WOW Dave! An electrical engineering degree would have been handy to stay with you during your explanation. But, you give us non-technical folks something to reach for. I'm glad that you dumbed things down at your conclusion. That being said... We newish hams are so fortunate that you continue to lecture on TH-cam. You sir, are a treasure to ham radio!
"It is the job of the antenna to do the impedance matching between the 50 ohms of the transmitter and the 377 ohms of free space." It's sentences like this right here that is why I'm not only a subscriber but a patron. You don't just go in depth, you word things in such a way that every so often one sentence completely tears down a conceptual barrier that's been planted in my head for years. Bravo!
it's not correct. The tuner matches the transmitter to the resistive part (R) of the antenna, so it does an impedance transformation between the 50Ohm of your transmitter to the whatever impedance your antenna has, and it eliminates any reactive part (X). Whether the antenna itself is radiating well (i.e. matched) to the 377Ohm free space at your sending frequency is a different story. Thus, the tuner does NOT match the transmitter to the 377 Ohm of the free space, only to the resistive part of the antenna, which, for a well radiating antenna (at a specific frequency), is then hopefully also well radiating. If you have a poorly radiating antenna, the tuner will do it's nice job and get the VSWR down, but that does not mean that your power is radiated, might just be used up in the non-radiating resistive part of the antenna (or any other lossy elements in between). Even for a poor radiator the tuner is helping, as it will increase the power which you actually get out, i.e. it will increase the radiated power as compared to the non-tuned case. But the best solution is always to take care to have an efficient radiator (in which case you only need an impedance transformation and then not even a tuner, but the tuner can do its job here as well within its limits, it just narrows down the bandwidth since the tuner is resonant and an impedance transformer is not). I'm always surprised how much misunderstanding and misconception is in the HAM community about things which are the actual core of their business.
In the meantime, I'm never surprised by how willing someone is to give a lecture about something that wasn't even mentioned, just to sound superior. It's nice that you know that 'the tuner does NOT match the transmitter to the 377 Ohm of the free space', but I didn't mention tuners once. Twice in your tome, you reaffirmed that it's the ANTENNA's job to match to the 377 Ohm of free space. This is the very concept I was commenting on.
@@joachimoberhammer3020 You just didn't listen carefully enough. He's right (as are you). The job of the ANTENNA is to match the impedance between the 50 Ohms coming in and the 377 Ohms of free space. Note he didn't say the job of the TUNER. The job of the TUNER is to match the impedance of the transmitter with the impedance of the antenna. They are, as you say, two different things. But that's exactly David's point. As it turns out you're both in accord.
I have an EE degree, I was very glad to hear Dave give the long answer to the question. 100% right as usual, but sometimes people don’t have the patience. To me, it was music. Excellent Dave
I watched this video and the local University sent me a BS in Electronics Engineering. Wow, Dave, I learned more about feed line and antenna theory in that one video than in all the rest of my HAM studies combined. 7-3 KD2SML
Thanks for the explanation, Dave. Antenna tuners are necessary evils in MW and HF radio. I've always thought of an antenna tuner as a device that "fakes" the transmitter into thinking it's feeding a resonant 50 ohm load. Without exception, AM broadcast stations have an "ATU shack" at the base of their tower(s) to fake the transmitter into a 50 ohm load when the tower is anything BUT 50 ohms. I try to put up antennas that are resonant for the bands I use. It is always painstaking and trial and error - usually hard to keep them that way.
The broadcast transmitter actually sees a 50+j0 load; there is no faking. When possible, broadcast towers are of the proper height to be close to natural resonance, and the ATU is mostly used to match the ~24 ohm radiation resistance of the tower to the 50 ohm coax. But they are also used to trim out minor reactance to make the tower electrically resonant at the assigned frequency if the tower is not exactly the right height. Environmental factors can also change the base impedance and may need to be trimmed out. Of course, if the tower is far from the correct height, as in the old days when stations went to 640 and 1240 for Conelrad, the ATU has to null out some major reactance to get the tower to resonate. Typically a station would have had a second ATU for Conelrad with big contactors to make the switch. When the tower is part of a directional array, the base impedance is determined by the array parameters. A few arrays have bizarre things like negative towers (towers with a negative base impedance which actually absorb power). Stations which run different patterns at different times usually have a separate ATU at each tower for each pattern with RF contactors to make sure the coax always operates at 50+j0. Towers which are not used for particular patterns are switched to detuning networks which make the towers electrically invisible. There is nothing inherently evil about an ATU. Broadcast stations typically use large air-core inductors made from tubing and vacuum capacitors for best stability and low loss. A properly designed and built ATU is a thing of beauty. Broadcast stations may use a device called an Operating Impedance Bridge in-line to measure impedance during normal operation to see if it has drifted too far, but when the antenna system is built from high quality, stable components, I found the OIB mostly unnecessary.
W0W! Thanks Dave for answering my question, I've been having a round or two moving snow off our roof up here...one of those years. Spring is coming fast and now I can spend more time getting my shack set up. Sooo appreciated your valued if not overwhelming answers, I will need time to fully digest it all. The "No" rather answered the Q, but the remaining lecture drove it home. Reminds of my USN ET school of many many years ago. Regards, Dave (also)
Overly lengthy yes. But in covering everything and not subtracting from the topic I took away 2 invaluable nuggets of information this time Dave Thankyou.
I see the variable inductor and variable capacitor in the MFJ-986. It makes perfect sense how it can make the whole transmission circuit resonant and balanced.
Well Dave, at 32 minutes in, you gave me the answer. I struggled to follow the first half hour. You did prove, beyond a reasonable doubt, that my degree is not in EE. Michael Edmonds is right. You're a great asset!
Fantastic explanation. Thanks !!! As a beginner ham I need to understand what is really happening in those RF circuits. Long time electronics design engineer, but never did RF. Basic rules of PCB design were most of the time sufficient like gnd plane, C-decouple, some filtering of I/O. But radio is a different animal all together 🙂 And you have mentioned the great Nikola Tesla. One of the people who truly understood the working principles of the nature all together. Being my fellow countryman make it even more special 🙂 Understand first build later, as he was saying... Anyway all the bast to you Dave and 73!
An antenna coupler tunes out the complex portion of the feedline/antenna in order to present the transmitter with a real 50 ohm impedance, it does this by selecting the capacitor and inductor values necessary to subtract the complex reactances out leaving only the real component.
hi Dave. great video! On these days I replace my EFLW antenna with a Doublet with balanced feeder line .... now I easily operate 80..20m just use a MFJ qrp tuner .... Just a proof of concept of you video 73 paolo
Howdy. I totally enjoyed Your assertiveness. For what it's worth, I am with You. What You say, I think, backs me up when I argue that a tuner + transmission line + non-resonant antenna + environment will radiate almost as much as a perfect resonant antenna. I recognize that the standing wave current nodes in the line will cause ohmic losses. Also, I recognize that the radiation pattern may anything but a clean doughnut. The pattern may have lobes sprouting at any direction. I have had discussions when it is argued that the tuner does not change the physical properties of the antenna. Yes. The implication being that the reflected power is all burnt up in the tuner and the transmission line. Regards.
Hi Dave, Respectfully, the antenna tuner and an antenna do not match the impedance of free space. There are two (or more) correct ways to look at a tuner, depending on if you want to look at it with wave theory or just as a matching system, but the ultimate result to users is the tuner corrects the antenna system impedance at the insertion point and brings the entire system into "resonance". We also have to be careful with reflected power and standing waves. The impedance mismatch between a load (like an antenna in this video) simply sets up a standing wave. The standing wave STANDS with the result voltage and current distributed along the conductors in a transmission line vary. That voltage and current change is what causes increased (or decreased) transmission line loss. Reflected power does not keep bouncing back and forth until it is dissipated. Reflected power does not make it back to the PA where it dissipates as heat. This is easily demonstrated with a few simple experiments. None of the common antenna tuners we use, or that are inside radios, are symmetrical in SWR performance. They generally don't do well at all with 3:1 mismatches that are lower impedances and capacitive, but they can actually work better and more efficiently into high impedance loads. Typical tuners often exceed ratings in the high impedance direction. We need to be very careful specifying some exact matching range based only on an SWR range a manufacturer used. It might be best to avoid certain details rather than say something misleading. Sometimes it is better to just answer a question as simply as possible and not start adding things that wind up being incorrect or misleading.
I am SO deficient in general "Antenna Theory" it's sad. I just don't get the "Magic" that make antenna's work. You have helped in such way that, I kind of, maybe, that I sort of, could possibly, maybe, understand this all one day...
Thanks for the explanation. Finally discovered your channel and I hope you are still actively broadcasting. By the way, noticed your Air Pilot in the background. Yeah, I too love lanterns only I absolutely can't stand the smell of kerosene. Another thing I love is my balanced fed, all band, tuned doublet antenna.
Thank you, thank you, thank you! I am a need to understand what is actually happening kind of guy, and you explained what is really suppose to be happening when a tuner is used. I have about a 1,000 feet of hardline coax (new end pieces) picked up around my neighborhood when our 3 cable companies rebuilt and repaired their build after Michael's 165MPH winds came through. My old FT101 serial number 458 (fresh from Japan) would have tuned to a 75 ohm feedline no issue but not so with the newer rigs. I have an still in the box new 7300 so if or not the tuner will mate with 75 ohm is unknown. I did aquire a few 75 to 50 transformers to also try. Anyway, the until now MYSTERY of tuning my meagure mind has been pondering all these 50 years has been revealed, even if a multiple of viewing this episode is still needed!!! Again THANK YOU !!!
@@davecasler I have several external tuners but would prefer just the internal or the internal along with a device seldom mentioned these days, it is made by MFJ and called a tuner extender. Just adjust it to the most noise on your receiver and retry the internal tuner and generally it will then tune, if not repeat the process with the next setting either side of the most noise. Thanks Dave, really appreciate yoir work.
Great video as usual! I’ll say that orchestras are moving slowly to 442. In Europe they have been there a while, and some major orchestras in the US are moving, but slow. 432 and lower tunings are still used by period ensembles, like Baroque and earlier. Yes, you can still buy tuning forks. Still used by some timpanists, after hitting the fork you can hold it against your head, near the temple and it’s amplified in your head and you can flick the timpani head using other hand and re tune heads in the middle of a passage. 73 de KJ4KPW
Another factor is that people are taller (and wider) than they were 200 years ago, and so our poor taller sopranos have a harder time hitting 440, let alone 442. It does seem to be a bit of a bone of contention amongst the cognoscenti (of which I do not claim to be a part). Most people have absolutely no clue what any of this means! Our church organ and my own personal organ can be tuned up and down, mostly to match any instruments it may be accompanying.
I call this "pitch wars". At some times, there seems to be a competition between orchestras to see who can tune to a higher pitch. No longer do they tune to 440, but 442, 445, or in extreme cases, even higher, in an attempt to make their music sound more exciting. Back in the day radio did a similar thing by running their turntables faster than 45 RPM. Not only would they have extra seconds for more commercials, but their slower competitor sounded like they were dragging; their music sounded tired and lifeless.
Square waves are equivalent to a sine wave at the same (fundamental) frequency added to an infinite series of odd-multiple sine-wave harmonics at decreasing amplitudes.
Tricky concepts for newbies and veterans alike, you did a pretty good job. A smith chart might make the concepts you are trying to convey a bit more clear, but like I said you did awesome.
Indeed a Smith Chart would help. Sadly, they confuse the daylights out of me. I never encountered them in my schooling, and they're pretty rare in ham radio.
@@davecasler I also did not encounter Smith Charts in my undergrad EE course work, they really are not necessary with today's tools, however, they are a fantastic visualization tool when teaching this type of material to newbies (and veterans). I would recommend a RF design book titled, "RF Circuit Design 2nd Edition by Christopher Bowick" it is one of the best books on RF design for the non engineer that I have come across and I think that I have them all :o) There is also a youtube channel named "w2aew" where the host Allen has 4 or 5 excellent videos on smith charts. With these two sources you won't be an expert but you will be well on your way to being one. Again thanks for what you do and keep up the excellent work.
@@davecasler I also did not encounter Smith Charts in my undergrad EE course work, they really are not necessary with today's tools, however, they are a fantastic visualization tool when teaching this type of material to newbies (and veterans). I would recommend a RF design book titled, "RF Circuit Design 2nd Edition by Christopher Bowick" it is one of the best books on RF design for the non engineer that I have come across and I think that I have them all :o) There is also a youtube channel named "w2aew" where the host Allen has 4 or 5 excellent videos on smith charts. With these two sources you won't be an expert but you will be well on your way to being one. Again thanks for what you do and keep up the excellent work.
Hi, Dave. I play frailing and melodic claw-hammer Appalachian banjo and have several tuning forks and they're still available quite commonly at music stores that sell acoustic instruments. Also, just for the fun of it I checked on Amazon just this moment and found dozens and dozens of different types of tuning forks for music as well as for other uses. Don't know why you'd think they're not available anymore lol.
Unless tuning at the feedpoint i will stick with a manual tuner. The reason for this is that sometimes the Q on the tuning is very fine and with a manual tuner you can hunt out that very specific zone of capacitance and inductance to better receive weak stations. Now ask yourself just how many combinations of inductance and capacitance is available with an automatic atu? For sure most automatic ATU's cover most of the HF bands but when you need that more tricky tune to be so finely adjusted so as to bring in that weak station there is no guarantee that the automatic ATU can get as close as you can with a dial, it will get close but no guarantee it's exactly where you want it to be. If you have tuned in weak stations on various antenna designs with a manual tuner you will know what i am talking about and if you know a bit about electronics and capacitors in parallel and series you will know that you can arrive at many combinations but you can't cover all of the gaps everywhere without a variable capacitor or two and ideally a variable inductor.
Hey Dave, thanks for all your great videos. I have to say that I am not a fan of using antenna tuners other than to take out the last little bit of mismatch. As it is better to have an antenna that is as close to resonance as possible. Otherwise, all the tuner is doing is to hide the problems of a non-resonant/lossy and therefore an inefficient antenna. All that is being done is to make a bad antenna a nice dummy load to present to the transmitter :) I was kinda hoping that you may have commented on that aspect. Regards, Dave, VK2TDN
Dave I love your channel, As to your comment about tuning forks, you can still get them from any reputable musical instrument store or science supply store.
Nikola Tesla's colorado springs antenna was 30" turned wood sphere covered with tin. Polished to a mirror finish. Covered in schalack. Finally, covered in black rubber paint. For the longest time I couldn't figure out why the medal needed to be polished to a mirror finish and then completely covered with rubber paint.
Dave there is a lot of talk about the radiating power lost when using a tuner, have you ever used a wattmeter at the transmitter and another at the antenna to see the actual wattages? And compare that to a 50 ohm antenna and the same 50 ohm feed line.
back in the day. I know you lived threw it. I puchased a army big stick for ten. used it on eleven and ten. that was the days when ten and eleven was in full swing.
A tuner tunes it's output to the conjugate of the impedance of the load on the output of the tuner. This implies that the tuner tunes the load by cancelling any reactance in the load.
haha, Dang Mr.Casler, it's not too long, I'm hopping for a part two, how to measure all these new words. How do I know I need a balun unun, what the heck is reactance....Thank you so much for this lesson. I've been searching for this kind of info for awhile. K8CDM, Dave
What is tuning? It is adjusting the resonant frequency. An antenna's resonant frequency may be adjusted by changing its length ala Stepir or it may be adjusted electrically by loading inductance or capacitance. An antenna tuner loads the antenna with inductance or capacitance to adjust its resonant frequency.
@Tom Smith Antennas do not possess some special form of resonance which only responds to changes in length. They work just like any resonant circuit. If you add inductance or capacitance, which a tuner can do, it will shift the resonant frequency, just as it would if you added to a tank circuit. This misunderstanding is why I advocate for a question on the FCC exam which would help prospective hams to learn the correct concept of antenna resonance. I think some of the confusion comes from the fact that an antenna tuner serves a dual purpose: tuning (changing resonance by adding inductance or capacitance) and/or matching (transforming impedance). Some grab onto the matching function and forget about the tuning function. --de N3TS
I think there's more to say that's typically not said: could you talk about the effect of a capacitor or an inductor in changing the relationship between the current and voltage, and how that relates to resonance?
Great video Dave. You mentioned it very briefly in the video, but I was wondering what causes all the noise when a tuner is tuning? I tuned up a random wire antenna today and my tuner clicked and clacked like crazy. Are the variable capacitors and coils that loud when they are adjusted or is something else going on? Personally, I attributed it to tiny people pushing around switches like crazy... but I'm 98% certain there aren't actually tiny people pushing things around in there.
What you’re hearing during this process are a whole bunch of tiny electromagnetic relays that switch on or off the flow of electricity into the various capacitors and inductors that make up the tuning circuitry. Relays actually involve shoving or pulling a little contact back and forth to either engage or disengage a circuit. That’s the clicking that you’re hearing.
I view it as: You are tuning the 'TUNER'. Nothing else is modified on either side of it. The tuner is an adapter of sorts between transmit system side and the antenna system side. It is like an adapter plate to mate different gear-boxes to an engine.
Hey Dave, thankyou Sir, unfortunately this level is a bit above My station at this moment in time!, however, just listening to Your voice was making Me feel drowsy, I've loved it, I'm sure something may well have sunk into My pickle jar of a brain somewhere!, Greetings from England btw👍
I blame the use of the phrase Antenna Tuning Unit (ATU) to the confusion of many amateurs. It could be more accurately termed an Antenna Matching Unit (AMU) but strictly speaking it is an impedance matching unit. The take away message here is in shack or built in matching units keep the radio happy by presenting it with a close 50 ohm match but does nothing for SWR and power loss in the feedline but the local control is convenient. The location any required matching network is best done at the antenna to minimise feedline losses but at HF frequencies the remote control or automation is expensive.
Rob, I completely agree. Antenna Matching Unit or Antenna Trans-Match is a clearer and more understandable term to explain what this device is doing. Tuner is misleading as it implies that you are actually changing the frequency of resonance of the antenna, which you are not. Simply you are impedance matching the 50 ohm signal from your transmitter which is presenting a frequency that your antenna is not resonant on and the antenna is presenting a potentially quite different impedance at the applied frequency. If your dipole was cut to resonance on 7040 CW and you QSY up to the high end of the phone band, say 7285 LSB, the antenna is still resonant at 7040 and presents a quite different impedance when 7285 is applied to it. I've attempted to convey this understanding to several newly minted hams when they are confused by the term Tuner. It would be nice if the manufacturers would change the label on that button to "Trans-Match". 73 Chris W6NOB
When you use an antenna tuner, you are changing the frequency of resonance of the combination of the tuner, the feedline, the antenna, and the environment. The whole thing works as a system.
@@davecasler Hi Dave. While I agree with your statement on matching the whole system, my point is you are by no means tuning the antenna as the casual interpretation of the name might imply, Simply put an "ATU" best matches any reactance present. If you were to ask an engineer and a layman , "Which is more elastic a steel ball bearing or a rubber ball?" you would get two different answers. The engineer would frame his answer in STRICTLY in terms of the Poisson ratio where as the layman would give the commonplace (mis)interpretation. I think a similar misinterpretation is being made by many amateurs because they tune up using VSWR with no regard to antenna feedpoint reactance and the "ATU" is simply acting to match the reactance at it's output to it's input it can not tune the physical length of the antenna. Hence the best VSWR typically get into a dipole is about 1:1.5 or 73/50 ohms. Call me biased and pedantic but I favour resonant antennas over random lengths and if you really must do impedance transformation it is best done at the antenna feedpoint not at the radio. This ethos can often be seen in monoband VHF and higher antennas where the impedance imbalance is often corrected by a network at the antenna feedpoint, not something that is easy on a multi band HF antenna. There in lays a subject I suggest for an Ask Save episode. The pros and cons of a matching unit or impedance transformer and it's physical location in a system.
@Rob B VK6ES And here I thought they put that matching network at the antenna end mainly because the system isn't dependent on the transmission line at that point, so they can make a predictable correction. Edit I also can't understand how, when you take the entire system and add capacitance or inductance, you can't be changing the characteristics of the entire system as a whole, including resonance.
@@patrickbuick5459 Your first assertion is accurate but of course there are practical limitations to the impedance transformation so logic would dictate a target match from say 10 to 1000 to 50 ohms resistive as a practical solution.. As for the the effects of L and C remember AC resonance occurs when voltage and current are in phase, that is Voltage is max at the same time Current is max. If an antenna presents something other than a pure resistance then the V and I are out of phase . Adding external L and C can oppose the phase error and bring V and I back into phase while at the same time transform the impedance from one side of a network to the other to make a good 50 ohm resistive match at the input in this case.
In my excitement and trying to make sure I wrote what I wanted to express, and my memory I frequently forget to add my call sign. But not this time. 73 de AG7MW
Good day; May I ask for the advice? I have a VHS radio on the boat, there is 50 Ohm output for the antenna . It works within the range 156 MHz - 162,05 MHz, with broadcasting power 1W or 25W.. Unfortunately the antenna on the top of the mast is connected with the 75 Ohm coaxial cable. There is need to replace it with 50 Ohm cable. I have two questions: 1, whether working on this unmatched cable can destroy the radio? 2. Is it possible to use any balun or other way to achieve matchig, down without laying down the mast? I shall be grateful for the help. Mark
Hi, Dave. I've learned a lot from your videos and articles in QST. My question concerns the usefulness of a certain type of HF antenna and tuner combination for Field Day use. I've set up an EMCOMM communications trailer and am currently running a 600 Ohm ladder line fed, inverted V doublet, 80-10 meters, fed from a manual tuner into a 4:1 current balun. It's a great antenna for EMCOMM because of its efficiency and the fact that I'm parked on only one or two HF frequencies. For Field Day I tend to "hunt and pounce" across a wide range of HF frequencies. I probably wouldn't be too popular during Field Day if I was constantly tuning up with the manual tuner every time I changed frequencies, so I'm wondering how well an external automatic tuner might work with this antenna set-up. I like the doublet HF antenna design because I can work all 80-10 meter HF bands with one antenna. I'm just wondering how well it might be suited for use as a Field Day antenna. 73 and thank you. K7SFA
A square wave is a sine wave and its ODD order harmonics. Multi stage tuning has nothing to do with hetrodyne or super hetrodyne. Hetrodyne has to do with mixing two or more frequencies to get a different frequencies. Thus they mixed a frequency with another to get a lower frequency so that it would be easier to amplify the lower frequency because then the higher frequency was more difficult to amplify.
Well, you're right about the square wave. Regarding superhets, the point is to get to a fairly low-frequency intermediate frequency (historically 455 kHz) for reasons of selectivity. The IF filter usually is the determining filter for the receiver's selectivity.
I have no call sigh. I am looking for the mechanical method of electron deceleration to the creation of a photon. Your channel has been very helpful. And radio waves are heat. The formula, "Wien's Law" => .0029/wavelength = temperature in Kelvin. So 40 meter = .0000725 Kelvin and that adds heat to nothing so it just passes through unless it is collected within properly aligned resonance such as an antenna. Thanks for the explanations from the practical end.
Heat and electromagnetic waves are both forms of energy, but there's no "heat field." But photons, as you go up in frequency, do carry more energy than those at lower frequencies. I'm not a thermal engineer (I'm an EE), and frankly heat has always mystified my.
@@davecasler Heat should not mystify you. We are surrounded by atoms radiating radio waves at a frequency that make up what ever radiant temperature that surrounds us, but like rain on a lake they aren't in a wave distribution that gives energy to free electrons in continuous motions when they hit an antenna of set length. As for "heat field", I think I will stick with "heat wave." Tomaato, Tomooto.
You mentioned tuning forks. I just watched one of your videos on J poles. Is there a commonality between the two? From what I know of both (not much) I see a lot of commonality.
I have an Yaesu FT-991A. Dave, in your honest opinion, should I use an antenna tuner? I was considering a MFJ-929, as that's the most I can afford. Thanks and Best Regards. 73
Thank you for the theory and answer to the guys question. You have also helped me understand more about the theory used in the question pools for advancement as I want to know what the answers are about...not to just memorize the answers to past the test! 73 N6ZKI
The so called antenna tuners within radios or close to radios are not literally antenna tuners, but they are matching networks. In the usual case of a badly adapted antenna with a non-50-Ohm impedance the matching network has to maximize the power transference from radio to the antenna at the used frequency, which then falls into the category of conjugate matching, where the impedance of the antenna is "mirrored" in such a way that the impedance is the same, but the reactance is negative. According to the following paper from 1965 "K. Kurokawa, “Power waves and the scattering matrix,” IEEE Trans. Microwave Theory Tech., 13, #2, pp. 194-202, April 1965." the power wave reflection is reduced to 0 in case of conjugate matching, but that does not mean that all the power is transferred, and it also does not mean that the travelling voltage wave reflection wave is 0 too, because the reflection coefficients for power and travelling waves are calculated differently. Nevertheless, in that conjugate matching case the incident and reflected travelling voltage waves are reflected between the antenna and the matching network, and that is the reason why they do not get to the radio, and their energy gets dissipated mostly in the transmission line and the matching network, i.e. although power transference is maximized the remaining reduced reflected power is lost. More details on matching networks can be found in chapter 13 of the "Electromagnetic Waves and Antennas" book from Sophocles J. Orfanidis that is freely available online. There are losses in conjugate matching, and therefore we should strive to reduce the losses by adapting the antenna side with impedance transformers or similar things getting closer to the reflectionless matching case or use antennas that have hopefully out-of-the-box 50 Ohm impedance. Thanks and 73 from Tihomir CA3TSK
The nice thing about a tuning fork is it doesn't need batteries. Should I turn my power down before adjusting the tuner extender on my radio - I'd hate to smoke a new IC-7300?
I have a butter nut laying in my hall. the misses is about to kill me because it is there, but I guess you have to tune each one of the forty 75 any thing between ten and eighty. the one I have has nine bands on it I guess, but each one has to be tuned. the reason it is still laying there, because of where I came from. if you tinned the antenna on the ground and the erected it the swr would be different one the ground as to being erected. so my worry is going to be like in the old days of the eleven meter band. different on the ground as to when you put it up. My question is if ground mounted a few feet of the ground will the matching still be good we just tuned it to one. point five or below. .
I would like to understand the differences between L-Network, PI-Network, and T-Network tuners. I once heard a vendor suggest an L-Network-based tuner has less circulating current than the other types suggesting more power is delivered to the feedline/antenna system?
Sounds like marketing hype. An L-network takes fewer expensive reactive parts, but you need to be able to switch the L in the other direction if called for.
so again Dave you have me thinking. is this sorta like a pure sine wave and then you have a modified sign wave in inverters. is this sorta the same on the radios?
I'm listing to you in one ear. I got part of it . square wave is something that is in cheap inverters and pure sign wave is what you need to run your sensitive radios and tv's that picture looks like a m f j manual tuner that I have. I have auto tuners on my radios. I know that I'm not talking about. what you are talking about but on antenna's if you have a die pole and it is not an inverted v what one that is stretched out straight. I live on the side of a hill and I stretch out my antennas. so I would like to know the difference
this has me thinking and that means trouble.. so where should the tuner be? before the amp or behind the amp. I''m thinking about all this. it is all mind boling?
Are you aware of anyone doing and posting results of a test where they measured parameters like X,R,Z, and theta at the shack and antenna ends plus field strength before and after tuning with the tuner at the shack, then at the antenna? Is it even possible? If possible, what equipment would be required? I truly want to put my mind at rest regarding all of this and there is nothing like empirical evidence to do so lol. Thanks.
WOW Dave! An electrical engineering degree would have been handy to stay with you during your explanation. But, you give us non-technical folks something to reach for. I'm glad that you dumbed things down at your conclusion. That being said... We newish hams are so fortunate that you continue to lecture on TH-cam. You sir, are a treasure to ham radio!
Thank you!
"It is the job of the antenna to do the impedance matching between the 50 ohms of the transmitter and the 377 ohms of free space." It's sentences like this right here that is why I'm not only a subscriber but a patron. You don't just go in depth, you word things in such a way that every so often one sentence completely tears down a conceptual barrier that's been planted in my head for years. Bravo!
it's not correct. The tuner matches the transmitter to the resistive part (R) of the antenna, so it does an impedance transformation between the 50Ohm of your transmitter to the whatever impedance your antenna has, and it eliminates any reactive part (X). Whether the antenna itself is radiating well (i.e. matched) to the 377Ohm free space at your sending frequency is a different story. Thus, the tuner does NOT match the transmitter to the 377 Ohm of the free space, only to the resistive part of the antenna, which, for a well radiating antenna (at a specific frequency), is then hopefully also well radiating. If you have a poorly radiating antenna, the tuner will do it's nice job and get the VSWR down, but that does not mean that your power is radiated, might just be used up in the non-radiating resistive part of the antenna (or any other lossy elements in between). Even for a poor radiator the tuner is helping, as it will increase the power which you actually get out, i.e. it will increase the radiated power as compared to the non-tuned case. But the best solution is always to take care to have an efficient radiator (in which case you only need an impedance transformation and then not even a tuner, but the tuner can do its job here as well within its limits, it just narrows down the bandwidth since the tuner is resonant and an impedance transformer is not).
I'm always surprised how much misunderstanding and misconception is in the HAM community about things which are the actual core of their business.
In the meantime, I'm never surprised by how willing someone is to give a lecture about something that wasn't even mentioned, just to sound superior. It's nice that you know that 'the tuner does NOT match the transmitter to the 377 Ohm of the free space', but I didn't mention tuners once. Twice in your tome, you reaffirmed that it's the ANTENNA's job to match to the 377 Ohm of free space. This is the very concept I was commenting on.
The statement of matching to free space is utter nonsense.
@@joachimoberhammer3020 You just didn't listen carefully enough. He's right (as are you). The job of the ANTENNA is to match the impedance between the 50 Ohms coming in and the 377 Ohms of free space. Note he didn't say the job of the TUNER. The job of the TUNER is to match the impedance of the transmitter with the impedance of the antenna. They are, as you say, two different things. But that's exactly David's point. As it turns out you're both in accord.
@@Jerrythenerdful Yes, Dave is a big comedian and I like his jokes 😂
De VU2RZA
To bring a musician’s understanding of resonance to the antenna system: BRILLIANT! Thanks, Dave.
I have an EE degree, I was very glad to hear Dave give the long answer to the question. 100% right as usual, but sometimes people don’t have the patience. To me, it was music. Excellent Dave
As a retired EE (microprocessor/computer world) and a new HAM, I thank you for an excellent and clear explanation. I appreciate the "long" answer.
You sir have forgotten more than I will ever know! Thank you for taking the time to make these videos.
I'll have to watch this 49 more times i guess.
Lol. I thought I was the only one.
Nope. I know even less now than before I watched.
Please don't. For your own sanity.
Oh go ahead and watch it 49 more times. I can always use the views!
I watched this video and the local University sent me a BS in Electronics Engineering. Wow, Dave, I learned more about feed line and antenna theory in that one video than in all the rest of my HAM studies combined. 7-3
KD2SML
I vaguely remember an old parable about blind men describing an elephant. That’s not what you get from Dave! You get everything explained.
Thanks for the explanation, Dave. Antenna tuners are necessary evils in MW and HF radio. I've always thought of an antenna tuner as a device that "fakes" the transmitter into thinking it's feeding a resonant 50 ohm load. Without exception, AM broadcast stations have an "ATU shack" at the base of their tower(s) to fake the transmitter into a 50 ohm load when the tower is anything BUT 50 ohms. I try to put up antennas that are resonant for the bands I use. It is always painstaking and trial and error - usually hard to keep them that way.
The broadcast transmitter actually sees a 50+j0 load; there is no faking. When possible, broadcast towers are of the proper height to be close to natural resonance, and the ATU is mostly used to match the ~24 ohm radiation resistance of the tower to the 50 ohm coax. But they are also used to trim out minor reactance to make the tower electrically resonant at the assigned frequency if the tower is not exactly the right height. Environmental factors can also change the base impedance and may need to be trimmed out.
Of course, if the tower is far from the correct height, as in the old days when stations went to 640 and 1240 for Conelrad, the ATU has to null out some major reactance to get the tower to resonate. Typically a station would have had a second ATU for Conelrad with big contactors to make the switch.
When the tower is part of a directional array, the base impedance is determined by the array parameters. A few arrays have bizarre things like negative towers (towers with a negative base impedance which actually absorb power). Stations which run different patterns at different times usually have a separate ATU at each tower for each pattern with RF contactors to make sure the coax always operates at 50+j0. Towers which are not used for particular patterns are switched to detuning networks which make the towers electrically invisible.
There is nothing inherently evil about an ATU. Broadcast stations typically use large air-core inductors made from tubing and vacuum capacitors for best stability and low loss. A properly designed and built ATU is a thing of beauty. Broadcast stations may use a device called an Operating Impedance Bridge in-line to measure impedance during normal operation to see if it has drifted too far, but when the antenna system is built from high quality, stable components, I found the OIB mostly unnecessary.
Thanks Dave for taking the time and creating this awesome video. I could watch another 2 hours so don’t worry about the length of the video.
You make complicated things a bit less complicated 🤓🤏👍 Thnx Dave
W0W! Thanks Dave for answering my question, I've been having a round or two moving snow off our roof up here...one of those years. Spring is coming fast and now I can spend more time getting my shack set up. Sooo appreciated your valued if not overwhelming answers, I will need time to fully digest it all. The "No" rather answered the Q, but the remaining lecture drove it home. Reminds of my USN ET school of many many years ago. Regards, Dave (also)
Excellent explanation of a very complex subject!! I love the introduction of music to explain resonance!
Overly lengthy yes. But in covering everything and not subtracting from the topic I took away 2 invaluable nuggets of information this time Dave Thankyou.
I see the variable inductor and variable capacitor in the MFJ-986. It makes perfect sense how it can make the whole transmission circuit resonant and balanced.
Well Dave, at 32 minutes in, you gave me the answer. I struggled to follow the first half hour. You did prove, beyond a reasonable doubt, that my degree is not in EE. Michael Edmonds is right. You're a great asset!
Fantastic explanation. Thanks !!! As a beginner ham I need to understand what is really happening in those RF circuits. Long time electronics design engineer, but never did RF. Basic rules of PCB design were most of the time sufficient like gnd plane, C-decouple, some filtering of I/O. But radio is a different animal all together 🙂 And you have mentioned the great Nikola Tesla. One of the people who truly understood the working principles of the nature all together. Being my fellow countryman make it even more special 🙂 Understand first build later, as he was saying... Anyway all the bast to you Dave and 73!
I got much more out of this video than what was advertised. Thanks Dave.
An antenna coupler tunes out the complex portion of the feedline/antenna in order to present the transmitter with a real 50 ohm impedance, it does this by selecting the capacitor and inductor values necessary to subtract the complex reactances out leaving only the real component.
Pretty sure I need to watch this one more time, with no distractions.
David, you're the best! Thanks for efforts!!!
Best description of tuning I have heard - great job 👏 thank you
hi Dave. great video! On these days I replace my EFLW antenna with a Doublet with balanced feeder line .... now I easily operate 80..20m just use a MFJ qrp tuner ....
Just a proof of concept of you video
73 paolo
Howdy. I totally enjoyed Your assertiveness.
For what it's worth, I am with You.
What You say, I think, backs me up when I argue that a tuner + transmission line + non-resonant antenna + environment will radiate almost as much as a perfect resonant antenna.
I recognize that the standing wave current nodes in the line will cause ohmic losses. Also, I recognize that the radiation pattern may anything but a clean doughnut. The pattern may have lobes sprouting at any direction.
I have had discussions when it is argued that the tuner does not change the physical properties of the antenna. Yes. The implication being that the reflected power is all burnt up in the tuner and the transmission line.
Regards.
This is a terrific video, Dave. It has filled in several gaps for me as a medium-new ham. Thank you!
Hi Dave,
Respectfully, the antenna tuner and an antenna do not match the impedance of free space. There are two (or more) correct ways to look at a tuner, depending on if you want to look at it with wave theory or just as a matching system, but the ultimate result to users is the tuner corrects the antenna system impedance at the insertion point and brings the entire system into "resonance".
We also have to be careful with reflected power and standing waves. The impedance mismatch between a load (like an antenna in this video) simply sets up a standing wave. The standing wave STANDS with the result voltage and current distributed along the conductors in a transmission line vary. That voltage and current change is what causes increased (or decreased) transmission line loss.
Reflected power does not keep bouncing back and forth until it is dissipated. Reflected power does not make it back to the PA where it dissipates as heat. This is easily demonstrated with a few simple experiments.
None of the common antenna tuners we use, or that are inside radios, are symmetrical in SWR performance. They generally don't do well at all with 3:1 mismatches that are lower impedances and capacitive, but they can actually work better and more efficiently into
high impedance loads. Typical tuners often exceed ratings in the high impedance direction. We need to be very careful specifying some exact matching range based only on an SWR range a manufacturer used.
It might be best to avoid certain details rather than say something misleading. Sometimes it is better to just answer a question as simply as possible and not start adding things that wind up being incorrect or misleading.
You are a genius, Dave. Thanks for simplifying things.
I am SO deficient in general "Antenna Theory" it's sad. I just don't get the "Magic" that make antenna's work. You have helped in such way that, I kind of, maybe, that I sort of, could possibly, maybe, understand this all one day...
Thanks for the explanation. Finally discovered your channel and I hope you are still actively broadcasting. By the way, noticed your Air Pilot in the background. Yeah, I too love lanterns only I absolutely can't stand the smell of kerosene. Another thing I love is my balanced fed, all band, tuned doublet antenna.
Thanks, David - great information here!
Thank you, thank you, thank you! I am a need to understand what is actually happening kind of guy, and you explained what is really suppose to be happening when a tuner is used. I have about a 1,000 feet of hardline coax (new end pieces) picked up around my neighborhood when our 3 cable companies rebuilt and repaired their build after Michael's 165MPH winds came through. My old FT101 serial number 458 (fresh from Japan) would have tuned to a 75 ohm feedline no issue but not so with the newer rigs. I have an still in the box new 7300 so if or not the tuner will mate with 75 ohm is unknown. I did aquire a few 75 to 50 transformers to also try. Anyway, the until now MYSTERY of tuning my meagure mind has been pondering all these 50 years has been revealed, even if a multiple of viewing this episode is still needed!!! Again THANK YOU !!!
The 7300 will tune 12.5 ohms to about 150 ohms resistive (3:1 SWR). For anything more complicated, you'll need an external tuner.
@@davecasler I have several external tuners but would prefer just the internal or the internal along with a device seldom mentioned these days, it is made by MFJ and called a tuner extender. Just adjust it to the most noise on your receiver and retry the internal tuner and generally it will then tune, if not repeat the process with the next setting either side of the most noise. Thanks Dave, really appreciate yoir work.
Great video as usual! I’ll say that orchestras are moving slowly to 442. In Europe they have been there a while, and some major orchestras in the US are moving, but slow. 432 and lower tunings are still used by period ensembles, like Baroque and earlier. Yes, you can still buy tuning forks. Still used by some timpanists, after hitting the fork you can hold it against your head, near the temple and it’s amplified in your head and you can flick the timpani head using other hand and re tune heads in the middle of a passage. 73 de KJ4KPW
Another factor is that people are taller (and wider) than they were 200 years ago, and so our poor taller sopranos have a harder time hitting 440, let alone 442. It does seem to be a bit of a bone of contention amongst the cognoscenti (of which I do not claim to be a part). Most people have absolutely no clue what any of this means! Our church organ and my own personal organ can be tuned up and down, mostly to match any instruments it may be accompanying.
I call this "pitch wars". At some times, there seems to be a competition between orchestras to see who can tune to a higher pitch. No longer do they tune to 440, but 442, 445, or in extreme cases, even higher, in an attempt to make their music sound more exciting. Back in the day radio did a similar thing by running their turntables faster than 45 RPM. Not only would they have extra seconds for more commercials, but their slower competitor sounded like they were dragging; their music sounded tired and lifeless.
@@timothystockman7533 fascinating 👌
Square waves are equivalent to a sine wave at the same (fundamental) frequency added to an infinite series of odd-multiple sine-wave harmonics at decreasing amplitudes.
Yes. Don't forget that the phases have to be right too.
James, I never thought of it that way. Neat.
Thanks for the excellent video Dave. It's good to know the theory behind my antenna tuner.
Probably one of your best! Thanks!
Great summary! I’m a physics guy, and I just learned a lot!!
Tricky concepts for newbies and veterans alike, you did a pretty good job. A smith chart might make the concepts you are trying to convey a bit more clear, but like I said you did awesome.
Indeed a Smith Chart would help. Sadly, they confuse the daylights out of me. I never encountered them in my schooling, and they're pretty rare in ham radio.
@@davecasler I also did not encounter Smith Charts in my undergrad EE course work, they really are not necessary with today's tools, however, they are a fantastic visualization tool when teaching this type of material to newbies (and veterans). I would recommend a RF design book titled, "RF Circuit Design 2nd Edition by Christopher Bowick" it is one of the best books on RF design for the non engineer that I have come across and I think that I have them all :o) There is also a youtube channel named "w2aew" where the host Allen has 4 or 5 excellent videos on smith charts. With these two sources you won't be an expert but you will be well on your way to being one. Again thanks for what you do and keep up the excellent work.
@@davecasler I also did not encounter Smith Charts in my undergrad EE course work, they really are not necessary with today's tools, however, they are a fantastic visualization tool when teaching this type of material to newbies (and veterans). I would recommend a RF design book titled, "RF Circuit Design 2nd Edition by Christopher Bowick" it is one of the best books on RF design for the non engineer that I have come across and I think that I have them all :o) There is also a youtube channel named "w2aew" where the host Allen has 4 or 5 excellent videos on smith charts. With these two sources you won't be an expert but you will be well on your way to being one. Again thanks for what you do and keep up the excellent work.
Hi, Dave. I play frailing and melodic claw-hammer Appalachian banjo and have several tuning forks and they're still available quite commonly at music stores that sell acoustic instruments. Also, just for the fun of it I checked on Amazon just this moment and found dozens and dozens of different types of tuning forks for music as well as for other uses. Don't know why you'd think they're not available anymore lol.
Unless tuning at the feedpoint i will stick with a manual tuner. The reason for this is that sometimes the Q on the tuning is very fine and with a manual tuner you can hunt out that very specific zone of capacitance and inductance to better receive weak stations. Now ask yourself just how many combinations of inductance and capacitance is available with an automatic atu? For sure most automatic ATU's cover most of the HF bands but when you need that more tricky tune to be so finely adjusted so as to bring in that weak station there is no guarantee that the automatic ATU can get as close as you can with a dial, it will get close but no guarantee it's exactly where you want it to be.
If you have tuned in weak stations on various antenna designs with a manual tuner you will know what i am talking about and if you know a bit about electronics and capacitors in parallel and series you will know that you can arrive at many combinations but you can't cover all of the gaps everywhere without a variable capacitor or two and ideally a variable inductor.
Bravo Sir!
Instruction AND drama... "Are you ready for this?.... Are you READY for this?" Loved it!
73 Chris M6VCJ
Hey Dave, thanks for all your great videos. I have to say that I am not a fan of using antenna tuners other than to take out the last little bit of mismatch. As it is better to have an antenna that is as close to resonance as possible. Otherwise, all the tuner is doing is to hide the problems of a non-resonant/lossy and therefore an inefficient antenna. All that is being done is to make a bad antenna a nice dummy load to present to the transmitter :) I was kinda hoping that you may have commented on that aspect. Regards, Dave, VK2TDN
Ohm-my God! I need a few engineering classes.
Dave I love your channel, As to your comment about tuning forks, you can still get them from any reputable musical instrument store or science supply store.
Thank Dave for this in depth explanation 👍🏻
Bravo Dave! I keep having to remind myself your name is Dave not Elmer.
Nikola Tesla's colorado springs antenna was 30" turned wood sphere covered with tin. Polished to a mirror finish. Covered in schalack. Finally, covered in black rubber paint. For the longest time I couldn't figure out why the medal needed to be polished to a mirror finish and then completely covered with rubber paint.
Excellent explanation. I just subscribed after listening to this video.
Great explanation Dave. Thanks
Dave there is a lot of talk about the radiating power lost when using a tuner, have you ever used a wattmeter at the transmitter and another at the antenna to see the actual wattages? And compare that to a 50 ohm antenna and the same 50 ohm feed line.
back in the day. I know you lived threw it. I puchased a army big stick for ten. used it on eleven and ten. that was the days when ten and eleven was in full swing.
A tuner tunes it's output to the conjugate of the impedance of the load on the output of the tuner. This implies that the tuner tunes the load by cancelling any reactance in the load.
haha, Dang Mr.Casler, it's not too long, I'm hopping for a part two, how to measure all these new words. How do I know I need a balun unun, what the heck is reactance....Thank you so much for this lesson. I've been searching for this kind of info for awhile.
K8CDM, Dave
There is at least one video of Julius Sumner Miller on TH-cam explaining resonance that are really good!
BTW Dave, you can get a tuning fork at a medical supply company. They are cheap if you want a 128,512 or 1024
What is tuning? It is adjusting the resonant frequency. An antenna's resonant frequency may be adjusted by changing its length ala Stepir or it may be adjusted electrically by loading inductance or capacitance. An antenna tuner loads the antenna with inductance or capacitance to adjust its resonant frequency.
@Tom Smith Antennas do not possess some special form of resonance which only responds to changes in length. They work just like any resonant circuit. If you add inductance or capacitance, which a tuner can do, it will shift the resonant frequency, just as it would if you added to a tank circuit. This misunderstanding is why I advocate for a question on the FCC exam which would help prospective hams to learn the correct concept of antenna resonance. I think some of the confusion comes from the fact that an antenna tuner serves a dual purpose: tuning (changing resonance by adding inductance or capacitance) and/or matching (transforming impedance). Some grab onto the matching function and forget about the tuning function. --de N3TS
@Tom Smith I said nothing about bandwidth.
I think there's more to say that's typically not said: could you talk about the effect of a capacitor or an inductor in changing the relationship between the current and voltage, and how that relates to resonance?
Great video Dave. You mentioned it very briefly in the video, but I was wondering what causes all the noise when a tuner is tuning? I tuned up a random wire antenna today and my tuner clicked and clacked like crazy. Are the variable capacitors and coils that loud when they are adjusted or is something else going on?
Personally, I attributed it to tiny people pushing around switches like crazy... but I'm 98% certain there aren't actually tiny people pushing things around in there.
What you’re hearing during this process are a whole bunch of tiny electromagnetic relays that switch on or off the flow of electricity into the various capacitors and inductors that make up the tuning circuitry. Relays actually involve shoving or pulling a little contact back and forth to either engage or disengage a circuit. That’s the clicking that you’re hearing.
I view it as: You are tuning the 'TUNER'. Nothing else is modified on either side of it. The tuner is an adapter of sorts between transmit system side and the antenna system side. It is like an adapter plate to mate different gear-boxes to an engine.
If you think about it in mechanical terms, an auto transmission matches the engine impedance to the road impedance.
Hey Dave, thankyou Sir, unfortunately this level is a bit above My station at this moment in time!, however, just listening to Your voice was making Me feel drowsy, I've loved it, I'm sure something may well have sunk into My pickle jar of a brain somewhere!, Greetings from England btw👍
I blame the use of the phrase Antenna Tuning Unit (ATU) to the confusion of many amateurs. It could be more accurately termed an Antenna Matching Unit (AMU) but strictly speaking it is an impedance matching unit. The take away message here is in shack or built in matching units keep the radio happy by presenting it with a close 50 ohm match but does nothing for SWR and power loss in the feedline but the local control is convenient. The location any required matching network is best done at the antenna to minimise feedline losses but at HF frequencies the remote control or automation is expensive.
Rob, I completely agree. Antenna Matching Unit or Antenna Trans-Match is a clearer and more understandable term to explain what this device is doing. Tuner is misleading as it implies that you are actually changing the frequency of resonance of the antenna, which you are not. Simply you are impedance matching the 50 ohm signal from your transmitter which is presenting a frequency that your antenna is not resonant on and the antenna is presenting a potentially quite different impedance at the applied frequency. If your dipole was cut to resonance on 7040 CW and you QSY up to the high end of the phone band, say 7285 LSB, the antenna is still resonant at 7040 and presents a quite different impedance when 7285 is applied to it.
I've attempted to convey this understanding to several newly minted hams when they are confused by the term Tuner. It would be nice if the manufacturers would change the label on that button to "Trans-Match".
73 Chris W6NOB
When you use an antenna tuner, you are changing the frequency of resonance of the combination of the tuner, the feedline, the antenna, and the environment. The whole thing works as a system.
@@davecasler Hi Dave. While I agree with your statement on matching the whole system, my point is you are by no means tuning the antenna as the casual interpretation of the name might imply, Simply put an "ATU" best matches any reactance present. If you were to ask an engineer and a layman , "Which is more elastic a steel ball bearing or a rubber ball?" you would get two different answers. The engineer would frame his answer in STRICTLY in terms of the Poisson ratio where as the layman would give the commonplace (mis)interpretation. I think a similar misinterpretation is being made by many amateurs because they tune up using VSWR with no regard to antenna feedpoint reactance and the "ATU" is simply acting to match the reactance at it's output to it's input it can not tune the physical length of the antenna. Hence the best VSWR typically get into a dipole is about 1:1.5 or 73/50 ohms. Call me biased and pedantic but I favour resonant antennas over random lengths and if you really must do impedance transformation it is best done at the antenna feedpoint not at the radio. This ethos can often be seen in monoband VHF and higher antennas where the impedance imbalance is often corrected by a network at the antenna feedpoint, not something that is easy on a multi band HF antenna. There in lays a subject I suggest for an Ask Save episode. The pros and cons of a matching unit or impedance transformer and it's physical location in a system.
@Rob B VK6ES And here I thought they put that matching network at the antenna end mainly because the system isn't dependent on the transmission line at that point, so they can make a predictable correction.
Edit
I also can't understand how, when you take the entire system and add capacitance or inductance, you can't be changing the characteristics of the entire system as a whole, including resonance.
@@patrickbuick5459 Your first assertion is accurate but of course there are practical limitations to the impedance transformation so logic would dictate a target match from say 10 to 1000 to 50 ohms resistive as a practical solution..
As for the the effects of L and C remember AC resonance occurs when voltage and current are in phase, that is Voltage is max at the same time Current is max. If an antenna presents something other than a pure resistance then the V and I are out of phase . Adding external L and C can oppose the phase error and bring V and I back into phase while at the same time transform the impedance from one side of a network to the other to make a good 50 ohm resistive match at the input in this case.
In my excitement and trying to make sure I wrote what I wanted to express, and my memory I frequently forget to add my call sign. But not this time. 73 de AG7MW
Wow, best explanation ever!
Good day; May I ask for the advice? I have a VHS radio on the boat, there is 50 Ohm output for the antenna . It works within the range 156 MHz - 162,05 MHz, with broadcasting power 1W or 25W.. Unfortunately the antenna on the top of the mast is connected with the 75 Ohm coaxial cable. There is need to replace it with 50 Ohm cable. I have two questions: 1, whether working on this unmatched cable can destroy the radio? 2. Is it possible to use any balun or other way to achieve matchig, down without laying down the mast? I shall be grateful for the help. Mark
thanks for the information on how auto tuners work. I have auto mfj on my 590
Hi, Dave. I've learned a lot from your videos and articles in QST. My question concerns the usefulness of a certain type of HF antenna and tuner combination for Field Day use. I've set up an EMCOMM communications trailer and am currently running a 600 Ohm ladder line fed, inverted V doublet, 80-10 meters, fed from a manual tuner into a 4:1 current balun. It's a great antenna for EMCOMM because of its efficiency and the fact that I'm parked on only one or two HF frequencies. For Field Day I tend to "hunt and pounce" across a wide range of HF frequencies. I probably wouldn't be too popular during Field Day if I was constantly tuning up with the manual tuner every time I changed frequencies, so I'm wondering how well an external automatic tuner might work with this antenna set-up. I like the doublet HF antenna design because I can work all 80-10 meter HF bands with one antenna. I'm just wondering how well it might be suited for use as a Field Day antenna. 73 and thank you. K7SFA
Excellent explanation! Thanks. 73
Your video is didactic and motivational. Congratulations
I've got one. I live in an apartment. Can I use (no other option) the electrical ground for ground? If they did it right, isn't it the same?
basically you are adjusting capacitance of your antenna to correspond to each frequency.
A square wave is a sine wave and its ODD order harmonics. Multi stage tuning has nothing to do with hetrodyne or super hetrodyne. Hetrodyne has to do with mixing two or more frequencies to get a different frequencies. Thus they mixed a frequency with another to get a lower frequency so that it would be easier to amplify the lower frequency because then the higher frequency was more difficult to amplify.
Well, you're right about the square wave. Regarding superhets, the point is to get to a fairly low-frequency intermediate frequency (historically 455 kHz) for reasons of selectivity. The IF filter usually is the determining filter for the receiver's selectivity.
so that is why inverters with square waver power inverter need to be pure sign wave to work good on sensitive radio equipment ?
I have no call sigh. I am looking for the mechanical method of electron deceleration to the creation of a photon. Your channel has been very helpful. And radio waves are heat. The formula, "Wien's Law" => .0029/wavelength = temperature in Kelvin. So 40 meter = .0000725 Kelvin and that adds heat to nothing so it just passes through unless it is collected within properly aligned resonance such as an antenna. Thanks for the explanations from the practical end.
Heat and electromagnetic waves are both forms of energy, but there's no "heat field." But photons, as you go up in frequency, do carry more energy than those at lower frequencies. I'm not a thermal engineer (I'm an EE), and frankly heat has always mystified my.
@@davecasler Heat should not mystify you. We are surrounded by atoms radiating radio waves at a frequency that make up what ever radiant temperature that surrounds us, but like rain on a lake they aren't in a wave distribution that gives energy to free electrons in continuous motions when they hit an antenna of set length. As for "heat field", I think I will stick with "heat wave." Tomaato, Tomooto.
Excellent video! Thanks!
love you dave.
You mentioned tuning forks. I just watched one of your videos on J poles. Is there a commonality between the two? From what I know of both (not much) I see a lot of commonality.
I have an Yaesu FT-991A. Dave, in your honest opinion, should I use an antenna tuner? I was considering a MFJ-929, as that's the most I can afford. Thanks and Best Regards. 73
I will go there tomorrow
so the five 90 would not have the problem that you talked about on early ken woods?
Thank you for the theory and answer to the guys question. You have also helped me understand more about the theory used in the question pools for advancement as I want to know what the answers are about...not to just memorize the answers to past the test! 73 N6ZKI
The so called antenna tuners within radios or close to radios are not literally antenna tuners, but they are matching networks. In the usual case of a badly adapted antenna with a non-50-Ohm impedance the matching network has to maximize the power transference from radio to the antenna at the used frequency, which then falls into the category of conjugate matching, where the impedance of the antenna is "mirrored" in such a way that the impedance is the same, but the reactance is negative. According to the following paper from 1965 "K. Kurokawa, “Power waves and the scattering matrix,” IEEE Trans. Microwave Theory Tech., 13, #2, pp. 194-202, April 1965." the power wave reflection is reduced to 0 in case of conjugate matching, but that does not mean that all the power is transferred, and it also does not mean that the travelling voltage wave reflection wave is 0 too, because the reflection coefficients for power and travelling waves are calculated differently. Nevertheless, in that conjugate matching case the incident and reflected travelling voltage waves are reflected between the antenna and the matching network, and that is the reason why they do not get to the radio, and their energy gets dissipated mostly in the transmission line and the matching network, i.e. although power transference is maximized the remaining reduced reflected power is lost. More details on matching networks can be found in chapter 13 of the "Electromagnetic Waves and Antennas" book from Sophocles J. Orfanidis that is freely available online. There are losses in conjugate matching, and therefore we should strive to reduce the losses by adapting the antenna side with impedance transformers or similar things getting closer to the reflectionless matching case or use antennas that have hopefully out-of-the-box 50 Ohm impedance. Thanks and 73 from Tihomir CA3TSK
IS THIS THE SAME WAY WITH CONVERTER ? i WOULD LOVE TO HAVE A PURE SINE WAVE INVERTER
what's with the electric typewriter back there? Haven't seen that in 30.
The nice thing about a tuning fork is it doesn't need batteries. Should I turn my power down before adjusting the tuner extender on my radio - I'd hate to smoke a new IC-7300?
The 7300 will protect itself. Use either the external tuner or the internal tuner but never both.
I have a butter nut laying in my hall. the misses is about to kill me because it is there, but I guess you have to tune each one of the forty 75 any thing between ten and eighty. the one I have has nine bands on it I guess, but each one has to be tuned. the reason it is still laying there, because of where I came from. if you tinned the antenna on the ground and the erected it the swr would be different one the ground as to being erected. so my worry is going to be like in the old days of the eleven meter band. different on the ground as to when you put it up. My question is if ground mounted a few feet of the ground will the matching still be good we just tuned it to one. point five or below. .
Love it Dave!! Love ya man!! W5OAG
E. H. Armstrong. Edwin Howard Armstrong. Enjoyed the Video. Thanks & 73 de N8YB
Doesn't the function of impedance matching not come into play, vs 'tuning'?
3:30 Yes Bridges, They should not be at 2 Cycles per second, or 1 is dangerous too, amazing how people walking in time can bring down a Bridge
I would like to understand the differences between L-Network, PI-Network, and T-Network tuners. I once heard a vendor suggest an L-Network-based tuner has less circulating current than the other types suggesting more power is delivered to the feedline/antenna system?
Sounds like marketing hype. An L-network takes fewer expensive reactive parts, but you need to be able to switch the L in the other direction if called for.
Superb! Thank you!
Video starts at 31:50 you can thank me later! (that was a little joke...please don’t take offence)
Swoosh.. that went over my head 😀
Thx . Really interesting!
so again Dave you have me thinking. is this sorta like a pure sine wave and then you have a modified sign wave in inverters. is this sorta the same on the radios?
Excellent explanation! Thank you very much for this video. 73 DL2SST
I'm listing to you in one ear. I got part of it . square wave is something that is in cheap inverters and pure sign wave is what you need to run your sensitive radios and tv's that picture looks like a m f j manual tuner that I have. I have auto tuners on my radios. I know that I'm not talking about. what you are talking about but on antenna's if you have a die pole and it is not an inverted v what one that is stretched out straight. I live on the side of a hill and I stretch out my antennas. so I would like to know the difference
this has me thinking and that means trouble.. so where should the tuner be? before the amp or behind the amp. I''m thinking about all this. it is all mind boling?
Since now the matching of importance is between the amplifier and transmission system, after the amp.
My Head hurt, thanks.
Are you aware of anyone doing and posting results of a test where they measured parameters like X,R,Z, and theta at the shack and antenna ends plus field strength before and after tuning with the tuner at the shack, then at the antenna?
Is it even possible?
If possible, what equipment would be required?
I truly want to put my mind at rest regarding all of this and there is nothing like empirical evidence to do so lol.
Thanks.