = 3756 V. at 89.97 deg. -- Current = 8.985 A. at -0.03 deg. Impedance = 0 + J 418 ohms Power = 0 watts Load 4 Voltage = 3125 V. at 89.97 deg. -- Current = 7.476 A. at -0.03 deg. Impedance = 0 + J 418 ohms Power = 0 watts Total applied power = 156.6 watts As can be seen, there is roughly a 25% reduction in current from bottom to top on the "loading coil". Interestingly, most of this current-shunting appears to take place near the top of the "coil". This model is admittedly quite crude. The conclusions I reached were that there was at least a qualitative effect from the parasitic shunting capacitances on the current flow through a loading coil and that quantitatively it appears to be fairly significant. I have included the text description of the model from EZNEC below: EZNEC ver. 3.0 Yuri's Mobile #1 11/7/2003 6:24:20 AM --------------- ANTENNA DESCRIPTION --------------- Frequency = 3.9 MHz Wire Loss: Zero --------------- WIRES --------------- No. End 1 Coord. (in) End 2 Coord. (in) Dia (in) Segs Conn. X Y Z Conn. X Y Z 1 GND 0, 0, 0 W2E1 0, 0, 36 0.1 8 2 W1E2 0, 0, 36 W3E1 0, 0, 42 0.1 1 3 W4E1 0, 0, 42 24, 0, 42 0.1 1 4 W2E2 0, 0, 42 W5E1 0, 0, 48 0.1 1 5 W6E1 0, 0, 48 0, 24, 48 0.1 1 6 W4E2 0, 0, 48 W7E1 0, 0, 54 0.1 1 7 W8E1 0, 0, 54 -24, 0, 54 0.1 1 8 W6E2 0, 0, 54 W9E1 0, 0, 60 0.1 1 9 W8E2 0, 0, 60 0, 0, 156 0.1 1 Total Segments: 16 -------------- SOURCES -------------- No. Spec. Pos. Actual Pos. Amplitude Phase Type Wire # % From E1 % From E1 Seg (V/A (deg.) 1 1 1.00 6.25 1 10 0 I -------------- LOADS (R + jX Type) -------------- Load Spec. Pos. Actual Pos. R X Wire # % From E1 % From E1 Seg (ohms) (ohms) 1 2 50.00 50.00 1 0 418 2 4 50.00 50.00 1 0 418 3 6 50.00 50.00 1 0 418 4 8 50.00 50.00 1 0 418 No transmission lines specified Ground type is Perfect Just to complete the picture, here is the Source data: EZNEC ver. 3.0 Yuri's Mobile #1 11/7/2003 6:48:30 AM --------------- SOURCE DATA --------------- Frequency = 3.9 MHz Source 1 Voltage = 16.43 V. at 17.66 deg. Current = 10 A. at 0.0 deg. Impedance = 1.566 + J 0.4984 ohms Power = 156.6 watts SWR (50 ohm system) = 31.937 I will be happy to send out the .EZ file for this to any interested parties. Splice together the e-mail address below to contact me. 73, Jim Bromley, K7JEB k7jeb (at) qsl (dot) net |
#250
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Roy Lewallen wrote:
It'll take a lot more than an EZNEC analysis, or back yard measurement for that matter, to disprove theory that's been verified and used successfully for more than a century. Nobody is out to disprove theory. But it seems apparent that the lumped inductor conceptual model and a real-world inductor have little in common. For the same reason, one cannot use a model of a lossless transmission line to determine real-world efficiency. Models do not dictate reality. It is supposed to be the other way around. -- 73, Cecil http://www.qsl.net/w5dxp -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
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