VNA Recommendations Please

Discussion in 'Ham Radio Discussions' started by N4MU, Jun 6, 2021.

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  1. N4MU

    N4MU Ham Member QRZ Page

    Started doing some research on a VNA. I have read a few threads but still have some specific questions about them. Thanks in advance for any suggestions and answers.
    1. I have always used an MFJ-359 for SWR msmts. Will a low cost VNA do the same?
    2. Can I narrow any sweep down to band only, or even portions of the HF bands to "see" SWR sweeps
    3. Are all cheap ($50 to $150) VNAs the same. Do they all have internal signal generator for making msmts without any external TX source (like the 359)? Don't need anything greater than 450MHz BTW.

    I'm familiar with most test equipment - TDRs, SpecAns, etc., - (lifelong profession) but have not ever used, or seen, one of the new cheapie VNAs. I don't need to do lab type research. I just want to see what the antenna/line is doing across a frequency range. Thanks again!
     
    KC1OCA likes this.
  2. W4NNF

    W4NNF XML Subscriber QRZ Page


    If you don't need a laboratory grade instrument, do yourself a favor and get a nanoVNA. It'll be the best 50 bucks you've spent in a long time, and in concert with a laptop computer, it is pretty darned powerful. :)


    View attachment 802915 upload_2021-6-6_8-16-44.jpeg
     
  3. W7HV

    W7HV Ham Member QRZ Page

    1. Yes. Better than the MFJ ant analyzers in many respects. The basic design is a signal generator and two RXs with directional couplers that measure amplitude and phase. For SWR you only use one. For characterizing filters and such you use both vna ports and RXs.
    2. Yes. You get up 201 points across the screen (configurable) over any frequency range you set with a resolution down to 10 kHz. 100kHz sweep works well on ants with a narrow resonance.
    3. No. A big no. There are a number of different designs and versions with differing performance capabilities and characteristics, and a lot of knockoffs of those designs that often don't work as well. Software is mostly open source and contributed to by a number of developers. The whole situation is pretty complicated. Perhaps the best thing is to do is go https://groups.io/g/nanovna-users.

    I recently got a nanoVNA V2 Plus 4 and am very happy with it for my purposes. Later designs like the nanoVNA H and H4 are out there too.

    Here's the legitimate site for the one I got. https://nanorfe.com/nanovna-v2.html
     
  4. W4NNF

    W4NNF XML Subscriber QRZ Page


    I read the warnings about knock-offs, but in the end just bought the first one to pop up on Amazon (Prime). If it worked out, I thought I might look for the larger screen Plus, but I'm completely happy with the original. If I need a quick check out in the field or at an antenna, I use the good, old MFJ 259. When I use the NanoVNA to find out what's really going on, I invariably use it with my laptop and the (excellent and free) NanoVNA Saver software, so the small screen on my little guy is not a factor. I will say that, yes, it's perfectly possible to just use the smaller VNA and rely on its little display. It's quite clear even for my failing eyes. but the software really takes this thing to the next level. :)
     
  5. N4MU

    N4MU Ham Member QRZ Page

    Arghhhh! Thanks for the info all. My head is already swimming with several versions I have seen on Amazon. I'm waiting for Prime day anyway so I have time. Looks like the 4" screen is really a bit over priced for the feature. We'll see. Now will look over specific links that you folks sent. Thanks...I'm seriously learning...and getting over whelmed by choices.
     
  6. N4MU

    N4MU Ham Member QRZ Page

  7. KO4LZ

    KO4LZ XML Subscriber QRZ Page

    I work in RF test and measurement equipment and have access to (quite literally) the best vector network analyzers that money can buy. That said, I've been very satisfied with my NanoVNA for amateur radio / hobbyist applications. Granted, it's not the most user-friendly form factor (mine has tiny, flimsy controls and the screen is very hard to read in direct sunlight), but for $50 it will do what most amateurs need from a VNA.

    For comparison, an entry-level professional VNA would set you back at least a few thousand and you can easily spend over $100K on a higher-end VNA.

    ZNB8 and NanoVNA.jpg
     
    W4NNF and WZ7U like this.
  8. KL7AJ

    KL7AJ Ham Member QRZ Page

    The first VNA I ever used was a $45,000 HP instrument. The NanoVNA does 99% of what the HP did (25 years ago) at about 0.1% of the cost. I am still amazed.
     
    KC1OCA, WD5GWY, KO4LZ and 2 others like this.
  9. N4MU

    N4MU Ham Member QRZ Page

    Yes, I've used the H-P...Wow! It actually had four color traces on the CRT! It was a LONG time ago and as I recall was a 4 port we were using for TV xmtr DTV filter tuning, etc. Don't know the number but I'm sure it was similar if not the same.
    BTW, thanks to all who responded. I'm getting smarter (I'm telling myself that) and even downloaded the "Dummies" file from groups.io (Basic primer). At this point am considering going for the 4" screen dash F model. Thanks!
     
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    ^I agree, and my first VNA was also made by HP, back when I worked in T&M engineering decades ago.

    I have a nanoVNA and it has some limitations but it's an amazing instrument.

    That said, there isn't a single piece of test gear at any price that made my signal 1 dB stronger anywhere.:) I like Walt Maxwell's take on "Too Low An SWR Can Kill You." Well, it never killed me and I'm still here, but low SWR is about #8 on the 10-list of important things for an antenna.:p
     

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