#316

TWO Part video: Part 1 shows how to use the Transform function in the NanoVNA to measure coax length or distance to fault. Part 2 (starting at about 4:40) digs a bit deeper into the effects of a transmission line on the observed impedance and SWR, how this is represented on the Smith Chart, and some of the "magic" of quarter-wavelength long lines. I refer to a video on a T/R Switch that uses PIN Diodes and a 1/4 wavelength line:
• #200: T/R Switch w/ PI...
Here are the notes and charts used during this video:
www.qsl.net/w2aew/youtube/Nano...
www.qsl.net/w2aew/youtube/Smit...
www.qsl.net/w2aew/youtube/wave...

[@joaopaulocoelho5401]

The like button on KZbin cannot convey how much I love your videos. They are brilliant!

[@James-hb8qu]

How can you not follow a guy who uses a scope probe as a pointer?

[@hectorpascal]

"You're simply the best, better than all the rest!" at de-mystifying RF things!

[@craigdupree1687]

When I was studying for my ham radio exams, and didn't understanding something, this was to place to come.

[@denelson83]

Wow... The more videos I watch about Smith charts, the more I seem to understand how they work.

[@Tobascodagama]

Most of the other nanoVNA videos I've seen don't go beyond checking antenna SWR. This series is great! Very informative.

[@anthonytai5790]

I enjoy watching you videos. You made complicated things easy to understand and remember. Unlike many who produce videos showing their faces talking 90% of the time with 10% of which conveying useful information, you make very good use of time in a pace I can follow and enjoy for as long as it takes. I just bought a NanoVNA H4. With your wonderful instructions I was able to explore the use of Smith Chart hands on, in so many ways than I could ever imagined. "When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind.” ... Lord Kelvin You understand your subjects well and you can connect the viewers to your knowledge in an unpretentious way. Thank you and please keep up the good work.

[@BradMorrisKA3YAN]

Alan, this video might be one of my new favorites that you've produced. I absolutely love how you're able to teach complex subjects by putting them into context that non-EEs can understand. Brilliant! Thank you!! 73 KA3YAN

[@glenwoofit]

I'm enjoying this series on the Nano VNA as it's teaching me how to use mine. Keep them coming please...

[@carldavis8228]

Some of this takes me back to your video #88. I used that circuit to find bad coax on the job when troubleshooting. The reason I remember that video is I use it to refresh my brain when I need to use that inexpensive TDR to find bad coax on the job. The video is in my saved for reference set of videos on youtube. That is now true for all your VNA videos also. Keep on expanding my knowledge base. Thanks

[@walterathow5988]

I really in joy your your videos I have watched most of them and always lean something I'm 66years old and just get started in ham. I plan on testing in Feb 2021 to test so I'm trying to get as much knowage as posable be for testing and getting on the air and you have help greatly. Thank You Keep up the Great videos

[@jalaltabasinejad1404]

Thank you w2aew for great videos. In the demonstration of forward (or backward) waves, the negative amplitude means reverse movement w.r.t. positive amplitude, but they are moving in the same direction.

[@Inspironator]

@w2aew Much appreciation and respect! I really like the whole series on measurements with the NanoVNA. Please keep making videos in this series to fully exploit the NanoVNA's capabilities. I recently purchased one, but getting details on it's limitations (101 sample points in the bandwidth settings) and how to use it (best settings for stop frequency vs resolution of length) was difficult for me to locate, until you started this series. This series and the extras (Smith Chart, transmission line effects on observations...) is GOLD! With your formula for setting the stop frequency for cable length, I suppose I could find the velocity factor of an unmarked cable after measuring a shorter length of a sample piece of the coax.

[@RobertResearchRadios]

You should consider using it in conjunction with a PC and nanoVNA saver; this will allow you to use practically arbitrary sweep point setups with more accurate averaging capabilities.

[@wadepatton2433]

I've only seen one other ham make instructional videos so well-made and easy to comprehend for us less-advanced hams, but sadly she went off in another direction. Thank you Alan for all the videos I've watched. I subbed after the first one I saw some years ago. 73 de w1ade

[@W1RMD]

Thanks for taking time to help answer questions. This looks like an awesome little tool. Nice to see a real "live" Smith chart. This is an excellent aid in understanding rf.

[@michaelglasman2001]

Sir, you are a treasure.

[@billygamer3941]

Your engineering mind set is showing! Calibrate then test. Test then evaluate by comparing with theory. A good lesson for us all.

[@caractacustube]

Keep up the amazing work. You have made RF accessible to me, even though I never studied electronics. You calm, clear and methodical teaching style is pure gold.

[@denp54z]

Ditto very good instructor. Wish my electronic teacher back in school was nearly as good as this fellow. Our guy was horrible.

[@BEdmonson85]

You have such a wonderful way of teaching this type of stuff. Thank you and keep 'em coming! :)

[@donbomer5630]

Another EXCELLENT presentation Alan, You've convinced me to buy one. I've always wanted a TDR. In the mid 70's I also attended Training on the 7704 O'Scope and all its plugins, to include the TDR PI. I was AMAZED at the perfection of GR connectors, the pure GARBAGE of "UHF" Connectors, plus the fact that you could observe a glitch in a half-inch coax when you squeeze it with your fingers. 😲 Fast forward about 10 years I was working in Saudi Arabia where my office had a flunky from the "Wiring Department" run cable for a 10BASE-2 network. Nothing worked! I borrowed a portable TDR and found opens at almost every computer in the network. Because...and get this...the flunky didn't know that he had to "crimp the center pins." 🤣😂🤣

[@smellthecoffee5314]

Just got my nanoVNA a week ago and was wondering what I could do with a Smith Chart. Off to measure my feeder line loss now :) Thats a great explanation of how to use the NanoVNA - Thanks w2aew.

[@Aleziss]

I remember RadioShack had mini electronic note books that were beautifully hand written for text and schematics, your writing reminds me those tiny booklets that dates back 30-35 years ago !!!

[@cwguy8960]

Yup! Forrest Mims "Engineer's Mini-Notebooks" - Fun circuits, well drawn - just like Alan's!

[@johnbrandolini2915]

The last analyzer I used was an Agilent PNA and wow, what a nice piece of equipment for over $30K. Being a ham and an experimenter I sorely missed having access to even the old "antique" HP analyzers. When I saw the nanoVNA being offered I figured I'd invest in the ~$50 for what I thought was going to be a cheap toy. I was wrong. The only complaint I have with it was the poor documentation and the touch screen; however, through your videos and others like it I'm able to realize the potential of this device. The menu screens are not intuitive and having you walk thru the set up process is a great help. Some of the screens don't match mine eg. it doesn't have marker peak search probably because I don't have the latest firmware. But, no matter I was still able to use it to measure a piece of coax. Just for giggles I took one of the cables that came with the device mainly because I didn't want to unbox a long length of RG-8U and measured it. I set the stop frequency to 500 MHz and the velocity factor to .66 and lo and behold once I converted from meters to feet the measurement was spot on. The touch screen drove me nuts in the beginning. You definitely need a stylus to access the menus. I managed to find the one I had for an old tablet and life was good! I really appreciate and enjoy all your tutorials. You really have a knack for clearly explaining what is really a complex concept. 73 de N1ABE>> Ps. Your lab is a hell of a lot neater than mine.

[@nikmilosevic1696]

Excellent tutorial and just the material I wanted to get started on as someone who is light on RF knowledge!

[@fullwaverecked]

Alan, I served in the Marines for 9 years and 6 months . (honorable) You are the best teacher I've had the pleasure of serving this great country for. I took biology 101ish from the University of Maryland. "Intertidal organisms of Okinawa". I have seen the best of the best. I just would like to thank you for providing a far superior electronics education than most, if not all, top notch institutions. Realizing that you can manage to give it the elbow and give your videos away... To be honest, it brought back memories of when I first sat down with myself and contemplated 1 micro volt is one millionth of a volt...? Let alone Microamperes! Are you kidding me? Thank you for all you do!

[@kg4lzc]

Sounds like we have the same past. I loved Oki. Did the whole UMUC thing too.

[@vaniuha1981]

I'm not a native English speaker, but your thoughts are so consistent and your speech is so easy to understand. I have nothing to say, but THANK YOU!

[@johnnicholas6962]

I am building a 60 foot length of RG-8X with a PL-259 on each end. This was very helpful. I had roughly measured 60+ feet (middle of chest to finger thumb hold = 36 inches). I was learning how to use my Nano VNA H4 to measure the length. You made it very easy to get an answer. I used the Transform with the linear format on Trace 0. The answer came up at 19.3 meters using 50 Khz Start and 230 Mhz stop frequencies. I had to use an 80% VF to get this number. Then I used a tape to measure the the length which came out as 12-5 foot lengths or 60 feet plus 40 inches. Right on 63'4" or 19.3 meters. I post as feedback on the 80% velocity factor, for the RG-8X. Mine was labeled Davis RF / Div of Orion Wire. It is new. I then measured the SWR and came up 1:1 from 140Mhz - 150Mhz and 420Mhz - 450 Mhz. I will use the to feed my 2M - 70cm J-Pole. Thank you for some great videos on the Nano VNA and the science behind what the instrument is doing. The Tiny SA just arrived and I will be looking at your videos on this. I really appreciate your notes. I punched my Tech and General last March. Very helpful to this new Ham.

[@polik971]

RF always seemed wizardry to me but Alan's way of teaching such stuff it's just incredible and effective

[@danmoretti8898]

You know, it strikes me that RF is *very* similar to audio engineering, but combined with core EM principles. In my 10 years of professional work in audio, I came away with a primary insight: the most important element in getting a good recording is the room itself. "Room acoustics" deals with things like cancellation of standing wave modes and problematic reflections. So anyway, just a tidbit for folks that are technically interested in audio; you can make the leap into RF stuff no problem because it equips you with the core intuition, very very nicely.

[@bundo13]

@@danmoretti8898 It is! Also the same as, say, engineering a car's suspension. Those pesky waves show up everywhere :) I think the main thing that's different with audio is that you very rarely have to worry about transmission lines so much because the wavelengths are huge relative to most of the parts. Audio synthesizers specifically have a lot of concepts in common with radios and are a good place to start learning the concepts because the components needed and test equipment requirements are far lower and less expensive.

[@danmoretti8898]

​@@bundo13 ​ Cheers! As you would imagine based on your example of the car suspension, there are plenty of energy buildup problems in audio! The rest of my post here is probably stuff you could have guessed, but I wanted to share anyway. As a rule in audio, transmission issues come into play anytime transduction occurs. So 1) capturing audio (particularly in stereo) and 2) playing audio through speakers. In the former case, phase coherence becomes a really important thing to have a handle on with mic placement. In the second case, we often run into problems with resonant cavities (rooms). If your room is too small, it becomes a high pass filter due to bass frequencies not being able to fully propagate through a cycle. This makes for a dishonest mixing environment, and your mix will sound weird on playback in most environments. HF buildup is a huge problem in small rooms as well. In auditoriums, propagation rates begin changing in a manner that's thermally dependent, which is why live sound sucks for the first couple of songs. The crowd brings a substantial amount of heat. Until thermal equilibrium is reached, the EQ is completely off. So anyway, longitudinal transmission through a gaseous medium is really where transmission stuff gets wacky. Between synthesis; microphone placement; mixing; and live acoustics, audio engineering is a very broad and interdisciplinary process. But again, its just the same as any other type of engineering in that sense.

[@bundo13]

@@danmoretti8898 Fascinating! Thank you for posting all this, I am certainly no expert in audio or RF but I learned at some point to post what I think I know on the internet because writing it out helps me solidify it in my own head. I should have clarified that I was thinking of the electronics. Audio frequencies propagating at very high speeds in electrical circuits have huge wavelengths, but can certainly come into play when at the speed of sound in air. So I think that reflections and other transmission line effects can mostly be ignored when designing the electrical side. Not to say the electrical side is trivial of course, just different things that are the big factors in overall quality. I have to admit the first thing I was learning about where I feel like I really started to get a handle on wave math was when I was learning about transmission line speakers, because they're just so darn cool. I found it much easier to imagine speakers and sound waves when thinking about stuff because those things are so much more familiar in our day to day lives. I often think about antennas as speakers and impedance matching circuits as horns still! I also use these as analogies when trying to explain what I think I know to other people as well. I find it much easier to imagine how a shout echoes off of a cliff wall than about how an electrical signal reflects off the end of an open transmission line. So I appreciate your examples, I've never messed with audio design at such scales. It's very interesting, and I feel like the more ways we have at looking at the same fundamental concepts, the better we can understand it. Interesting tidbit is that Bose has even worked on electromagnetic dynamic suspensions for cars. I may not always agree with the value prospect of Bose's products, but I've always respected their engineering!

[@danmoretti8898]

@@bundo13 Cheers, I feel the same way about writing or sharing these concepts aloud! Much appreciate the opportunity to nerd out, my friend.

[@KF0UFO-Andrew]

Thanks for taking the time to make this video :) Very Helpful as a quick review

[@RapperBC]

Goin' straight into my "Electronics Lectures" playlist. Thanks again!

[@Kevin_KC0SHO]

This is exactly what I was looking for. The PDF documents are very helpful.

[@rwnelson51]

Great lesson!! Also how the NanoVNA's low cost can yield good measurements versus a 20K VNA!!! Be great for EE class labs where super expensive instruments were handled by the instructor (1971 for me ) and how "hands-on" lab work is so much more instructive. The instrument automation expedites the time and attention factor for instructional learning. Many Thanks!!!

[@silasmarner7586]

They are evolving so quickly eventually SOON a NanoVNA will do what an 8753ES will do, which costs 7-8k used in ok condiiton. Once they have a reversible test head it'll allll be over.

[@nathanhaltman7235]

Silas Marner considering the price point, the nano VNA offers value for education, and hobby use. However, the performance doesn’t come close to a 8753 or a field fox: span, dynamic range, points, coupler,....

[@thunderbuilt77]

Another awesome explanation on multiple topics with vna. You're on a roll Alan. You could teach a stump about this device, [living proof].

[@Linas_LY2H]

Extremely educational and understandable , thanks! I've just ordered today the nanoVNA -F , so it's time to get back to the school desk before it arrives in a few weeks time! 73 ! Linas LY2H

[@cobrasvt347]

Thank you for supplying me with max expected distance formula. That helps out a lot.

[@AERVBlog]

Great vide4o. Ran off to Ebay and bought one of these (US seller, with case). Looks like a nice little box. Much easier than my HP TDR for sure plus it has the advantage of me not having to remember how to do a smith chart every time I use one. Thanks W8DKM

[@scienteer3562]

Try this with 75ohm cable. The rotation should be centered on the new characteristic impedance rather than the center of the chart. This trick is often used in splitter networks to transform when 50ohm is split into two 100ohm lines. Rotating round 75 for ¼wave will transform the 100 back into 50ohms. Great video. Very clear.

[@RobertResearchRadios]

you could always just normalize to a 75Ohm load during calibration to get around this, but the firmware isn't setup to tell you the correct calculated impedances from this normalization. If the NanoVNA firmware developers are reading, a feature to change the impedance normalization of the chart after calibration or before the calibration so the calculated impedances would be correct would be great.

[@user-xh9cj7in3p]

Nicely done. Thanks for your time creating this very instructional video. 73.

[@kopiteinnz]

Thank you for your very clear and concise videos and information, I have and continue to learn from them.

[@grahambambrook313]

The more I watch your videos, the more I realise how little I know!!

[@vk2byf]

Thanks for the video which helped me to get more out of my newly acquired NanoVNA h4

[@mikerosenberg7726]

Thank you for putting this video together.

[@qzorn4440]

wow I have been checking out how to make a backyard 21cm 1420 MHz radio dish telescope to point at stars and found another learning sweet curve. 😎 thank you and "Keep on Trekking"

[@marianoalonso7532]

Thank you Allan ! I appreciate so much your videos. I wish I could have this illustration when I was studying at the University. I learned this concepts with ugly math as you said!

[@kb441ate]

honestly, I understand relatively way more straight ahead, than in any of material in my native language (I`m Russian). Thanks so much for sharing!

[@RapiBurrito]

w2aew with another gem.

[@nelsnelsen6741]

Now I see where I made my mistake, thank you very much. Very very much.

[@zerolabs]

Amazing tutorial! Thank you so much for this. 73, de W1MM.

[@DaffyDuck35]

Really nice video, with a lot of interesting informations, thanks a lot !!!

[@tseckwr3783]

Tnx fer the tutorials on the NanoVNA. One day, I will pull mine out of the box and try it.

[@oldbassist60]

You make this so easy to grasp. Your presentations are incredibly organized and smooth flowing. You obviously know your stuff. How I found you is that "The IMSAI Guy" referenced your videos in one of his in regard to your making dummy loads. AD6AE

[@pirate959]

Awesome video! Big help as I learn the VNA

[@Monorijder]

Great lecture! even I understand all of it :-). Keep up the good work!

[@oldbassist60]

Good Idea to add the SMA M/F thru connectors to make the DUT attachment easier.

[@tonywalker2372]

Brilliant tutorial, as usual. Thankyou.

[@ammocraft]

Another great NanoVNA video. 👍

[@DonDegidio]

Hi Alan, Was taking a break from practice exams for my online Extra test session Monday evening and noticed you uploaded this video. Much of the video is in questions on the test regarding impedance for 1/2 and 1/4 wave transmission lines. I now have them straight thanks to the video. Stay safe. 73 WB3BJU

[@boxingday11]

Thank you very much Alan, very informative and interesting ,👍🇬🇧

[@jebthereb2]

Great content sir. This helped tremendously.

[@fred9303]

Enjoying your NanoVNA series. How about a video using it to measure a few common mode chokes?

[@kd5ozy]

I like the PDF. I wish I had all of your nanovna videos in PDF step by step set ups

[@w2aew]

I'll try to do more of them with future videos.

[@kd5ozy]

Thank you sir! I’m an old timer and this menu driven stuff is a little different. My HP 8921a is bad enough. I’m trying to keep up. Haha.

[@sergiocavazos8963]

great video! so if I want to measure a 1/2 phasing delay coil on a vhf collineal antenna should look for phase shift using S21 and it is on the point where the chart goes from -180 to 180 ....is that correct? tks for the advice

[@jbx907]

Best video i have seen, i was trying to find a use of the nanovna to make it easier to make phasing harness for col linear stacked folded dipole, for example 2 stack variloop, 4 stack and 6 stack, i cant seem to find any video on phasing harness

[@bobkozlarekwa2sqq59]

Can you consider a video that explains how to measure coaxial chokes that we use to keep RF of the outer shield of antenna feed line?

[@anullhandle]

Great video as always. Clear concise and practical. Almost like you're an applications eng. for this stuff :) Could you use this technique to find a break in direct burry mains or zip cord light / sprinkler wiring?

[@edinfific2576]

I watched a few other videos on NanoVNA and parameters, and you clearly know the details of what you're talking about. How come you don't have a "Thank you! $" button under your videos?

[@bfx8185]

Excellent explanation, that animation is superior! Thank you!

[@w2aew]

A little powerpoint animation recorded into a .gif.

[@bfx8185]

@@w2aew Doesn't matter how it's done , important is content , everybody see the main principle. Really great!

[@rjollis]

Thanks for this systematic explanation of measuring coax length and distance to fault. It is very easy to follow. I have followed the process to check a 100 ft. (30.5 m) coil of RG8X. On the linear scale, sweeping from 500Khz to 125Mhz with the transform function set up in low pass, I get one single peak at 14.65m . If I flip the ends if the cable I get the same figure. Is my nano vna-h defective? I have calibrated before. starting.

[@JonathanKayne]

So if you have access to a PC, you can use a piece of software called NanoVNA-saver to do this too. If you increase the number of segments you can get around the 101 point limitation. It even will calculate the coax length and you can select the coax type or manually enter the velocity factor that way.

[@hebrewhammer1000]

Thanks for sharing. Great video.

[@aerorcuav]

Thanks you Sir..I like you video's and explanations.Very Informative.I learned aload from you sir.Can you make a video how we tune the phase harness for a 1x2 array antenna matching circuit.Thank you sir.

[@bill-2018]

Thanks for the video. I got a NANO VNA last year. Great little bit of test gear for the price. Helped to set up my dipoles and inverted vee instead of just an SWR meter, I knew if I need to shorten or lengthen them. I'm going to try measuring the length of a piece coax. How to amaze people with technology if they say you need a tape measure. I guess this is how a cable fault locator works. G4GHB

[@peterleather6866]

Thanks for really helpful series of videos on the NanoVNA. Like many radio hams, I bought one to experiment with, without knowing anything about them. The more I watch, the more I (slowly) begin to grasp how to use it and what a nanoVNA can do. Can these instruments measure how a home-made rf choke is performing or what frequency an antenna trap is working etc? It would be very useful if it did.

[@w2aew]

yes it can - maybe in a future video.

[@silasmarner7586]

A good cal, as the spiral (loss caused) is centered on the center of the Smith chart...

[@m0bah]

This is really useful at the moment, I have the NanoVna and was searching for this very subject. Thank you so much. I have a long piece of coax that has a VSWR problem and I'm sure this will solve the issue or at least let me know where the fault is along the cable. Thanks again. Andy. PS just Subscribed and Bell'd ( is that a verb?)

[@acestudioscouk-Ace-G0ACE]

Explained and a way the common man can understand, thank-you. I fear I have unwittingly ordered a cheap clone, how will I know if it's good or bad?....or will it be obvious. Bear in mind I'm learning so not much experience.

[@Nobody-ld7mk]

Hard to believe such an inexpensive piece of equipment is able to produce so much information in the right hands. Mine will be here from R&L next week. Wonder if it uses the AT Mega 328 Microcontroller? No tellin how far these will go as VNA's, or how big the screens will get.

[@quietprolink5322]

Awesome, clear concise. Thanxs for sharings.

[@adrian_sp6def]

Great content! Thanks for sharing. I have question: could You explain how super regenerative receiver works, and how and why sawtooth signal appears in that circuit? I tried to analyse simplified one transistor (OB configuration) schematic and I do not understand how sawtooth is generated and contain high frequency modulation. At the end thanks for all Your videos I learned a lot from Your channel!

[@best3140]

Can we use nanovna to mesure velocity factor of single line wire ?

[@2007Premacy]

Thank you for explaining how to measure the impedance of a coax cable. Would you measure the parallel wire (Ladder line)? I did the same thing for tha ladder line using 1.2mm wires taped together without a spacer. It seems to be more or less 45 to 50 ohms. Is it correct? Or I am doing something wrong.

[@StropSharp]

Does the unit come with PL259 adapters or SO239 receptacle connector ?

[@exus4mie]

I've recently discovered your channel and truly amazed by the quality of your videos! I started from #1 and planning to work my way up to the top :) May be in one of your future videos you can explain what complex impedance means applicable to the antennas? For example an impedance for a half wave dipole is 73 + j42.5 , but what does it mean? Are we always supposed to see reactance in the resonate antenna? Thanks and please keep up the good work. 73! Victor, PA8MM

[@w2aew]

Thank you - I hope you enjoy my series as you work through them, and please excuse the poor video quality and shaky cam on my early videos. I do talk a bit about complex impedance in later videos. Note that the definition of resonance is the lack of reactance (only resistance). Resonance does NOT always mean 50 ohms!.

[@BGLENN-dp4tx]

Brilliant. Reminds me of my great professors at GA Tech. :-)

[@HalfLife2Beta]

hey can you please tell which nanovna to take? nanovna 2 or 1 ?

[@Aleziss]

Would there be a way to find values of unknown coax ? which impedance and velocity ? Can we test in reverse without knowing the velocity factor ? I know the rigexpert can do this but how to do this with a VNA ?

[@Simon_Rafferty]

Thanks for the video - I used to know Smith Charts, but couldn't for the life of me remember how to use them! Thanks for the 15 min refresher! G7DMQ

[@paul.alarner6410]

what about measuring a single wire,ie one leg of a ladderline fed doublet to measure the leg lenghts?

[@jagank4484]

Could you make a video on ZIF( zero IF) and OZIF( offset Zero IF)?

[@gordonwedman3179]

Amazing what that little box can do. I am going to need a Nano Vna for dummies book.

[@TheLightningStalker]

How to tune choke and sleeve baluns with NanoVNA?

[@michanoymark2109]

Any ignition of the device needs to be recalibrated? Or the calibration is maintained?

[@bumohamedubualooy7111]

might be unrelated, but i'm stuck trying to know which modern op amps to buy, each time you show a strange chip from lt, bb, ad and ti I get confused with the lm 358 i have, could you please state some of those op amps to keep stock of

[@michaelayres6377]

Great instruction----Where's the PDF links????????

[@clems6989]

Great video!

[@Orcallo.]

Any chance of covering NASA Deep Space Network and how they communicate with remote spacecraft using the three big 70m antennas? I'm reading details about it but can't understand differences between RF carrier and RF subcarrier.

[@paulhastings3109]

Thanks for this video. As I see it you can have a Los SWR but not Resident. Or my thinking wrong. And it's gotta be better than my MFJ259. Been off the air for 20 plus years. 73 KQ4CD Paul

[@w2aew]

That's right, lowest SWR does not occur at resonance. Resonance *only* means that the impedance has not reactive component, only resistive.

[@adonikam1]

Excellent again!!!! THANK YOU!!!

[@Aimsport-video]

How about electrical length of bare wire in wavelength units? How to attach bare wire to namoVNA for that purpose?

[@michaelmcghie]

When measuring the distance say from the TX to the antenna feed can you measure through a lightning arrestor? Or even should you?

[@w2aew]

sure you can