Ham Radio Myth - An Antenna Tuner Only Makes The Transmitter Happy.

[@richb.4374]

Excellent presentation Mark. I've lost count of how many on air arguments over this topic I've run across on the bands. After seeing your presentation, I had to laugh because...all of them were wrong. I also enjoyed learning how the tuner actually works, which is something I didn't fully understand till now. Thanks for sharing your knowledge.

[@BustRadioMyths]

Yes what actually goes on inside of a tuner is a mysterious and marvelous thing. It can be difficult to understand and I tried to use as many reputable sources as I could. Problem is those guys are engineers and they write like engineers.

[@RX314]

A "properly tuned" transmatch accomplishes 2 things: (1) it cancels any reactance (jX) of the system connected to its output (feedline, antenna) by providing a conjugated match, and (2) it transforms the resistive impedance R of the system to the value the transmitter is designed to work with, most often 50 Ohm. This second function is not emphasized in the video.

[@BustRadioMyths]

Thanks for filling in the blanks!

[@etusuku8848]

I think the ATU or Matchbox or whatever greatly extends your possibilities to explore with different antennas. You can test all kinds of wire and loop or vertical antennas and see are them good for near or far away qso:s. You actually get the full power to the antenna so you can compare them. And many times I just feel lazy and toss a random wire to 20 feet and tune it with the atu and have fun.

[@spweber54]

Thanks, Mark, for your patience and persistence in dealing with this topic. I'm one of those Electrical Engineers that understands enough of what's going on with the antenna tuner and my OCF dipole to appreciate the inner workings, but not causing me to miss out on the enjoyment of operating with it. I find, after 50 years of hamming, that some folks get preoccupied with certain aspects of our hobby and they miss out on the actual joy of experimenting and learning. Even a poorly radiating antenna, in a compromised location, is better than not being on the air at all. Keep doing what you're doing. It will educate many new (and old) hams. In addition to myth-busting, I think the bottom line to your videos is: Don't waste precious time trying to get the perfect antenna system, just put it out there, use an antenna tuner, and get on the air! Stan - WB5UDI

[@BustRadioMyths]

Exactly Stan thanks for chiming in!

[@charleswoods2996]

So, what if, you have a "transformer" such as the Chameleon CHA MIL Hybrid rated at 500 watts PEP SSB at the bottom of a multiband antenna, that comes into an LDG AT-1000 Pro2 Autotuner? And the TXr is a Icom 7300? KD8EFQ/SUBSCRIBED/waiting eagerly for a reply/73.

[@n0vty873]

My field strength meter says it alters the antennas field when properly tuned

[@thuff3207]

Thank you and I need to find the book reflections.

[@darylcheshire1618]

I had a vague recollection that I read years ago that an antenna line is a series of inductors and capacitors. I'm just starting out in the joys of HF transmission and I'm looking forward to obtaining a second hand manual antenna tuner from a club member who has an excess of antenna tuners. I didn't want to just start with automatic tuners. With MFJ closing, manual antenna tuners are becoming scarce. He did say it's "realy fiddly". I can't imagine they would be impossible to obtain because they are relatively simple but I'm not prepared to build my own right now.

[@BustRadioMyths]

There are a lot of tuners on eBay.

[@davepuckett3197]

You remind me SO much of one of my favorite teachers in high school, Mark! I never missed one of HIS classes either. Thanks for all the great content! 73 from W5ODP 😎

[@stevegordon2869]

Here in southern Illinois a g5rv antenna at 40ft in inveted v wired pointing east and west. Best antenna i ever tryed.i do use a a99 antenna on higher bands.N9wzl.

[@theroguetomato5362]

Thanks for this. This is one reason why a non-resonant doublet works well enough for me. My antenna problem comes primarily from the fact that I can't get it higher than 20 ft. at the center.

[@BustRadioMyths]

I'll bet it still works pretty good even at 20 feet.

[@JohnStanley-m3t]

Mark, your explanation is correct, but strictly speaking applies in a lossless system where both the feedline and the tuner have zero loss. When there is a bit of loss, your analysis nearly applies, as in an open line fed with a well designed tuner. However when there is significant loss, such as a couple of dB in the coax even with no loss in the tuner, if one tunes for a match at the transmitter, the match at the antenna will be only partially matched/tuned. Certainly the match will be better than without the tuner, but not perfect. With the program TLW that comes with the antenna book, one can calculate exactly how much the match at the antenna will improve. A Smith chart that allows for loss or the formulas can also do this calculation. A 100 ohm antenna (SWR =2) into 50 ohms, with a 2 dB loss coax and a perfect tuner, will see 65 ohms or 1.56 SWR after matching. So, yea, the tuner helps tune the antenna, but not perfectly. With .85 dB coax loss, the 2:1 unmatched SWR at the antenna would drop to 1.26 SWR, (79 ohms). With .08dB (ladder line?), the SWR at the antenna would be 1.06, a very good match. However, if we allow even a few % loss in the tuner, typically the match at the antenna would not be better than about 1.2 SWR. Still a lot better than 2:1 so yes, we can match (tune) the antenna with the tuner at the rig, but never perfectly, since lossless lines and tuners don't exist. I think that to truly make your point, you need to do these calculations. Perhaps that way you can set this argument to rest for good.

[@BustRadioMyths]

This is true. No such thing as a lossless system but I believe the principle applies. It helps us to understand what's going on even if reality is a bit different.

[@JohnStanley-m3t]

@@BustRadioMyths Yes, the principle certainly applies. Indeed analyzing the lossless case helps us to understand what's going on even though it doesn't exist. The infinite loss case is also instructive. With an infinite loss coax, the tuner will have no affect on the antenna at all!. That means that folks who insist that the tuner has no affect on the antenna are only right if the coax/tuner has infinite loss! We can concede that in that case, indeed the tuner doesn't tune the antenna.

[@Pioneer936]

​@@JohnStanley-m3tso would you agree that a tuner at the base of the antenna tunes the antenna

[@timothystockman7533]

Wow, I did not realize those words were in the ARRL antenna book. This is what I've been telling people for years. This should be a question on the test so everyone has to learn it!

[@BustRadioMyths]

True!

[@geirha75]

Thanks for good information. I would appreciate some arrows showing wave directions in the sketch..

[@dandypoint]

Again very good. I will add a couple comments. Too many people think that tuning the antenna means making the SWR on the transmission line 1:1. Matching the feedline to the antenna is just that matching the antenna impedance to the feedline. It is one way to tune the antenna but not the only way. To me tuning the antenna is bringing it into resonance. (That may or may not give a 1:1 SWR on the line) That resonance can be established by adjusting the length off the antenna or providing some matching circuit at the antenna terminals that will result is a purely resistive load at the antenna terminals. The usual goal is to make that resistance 50 ohms. However, that resonant condition can also be established at the radio end with a matching device there. If done properly, a resonant condition is indeed established. That has nothing to do whatsoever with the SWR on the line. In all cases the losses should be estimated to see if they are acceptable or not. With good coax and a reasonable SWR on the line, they usually are. How far out of resonance is another matter that normally deals with the antenna pattern as you mentioned. I use my 40 meter dipole on 30 meters all the time. The coax has a matched loss of 1 dB per 100 feet at 10 MHz. The SWR is about 2.5:1 on 30 meters. The additional loss due to the 2.5:1 SWR on 100 foot of cable is 0.3 dB. If the SWR was even 3:1 the additional loss would still be less than 1/2 dB. Hardly enough to worry about!

[@BustRadioMyths]

Good observations. I'm saving another video for the myth that an antenna tuner, tunes out SWR between it and the antenna for another time.

[@BVN-TEXAS]

Talk about feed line loss in depth which the real issue. We can tune a wet noodle to be resonate but you will have massive losses and heating in the coax.

[@BustRadioMyths]

Losses are not "massive" if you have reasonable levels of SWR and good coax. 100 feet of RG-213 at 10 MHz with an SWR of 3:1 creates an additional loss caused by SWR of three tenths of a db. Is that "massive?"

[@analog_guy]

You are dealing in semantics here. This video is just a semantic argument. When you say "the transmatch tunes the antenna", you are really making a shorthand statement that the transmatch provides the ability to produce a conjugate match in the transmission line/antenna system. The transmatch has no material effect on the antenna, so in that sense the transmatch does not tune the antenna. Adjustment of the transmatch does alter the magnitude of the voltage and current at the antenna, but the ratio of voltage to current (input impedance) at the antenna terminal remains the same. The input impedance to the transmatch changes as the transmatch is adjusted, and the transmitter 'sees" the transmatch input impedance as transformed by the cable between the transmitter and transmatch. To tune just the antenna, it is necessary to make a physical change to the antenna itself or to the surroundings of the antenna. 🙂

[@BustRadioMyths]

That’s like saying the only way to change the impedance of the coax line is to either cut or lengthen it, instead of just electronically changing it with a tuner.

[@analog_guy]

@@BustRadioMyths I don't see an argument here. The signal impedance on the line changes in general with position, but the signal impedance can be changed with lumped elements as well. We will distinguish between the characteristic impedance of the line and the signal impedance at any point on the line. I think you will agree that the characteristic impedance of the line is determined by its geometry and materials. I think you will agree to the following as well: The impedance of the signal at points along the line is altered by the length of the line when the line is not terminated in its characteristic impedance. Alternatively, the impedance of the signal can be altered if we add a tuner downstream of the measurement point. The typical tuner for the high frequency (HF) bands changes the signal impedance by adding discrete inductors and/or capacitors, and may include a transformer, and will include some inevitable loss. The coax line changes the signal impedance by adding distributed inductance and capacitance, plus some inevitable loss due to resistance. Tuners for UHF and microwave frequencies sometimes do use adjustable length line sections, as well as other techniques, because it is practical to do so at those frequencies. If we happened to have an antenna that had a terminal impedance of 112 ohms resistive and zero reactive, and we wanted our transmitter to experience a 50-ohm load, we might choose to feed the antenna with a quarter electrical wavelength of 75-ohm characteristic impedance coax and thus present a 50-ohm impedance to our transmitter, rather than use a tuner and 50-ohm cable. We could have lower cost and slightly lower loss by doing so. On the other hand, if we also wanted to use the antenna on other frequencies where the impedance is substantially different, we might opt for adding a tuner. As another option, if our transmitter will tolerate the mismatch, we can dispense with the tuner and operate happily, knowing that the tuner is rarely, if ever, going to make any noticeable difference in our contacts. 🙂

[@Pioneer936]

​@@analog_guyhas the conjugate match tuned out the reactance at the antenna feedpoint ?

[@BustRadioMyths]

"And according to the theorem, when a conjugate match is accomplished at any of the junctions in the system, any reactance appearing at any junction is canceled by an equal and opposite reactance, which also includes any reactance appearing in the load." ARRL Antenna Book.

[@analog_guy]

​@@Pioneer936 The reactance and the resistance looking into the antenna feedpoint remains the same regardless of the setting of the tuner. The reactance and the resistance looking from the antenna back into the transmission line toward the tuner and transmitter will change depending of the setting of the tuner. If we say a conjugate match "tunes out" the reactance, we can mislead the listener if we are not careful about specifying a point for the measurement. A conjugate match requires that at any point in the system the resistance looking forward is equal to the resistance looking backward and the reactance looking forward is equal in magnitude and opposite in sign to the reactance looking backward at that same point. Thus, a conjugate match does not require zero reactance anywhere. Only if our system has a transmission line that is sufficiently long (at least a quarter wavelength) will we be guaranteed of having a point with zero reactance. The reactance is still there at the antenna feedpoint so it is not actually tuned out. In ham radio practice, we generally tune out the reactance at the point looking into the tuner. In general, we don't want a conjugate match. We generally do want the reactance looking back at any point to be equal in magnitude and opposite in sign as compared to the reactance looking forward from that point. Regarding the resistance, we generally want the transmitter to see a 50-ohm resistance, because the transmitter was typically designed to give best performance (rated power at good efficiency) into a 50-ohm load. We don't want a conjugate match because a conjugate match requires power equal to the output power to be dissipated in the transmitter. Instead we want rated power from our transmitter at good efficiency. We don't want maximum power at poor efficiency which would likely reduce the lifetime of the transmitter or even might cause catastrophic failure if sufficient protections are not in place.

[@davidc5027]

This isn't a myth I have every bought into. My antenna is a long wire multi-band loop and I tune it with an antenna tuner. Of course I've built resonant antennas, but for me the loop is just the easiest to maintain and use. Having said that, this type of antenna can be the most temperamental! I wouldn't recommend it to a new ham unless they have a good Elmer to help. Over the years I've done a lot of tinkering with the antenna to get it the way I want. I.E. changing feedline lengths, baluns, and tuners. For me half the fun has been in the tinkering and learning from it.

[@BustRadioMyths]

That's really what ham radio is all about to me - fiddling with antennas and solving problems. If a ham doesn't even understand how that all works he's going to have a hard time dealing with antenna problems which we all are going to have.

[@KiloWatt304]

i use an antenna tuner in receive as well you can cut noise and increase receive gain so yes it does more then just act as a dummy load LOL

[@abundantlifehomestead3100]

I think the problem with the great tuner debate is that you all are arguing over 2 different sides of the same coin. You could call these sides "common" and "proper" tuning methods. For example, I set up a 17.5' vertical wire with some radials and a 4:1 unun. On the common tuning side, I plug the feedline directly into my transceiver and tap the AT at any frequency between 10 and 40 meters, and on transmit, I get a decent SWR, and I am able to make contacts. OR: On the same side, I tie in a manual tuner between the antenna and transceiver, and follow the instructions to quickly tune for lowest SWR. On any of the same frequencies, I get similar performance to a radio's internal tuner. The common tuning method side of the coin is a compromise that quickly matches the transceiver impedance to the antenna impedance. I get an ok SWR, forward power and readable signal reports; to hell with whatever consequences the t-match has on the signal. This is where, it seems, most HAMs stand on the subject. However, on the proper tuning method side of the coin, I can see a whole different value to finding a better match. Same antenna as above; I attach a nanoVNA or other analyzer to the input of the manual tuner. With just a couple minutes of turning knobs, I find that there are many combinations of capacitance and inductance that can achieve very low SWR on any given frequency. In practice though, 1 of these combinations gains me longer distance contacts, better signal reports, and even complements on crisp audio quality. Consequently, the same combination on the tuner shows a definitive jump in forward power on the meter. This is the true purpose of finding the conjugate match: tuning for maximum power transfer to the antenna. The common tuning methods rarely produce this efficient match. To find this efficient match, I look at 4 data points on the VNA: 1- Very low VSWR. 2- Return Loss < -30dB. 3- Higher and lower frequencies are capacitive and inductive. Doesn't matter which direction they go, so long as both are not capacitive or both inductive. 4- Perceived resonance within (or very near) the given band. Any time I make physical changes to my antenna, I will spend upwards of 2 hours finding and noting this tuning combination for the upper, middle, and lower portions on each of the bands 10-40m. It is tedious work, but the returns greatly outweigh the quick and common methods of just tuning for lowest SWR. The reality is that neither side of the debate is right or wrong. If you think that your antenna tuner just provides impedence matching between your radio and antenna, then you are probably right because that's as far as you take it, and that's ok. If you think that your antenna tuner provides better system performance and efficiency, then you are probably right because that's as far as you take it, and that's ok.

[@BustRadioMyths]

Good post. Here's how antenna engineer Kurt Sterba says to adjust the tuner for maximum efficiency. There is another major source of circuit loss that the you can control. This is because there is more than one control setting that results in 1:1 SWR on the transmitter cable, but only one of these settings gives the best efficiency. Here is how to get it: Start with both of the capacitors set at maximum capacitance. Next adjust the “antenna” or “load” capacitor and the coil to get minimum SWR. If this minimum is not 1:1 then reduce the capacitance of the “transmitter” or “input” capacitor and try again. Keep doing this until you get 1:1 SWR with the “input” capacitor as large as possible. Following this procedure you may cut your losses in half!

[@K4FR_Radio]

Thank you for presenting this information and for diving into the details. 73 de N4AAJ

[@robertl.tisdale5166]

The funniest thing I've heard one of these KZbin experts say. If you have a mismatch. The power just keeps bouncing back and forth between the antenna and the tuner. If that was true, after a long talk, I'd have tens of thousands of watts bouncing back and forth in my feed line. For some reason, I think this would fry the coax.

[@BustRadioMyths]

They are not considering the reality that coax and everything else has loss and also some reflected wave is going to be radiated each time it makes a round trip. They think all reflected power is lost which is a myth.

[@coreybrown185]

No. The system stabilizes after a few cycles. Example: The transmitter puts out 100 watts and 25 watts are reflected by the antenna. The reflected power is added to the forward wave for a total power of 125 going back to the antenna. The antenna reflects a percentage of that power which again is re-reflected but is added only the the original 100 watts that the transmitter is putting out, not the 125 watts of the previously re-reflected wave.

[@BVN-TEXAS]

An antenna tuner that’s at the base of the antenna DOES make everything copacetic. BUT when you have a tuner in the shack at the end 50 ohm coax, you are going to have massive losses losses when tuning a non resonate antenna. This is why running ladder line on a doublet is so much better. You remove those losses. This is the biggest issue with tuning a non resonate circuit.

[@BustRadioMyths]

Losses are not "massive" if you have reasonable levels of SWR and good coax. 100 feet of RG-213 at 10 MHz with an SWR of 3:1 creates an additional loss caused by SWR of three tenths of a db. Is that "massive?" LDF6-50A coax cable has less loss than ladder line.

[@doc145]

No you’re not going to have massive losses. You’re assuming the loss will be on the coax to the antenna. If you use low loss coax the loss will be minimal not massive.

[@ouijim]

Thank you again. Going tell Net participants this evening that you have another video online. I hope I don't send you any arguments from nay sayers ; )

[@waynewelshans1249]

your the man!

[@BustRadioMyths]

No YOU are!

[@Atomshamradio]

I know who you are talking about it’s a friend iam not calling him out he is knowledgeable the tuner fools the radio wants to see a 50 ohm load period

[@danjor_droneitsme6874]

Its a theory

[@coreybrown185]

No, it's pretty much fact. The issue of SWR is well know in many industries, including the cable TV industry.

[@A1PILOT7]

If you are claiming that an "antenna tuner" actually places the antenna system connected to its output into a condition of resonance, or creates a matched condition on the antenna system connected to the tuner's output (load) terminal, then I challenge you to place an swr bridge or a directional watt meter in line on the antenna terminal of the "tuner" and see what it shows. I think you have grossly misinterpreted the excerpt from the book.

[@etusuku8848]

Of course it shows swr. Impedance at that particular point is not 50+j0 The whole system is at resonance though. 73, Eeli

[@BustRadioMyths]

OK here it is from the ARRL Antenna book. Let’s hear your interpretation. “And according to the theorem, when a conjugate match is accomplished at any of the junctions in the system, any reactance appearing at any junction is canceled by an equal and opposite reactance, which also includes any reactance appearing in the load. This reactance cancellation results in a net system reactance of zero, establishing resonance in the entire system. In this resonant condition the generator delivers its maximum available power to the load. This is why an antenna operated away from its natural resonant frequency is tuned to resonance by a Transmatch connected at the input to the transmission line.”

[@A1PILOT7]

@@BustRadioMyths OK, I'll try my best. Bear in mind that I am not a professional writer. I will use capital letters for emphasis only. First, the term "antenna tuner" is a misnomer. The only way to actually tune an ANTENNA (as opposed to an antenna SYSTEM), is by changing its length (physically or electrically), for resonance, as measured AT ITS FEEDPOINT. By definition, an antenna is resonant when its electrical length is the wavelength (or depending on design, half or quarter wavelength) of the frequency applied to it (providing zero reactance). What is commonly referred to as an "antenna tuner" is more approriately called a matching network. All they do is provide whatever reactance is needed to provide a match (by cancelling the reactance of the antenna system, or what is termed the conjugate match) to the transmitter ("generator") output impedance, which is typically 50 + j0 Ohms. If you place an SWR bridge or directional watt meter on the OUTPUT (LOAD, ANTENNA) side of the "tuner", it will still show the actual mismatch of the antenna system. The antenna system itself still has the original mismatch. The match is provided only at the input (transmitter) side of the matching network ("tuner"). Consider this: The tuned output (tank circuit) of an amplifier is essentially the exact same thing as what is typically called an antenna tuner. It provides a match to the amplifier's active device(s), tube or transistor, to attain maximum transfer of power to the antenna system. In the same manner as I stated earlier, if you place an SWR bridge at the output of an amplifier, it will always show the match or mismatch condition of the antenna system, even if the amplifier has been "tuned" (loaded) to the antenna system. Once more, for emphasis, read the SWR on the output (antenna) side of a "tuner", and you will see that the antenna system itself still has a mismatched condition. It hasn't been "tuned". If the radio has an internal "tuner", you can do the same thing by reading an outboard (in-line) SWR meter, and compare to the meter on the radio. The internal tuner has only provided a match to the final amplifier, and has not magically made the antenna system itself resonant, or "tuned". I'm not certain that I captured everything here as I intended, but hopefully I clarified my earlier statement.

[@BustRadioMyths]

That's not a bad explanation but you still are missing the point in the Antenna Book that "an antenna operated away from its natural resonant frequency is tuned to resonance by a Transmatch connected at the input to the transmission line.” What is it about that you do not understand or do you just not believe it?

[@Pioneer936]

​@@A1PILOT7you've agreed a tuner tunes the antenna in your description

[@Redbelly357]

Another myth is that tuners are simply for people that are too stupid or lazy to make a decent antenna. But it's just a myth.

[@k7jeb]

I resemble that remark 😀

[@BustRadioMyths]

Might be a good topic for a future video thanks.

[@Quoodle1]

Rothammel’s antenna book matches the Arrl antenna book in describing a transmatch.

[@etusuku8848]

Looking forward for many future videos :)

[@etusuku8848]

Many times I feel lazy with my rv trailer and just have a short wire to nearest tree altough I could use my dipole 🙂 Both works just fine.

[@billbrown3414]

An “antenna tuner” does exactly one thing: It transforms whatever impedance presented by the feed line in the shack into an impedance that the transmitter is designed to operate into for maximum power transfer. Perhaps the greatest misunderstanding is that the operator has the responsibility to design the antenna, feed line and the “tuner” for maximum efficiency/minimum losses. From a practical standpoint, this means using a feed line that has low loss even if operating with a high SWR (i.e., open wire). It is also desirable to select the antenna AND feed line length that presents the tuner with neither a very high impedance (which produces very high voltages at the tuner, which can cause flash-over damage) nor very low impedance (which produces very high currents, which greatly increases I^2R losses). A tuner is a very desirable station accessory, but it is no more than an inefficient bandage for an improperly built antenna.

[@BustRadioMyths]

Well stated!

[@Ragchewer]

Inefficient bandage? I think not. With a 220 foot long, non-resonant doublet, 180 feet of 300 ohm window line and an automatic tuner I can go anywhere from 1.8 to 54 megahertz with a single antenna. Just change the band on the radio and start talking! SWR on the feedline? I couldn't care less as all the power radiates. W6PDL

[@Pioneer936]

Disagree that it's an inefficient band aid

[@BustRadioMyths]

"Inefficient band aid" only for an improperly built antenna, like @billbrown3414 said. The massive doublet used by @Ragchewer is highly desirable and not improperly built at all. Examples of an improperly built antenna would include one that is too short, a vertical with no radials and so on.