Post Production Note: I received an email from one of the developers of the "V2" platform, and he informed me that while they intentionally open-sourced the design in order to give users more choice, there have been at least one clone maker that has manipulated the market in various ways (false rankings, and selling at cost) which does a discredit to the original developers. This is the case with the SAA-2N featured in this video. The official website for the V2, from the original developers, is nanorfe.com/nanovna-v2.html. Please consider this when making your choice about what V2 hardware to buy.

@razblack

3 жыл бұрын

good to know!, i almost bought this exact one you show.. had it already in my cart on Amazon.. gone now though lol. I do wish that they provided sales through Amazon though :( perhaps you could get them too ;)

@mpslevan

3 жыл бұрын

I do not see the SAA-2N version on their website. They only show an SAA-2. Is there a store that you would recommend for sourcing the SAA-2N?

@DJBlackhawk

3 жыл бұрын

Was the version you tested able to support updated firmware? Is the SAA-2N with cables, calibration standards and bag from licensed source? NanoVna SAA-2N VNA Antenna Analyzer,SEESII 50KHz -3GHz Vector Network Analyzer with Bag & Testboard Kit,4" inch LCD,HF VHF UHF Measuring S Parameters, Voltage Standing Wave Ratio Smith Chart www.amazon.com/dp/B08H4NFZZ2/ref=cm_sw_r_cp_api_fabc_9.9PFbJ94BHR2

@w2aew

3 жыл бұрын

@@DJBlackhawk The SAA-2N I used is compatible with the "blackmagic" version 2.74 of firmware. nanorfe.com/nanovna-versions.html nanorfe.com/downloads/20201013/nanovna-v2-20201013-v2_74.bin

@rodolfososaalvarez8083

3 жыл бұрын

so bad. i did buy; SAA-2N

The nanovna is awesome for making filters, i was able to make a filter that worked perfectly and measure it. Great tool.

I learned a bunch from this video. Even my NanoVNA can tell that the chinesium duplexer I bought only gave -46dB rejection with insertion loss of 4dB from the factory. If I can turn the screws and improve those characteristics a bit, I'll be a happy HAM!

Makes me happy I just bought the same nano vna with the N connections! Thanks for the video man!

Sir Your videos are alsom alsom alsom...... You tell events of rf electronics is perfect than many professors. I respect your works sir. Thanks a lot.

Nice to hear you after a long time.

I ordered a nanoVNA to play with. It is good to understand the limitations as well as how they can be used. This comparison dramatically illustrates the clarity a better VNA provides, though, for casual use, cannot be justified in price. It would be interesting to see how this Tek VNA compares to some entry Rigol and Siglent units. Those are closer to my price range as a hobbyists.

Great video, thanks for easy to understand explanation!

For the price the Nanos are a great little tool, And getting better all the time , Who knows what they will be like performance wise in the next year or two as improvements are made in both hardware and firmware .... Again though Alan another great video.

Timely and perfect in my situation. Thanks a lot 👍

@0504328

2 жыл бұрын

Hey Allan if there is a chance that you may also test " The one claiming ORIGINAL VNA" to test/tuning Chinese cheap Duplexer, it would be a great help as well.

Superb video and use-case for amateur ops!

Great video on the Nano. I didn't know there was an SAA-2 until now. I'll have to look into it further.

Just a quick comment regarding NanoVNAs. As a radio broadcast Engineer I needed to retune an an antenna for an LPFM and the NanoVNA worked spot-on! I was able to get the antenna resonant on the station's frequency. A very handy device to have in the field. Thank you for all your videos and keep them coming.

Great! Have just decided to buy an SAA-2N so at least I'll have a VNA toy now. (but still looking for a professional one though)

Thanks for the heads up on the original source of these tools. I shall wait and save the extra bit for the latest V2 Plus4 in metal case..from the developers. Thank you.

Hello friend, thanks for your video. Jorge from Medellín Colombia

You have been doing very nice videos, giving vast knowledge. I liked them very much but since all those stuff look very expensive, seemed hard to follow. Think of doing a series which ordinary hobbyists like us can follow will be a great idea. Your standard of knowledge in radio armature looks pretty amazing.

@ydonl

3 жыл бұрын

I wonder if you've looked through his other 300 videos... I think there are some in there that would be what you describe.

@w2aew

3 жыл бұрын

I have a LOT of 'back to basics' videos on my channel too. Check my video index file, as well as my playlists.

@ammocraft

3 жыл бұрын

There's a heap of basic videos, plus the Nano VNA is very affordable, and there are some great videos on using them for hobbyist uses too.

@sleeve8651

8 ай бұрын

​@@ammocraft Sadly, the above shows just where Amateur Radio, and likely society has gone ! Like asking a teacher to grade on a curve ! Dumb this down for me, can you ? 😳 A question a few years ago, no one would suggest, if it was killing them ! And trust me..... I'm no Genius ! 😂🤣😂 I bought a VNA sometime ago,( Hoping it's not a knock off 🤞 ),and there it sets ! Watched a couple of videos, and sat thru the calibration, etc. ! But have yet to try it ! I am intrigued by them though. And I have to ask myself if running across your video was coincidence, or offered up by whatever listens to our phones ? As another Ham friend and I were discussing using a VNA, to see if we could tell what frequency a single "CAN" he has is on ? He was gifted a VNA but like me, has yet to try it ! And he was a local Broadcast Engineer, for some 40 years ! P.S.......I sent him this video ! 👍😉

Wow, glad you are back. You make wonderful videos that instruct and entertain. Thank you. 73 KG5OBD

Another great video, Alan An interesting follow up could be an exploration of low cost testing alternatives that could be successful at tuning a duplexer. Would an RTL-SDR dongle and a noise source be good enough? Better or Worse than a Nano VNA? I'm certain you can think of other old school and low cost methods of performing such a test. Keep up the great work.

Thanks for this :)

With a Nanovna-f I was able to get -59 on my UHF duplexer, so much to learn

Tnx Alan!

I had a feeling the noise floor was going to be the determining factor here. I have a Rigol DSA-815-TG and even wish it had a lower noise floor. Nice job on the video. I didn’t know about the SAA2.

I’m chucking my “cheap” Rigol DSA815tg now... $1800 vs $60? 😷😆🤣 Seriously.. thanks for another great video. NORTH Jersey Rocks!

wow you did a video

I have both he H4 and the F series with metal case. The F series appears to be a better instrument, in both sensitivity and dynamic range. I found it does not get noisy until I get past the -90dB point when adjusting a single cavity, but have noticed that point wander about a little. The H-4 does not like resolving notch depths much beyond -85dB, and has a tendency to pick up extraneous signals, messing up mesaurements in the 'weak signal' range of the VNA. The TinySA is also a great tool, but takes far more patience to become proficient with it. Love the videos!

@w2aew

3 жыл бұрын

I agree, I think the -F is a better instrument than the -H4, just a bit pricier.

Great Video; cool example of where dynamic range really comes into play. 2 questions (1) Is 1kHz measurement BW the minimum size for the nanoVNA-H firmware you were using or is it possible to squeeze out a bit more dynamic range by going smaller; if not, is this a hardware limitation? (2) is the measurement BW adjustable in the SAAV2 firmware you were using?

@w2aew

3 жыл бұрын

For that firmware, you can adjust it down as low as 33Hz, but I didn't see any real improvement below 1kHz, just slower measurement speed. I don't think the BW was adjustable in the SAA-2N firmware I was using (although you could go up to 201 trace points).

I have my Rigol spectrum analyzer with TG for measuring stuff but it's not really portable so I will buy one pocket sized VNA for sure some time in the future. Also these must be really great for beginners as the "real" analyzers cost at least four figures. But I also think if you really start setting up a relay station you will have to use proper measuring equipment as the material for the station by itself can be very expensive and youdon't want to go cheap on tuning.

It's only going to get better. The cost makes it available to all of us. What's not to like.

👍

Fascinating. I had never considered the need of duplexer on a repeater. Knowing what you now know, is it possible, but perhaps not wise, to extrapolate the rejection curve down below the nanoVNA noise floor to simulate more resolution?

Hi, although exact frequency at which dip occurs can't be seen (because of low SN ratio of nanoVNA), I think that frequency at which dip occurs could be still calculated relatively precise by extrapolation of S21 curves using some curve fit algo and using S21 points in range from 0 to around -55dB (approaching from left and right side). Resulted dip is where both curves meet. It would be interesting to see how that result compares with professional VNA. (It may be even possible to get some approximation of how deep that dip is)

Nice, thanks for sharing where website did you buy the SAAN 2N from? Thank You

Thank you for doing more videos on duplexer tuning. I've tuned several of these mobile notch duplexers on an HP 8920 I purchased calibrated from a well known source that provides these service monitors to mobile radio shops. With a 3Khz resolution bandwidth the best I've been able obtain is ~84db notch. The specs sheets on these units usually say something around 75db, such as resources.tessco.com/attachments/76905_633-6A-2N.pdf. So I'm confused on how you're getting 100-110db notch.

@w2aew

3 жыл бұрын

Guaranteed specs are one thing, actual typical measured results are another. If you look at the plots in that datasheet, they're showing a 90dB notch. I'm sure they spec 75dB to cover tolerances and operating temperature variations.

@philjensen5151

3 жыл бұрын

@@w2aew Also, the HP 8920 and 8935 dynamic range for the spectrum analyzer is a bit less than 90db and would line up pretty close with the ~84db mentioned.

Awesome video! Have you used the Pico VNA before? it seems a bit cheaper than the Tek VNA you have at maybe similar performance?

@w2aew

3 жыл бұрын

I have no experience with the PicoVNA, so can't comment.

We all know that one should use an attenuator when the input signal is too strong. I think there a similar workaround is possible: we can use an amplifier in a measurement circuit. It will not do great magic but in some cases is possible to pull the signal through a bandstop filter. Probably it should be a logarithmic amplifier that will compress the dynamic range. If we could figure out the dynamic response of that test circuit we could obtain characteristics of the filter or device. There are a lot of drawbacks but the concept seems to be possible.

Wow thank you so much, exactly what I was looking for! Can you please do a video on how to calibrate duplexer using NanoVNA. 1. To learn the process. 2. Shop won’t touch my inexpensive made in China duplexer needed for shelter repeater system. Thanks and 73 DE KK4MND

Great video, thanks! What is your opinion on SDR Kits VNA for tuning duplexers? Also the new Rigol SA / VNA like the RSA3015N might be a good "low cost" option for ham repeater work. What do you think? Regards.

@w2aew

3 жыл бұрын

I have never used wither of these, so can't comment on their suitability.

@Christian-qd5kb

3 жыл бұрын

I haven't used the VNWA for duplexers, but based on it's specs it should be pretty good below 500MHz with a specification for 90dB of dynamic range. The one thing I like about the VNWA is the software; it's very, very powerful and can do an amazing amount of things. I have one of the VNWA3s that I've upgraded to the SE so it does automatic S parameter measurement switching which is handy along with their electronic calibration makes thing super easy and repeatable (downside is that it does cost quite a bit more than a NanoVNA but still only a fraction the cost of professional VNAs. I like mine quite a bit; for completely portable use without a laptop though the NanoVNAs are pretty hard to beat.

I hope soon we can have a v3 version with 100db of din range

@dg9bfc

3 жыл бұрын

v2plus4 comes close ... +100db in lower range and at least 90 in upper area

@w2aew I was looking to see if you have reviewed the MINI1300 analyzer and see if it can be used to check/tune a flatpack duplexer. The mini1300 seems to be getting a lot of interest lately.

I know absolutely nothing about any of this. Yet it came across my feed and I must say, it is very interesting! Might have to look into it more.

Add attenuator and set offset.... improve Dynamic range....

I think the notch was a little to the right on the pro vna too, albeit not as far perhaps.

The problem may be sample points more than dynamic range. with software you can greatly increase the number of same points. That would be a fairer comparison.

Great video. Thanks for posting. Would putting a 20 db pad inline help with the readings? I just received my NanoVNA H4 yesterday and it came through with the firmware that allows 401 sampling points. I noticed the SAA2 only had 101 sampling points. I hope they come out with new firmware that will allow up to 401 sampling points. These little guys are great. I also have the TinySA. Great for hunting down noise sources. Barry, KU3X

@w2aew

3 жыл бұрын

Hi Barry - I don't see how adding a 20dB pad would help, since the problem isn't with distortion products but rather with the inherent noise floor.

Hi Alan, Another great video thankyou. I was wondering if you have a video in the pipeline for checking crystal parameters With a view to make a crystal filter? Regards......Peter

@w2aew

3 жыл бұрын

I don't yet, but check out W7ZOI...

Curious to know how the nano works in a high RF environment. For example, a repeater site with multiple megawatt ERP transmitters.

@w2aew

3 жыл бұрын

I would imagine that there may be issues in a high RF environment...

hi, you showed only one shoulder-LOW, in this shoulder everything is good, and what happens in the other shoulder-HIGH?

so you don't recommend the SAA-2N? I'm looking at the new nano V2 Plus4 but it's 2x the cost and 3 month wait.

@DavidLindes

3 жыл бұрын

I'm sort of thinking that, too... but, yeah, would be nice to have a review of it to base things on... or... maybe I'll just get more than one, and compare them myself? We shall see. :)

Eliminated one of the units from consideration. WOW, the Tektronix unit sure is a budget buster!

I recall seeing one of those nano VNA’s that could be connected to a computer and run an open source program that gives you a desktop view so that you could have a higher dynamic range. Much like your professional unit is operating but still not as a high quality image.

@w2aew

3 жыл бұрын

Using the desktop program will help you increase the number of points and do some averaging, but will no increase the dynamic range.

Interesting point to be aware of. I never concidered dynamic range that important. I probably won't need it for antenna matching and SWR analysis etc.?

@w2aew

7 ай бұрын

Correct, dynamic range isn't important for SWR, etc.

Hi i have the mini1300 and the vna-f, but i do like the look of the SAA-2N , can you please do more tests with it and tell us what you think of it, i have a kenwood ts2000 so i want to play with 23cms, Thanks Dave 2E0DMB

There is a Nano VNA Plus 4 with 90dB dynamic range. Please if it's possible do the same comparison with this one. It will be very interesting.

Can you post a link to the firmware you mentioned that you're using with the NanoVNA H4? Thanks again for your informative videos, I look forward to all of your updates. N9PBD

@RobB_VK6ES

3 жыл бұрын

Possibly more to the point do the existing PC apps like NanoSaver still work with the 401 points ?

@w2aew

3 жыл бұрын

The one I am running is in this message thread: groups.io/g/nanovna-users/message/17853

@w2aew

3 жыл бұрын

@@RobB_VK6ES Haven't tried it yet.

@ke4est

3 жыл бұрын

I was following the thread to the link Alan posted above. I have been playing with the same firmware and it is nice on the H4!

Do you mind me asking where you got the SAA-2N from? I'm wanting to upgrade my old original, just concerned whether the "fake VNA" thing is still an issue with the newer models.

@w2aew

3 жыл бұрын

I picked mine up from R & L Electronics (www.randl.com).

@ammocraft

3 жыл бұрын

@@w2aew Thanks!

We have a TTR506A at work that I use daily and it's a fantastic device but for doing home stuff I love the NanoVNA stuff. I'm looking forward to the next V2, according to the developers on EEVblog it should be expanded up to 4GHz with a faster sweep speed too.

@w2aew

3 жыл бұрын

Nice - what kind of work do you do with the TTR506A?

@Christian-qd5kb

3 жыл бұрын

@@w2aew We do a decent amount of antenna characterization for prototype systems here; not extremely demanding work for the VNA but I like the interface and the portableness of it, plus the support has been pretty top notch too. I was a little disappointed to see the removal of the TDR measurements but I wrote a quick little python script that pulls the data from VectorVu and sends it over to the SDR Kits VNWA program for TDR analysis and it works pretty well.

@w2aew

3 жыл бұрын

@@Christian-qd5kb Very cool, thanks. I'm work as a Field Applications Engineer for Tektronix, supporting mainly RF applications, that's why I was curious.

@Christian-qd5kb

3 жыл бұрын

@@w2aew I will say your channel was one of the reasons in the purchase; when we were looking at spec'ing a semi-portable VNA unit I saw some of your earlier videos using it and liked the interface and simplicity of it versus an equivalent Keysight unit (which also had a moderate price increase also, and the rugged portable FieldFox ones were definitely out of the range we wanted to stay in) or Copper Mountain (their software was a bit sketchy to me when I used a demo version).

@w2aew

3 жыл бұрын

@@Christian-qd5kb Cool - thanks! Just curious, where are you located?

Hello w2aew, I follow your videos for quite a long time, and I am amazed to find out that I can always learn something new from you. I wanted to contact you via private instead of writing on the comment wall, but I coudn't find such a contact on your channel, and I see that you read these comments as well. I would like to translate your videos to my own language to help the students of my former university, because not everyone speaks English there, and your videos are unique in a way that I would like to reach as many interested people as possible. I would do this for free. Translating is actually something that gives me a plenty of joy on its own. I am the main translator of the also really famous Afrotechmods channel where I have already translated 20+ videos in the past 3 years. So if you support this idea, please allow the videos to accept translations, or alternatively give me a business email where I could send you the finished subtitles (the former one would be the easier way though IMO). Thank you for reading, and keep up the great work! :Niz

@w2aew

3 жыл бұрын

I like the idea, I just need to figure out how to "allow translations". I'll look into that.

One question, can I improve the dynamic range adding a wide range LNA amplifier (20 or 30dB) in the port 21? Only to improve the noise floor and maybe the Notch peak measurement capacity. I have both, V1 and V2 NanoVNA. Thanks

@w2aew

3 жыл бұрын

Maybe - but you have to take great care to remember that the NanoVNA's output is NOT a sinewave, it is usually a squarewave, thus has a lot of harmonic energy. The V1 devices actually use the 3/5th harmonics when measuring above 300MHz. So, these harmonics are always there, and might overload the amp or Port2 (CH1) if they aren't filtered out before the LNA input.

@dg9bfc

3 жыл бұрын

maybe a skyworks 65017 ... nearly flat 20 db from a few megs up to 6 gig

How are you? After a long time.

@w2aew

3 жыл бұрын

Doing well - my day job has been keeping me very busy...

@ahmatrizki5154

3 жыл бұрын

@@w2aewinteresting explainations, especially basic circuit and components,

Some people do review about nanoVNA like this vlog

Can dulexer be tuned with tinySA? If so pls make such a video

Is the reference level fixed on a nano? If it is configurable wouldn't it be possible to measure the I.L. of the pass at a reference of 0 or slightly greater, then change the reference to say -40 or so to measure the I.L. of the reject to work around the smaller dynamic range? Is the actual limitation the Noise floor or effective sensitivity? I may be unaware of how doing this would create a false measurement I'd greatly appreciate your input.

@w2aew

3 жыл бұрын

Reference level is fixed.

Would it be possible to aggregate data from numerous sweeps to extend the effective dynamic range?

@dg9bfc

3 жыл бұрын

using avg lowers noise so adds dynamic range ... more measure points with finer stepping also helps ... we now have fw with avg x 80 and 511 measure points .. but you can never get below 90 to 100 db cause the internal leaking is in that range

Nice presentation of the nano in observing of tuning of a series of filters pass or notch. The mobile duplexer in your presentation is a notch duplexer NOT a band reject duplexer. It’s not semantics either, it’s the correct identification of the duplexer design. I disagree that the NANOVNA is not suitable for tuning the duplexer. It certainly is if you have ever tuned one and is confirmed in your video. What you cannot measure with the NANO is exact amount of notch depth but this isn’t important if the minimum point of the NANO is set to the frequency desired as notch depth and notch skirts will be properly set and tuned based on the cavity Q.

@w2aew

3 жыл бұрын

Thank you -- I appreciate the clarification of the duplexer type, and my mis-characterizing it as a band-reject. I understand the difference, and it was verbal sloppiness on my part. I guess my concern in not being able to see the notch is that the actual notch position (below the visible noise floor) might be a little tricky to determine if the shape of the skirts on either side of the notch are not symmetric. Do you agree with this? At the very least, it may make it harder to align each of the multiple cavities I would think... It sounds like you've done this more than I have, so I defer to your experience on this.

Would attenuating the amount of signal to the duplexer show a better plot of where the duplexer is tuned at? TNX again for another great video! 73 N8AUM

@w2aew

3 жыл бұрын

No, I don't see how attenuating the signal would help. The only thing that would do is present a good broadband load to the stimulus.

Considering the equipment costs involved, most people cannot afford to use the professional equipment so the nano and its results are much much better than nothing at all. So the professional equipment does a better job but at what cost ???

Do you know if the SAA2N has an option of 401 points too?

@w2aew

3 жыл бұрын

Not yet, but I would think that one of the software developers (maybe DiSlord) may come out with that at some point.

@dg9bfc

3 жыл бұрын

511pt with new fw from dislord

If u have a few dollars invest in a Kc901s+ by DeePace. Amazing unit and can definitely tune filters easily.

@w2aew

3 жыл бұрын

Hmmm - $1400 is a little more than a "few" dollars!

40db of additional dynamic range for 40db increase in VNA price.

I'm no RF engineer, but I am curious about the possibility of using the averaging of high numbers of samples to reduce the noise floor sufficiently to tune duplexers. I realize that it would seriously slow down the alignment, but I have a lot more time than I have the sort of money that a professional VNA costs. So I'd be willing to take my time with the alignment if the technique actually worked. Would it? The reason I am curious about it is because high numbers of sample averaging worked very well for digging out weak BPSK signals from my Longwave beacon transmitter, and it seems like the same sort of problem.

@w2aew

2 жыл бұрын

Averaging can help, but isn't a cure all.

🙏🙏🙏👍🙏🙏🙏

Many many years ago I had an idea to build a sine wave synthesizer which can generate all the nth harmonics of the fundamental frequency (tunable) simultaneously. The idea behind is a musical application, the effect of a plucking string, but I failed to do it. Wanted to make it all with analog technology. Can you do a video on that?

Hola,¿ vna sv4401a review ? Saludos.

Only to your information, the latest firmaware from Nano SAA-2N give us a 90dB of dinamic range...not so far from your TTR...

@w2aew

2 жыл бұрын

Is this the latest from Dislord? What version?

Can you make a video with a paper telling the difference between Diplexers and Duplexers and examples of what both are used for to get a theory of operations on both. Why are you tuning the duplexer filters using S11 return loss? Why doesn't the NanoVNA have the definition to go all the way down to -100dB or more even if you change the scale to 20dB per division it still won't give the same results is because the front end or what in the NanoVNA is preventing this? Do you think a newer firmware update will fix this problem or its the ADC/DAC converters that is causing this issue?

@w2aew

3 жыл бұрын

There are many factors (phase noise, isolation and shielding, quality of couplers, etc.) that affect the dynamic range of a VNA. Addressing all of these things gets costly, which is why VNAs with 120dB of dynamic range cost a lot more money than a NanoVNA.

@waynegram8907

3 жыл бұрын

@@w2aew ok thanks, I never looked into the specs of VNA about dynamic range. When looking at the specs of a VNA how do you really know that the dynamic range is going to be working good with 120dB or 150dB dynamic range? because the specs can be false and say it has the dynamic range until you put it to test to really find out if it works or doesn't. I don't know what other RF components or RF circuits that would want to measure a Dynamic Range of 100db to 150dB besides Duplexers. What other RF circuits would you want to use a very big Dynamic Range for testing and tuning for?

@w2aew

3 жыл бұрын

@@waynegram8907 Duplexers and other high-rejection filters are likely some of the more demanding devices to test with a VNA. You have to interpret the manufacturers specifications very carefully when looking at dynamic range performance to be sure that it will meet the performance you need.

@waynegram8907

3 жыл бұрын

@@w2aew thanks, I never ran into that problem before I overlooked it. I have only used old 80's HP network analyzers and never had a dynamic range issue. The Rejection filters and Duplexers I guess I have tuned didn't go all the way down to 120dB to 150dB when I was tuning them. I'm guessing not all Duplexers and Diplexers rejection filters have the same dynamic range. I never thought about a Duplexers and Diplexers Dynamic Range criteria specs.

Would you say the Rigol DSA 815 TG is up to this task?

@w2aew

3 жыл бұрын

Not sure of what dynamic range it has, so I don't know.

Please write down on sharpe the freqs on that duplexer, i've had those little red and green wear out or fade off!

Alan can you give a link to the SAA-2N that you purchased? --KE4EST

@w2aew

3 жыл бұрын

www.randl.com/shop/catalog/product_info.php?products_id=75242

@ke4est

3 жыл бұрын

@@w2aew Thanks Alan.

Can you tell us more on the firmware for H4 with 401 points. Tks Dan KCC4GO

@w2aew

3 жыл бұрын

I found it here: groups.io/g/nanovna-users/files/Dislord%27s%20Nanovna%20-H%20Firmware and in the message threads on the same group.

They really need to work on instructions and nomenclature tho!

@w2aew

3 жыл бұрын

Agree! At least the NanoVNA-F properly calls the ports Port1 and Port2. Whoever came up with the CH0 and CH1 nomencaluture!?!

Hi Alan. Regarding the nanoVNA H4. I know this is an older video. I was wandering did you have in this firmware version the possibility to select bw? Maybe you don't recall it anymore... I bought a H4 about some half a year ago, and see I have pre-installed fw version @Dislord @edy555 1.1.01 from 30 Dec 2021. I have noticed on your screen CH0 and CH1 (and on mine S11 and S21 instead) and have seen on developers site they changed that from version v1.0.63 dated 30 May 2021.. Regarding the bw (in this v1.1.01) I can go as low as 30Hz. It doesn't really lower the noise floor (better dynamic range), as I have expected, compared with 1kHz (on the same range you used in this video), but rather the signal/trace is much less noisier (I have just an open CH1 connector and measuring the noise floor). Also I see you have 7.5 vertical divisions, and I have 7. I will try now to upgrade to the latest fw version v1.2.20 from 12 March 2023. Do you know by chance are there differences in fw these days for this little unit, regarding DiSlord and Hugen (as I am not an advanced user yet) and just try to understand?

@w2aew

6 ай бұрын

I haven't changed the firmware beyond 1.0.69 yet, so haven't really looked into the changes. Since you stated that changing the BW to 30Hz didn't lower the noise floor, I suspect that this is a video (post-detection) filter, not an actual IF filter. I really should update my unit too ;-)

@ernestb.2377

6 ай бұрын

@@w2aew Good point about the VBW! One other thing that I am confused about is the usage of Reference Position. I was mistaking that for Reference Level, as I know from Spectrum Analyzer. It seems that this function works differently, in the way I don't really understand yet. I read that the newest (beta) version v1.2.26 has more settings possibilities as Top and Bottom value.

@w2aew

6 ай бұрын

@@ernestb.2377 Right- Reference Level on a Spec An sets up the signal level at the top of the display, and also ties into the setting of the front-end attenuator value. The Reference Position on the NanoVNA simply is a display offset which tells the analyzer which horizontal line will be the the 0dB value. It does not change or alter any input attenuation or anything like that, because the NanoVNA doesn't have any of that.

@ernestb.2377

6 ай бұрын

@@w2aew Indeed, I see know, Reference Position shifts the 0dB point up and down the screen (0 the bottom gird line and 8 the top grid line). Lower or bigger numbers than 0-8 takes it off the screen...

Can't you put an attenuator inline to stay within the dynamic range of the device?

@w2aew

3 жыл бұрын

I don't see how adding an attenuator would help you "stay above the noise floor". If anything, it would push your signal/measurement deeper into the noise floor.

@justanotherguy3850

3 жыл бұрын

@@w2aew :: it reduces the amount of power so you don't end up pushing the bottom of the noise floor. It doesn't give you an accurate reading but it's simple. If you use a 10 dB attenuator you will add that to the amount of attenuation when you look at the final

@tomasguerrero6576

3 жыл бұрын

@@w2aew this is a common technique to make sure that you're not overdriving your signal and pushing it into the area if the bottom other range than NanoVNA. If it doesn't have the dynamic range you put less signal into it and you can still tune down further than without. You may have to increase the amount of attenuation on the signal sampler to keep the signal a bit noisy as you improve the pass band tuning, doing this will allow you to heard the gains made. Continue with this procedure until no more improvement can be heard.

@justanotherguy3850

3 жыл бұрын

@@tomasguerrero6576 :: that's exactly what I was talking about but apparently we're not allowed to ask questions of the Master. I posted a question that didn't really deserve getting snapped at. I know that it's not uncommon to use an attenuator with a spectrum analyzer when tuning a duplexer. The Master could have simply answered the question minus the sarcasm.

@w2aew

3 жыл бұрын

@@tomasguerrero6576 This technique works when trying to tune the bandpass response, but does not help when trying to tune the notch depth.

I'm really curious how a SV4401A would do in the same comparison. 🤔

@w2aew

2 жыл бұрын

It would probably do quite well, given its specifications (and price tag).

@Garthinyus

2 жыл бұрын

Seems quite the bargain, if it can be compared to the functionality of the pro units.

Instead of finding good uses that these vna's are good for, it seems everybody who is testing these nanovnas want to find all the limitations where the vna is not good for. Negative outcome tests are getting old.

You stated that with the Nanovna it isn't possible to adjust a duplexer for maximum performance at given frequencies within the designed operating range. I completely disagree since it is not necessary to actually "measure" the magnitude of the notch in the example of your demonstration but the position of it specturaly. The Nanovna will do this however, even though it cannot measure the magnitude of the actual notch depth, that is not important for proper adjustment. Once the notch is properly set within the center of the frequencies of the notch, that is all that is necessary since the design of the duplexer will provide maximum attenuation assuming the duplexer is properly functioning. If it isn't the nano will show this too. There are more measurements errors caused by improper field instrumentation than anything else. Moreover, a VNA for field application such as that for amateur radio requirements is super overkill since only return loss S11/S22 and transmission loss S21 are the primary parameters of interest which a scalar analyzer will provide quite accurately. Finally, the use of "Band Reject" is improper since the filters are tuned for a specific notch frequency, hence the correct name is notch duplexer, not band reject duplexer. Otherwise a very nice and informative presentation. :-)

@w2aew

3 жыл бұрын

Thank you for your helpful critique and clarification, very much appreciated. I understand what your saying regarding it not being important to know the actual depth of the notch, but just to know that the notch is set at the correct frequency. I assume that you'd determine this by looking at the midpoint between the frequencies where the S21 hits the noise floor of the unit. My question is, how common is it that the shape of the S21 curve is not uniform around the notch, such that the actual notch frequency is a little higher or lower than the midpoint between the visible portions of the curve? Keep in mind that I am approaching this from my own very limited observations, since I don't have much direct experience tuning many duplexers as it sounds like you have.

@bkj242

3 жыл бұрын

The exact position of the notch is a function of the notch duplexer tuning. The maximum notch depth is a function of the coupling of the two filters but primarily determined by the Q of each filter. It’s placement is determined by the tuning of the two filters. The rigid RG142 is used to minimize losses and to preserve the integrity of the harness given the environment of the intended application and to increase yield in production. I hope that was the characteristics you were describing in your question. If not let me know.

@w2aew

3 жыл бұрын

@@bkj242 Let's see if I can make my question a little clearer. When tuning the notch frequency, if the analyzer's noise floor prevents you from seeing the full shape of the filter, thus obscuring the "peak" of the attenuation, then you have to make a judgement call as to the actual notch frequency based on where the skirts of the filter crash into the noise floor. My question is - the shape of the skirts on either side of the notch may not be the same (have the same slope), thus the actual notch frequency might not be midway between them. How much of a problem would this be? Or, are you suggesting that you try to measure each cavity individually so that the notch isn't as deep and more likely to be set correctly with a more budget friendly instrument?

@bkj242

3 жыл бұрын

@@w2aew the shape of the notch displayed on a lab grade VNA will be noise free and should be symmetrical with a defined notch width free of noise. Since that resolution cannot be supported on the less expensive field type VNA the resultant shape of the skirt will not appear to be symmetrical which is what I believe is your observation you describe.

yeah no ish, a $100 unit wont be near the same as a $16,000 unit. lol

Well.......that Sucks ! 🫲☹️🫴 But there again like you mention ! Not a Commercial, or Professional unit, but made so the Radio Amateur may find value ! If nothing else, it may help with the understanding of the Smith chart ? Having said that, it may be reckless, but if you can get those Cans that close, especially that far down DB wise, couldn't you tune the rest by ear ? Or even call it good ? Speaking from an Amateur Radio perspective, that is !