When doing the port extension experiment, you could have used the SMA through at the end of the cable, and applied your SMA standards at the end of that assembly. Then, the port extension would have to only account for the additional electrical length of the SMA to N adapter, minus the SMA bullet.
Yes, yes! I thought about that and considered it. A lot of the nanoVNAs do not come with the thru adapter. So, I thought to myself, "Let's assume they don't have one and see what happens." But, you are absolutely right, the preferred way to do it would have been exactly as you described and would have been my own way to do it under normal circumstances. Thanks for the comment!
Great Video--These are right up my ally for interest! So thanks Ralph for making them. A long time ago, I was on the cusp of purchasing a MFJ analyzer when I came across a article where you could build a VNA by following this article and self-sourcing the components. In that article they did a comparison of their VNA with lab-grad ones and got great results; however when they compared them with the MFJ it was a disaster! As a result, I held off my MFJ-purchase and finally got a NanoVNA and later a SAA2N and have never looked back. I realized that you have to come up to some minimal standard to use test-instruments to declare values; otherwise you are much better-off not trying to obtain exact-values, then calculating your way to Avalon--only to also find that your layout dorked you anyway! So, if you don't have suitable-equipment, you are more well served to just work empirically for performance-results and don't sweat individual values and their contributions. Along time ago I was reading the Motorola RF manual whereby the engineer said that they calculate/simulate first, then build as well as they can; if they acheive being within 30% of that, they're happy! So, this allowed me to cope with not being able to afford expensive equipment in those years. Thanks Again and 73...
Yeah, that nanoVNA is an amazing little instrument! If you read some of the really old manuals for electricians you will find instructions on how to get a rough idea of the voltage present using their fingers (yeah, 120 and 240 volts!). Aaaah the things which we used to do. I NEVER did it with my fingers ... least ways, not on purpose! LOL :-)
@@dalesmith8666 reminds me of the old saying: “If wishes were horses, then beggars would ride!” I’ve looked at some on eBay and even if you pay beyond my price-point ability, you can still get stung. And, the lower ones many times have unfixable problems, or are so expensive to purchase subassemblies. I purchased an HP-8664 and got stung but managed to repair it to a level that yields some usability but a network analyzer just seems so daunting to try and tackle.
I appreciate you making this video. I usually watch videos and taking from them what I can but, I also try to not skip ads, thumbs up, and more scarcely subscribe just to help out. You're doing a great job. Thank you.
Excellent. Very helpful. I am about to build from scratch a receiver & all my old component testors are kaput. I tested a bunch of coils & variable capacitors & it worked great. BTW, the waffle complaint guy needs to learn how to use the video advance slider, me thinks.
Now that's one of the things on my bucket list, to build a receiver from scratch...just for fun.The other one is to build a solid state linear amplifier from scratch. Not to use myself, but for the whole learning aspect of it and then give it away to someone. Yeah, the nanoVNA is so awesome! I'm glad the video helped you get a leg up on it all. Regarding the video slider...I also provide time marker links in the description for every video I make. If someone is interested in a particular thing in the video, they can look it up and jump to that spot in the video by clicking on the link. 🙂
How would one adjust port extension for open wire feedline? It is supposed to exhibit very low losses. I just checked and velocity factor is in the 90% range so i guess i just use the same formulae and the velocity factor of the open wire. Say for example my antenna feedpoint or reference plaine is around 100ft high and potentially 170ft from the transceiver. I was looking for a vna i could hoist up to the feedpoint (after adapting with a 1:1 balun), but now i suppose i just need an accurate measurement of the feedline length. I really would like to learn more about calculating good open wire feedline lengths and if i can add open wire stubs to tune or work as filters in a balanced network. Thanks for the video. Very informative!!
Port extensions assume that the adapter or cable is the same 50 Ohm impedance that you calibrated the VNA at. Open wire feed line generally has a MUCH higher impedance. So, port extensions wouldn't wok for that. Yes, as I understand it, you can use open wire stubs to tune and filter. Unfortunately, I have very, very (VERY) little experience with open wire feedlines. 😞 I don't want to lead you down the wrong path, so I will just have to leave it at that.
Mine is awesome. I love it. 🙂 Can you believe that Tek stopped making them already?! 😞 One note ... do not shut down/restart your computer with it plugged into the USB port. You will have to uplug the whole thing and plug it back in (main power) to get it to talk to the USB properly. 😕
very nice,,I have lots to catch up using my vna,,just a tip I use the magnetic data connectors for my vna tiny ultra,phones add tablets,,saves ports being pluged in and out all the time,,also for sma and n connectors i use plug savers, avoid screwing on and off threads
Thanks! I cannot say that I am familiar with those sorts of connectors. As totally persnickety as RF measurements are (REAL VNA experts use a torque wrench to tighten there connections!), I'd be a bit leery of quick connect stuff for that application.
Hello Dennis, just saw your reply to Ralph in which you mention "for sma and n connectors i use plug savers" can you expand on what "plug savers" are, please? Thanks, Luigi VK3ola
Wow, and the MFJ device is, as I remember, roughly 5 or 6 times the cost of the typical nano VNA. I just purchased my nano vna roughly two months ago and only recently began using it. I do like the nanovna-saver software and fortunately it runs under Windows 10 with no issues. The other software VNA-QT, latest version, installed on both my laptop & desktop, but hangs up with a not responding issue on both machines when I try to connect to the vna thru the com port, so I use the saver program. All in all the nano vna is a great tool and I likely will purchase another for a bit more money than the $40 I spent so as to have a larger screen when using without aid of the computer.
The nanoVNA is an awesome tool for the price! It still cannot tune a duplexer (not enough dynamic range for that), but it does everything else pretty well. I, too, like the saver program. I had times when it wouldn't connect and I had to connect using a different program, close that one and then saver would connect. But, I haven't had that problem recently. So, either they fixed that in the release I have or it fixed itself when I changed computers (??). In a few weeks I plan on a menu walk through on the nanoVNA. It is by way of helping folks know how to get things set up to do what they need to do ... not your typical "this menu is for this" kind of thing.🙂
@@eie_for_you Exactly, a great tool. I just checked my Mag Loop antenna I recently made out of 4 inch aluminum dryer vent in the shape of a 4 foot square using a 23 inch per side square of 3/4 inch copper pipe as the inner loop that if strictly receive would be called the sense. Turned out I did well. Its actually most efficient on 20 meters, but 40 m works too. I was listening on 40 m this morning to some Spanish guys using my phone translator to understand their dialog and had left the capacitor setting at their frequency. The nano vna shows a reflected power of 1.3 at that frequency of around 7.13MHz. When I built the antenna I had read the larger the inner loop the lower the impedance. At the time I did not know how to use the nano vna so by trial and error, where it only took two attempts, using a simple analog SWR meter I came up with the inner loop's circumfrerence. Boy, do I wish my variable capacitors I use dependent on band had some kind of vernier that I could mark using the nano vna as my guide. I am a bit surprised that the notch of low reflected power having less than a 2 for SWR reading is actually fairly wide at 90 MHz. My inverted V that admittedly is a compromise by being low to the ground with its apex 12 feet off the ground and the ends nearly touching ground has only a 200 MHz interval of below either 2 or 1.5 with respect to SWR. Anyway looking forward to the upcoming video.
Thank you and your are welcome at the same time! 😁 To answer your question ... I just did an experiment calibrating each with the same standard and measuring the same inductor. The nanoVNA was within 0.5% of the Tek VNA. In other experiments previously done, it was within 1%. Quite respectable!
For the measurements in the beginning, why did you use the 2nd marker at 50MHz? Because it was in the middle of the sweep? Other tests I’ve read about. rely on finding the resonant freq (phase plot where it goes from 180 to -180) before calculating the inductance (e.g., inductor in series with a known capacitance, one end connected to DUT ground and the other end connected to DUT tip..then the inductance can be calculated with the standard formula that uses the resonant frequency)
Yeah, I've done it with resonant frequency before, but this throws one more bit of measurement uncertainty into the measurement: the actual value of the capacitor. It is better to measure the value directly and at as low a frequency as possible to avoid any interaction with possible self-resonances. As far as the whole 50MHz thing ... as I recall it was just convenient *and* well below where I figured any self-resonance might occur. Hope this helps. 🙂
Rather eye opening! But, you can get MUCH better performance out of the Rig Expert using the procedure I shared in this video: th-cam.com/video/Mp6O3xal0n8/w-d-xo.html
I expected t measure an antenna center frquency by the NanoVNA. Of course, something is calculated, however it would be good to have a bell curve to see the result. Is there any way to have a look that ?
Take a look at my video on the menu system of the nanoVNA which will help guide you through the whole thing so you can decide what you want to see and how you want to see it. th-cam.com/video/_96N3oGFatE/w-d-xo.html MORE THAN THAT ... If you connect the nanoVNA to a computer and use software such as the "nanoVNA Saver" program (nanovna.com/?page_id=90), you can export the measurement data to a file. Then you can import this file into a spreadsheet program and do all sorts of analysis and fun things with it. Yes, this is true for impedance data. Hope this helps. 🙂
If you want to increase the accuracy of your homebrew 50 ohm standard solder two 100 ohm 1% resistors in parallel which will give you 50 ohm .5% standard. You can also use four 200 ohm 1% resistors in parallel to make a 50 ohm .25% standard. BTW I'm just downstream from you in Davenport
Actually ... I have to disagree with you. A 200 Ohm, 1% resistor could be as high as 202 Ohms. Suppose, by luck of the draw, I put four 202 Ohm resistors in parallel. This will give me a 50.5 Ohm resistor. But, this is a 50 Ohm + 1% resistor. So, I have gained nothing.
I was a bit confused (at first) by that impedance display. It used the upper case Greek letter Ω (for Ohms) and I was confusing it with the radian frequency which is typically the lower case Greek letter ω, such as Z = R + 2πjωL. 😀 _73 de AF6AS_
The MFJ was the only cheap instrument to measure antenna SWR and X&R to give you an idea of your system. 10% accuracy is more than enough but at higher frequency not very good. You should know the limit of any instrument that you are using.
True that! I looked very, very carefully at everything that I could find to try to see what sort of accuracy MFJ *claimed* the 259 had ...... nothing and for good reason. 🙂
Interesting thought. I would think that it would be done in a similar fashion as tuning an antenna trap as seen in this video: th-cam.com/video/jpt51hDA5DQ/w-d-xo.html 🙂
Excellent explanation! Is there a reason to sweep from 40-60MHz across 11 segments after calibration since you are only looking at the 50MHz marker? For example why not sweep 1 segment from 49-51MHz (and set to continuous sweep) to measure the parts? I also found the S11 Serial L & C displays to be helpful.
How many segments you are using and the start and stop frequencies are all up to what you are looking for. The more segments, the finer the frequency resolution of the measurements made because it only takes a certain number of measurements in each segment. So, to get this finer resolution over a wider span, I need more segments. If I am interested in seeing how the part performs between 40-60 MHz, then my span is there. If all I am really interested in the 50 MHz, then, yeah, we could narrow the span a LOT and use fewer spans, like just 1. 🙂
@@eie_for_you Thanks for the reply. Yes I am seeing with the Series L display how different inductors behave across the larger span where 1mhz is mostly a flat line. Fun!😀
I plan to experiment with various LC impedance matching techniques for single band efhw vertical ground mounted antennas for HF Ham use. My problem is determining the load impedance of the radiator wire for each frequency that I need. Assuming 468/f MHz for say a 28.075 to cut length, and hung vertically at 10M high, soldered to center conductor of SO 239 connector with a .05 wavelength counterpoise attached to outside of the SO-239 connector at ground level, how would one use the nano vna to measure the impedance? I read that the impedance of a EFHW antenna is within a fairly broad range of 2000-5000 ohms. My problem is that I would prefer to know in advance what specific impedance I am trying to match to 50 Ohms given my known factors, such as location, environment, frequency, materials, construction, etc. Ofcourse I can just keep iteratively building, testing, by best guess but I'd prefer to save time and just measure it if I have the ability to do so with reasonable precision. Thanks for your help.
Any VNA assumes a 50 system between itself and the point where you are measuring. Port extensions only work when the connector or cable being added adhere to this 50 Ohm system. You say (if I read this right) that what you are measuring is terminated in a UHF female (SO239) connector. I am assuming the shell is ground and the center is the item in question(???). If I understand this right, then I would calibrate the nanoVNA at the end of whatever cable you need to plug *directly* into this UHF female. Remember ... ANYTHING that lay between where the VNA is calibrated and the entity to be measured WILL change the measured impedance. The higher the frequency, the more critical this becomes. With my miniVNA tiny I literally mounted the VNA on the antenna and used a very long USB cable to connect it to my computer. Because it lives in a very plastic case, its presence did not affect the antenna even at 146 MHz. I measured the impedance of a folded dipole at 146 MHz this way and created a stub match to give me a very good SWR into a 50 Ohm feedline (you could see my video: th-cam.com/video/LY4GysxSEa0/w-d-xo.html).
@@eie_for_you Thank you. I guess my question is will a nano VNA measure an impedance of an unmatched antenna anticipated to be between 2000 and 5000 ohms? I am not sure if a nano vna is capable of this high impedance range.
@@kennymanchester I do not know the answer to that question and the manual doesn't say that I could find. If you just leave the connector open, what impedance does it report? After calibrating mine at the connector, mine is popping all over the place with displayed readings even up into the tens of kohms. Nonetheless, I'm thinking it probably is outside of its capabilities for making really accurate measurements. If it were me, I'd do some bench experiments to see what its limits are.
I'm having trouble measuring inductors and capacitors with my NanoVNA. The values I get don't match my capacitance meter. I followed your video, but I'm not sure if my calibration or connections (using crocodile clips) are wrong. Also, varying the marker frequency changes L and C values a lot. Any help would be appreciated!
Hmmmm...I thought I replied, but it doesn't show... well, here I go again... First, what frequency are you trying to use? You need to use a low frequency to avoid the weirdnesses of self-resonance. The capacitance meter uses lower frequencies, maybe as low as 100 KHz. Second, did you calibrate the VNA right at the clips like I showed in the video? This includes to position of the clips (especially if you are using higher frequencies to do the measurement). Third, if I had to choose between a properly calibrated VNA and many of the stand-alone LCR meters as to accuracy, I'd choose the VNA every time. The LCR meters that most folks can afford usually are not as accurate as we'd like to believe they are. Even a high-end LCR meter well beyond its last genuine calibration is suspect. I though I said something else of value in my first attempt to reply, but it escapes me at the moment. It has been a very long, tiring day. 🙂
@@eie_for_you Thank you for your detailed response and advice. I appreciate your expertise, but I have some questions and observations: Frequency for measurements: You recommend using low frequencies, around 100 kHz for capacitors, which makes sense. However, you also mentioned 40-60 MHz for some measurements. In my experience, these higher frequencies only gave accurate results for air-core inductors. For inductors with ferrite cores, the measurements were incorrect. Wouldn't it be better to use lower frequencies (100 kHz - 2 MHz) for both capacitors and inductors? This range seems to provide more consistent and accurate results across different component types. VNA calibration: I understand the importance of calibrating the VNA at the clips, as you showed in the video. This is crucial, especially when using higher frequencies. VNA vs. LCR meters: I agree that a properly calibrated VNA is often more accurate than many standalone LCR meters, especially the more affordable ones. Your point about even high-end LCR meters being suspect if not recently calibrated is well-taken. My main question is: Why do you recommend 40-60 MHz for some measurements when lower frequencies seem to work better and more consistently for both capacitors and inductors, including those with ferrite cores? Wouldn't it be simpler and more reliable to stick to a lower frequency range (100 kHz - 2 MHz) for all these measurements?
@@hellmind Ya know ... I had to go back and watch my own video ... LOL! You are absolutely correct about using low frequency to make these measurements. The lower, the better with a lot of variables. So, why did I do this at 50 MHz? I have to admit that I wondered that same thing myself. Why on earth did I measure the values at 50 MHz? The answer is because I was going to be using the MFJ antenna analyzer to measure these same components and it has serious problems measuring them at lower frequencies (like it wouldn't do it at all!) Remember the statement from the manual about the limitations on the reactance value. While the limitations on the reactance values for accurate measurements are much wider with the nanoVNA, they still exist. So, there is a balancing act going on here. On one hand we have to avoid the self resonant frequency of the device being tested and, on the other hand, we have to be mindful of the limitations of the VNA regarding the reactance values it can accurately measure. Too large or too small and we start getting into the dirt. Hopefully this makes some sense. 🙂
Hi nice video , I do have 2 of rf scanners pro-sl8 and pro-7000fx , spec states up to 8ghz but it have mcx connector on it and poor antena . If the device can not handle more than 6ghz than I need to measure and build best antena from the lowest to 6ghz , but if it can handle more maybe if to change mcx to sma ? can I improve the frequency range ? .only what im scare to not burn it at the very beginning. Im not spec tech but I know mcx limit is 6ghz . This is not cheap toy for my pocket so I'll need instructions. I know how to use soldering iron;) .my intention is to measure the real values that's this toy can really measure also chcek antenas to confirm what is the lowest and highest frequency that it can handle , , also im thanking to maybe add lpa antenna and some pre amp and amplifier my dream would be 12ghz . Can u advise what tools shoul I get to measure all my needs and not to burn it ? And some step by step info pls?
First of all, the limitation of these bug detectors is not found in the antenna, but in the internals of the device itself. Regardless of the antenna you might put on it, it will only be capable to the frequency limits stated in its specifications. The only benefit that you might have in changing antennas might possibly be in sensitivity. For best sensitivity, the antenna should be *physically* tuned to the frequency that you are interested in detecting. A bigger, longer antenna does not yield better reception. You could get more antenna gain using a colinear antenna. Again, this is frequency band specific, like any properly tuned antenna. Here is a document that talks about their design: k5frc.org/training/coliner antenna.pdf Hope this helps.
Thanks for all your videos, you explain things very well, I have a question about what series L, series C compared to Parallel X and Parallel X when and how I would use this info, I see it on both VNA and my rig expert. If you have covered this please guide me to your video that it is covered, or if not covered maybe you could do a video. Thanks; 73 N8KEN
Now THAT'S a really good question! 😀 Think of it this way ... the VNA "sees" a particular impedance as it it "looking" out its port. The "Series L/C" is answering the question, "What series combination of a pure resistance and a pure reactive component, like an inductor, do I need to create the impedance I see out my port?" The "Parallel X" is answering the question, "What parallel combination of a pure resistance and a pure reactive component, like a capacitor, would I need to create the impedance than I see out my port?" Being that the capacitor model and the inductor model have as their major components a series resistor (e.g. ESR) and an ideal capacitor or inductor, the Series L/C is the choice for measuring the value of the component. Hope this helps.
Ok I think I understand better, thanks for quick reply and keep up the great work, you have one of the better you tube channels if not the best of all things RF! If you want an idea for another topic this might be good, I watch many you tube channels and don't think I have seen that explained.
@@nj6h Yep! I, indeed, just added it to my queue! In fact, while my wife is at Bible study tonight, I am going to start development on just that. Thanks for the input! 🙂
So how antennae. I have 3, 15, 6, and 2 meter dipoles. I know from your other videos that they will effect each other, and I want to trim them foe the middle of each band. How do I do that. Would make a great video.
@ separate with separate feed lines running parallel to each other. Would consider traps, but can’t measure the resonant frequencies, plus they tend to be less efficient and the antennas are not very high (10-15 ft). 2meter at top, 6 meter below and off to the right of the 2, and 15 meter below the 6 running the width of the house.
@@Joe-ho6fo Ahhh... the next question ... are they separated by more than 1/4 wavelength? If so, you tune them like any other dipole. Cut long, then trim to length. The higher the frequency, the shorter the pieces you trim as you tune. If they are closer than 1/4 wavelength, then tune the lower bands first. In either event, this will take some iterations. Don't tune to the perfect frequency the first pass through. Get "close," but not exactly where you want them. Then the second pass bring them into tune right where you want them. Finally, third pass, check that nothing has moved. Remember, tuning has to be done in the same space that the antenna will live. Buildings, plants, wires and other environmental things can change the tuning. Hope this helps. :-)
At 28:37 minutes, it appears the reading was 252 microhenries or 252uH, not 252 nH. Would you double check me on this, please? I enjoy your videos very much, thank you!
They are an amazing little device. Granted, they do not have the dynamic range needed to do things like tuning a duplexer, but they do so many other things well, they are well worth the investment. 🙂
@@eie_for_you The only thing I don't like about them is the small display, but as you demonstrated there is software to display everything on a computer screen. I got mine as a cheap antenna analyser, but now use the 2 ports just as much, for looking at filter responses and the like. I want to try measuring some standard capacitors I have and see how the results compare. I might try putting one in a sturdy water resistant box, with n-type connectors, together with a Raspberry Pi and a larger and brighter TFT display and battery. Make it for field capable. 73 VK4QP
As VNAs go ... they are VERY cheap (last I checked). Inexpensive nanoVNA clones can be had through various outlets (e.g. Amazon) for under $100, but you get what you pay for ... a inexpensive clone with definite limitations. With that said ... if the inexpensive clone will do everything that you need to do and do it well enough for everything you will need it for, then go with the inexpensive clone. The official, genuine article nanoVNA that I have is running around $300, which seems like that is more than I paid for it.🙂
I have no idea what "waffle" you are referring to. 😕 I try hard to stay on target in all of my videos....concise and to the point. Let's not waste people's time and yet provide ALL of the relevant, useful information. 🙂
@eie_for_you Thanks for the waffle. It is sometimes difficult for learners when the presenter assumes that the audience has a very high understanding, so waffle can help. I personally find the "waffle" of a knowledgeable person very helpful. God bless.
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When doing the port extension experiment, you could have used the SMA through at the end of the cable, and applied your SMA standards at the end of that assembly. Then, the port extension would have to only account for the additional electrical length of the SMA to N adapter, minus the SMA bullet.
Yes, yes! I thought about that and considered it. A lot of the nanoVNAs do not come with the thru adapter. So, I thought to myself, "Let's assume they don't have one and see what happens."
But, you are absolutely right, the preferred way to do it would have been exactly as you described and would have been my own way to do it under normal circumstances. Thanks for the comment!
Great Video--These are right up my ally for interest! So thanks Ralph for making them.
A long time ago, I was on the cusp of purchasing a MFJ analyzer when I came across a article where you could build a VNA by following this article and self-sourcing the components. In that article they did a comparison of their VNA with lab-grad ones and got great results; however when they compared them with the MFJ it was a disaster!
As a result, I held off my MFJ-purchase and finally got a NanoVNA and later a SAA2N and have never looked back. I realized that you have to come up to some minimal standard to use test-instruments to declare values; otherwise you are much better-off not trying to obtain exact-values, then calculating your way to Avalon--only to also find that your layout dorked you anyway! So, if you don't have suitable-equipment, you are more well served to just work empirically for performance-results and don't sweat individual values and their contributions. Along time ago I was reading the Motorola RF manual whereby the engineer said that they calculate/simulate first, then build as well as they can; if they acheive being within 30% of that, they're happy! So, this allowed me to cope with not being able to afford expensive equipment in those years.
Thanks Again and 73...
Yeah, that nanoVNA is an amazing little instrument!
If you read some of the really old manuals for electricians you will find instructions on how to get a rough idea of the voltage present using their fingers (yeah, 120 and 240 volts!). Aaaah the things which we used to do. I NEVER did it with my fingers ... least ways, not on purpose! LOL :-)
HP8753d/e is your best friend!
@@dalesmith8666 reminds me of the old saying: “If wishes were horses, then beggars would ride!”
I’ve looked at some on eBay and even if you pay beyond my price-point ability, you can still get stung. And, the lower ones many times have unfixable problems, or are so expensive to purchase subassemblies. I purchased an HP-8664 and got stung but managed to repair it to a level that yields some usability but a network analyzer just seems so daunting to try and tackle.
Fantastic tube no nonsens, remarkable video to !
Helped me a lot using my VNA TNX, 73 Germain ON4SG
So glad this was such a wonderful help! 73 🙂
I appreciate you making this video. I usually watch videos and taking from them what I can but, I also try to not skip ads, thumbs up, and more scarcely subscribe just to help out. You're doing a great job. Thank you.
Well, thank you! ... and you are welcome! 🙂
Knowledgeable and pedagogic. Spot on!
Thanks, man! :-)
Excellent.
Very helpful.
I am about to build from scratch a receiver & all my old component testors are kaput. I tested a bunch of coils & variable capacitors & it worked great.
BTW, the waffle complaint guy needs to learn how to use the video advance slider, me thinks.
Now that's one of the things on my bucket list, to build a receiver from scratch...just for fun.The other one is to build a solid state linear amplifier from scratch. Not to use myself, but for the whole learning aspect of it and then give it away to someone.
Yeah, the nanoVNA is so awesome! I'm glad the video helped you get a leg up on it all.
Regarding the video slider...I also provide time marker links in the description for every video I make. If someone is interested in a particular thing in the video, they can look it up and jump to that spot in the video by clicking on the link. 🙂
Extremely valuable information. Thank you for sharing.
You are very welcome! 🙂
How would one adjust port extension for open wire feedline? It is supposed to exhibit very low losses. I just checked and velocity factor is in the 90% range so i guess i just use the same formulae and the velocity factor of the open wire. Say for example my antenna feedpoint or reference plaine is around 100ft high and potentially 170ft from the transceiver. I was looking for a vna i could hoist up to the feedpoint (after adapting with a 1:1 balun), but now i suppose i just need an accurate measurement of the feedline length. I really would like to learn more about calculating good open wire feedline lengths and if i can add open wire stubs to tune or work as filters in a balanced network.
Thanks for the video. Very informative!!
Port extensions assume that the adapter or cable is the same 50 Ohm impedance that you calibrated the VNA at. Open wire feed line generally has a MUCH higher impedance. So, port extensions wouldn't wok for that.
Yes, as I understand it, you can use open wire stubs to tune and filter. Unfortunately, I have very, very (VERY) little experience with open wire feedlines. 😞 I don't want to lead you down the wrong path, so I will just have to leave it at that.
Great info as I save for a used Tek TTR503A.
Mine is awesome. I love it. 🙂 Can you believe that Tek stopped making them already?! 😞
One note ... do not shut down/restart your computer with it plugged into the USB port. You will have to uplug the whole thing and plug it back in (main power) to get it to talk to the USB properly. 😕
very nice,,I have lots to catch up using my vna,,just a tip I use the magnetic data connectors for my vna tiny ultra,phones add tablets,,saves ports being pluged in and out all the time,,also for sma and n connectors i use plug savers, avoid screwing on and off threads
Thanks!
I cannot say that I am familiar with those sorts of connectors. As totally persnickety as RF measurements are (REAL VNA experts use a torque wrench to tighten there connections!), I'd be a bit leery of quick connect stuff for that application.
@@eie_for_you magnetic cables are only for the data and charging not rf
Hello Dennis, just saw your reply to Ralph in which you mention "for sma and n connectors i use plug savers" can you expand on what "plug savers" are, please? Thanks, Luigi VK3ola
Thank you for the very informative content. By the way nice jacket
You are welcome!😀
Wow, and the MFJ device is, as I remember, roughly 5 or 6 times the cost of the typical nano VNA.
I just purchased my nano vna roughly two months ago and only recently began using it. I do like the nanovna-saver software and fortunately it runs under Windows 10 with no issues. The other software VNA-QT, latest version, installed on both my laptop & desktop, but hangs up with a not responding issue on both machines when I try to connect to the vna thru the com port, so I use the saver program.
All in all the nano vna is a great tool and I likely will purchase another for a bit more money than the $40 I spent so as to have a larger screen when using without aid of the computer.
The nanoVNA is an awesome tool for the price! It still cannot tune a duplexer (not enough dynamic range for that), but it does everything else pretty well.
I, too, like the saver program. I had times when it wouldn't connect and I had to connect using a different program, close that one and then saver would connect. But, I haven't had that problem recently. So, either they fixed that in the release I have or it fixed itself when I changed computers (??).
In a few weeks I plan on a menu walk through on the nanoVNA. It is by way of helping folks know how to get things set up to do what they need to do ... not your typical "this menu is for this" kind of thing.🙂
@@eie_for_you Exactly, a great tool.
I just checked my Mag Loop antenna I recently made out of 4 inch aluminum dryer vent in the shape of a 4 foot square using a 23 inch per side square of 3/4 inch copper pipe as the inner loop that if strictly receive would be called the sense.
Turned out I did well. Its actually most efficient on 20 meters, but 40 m works too. I was listening on 40 m this morning to some Spanish guys using my phone translator to understand their dialog and had left the capacitor setting at their frequency. The nano vna shows a reflected power of 1.3 at that frequency of around 7.13MHz.
When I built the antenna I had read the larger the inner loop the lower the impedance. At the time I did not know how to use the nano vna so by trial and error, where it only took two attempts, using a simple analog SWR meter I came up with the inner loop's circumfrerence.
Boy, do I wish my variable capacitors I use dependent on band had some kind of vernier that I could mark using the nano vna as my guide. I am a bit surprised that the notch of low reflected power having less than a 2 for SWR reading is actually fairly wide at 90 MHz. My inverted V that admittedly is a compromise by being low to the ground with its apex 12 feet off the ground and the ends nearly touching ground has only a 200 MHz interval of below either 2 or 1.5 with respect to SWR.
Anyway looking forward to the upcoming video.
Another excellent explanation.
Thanks!
Excellent video. Thank you.
Thank you and you are very welcome! 🙂
Excellent video! Thank you for making it. Overall, how does the Nano VNA compare to the Tektronix VNA?
Thank you and your are welcome at the same time! 😁
To answer your question ... I just did an experiment calibrating each with the same standard and measuring the same inductor. The nanoVNA was within 0.5% of the Tek VNA. In other experiments previously done, it was within 1%. Quite respectable!
For the measurements in the beginning, why did you use the 2nd marker at 50MHz? Because it was in the middle of the sweep? Other tests I’ve read about. rely on finding the resonant freq (phase plot where it goes from 180 to -180) before calculating the inductance (e.g., inductor in series with a known capacitance, one end connected to DUT ground and the other end connected to DUT tip..then the inductance can be calculated with the standard formula that uses the resonant frequency)
Yeah, I've done it with resonant frequency before, but this throws one more bit of measurement uncertainty into the measurement: the actual value of the capacitor. It is better to measure the value directly and at as low a frequency as possible to avoid any interaction with possible self-resonances. As far as the whole 50MHz thing ... as I recall it was just convenient *and* well below where I figured any self-resonance might occur. Hope this helps. 🙂
Thanks!
@@lemonkeyYou are very welcome! 🙂
Interesting experiments
Rather eye opening! But, you can get MUCH better performance out of the Rig Expert using the procedure I shared in this video:
th-cam.com/video/Mp6O3xal0n8/w-d-xo.html
I expected t measure an antenna center frquency by the NanoVNA. Of course, something is calculated, however it would be good to have a bell curve to see the result. Is there any way to have a look that ?
Take a look at my video on the menu system of the nanoVNA which will help guide you through the whole thing so you can decide what you want to see and how you want to see it.
th-cam.com/video/_96N3oGFatE/w-d-xo.html
MORE THAN THAT ... If you connect the nanoVNA to a computer and use software such as the "nanoVNA Saver" program (nanovna.com/?page_id=90), you can export the measurement data to a file. Then you can import this file into a spreadsheet program and do all sorts of analysis and fun things with it. Yes, this is true for impedance data. Hope this helps. 🙂
Great explanation! Tnx! Subscribed.
@@martymctry20 Thanks so much! I’m so glad you found this helpful! …and you are welcome. 😀
If you want to increase the accuracy of your homebrew 50 ohm standard solder two 100 ohm 1% resistors in parallel which will give you 50 ohm .5% standard. You can also use four 200 ohm 1% resistors in parallel to make a 50 ohm .25% standard. BTW I'm just downstream from you in Davenport
Actually ... I have to disagree with you. A 200 Ohm, 1% resistor could be as high as 202 Ohms. Suppose, by luck of the draw, I put four 202 Ohm resistors in parallel. This will give me a 50.5 Ohm resistor. But, this is a 50 Ohm + 1% resistor. So, I have gained nothing.
Very helpful informations! Thank you very much! ❤
I'm glad that this was helpful! You are welcome! 🙂
I was a bit confused (at first) by that impedance display. It used the upper case Greek letter Ω (for Ohms) and I was confusing it with the radian frequency which is typically the lower case Greek letter ω, such as Z = R + 2πjωL. 😀
_73 de AF6AS_
All these Greek letters ... it can get a bit confusing sometimes.
Yes, Z= R + jωL and Z(C) = R - j/jωC 🙂
Excellent content .. Thank You for sharing .. Cheers :)
Thank you! ... and You are very welcome! 🙂
Good info. Thank you very much .......
You are very welcome! I am so glad that you found this to be helpful. 🙂
The MFJ was the only cheap instrument to measure antenna SWR and X&R to give you an idea of your system. 10% accuracy is more than enough but at higher frequency not very good. You should know the limit of any instrument that you are using.
True that! I looked very, very carefully at everything that I could find to try to see what sort of accuracy MFJ *claimed* the 259 had ...... nothing and for good reason. 🙂
Can you show how you can mesure resonance of LC of toriodal inductor and capacitor?
Interesting thought. I would think that it would be done in a similar fashion as tuning an antenna trap as seen in this video: th-cam.com/video/jpt51hDA5DQ/w-d-xo.html
🙂
Excellent explanation! Is there a reason to sweep from 40-60MHz across 11 segments after calibration since you are only looking at the 50MHz marker? For example why not sweep 1 segment from 49-51MHz (and set to continuous sweep) to measure the parts? I also found the S11 Serial L & C displays to be helpful.
How many segments you are using and the start and stop frequencies are all up to what you are looking for. The more segments, the finer the frequency resolution of the measurements made because it only takes a certain number of measurements in each segment. So, to get this finer resolution over a wider span, I need more segments.
If I am interested in seeing how the part performs between 40-60 MHz, then my span is there. If all I am really interested in the 50 MHz, then, yeah, we could narrow the span a LOT and use fewer spans, like just 1. 🙂
@@eie_for_you Thanks for the reply. Yes I am seeing with the Series L display how different inductors behave across the larger span where 1mhz is mostly a flat line. Fun!😀
@@johnclements3441 Yeah ... it *is* fun! 🙂
I plan to experiment with various LC impedance matching techniques for single band efhw vertical ground mounted antennas for HF Ham use. My problem is determining the load impedance of the radiator wire for each frequency that I need. Assuming 468/f MHz for say a 28.075 to cut length, and hung vertically at 10M high, soldered to center conductor of SO 239 connector with a .05 wavelength counterpoise attached to outside of the SO-239 connector at ground level, how would one use the nano vna to measure the impedance? I read that the impedance of a EFHW antenna is within a fairly broad range of 2000-5000 ohms. My problem is that I would prefer to know in advance what specific impedance I am trying to match to 50 Ohms given my known factors, such as location, environment, frequency, materials, construction, etc. Ofcourse I can just keep iteratively building, testing, by best guess but I'd prefer to save time and just measure it if I have the ability to do so with reasonable precision. Thanks for your help.
Any VNA assumes a 50 system between itself and the point where you are measuring. Port extensions only work when the connector or cable being added adhere to this 50 Ohm system.
You say (if I read this right) that what you are measuring is terminated in a UHF female (SO239) connector. I am assuming the shell is ground and the center is the item in question(???). If I understand this right, then I would calibrate the nanoVNA at the end of whatever cable you need to plug *directly* into this UHF female.
Remember ... ANYTHING that lay between where the VNA is calibrated and the entity to be measured WILL change the measured impedance. The higher the frequency, the more critical this becomes.
With my miniVNA tiny I literally mounted the VNA on the antenna and used a very long USB cable to connect it to my computer. Because it lives in a very plastic case, its presence did not affect the antenna even at 146 MHz. I measured the impedance of a folded dipole at 146 MHz this way and created a stub match to give me a very good SWR into a 50 Ohm feedline (you could see my video: th-cam.com/video/LY4GysxSEa0/w-d-xo.html).
@@eie_for_you Thank you. I guess my question is will a nano VNA measure an impedance of an unmatched antenna anticipated to be between 2000 and 5000 ohms? I am not sure if a nano vna is capable of this high impedance range.
@@kennymanchester I do not know the answer to that question and the manual doesn't say that I could find. If you just leave the connector open, what impedance does it report? After calibrating mine at the connector, mine is popping all over the place with displayed readings even up into the tens of kohms. Nonetheless, I'm thinking it probably is outside of its capabilities for making really accurate measurements. If it were me, I'd do some bench experiments to see what its limits are.
@@eie_for_you Thank you. I'll do that and see what happens. Thanks again.
@@kennymanchester Let me know what you discover.
Nice, subscribed.
Thanks, man! 🙂
I have ordered one.
They *ARE* an amazing tool! 🙂
I'm having trouble measuring inductors and capacitors with my NanoVNA. The values I get don't match my capacitance meter. I followed your video, but I'm not sure if my calibration or connections (using crocodile clips) are wrong. Also, varying the marker frequency changes L and C values a lot. Any help would be appreciated!
Hmmmm...I thought I replied, but it doesn't show... well, here I go again...
First, what frequency are you trying to use? You need to use a low frequency to avoid the weirdnesses of self-resonance. The capacitance meter uses lower frequencies, maybe as low as 100 KHz.
Second, did you calibrate the VNA right at the clips like I showed in the video? This includes to position of the clips (especially if you are using higher frequencies to do the measurement).
Third, if I had to choose between a properly calibrated VNA and many of the stand-alone LCR meters as to accuracy, I'd choose the VNA every time. The LCR meters that most folks can afford usually are not as accurate as we'd like to believe they are. Even a high-end LCR meter well beyond its last genuine calibration is suspect.
I though I said something else of value in my first attempt to reply, but it escapes me at the moment. It has been a very long, tiring day. 🙂
@@eie_for_you Thank you for your detailed response and advice. I appreciate your expertise, but I have some questions and observations:
Frequency for measurements:
You recommend using low frequencies, around 100 kHz for capacitors, which makes sense. However, you also mentioned 40-60 MHz for some measurements. In my experience, these higher frequencies only gave accurate results for air-core inductors. For inductors with ferrite cores, the measurements were incorrect.
Wouldn't it be better to use lower frequencies (100 kHz - 2 MHz) for both capacitors and inductors? This range seems to provide more consistent and accurate results across different component types.
VNA calibration:
I understand the importance of calibrating the VNA at the clips, as you showed in the video. This is crucial, especially when using higher frequencies.
VNA vs. LCR meters:
I agree that a properly calibrated VNA is often more accurate than many standalone LCR meters, especially the more affordable ones. Your point about even high-end LCR meters being suspect if not recently calibrated is well-taken.
My main question is: Why do you recommend 40-60 MHz for some measurements when lower frequencies seem to work better and more consistently for both capacitors and inductors, including those with ferrite cores? Wouldn't it be simpler and more reliable to stick to a lower frequency range (100 kHz - 2 MHz) for all these measurements?
@@hellmind Ya know ... I had to go back and watch my own video ... LOL!
You are absolutely correct about using low frequency to make these measurements. The lower, the better with a lot of variables.
So, why did I do this at 50 MHz? I have to admit that I wondered that same thing myself. Why on earth did I measure the values at 50 MHz? The answer is because I was going to be using the MFJ antenna analyzer to measure these same components and it has serious problems measuring them at lower frequencies (like it wouldn't do it at all!) Remember the statement from the manual about the limitations on the reactance value.
While the limitations on the reactance values for accurate measurements are much wider with the nanoVNA, they still exist. So, there is a balancing act going on here. On one hand we have to avoid the self resonant frequency of the device being tested and, on the other hand, we have to be mindful of the limitations of the VNA regarding the reactance values it can accurately measure. Too large or too small and we start getting into the dirt.
Hopefully this makes some sense. 🙂
Hi nice video , I do have 2 of rf scanners pro-sl8 and pro-7000fx , spec states up to 8ghz but it have mcx connector on it and poor antena . If the device can not handle more than 6ghz than I need to measure and build best antena from the lowest to 6ghz , but if it can handle more maybe if to change mcx to sma ? can I improve the frequency range ? .only what im scare to not burn it at the very beginning. Im not spec tech but I know mcx limit is 6ghz . This is not cheap toy for my pocket so I'll need instructions. I know how to use soldering iron;) .my intention is to measure the real values that's this toy can really measure also chcek antenas to confirm what is the lowest and highest frequency that it can handle , , also im thanking to maybe add lpa antenna and some pre amp and amplifier my dream would be 12ghz . Can u advise what tools shoul I get to measure all my needs and not to burn it ? And some step by step info pls?
First of all, the limitation of these bug detectors is not found in the antenna, but in the internals of the device itself. Regardless of the antenna you might put on it, it will only be capable to the frequency limits stated in its specifications.
The only benefit that you might have in changing antennas might possibly be in sensitivity.
For best sensitivity, the antenna should be *physically* tuned to the frequency that you are interested in detecting. A bigger, longer antenna does not yield better reception.
You could get more antenna gain using a colinear antenna. Again, this is frequency band specific, like any properly tuned antenna. Here is a document that talks about their design:
k5frc.org/training/coliner antenna.pdf
Hope this helps.
very good - thanks
You are very welcome! 🙂
Thanks for all your videos, you explain things very well, I have a question about what series L, series C compared to Parallel X and Parallel X when and how I would use this info, I see it on both VNA and my rig expert. If you have covered this please guide me to your video that it is covered, or if not covered maybe you could do a video. Thanks; 73 N8KEN
Now THAT'S a really good question! 😀
Think of it this way ... the VNA "sees" a particular impedance as it it "looking" out its port. The "Series L/C" is answering the question, "What series combination of a pure resistance and a pure reactive component, like an inductor, do I need to create the impedance I see out my port?"
The "Parallel X" is answering the question, "What parallel combination of a pure resistance and a pure reactive component, like a capacitor, would I need to create the impedance than I see out my port?"
Being that the capacitor model and the inductor model have as their major components a series resistor (e.g. ESR) and an ideal capacitor or inductor, the Series L/C is the choice for measuring the value of the component.
Hope this helps.
Ok I think I understand better, thanks for quick reply and keep up the great work, you have one of the better you tube channels if not the best of all things RF! If you want an idea for another topic this might be good, I watch many you tube channels and don't think I have seen that explained.
@@nj6h Yep! I, indeed, just added it to my queue! In fact, while my wife is at Bible study tonight, I am going to start development on just that. Thanks for the input! 🙂
@@eie_for_you
I, too, had this same question. Many thanks for the concise and understandable explanation!
@@boatknuckle You are very welcome! 🙂
So how antennae. I have 3, 15, 6, and 2 meter dipoles. I know from your other videos that they will effect each other, and I want to trim them foe the middle of each band. How do I do that. Would make a great video.
Are these separate antennas or are they arranged as a single trapped antenna? 🙂
@ separate with separate feed lines running parallel to each other. Would consider traps, but can’t measure the resonant frequencies, plus they tend to be less efficient and the antennas are not very high (10-15 ft). 2meter at top, 6 meter below and off to the right of the 2, and 15 meter below the 6 running the width of the house.
@@Joe-ho6fo Ahhh... the next question ... are they separated by more than 1/4 wavelength? If so, you tune them like any other dipole. Cut long, then trim to length. The higher the frequency, the shorter the pieces you trim as you tune.
If they are closer than 1/4 wavelength, then tune the lower bands first.
In either event, this will take some iterations. Don't tune to the perfect frequency the first pass through. Get "close," but not exactly where you want them. Then the second pass bring them into tune right where you want them. Finally, third pass, check that nothing has moved.
Remember, tuning has to be done in the same space that the antenna will live. Buildings, plants, wires and other environmental things can change the tuning.
Hope this helps. :-)
Show!
At 28:37 minutes, it appears the reading was 252 microhenries or 252uH, not 252 nH. Would you double check me on this, please? I enjoy your videos very much, thank you!
I took a look at the video and it indicates 0.252uH = 252nH. Double checked! 🙂
I am glad that you enjoy the videos! 😀 You are very welcome!
Very nice presentation. 73's, ve3aam
Thanks! :-)
🥰nanoVNA🥰
Yup! They are awesome little machines!
I'm rushing to my nano VNA now...
They are an amazing little device. Granted, they do not have the dynamic range needed to do things like tuning a duplexer, but they do so many other things well, they are well worth the investment. 🙂
@@eie_for_you The only thing I don't like about them is the small display, but as you demonstrated there is software to display everything on a computer screen. I got mine as a cheap antenna analyser, but now use the 2 ports just as much, for looking at filter responses and the like. I want to try measuring some standard capacitors I have and see how the results compare. I might try putting one in a sturdy water resistant box, with n-type connectors, together with a Raspberry Pi and a larger and brighter TFT display and battery. Make it for field capable. 73 VK4QP
has the price fallen yet?
As VNAs go ... they are VERY cheap (last I checked). Inexpensive nanoVNA clones can be had through various outlets (e.g. Amazon) for under $100, but you get what you pay for ... a inexpensive clone with definite limitations. With that said ... if the inexpensive clone will do everything that you need to do and do it well enough for everything you will need it for, then go with the inexpensive clone.
The official, genuine article nanoVNA that I have is running around $300, which seems like that is more than I paid for it.🙂
Got stuck on the waffle. Get to the point please. Like John 3.16. Good luck but brevity is the go. Cheers.
I have no idea what "waffle" you are referring to. 😕
I try hard to stay on target in all of my videos....concise and to the point. Let's not waste people's time and yet provide ALL of the relevant, useful information. 🙂
@eie_for_you Thanks for the waffle. It is sometimes difficult for learners when the presenter assumes that the audience has a very high understanding, so waffle can help. I personally find the "waffle" of a knowledgeable person very helpful. God bless.