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Yeah, he made it so understandable! I was struggling for months until I seen this video. Now I feel confident enough to join the local Ham club to get more advice!! So nice to be able to understand SWL now. WRYM788 73!
Before getting my ham license, I was a SWL'er for 60 years... in the last twelve of those I was using a Nye-Viking antenna tuner with great results on my SWL long wires. I found it very important to have the long wire as far AWAY from the QTH, gutters, roofs and any electrical noise makers to reduce the noise floor. I also used a fairly little know device, no longer made, by Palomar called the Palomar RX-100 Noise Bridge. The RX-100 and the tuner make for a great combo to "find" the "spot". Now days, I use the Palstar AT2K and with my Yaesu FTdx101MP I can suck just about any faint stray magnetic wave off the long wire and DNR and Contour it to a listenable bit of information. Thanks for this video... If I only had room for a RHOMBIC antenna farm...... now that would be something... 73 and happy holidays amigo.. Art W1SWL
Around 40 years ago, after college, I used chicken wire from our 1st floor flat up to the terrace above 3rd floor, then clear across it at 1 ft above head height. Say 150 feet total, L shape. In Calcutta, India. Then via a homebrewed L tuner to our old SW valve AM radio. I would tune for least noise, easily done. Pulled in Radio Brazil, Radio Switzerland, Radio Finland etc. My best was AFRTS (armed forces radio and tv network) somewhere near the Artic circle. The simple antenna tuner made a HUGE difference, no question
One thing to consider. Detuning the system with a manual tuner can do wonders to reduce noise. This is why many hams use separate receive antennas. This gives them options. Automatic antenna tuners need a transmitted signal to work. Thus, using manual tuners for receive is the option. One can be built easily because it's not being used to transmit. Turning knobs to peak noise is quick and easy. Turning knobs to reduce noise is the same. A longwire and a manual tuner is a win for shortwave listening.
Quite right.. that is the process I use.. my location is subject to TREMENDOUS rfi.. I have something fairly nearby that covers the spectrum from 100kc to over 50 mc.. Preamp and attenuators are too coarse, but tuning the tuner for a sig/noise sweet spot has proven to be my best tool.. an outboard RF gain sorta..
Thank you for confirming my suspicions. I will soon be moving where in I will be using a vertical antenna. Knowing that verticals are especially bad about receiving noise, I am researching the possibility of adding an active receiving loop. What is the best active receiving loop on the market? Thank you! BretC/AC0AE
Thanks a very interesting topic. The issue really is signal to noise ratio (SNR). Making the antenna resonate, either in its own right or with help of a tuner improves sensitivity to the wanted signal and hence SNR. My particular AR interest is in high SNR reception In looking at long wire, dipoles and wire antennas generally, they tend to have a large spatial extent and therefore capture a good deal of noise (unwanted, particularly local) as well as the wanted signals. Receive only antennas like active mag loops and Miniwhips with their small spatial dimensions tend to capture less noise (unwanted) and can provide significant improvements in signal to noise ratio, particularly in lower HF bands below 20m. In part this is because such antennas can be positioned in a way to minimise local noise pickup. The magloop for example can be placed low, where local E field noise is minimal but in coming H field component of wanted signals is still strong. This is the same principal behind an AM band ferrite loop stick antenna. In my own case, I use a multi band vertical and a long wire (110m) for transmission but can select separate receive only antennas. My low noise receiving antenna setup is based around an electrostatically shielded Pixel active magloop phased with a miniwhip spatially separated by about 10m. While sometimes having slightly less sensitivity, this setup has consistently lower noise, typically 20dB+ less than the vertical and wire antennas, making for much more pleasant listening. In many cases what are noisy signals when received on the vertical and wire, have almost FM quality when received on the low noise receiving antenna setup.
Agree with you 100%. I was a long time SWL'er before taking my M6 in 2010. An ATU tunes whatever antenna it is attached to near 50 ohm as possible. It tunes a range near to where you are listening to and detunes other stations outside the range, so as Tahoma says reducing unwanted noise. A great antenna to use SWLing is a rotatable loop in vertical and horizontal phases, so you can null out stronger stations and possibly pick out the weaker and DX signals. Magnetic loops are in a way like a rotatable loop with coupled ATU built in. Tuning a small section of the frequency desired and detuning anything outside the bandwidth. I found that a great antenna to use for SWLing was a long horizontal wire connected to a vertical CB antenna ( inner only ) with the matching coil removed. Slung North to South, this L shaped antenna having both polorizations and coupled with a manual ATU was excellent for a small plot, local and DX stations. Have a lovely Christmas and get some rest. I look forward to seeing some new videos in the New Year. Stay safe, 73's Andy M6APJ. Don't worry about the minorities so much, it will haggle your brain ! LOL
I thought this was obvious. the impedance mismatch is a barrier that acts both ways and causes part of the signal energy to reflect back to where it came from. if the source of the energy is your radio (when transmitting), then you have the normal reflection of transmitted power. if the source of the signal is the antenna (when receiving) then some of the signal power reaches the radio and the rest is reflected back to the antenna, effectively reducing the power of the signal received. great content btw Kevin and your channel is one of the best out there.
The ATU is going to match the Antenna to the input impedance of the Tuner but we can use an 9:1 or 16:1 UNUN to couple a Longwire antenna to the radio.
Yes, assuming the longwire is medium impedance (e.g. several hundred Ohms) at the frequencies of interest, it makes sense to use a 9:1 or 16:1 unun at the antenna to reduce the impedance down to nearer 50 Ohms for connection back to the shack where it can get some final adjustment using an "ATU" to make it exactly 50 Ohms resistive presented to the receiver.
Good job. The frustrating part is its name - Antenna Tuner. As you explained it does NOT change the antenna. That element picks up RF energy more efficiently at frequencies close to or at the element's resonant length. The feedline has the same SWR - doesn't change. The Antenna Tuner changes the impedance between the feedline and the radio. There is a theorem that says something like this. Maximum energy transfer occurs when the source and load impedances are the same. The tuner does that. Doesn't matter which way the energy is flowing - transmitting or receiving - the transfer will be optimum when the impedances match. Good job! Bob - W6OPO
ATU’s absolutely help with listening as well as transmitting because they act to help tune the antenna to the receiver’s input impedance and can act as a bandpass filter to reduce interference from powerful stations transmitting on harmonically related frequencies. Is it essential? No, you can hear signals just fine without an ATU but with more noise and interference in the background.
Kevin thank you so much for all that you do to promote ham radio. I find your videos to be very informative and this one in particular. All the best, Dave K7CI
Helpful video, Kevin. Thank you. I think much of the confusion about this subject results from the name “antenna tuner”. These devices are actually impedance matching devices, not antenna tuners. I.e., as you point out, they don’t change the actual antenna, only the coupling of it to the feed line. At least that’s the way I think about it. Meanwhile, enjoy you time off and Happy Holidays to you as well. - Jim (KK7CSC)
Antenna tuner is the correct term. It changes the antenna's resonant frequency with loading capacitance or inductance, thus tuning it to a new resonant frequency. Resonance is about oscillating currents, not necessarily about physical size. An 8 foot mobile whip can be made quarter-wave resonant, for instance, at 40 meters, by using a large loading inductor. An antenna tuner also matches the radiation resistance of the antenna to 50 ohms, much like a transformer would. Perhaps the antenna tuner is misunderstood because it is a dual function device. IMHO there needs to be a question in the General Pool about antenna tuners and antenna resonance. I think the only way to stomp out this misconception is to force amateurs to learn it right when they study for the test.
I had a Sony ICF-2002 that had a simple tuner in it. It did help a little in improving reception, but did not make the antenna pick up any more stations.
I’ve been thinking about this topic quite a bit since first seeing Kevin’s interesting video. At least as of today, here’s my (another) two cents on the subject. I view the antenna system as being comprised of four components: antenna, matching network located at antenna feed point, feed line and antenna tuner (Note that I’m keeping baluns/unbaluns off the table for simplicity). As to the antenna, I think its performance will be optimal if it’s resonant for the band of interest. Given a resonant antenna and an assumed feed line impedance of 50 Ohms, the job of the matching network is to transform the antenna feed point impedance to 50 Ohms. This should result in low SWR on the line. This begs the question as to the role of the antenna tuner (in the receiver). I noted one comment in which the author suggested that the antenna tuner helps to make the entire antenna system resonant. This doesn’t seem quite right to me in that I think you want only the antenna itself to be resonant. According to (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zhsXIyq64Wc.html), at least to the degree I understand it, an “antenna tuner” is used to compensate in scenarios where you are driving an antenna with frequencies off of resonance. Happy Holidays! - Jim (KK7CSC)
Your right, an antenna tuner does not make the antenna resonant, it's a transformer that let's the radio side see 50 ohms at any frequency in its range. The antenna side of that is resonant on whatever frequencies the antenna is resonant. Having the transformer (tuner) is doing nothing but transforming the impedance of the antenna on that frequency to 50 ohms, which allows more energy from the antenna to be transferred to the radio. The tuner does nothing to the impedance of the antenna on any frequency, only the physical parameters of the antenna and it's surroundings can change the resonance of the antenna.
Happy holiday Kevin hope you have a good one and thanks for all the videos you've put out this year I've watched it all it a pleasure to watching it 73s 🇬🇧
Excellent presentation. I really like the tone of your videos and the thoroughness of the information. I do shortwave listening with an Elite 750 with a 6/10/20/40 OCFD and I've been struggling with performance. This should help.
A radio receive amp is non-selective, therefore if your antenna is receiving a signal at its resonant frequency, that will engage the radio's AGC to desensitize the receive amp. When you change the resonant frequency of the antenna with an antenna tuner, the signal you want is the dominant signal, in turn stopping that other signal from desensitizing your receiver's amp. Just a dumb guess.
Thanks for your video. Very informative. Seeing as you have a wide audience re your Christmas greeting, remember it's not winter everywhere. It's summer down here in sunny Tasmania. Merry Christmas.
Just getting back into SWL, replaced my ancient Sangean with a sweet Tecsun PL-880, a really nice radio. I have 3 poles and 30 metres (98 ft) of wire suspended in my backyard but am learning there's more to it than throwing up a length of wire (which works amazingly well, but I'm learning that to get a quality signal some learning and fiddling is needed). I need to learn about impedance, and videos like this are great, thanks so much from Melbourne, Australia!
I think you arrived at the right answer for the wrong reason. Yes, an antenna tuner can help when receiving. I have an antenna with an auto-tuner near the feed point. I can QSY and then listen. Now if I transmit a few seconds of dead carrier so the auto-tuner will do its thing, the received signals will come up a few S units. So obviously the tuner is helping reception. But why? Matching the radiation resistance is only part of the picture. I think you should also have your VNA plot the reactance of the antenna. Something many people notice is that a resonant antenna usually performs better than a non-resonant, active antenna. Why is this? It is because, at resonance, the oscillating currents in the antenna reinforce to produce stronger oscillations. In a non-resonant antenna, the oscillating currents do no reinforce, so it delivers a weaker signal. Remember that resonance is an electrical principle involving oscillating current; too often when considering antenna resonance, many people think that it has only to do with physical size. Any size antenna can be made resonant with the appropriate loading inductance or capacitance. This is one function of an antenna tuner, canceling out reactance. The other function of an antenna tuner is to match the radiation resistance of the antenna to 50 ohms. To take a little side trip, although you can make a very short antenna resonant with a large loading inductor, it will still be an inefficient antenna because it has a very low radiation resistance. Another side trip. In your setup, the antenna tuner is at the shack end of the coax. So the entire feedline is mismatched. This generates reflected power which reflects back from the antenna tuner to the antenna where it will reflect back to the tuner. With a lossy feedline, such as coax, the energy in these reflected waves is eventually burned up in the coax. Using a low loss feedline like ladder line can minimize this problem. Your auto-tuner is eliminating the reactance it sees, allowing the currents in the antenna an feedline to oscillate at the frequency the auto-tuner has tuned. This would be even more pronounced if the ATU was near the feed point so the feed line was not part of the antenna oscillation. Also it is matching the resistance it sees to the receiver input. Once again, this would be more effective if the ATU was near the feed point so the transmission line could see 50+j0 at both ends. I disagree with your premise that the antenna tuner does not change the antenna. When it cancels the antenna's reactance, it adds loading to the antenna to change its resonant frequency so that the antenna oscillates a different frequency. This is no different than adding inductance or capacitance to a tank circuit to change its resonant frequency. I propose a new term for antennas: "natural resonant frequency", the frequency at which an antenna resonates with no added loading inductance or capacitance. Because when you add capacitance or inductance to cancel reactance, you are changing the actual frequency at which the antenna currents oscillate.
Great subject and video. I always wondered about this issue and had noticed signal levels would come up as my SteppIR yagi would tune. Made sense to me and now I know why.
A novice in radio, not even a license, this topic interested me months before I saw your video. I had heard that a tuner would not affect receiving but I thought it would, for the reason you cited. Thank you for your experiment. Great video.
Hey Kevin that was a great video about the short wave and antenna tuner. I do remember that gentleman of ham radio and short wave. And I remember watching what he had to say, what are you enjoyed your video about you went into a more in-depth reason why it is good or if it’s not as good. And I really did enjoy the demonstration. How do you also hope you have a good and safe holiday enjoy the time for yourself if you don’t put out any videos before Quartzsite be safe. 73 WD5ENH Steve
For the past twenty years I've used an antenna tuner for my SWL pastime. No matter how good or bad the receiver, it always made a difference, as you amply demonstrated. Now that I'm licenced, of course I use one, as I've no wish to damage my equipment. So, good all around, in my view.
I think it's for to retune the receivers preselector circuit when the antenna pulls it out of tune. For sure it helps to match the antenna, but I'm not sure if it can solve the problem completely. I have to try my Hammarlund HQ100 some day with the tuner and without it and see if there is any difference. At the moment, I have a 55m long doublet with 240ohm twin lead feedline. Cheers: OH8UBJ/Juha
Good video. I have a tuner and I have done similar experiments to prove to myself that the tuner helps with receiving as well. Anyway thanks for the video and showing your VNA and receiver for the proof for all.
I look at it this way. When you transmit and your ant is not offering a 50 ohm match to the radio the wave is reflected back down from the antenna to the radio. The opposite happens when the signal received by the antenna (it's now acting like the transmitter) sending a signal to the rig (50 ohms)that doesn't match the antenna impedance. The reflection happens at the radio sending the signal back up the transmission line. The tuner re-reflects the signal in the appropriate direction. For transmit it would send the reflected signal from the antenna back to the antenna. For receive it sends the reflected signal from the radio back to the radio.
The information presented here makes a lot of sense. I voiced a similar opinion to yours and got shouted down, so I feel vindicated that someone with your experience and knowledge makes the same points so clearly. Season's greetings to you Kevin.
I have an MFJ-901B antenna tuner which provides an SWR of 1. You have answered my question concerning reception. I don’t have hi tech ability to measure impedance so I must assume the impedance is good, based on the SWR. Your video is very revealing. Thank you!
Lots of theory but how many times do we see, even when tuning for a transmitter, first to “tune for maximum noise” on a receiver? Proof empirical that an ATU when matched gets more signal to the receiver. Thanks for demonstrating this, Kelvin.
I think what you are missing is a very important point. If the tuner allows more signal into the receiver- it also allows more noise into the receiver in an equal amount. If not then you are saying that the tuner knows the difference between noise on the RX frequency and signal. an obvious impossibility. Yes, signals were louder, but so was the noise. The waterfall display color clearly shows this. This is basic S/N theory. Dale W4OP
@@loughkb So, the signal to noise does not change, then what is the tuner helping with besides making everything louder? All of today's receivers have more than enough gain to allow for low gain antennas (i.e. mismatched antennas, Beverages, Flags etc) to overcome HF noise figures.
@@loughkb Deos the tuner allow you to receive a signal that you could not receive with just the antenna? Perhaps a weaker signal than the one in the video?
@@andrewking3087 It can, when applicable, certainly make some CW contacts much easier on the ears. More signal for the filters to process. Along those lines, digital modes would be a bit better detected by demodulating and decoding software. Less dropped characters in RTTY or PSK31. A bit less snow from less AGC action in an SSTV image. And there's the additional benefit of getting the most out of the antenna across the spectrum, rather than just at it's resonant and harmonic points.
Excellently explained ! Couldn't be better . I am from India and learning to be a ham. This here explained a basic findamental so well. Thank you ! Could you please elbaorate more on which LDG tuner model you are using and details on yhe doublet antenna
that was a great demonstration. I do a lot of short wave listing. antenna tuners some times pre selectors do help on fixed antenna. I use a MFJ analyzer to set tuner to 50 ohm. also I found a outher benefit. the tuner is aet to a frequency. everything else makes impendence go way down or up.makeing a high Q point. with strong stations or noise not in what you tuned to can over load front end of receiver. helps drop noise floor on selected frequency as well. this helps pull out weak stations. 73's
A simple pi network antenna tuner is tuned on receive simply by listening where the maximum noise is, and then finely tuned by transmitting. So yes, it definitely helps the receive
Hi Kevin, Happy Holidays. Great explanation. I agree with many of the comments that antenna "tuner" creates much confusion. They should be termed antenna matching units. Stay safe. 73 WJ3U
Hey Kevin, ⛄ Merry Christmas & a MOST JOYOUS Yule 🎄 to you & yours! Have fun playing with your new toy, hope to see it soon. My new MGK-269D PRO should be coming in today, so I KNOW how you feel about your "toy" 😁 See you in the New Year, take care o'yourself Brother and stay WARM! L8R 🎄
Great video topic to discuss! There aren't many discussions about this topic. Q: can you discuss how use of different feedline with different impedance and matching that with an antenna that has a different impedance at the feedpoint. Such as using 50 ohm coax vs 300 ohm ladderline vs 450 ohm ladderline connected to a dipole. As you mention in your video, as the frequency changes, so does the impedance at the feedpoint, but the antenna tuner is typically at the radio point and not between the antenna and feedline connection point. I'd like to hear this perspective
The theory of reciprocity says a tuned antenna that is matched for optimal transmission must perform better on receive whilst the transmission match exists, but some ATU’s drop their tuning relays on receive thereby mismatching the antenna.
I had no idea if a dipole and a tuner would work,but I made one anyway for my shot wave. It works, OK. I did get more channels than I did without it. I still want to find a better way to listen to my shot wave thow.
Sure it helps. Just think of adjusting a small loop during receive. You can hear a huge increase in signal when nearing a good match, the same match you want for transmit.
Interesting stuff. Is the antenna tuner you are using a passive device? I've e been playing with my antennas over the last little while. I mainly am interested in Mediumwave DX and have a couple of antennas , two flags, a delta loop and a youloop. As you described, the impedance varies with frequency. 200 to 1000 ohm on the one flag antenna, as measured with my NanoVNA at the two ends of MW. So getting a linear match across the whole MW band is impossible with just a fixed balun. Would some kind of adjustable LC circuit help? PS i like your postcard of Cape Town. My hometown. 73, Vince
Nicely explained video.Yes an antenna tuner helps but there is no substitute for a good antenna in the first place.For SW listening it's been my experience to avoid antennas fed with coax.Ladder cable being the far better option.The braid on coax lets in all sorts of noises and interference which is not needed.🐻🐵☺️👍
Thanks Kevin. This was an interesting video. I was an SWL for many years. The term covers a broad range. At least in the dark ages, before the Internet, most SWL's were people who listened to international broadcasters like the BBC, VoA and Radio Netherlands. For receive-only applications, there are two prime considerations: signal to noise ratio and frequency agility. A third consideration is immunity from elective fading. When listening to high power radio broadcasters the signal strength is usually high enough that the limiting factor is noise, either natural or man made. A less efficient but lower noise antenna works best. Because of automatic gain control (AGC) and the fact that most modern receivers are extremely sensitive, a little less signal at the radio's front end does little to affect reception. In most cases using a tuner increases the received noise as much as the received signal. Using a tuner in the general case only decreases frequency agility, adds complexity and frustration to tuning and an additional expense. The exception to this rule occurs where an antenna delivers relatively little signal to the radio. With very weak signals the radio's internal noise is at the level of the received signal. Examples include using a very short antenna or an untuned loop without a pre-amp. Most SWL's will get the most benefit from an antenna setup that picks up the least noise. Transmitting is a different case. You need to protect your transmitter from reflected power and you want to get the most power possible into the antenna.
The winter Solstice was big in the old pagan religions and the days around/near the solstice have been incorporated into the younger and newer religions as some form of holiday from work with the calendar rolling over 10 days post solstice.. Now, being descended from Irish and Danish ancestors my Celtic DNA prefers the old celebrations on the Solstice complete with a big feast, lots of booze, and a good orgy. So happy holidays to you also (a few months in advance)
In addition to match the impedance of the Antenna/Feedline system to the impedance of the RX input there is a second benefit. The antenna tuner is made up of a L/C circuitry and is frequency selective. Its not a broadband transformation. It selectively filters out the spectral portions near the RX frequency and suppresses the spectral part far from the RX frequency. As result you get less total Signal amplitude to the 1st stage of the RX and reduce the risk to get into non linear operating conditions. It suppresses cross and intermodulation and makes the whole system more robust to very strong signals outside the selected RX band. Greetings from former DJ0PA
Kevin….. I see ur AT Max hat. Do you do some detecting ?? I haven’t got out in a couple years but own a Teknetics Gamma 6000. A lot of fun. Frozen tundra up here in Northeast Minnesota now. Thanks for another great video and 73. W0ZRK
Would a jfet preamp, with a very high input impedance, work better with whatever length of wire you are using? For receive only. It wouldn't load down the antenna and most of the signal voltage would be seen across the 1 - 10 Mohm input impedance. I did this for a direct conversion receiver I made. The preamp was a J310 jfet in a self bias config with a 10 Mohm gate resistor. The jfet fed an emitter follower. The overall gain was about unity but the input resistance was now 10 Mohms. It made it so a 2 ft telescoping antenna worked really well. Of course the long wire still worked somewhat better but the performance was very good either way. The only other issue was the preamp was also picking up 60 hz, but an appropriate choke going from the antenna to ground removed the 60 hz and didn't affect the hf.
Howdy. Wonderful demonstration. I would, however, advocate that an out of resonance antenna tuned to resonance with a tuner will "suck in" more energy from the air than a non resonant does. Yet, I agree that matching impedances is the most significant aspect. In high regards.
The antenna itself is not changed, it remains out of resonance. The other side of the matching network presents a resonant impedance, derived from the network itself.
In some ways. The tuner will act as a pre-selector. Reducing nearby out of band RF that could swamp the rf pre-amp in the receiver. It will also improve the transfer of energy on the desired frequency range by creating an impedance match between the antenna and the receiver.
I understand that but what about the loss in signal because of the internal electronics? I have a Yaesu frt-7700 for my frg-8800; switched off, there's a slight loss in signal when in line!
