miniVNA Tiny, what am I doing wrong ? - Page 1
Forum section: electronics / rf-microwave

author: cgroen
author_rank: Unknown
timestamp: November 22, 2019, 03:52:30 pm
content: Hi all,I got my first VNA, a miniVNA Tiny from miniradiosolutions.Now, as this is my first VNA (I have a basic understanding of it, I can use my spectrum analyzer etc, so not totally lost) I feel that either I'm doing something wrong, or there is something wrong with the miniVNA (I hope the firstI have gone thru the calibration steps (open, short and 50 ohm).I can basically go thru the calibration procedure, save the file and press "update". When I then do a "single scan" with the 50 ohm load on the DUT port, I get a "ok'ish" scan (I think). Now, if I then load the calibration data that I just created, things starts to look very strange! I get a large "spike" (when looking at Z) around 1525 MHz. If I then do a calibration again, save and update data, the scan looks again ok (without the spike at 1525). If I load these data again (stop/start the program, load calibration), I get the same spike around 1525 MHz again.What am I doing wrong ? I also did some tests at "short", same story.....(I also get a smaller spike at 1044 MHz as seen on the screendumps...)Is anyone able to tell me what (could be) wrong ?? Does the miniVNA Tiny go back again or whats the deal ?I hope the screendumps names below makes sense......

author: OwO
author_rank: Super Contributor
timestamp: November 22, 2019, 04:22:52 pm
content: Wow, that looks like more noise than even the Nano. I don't own a miniVNA myself but if you search you can find plenty of threads discussing its performance on this forum. I also have another sub-$300 VNA and looking at |Z| after calibration gives 50.0ohms +/- 0.05ohms all the way to 3GHz, so I'm surprised by the graphs you posted.

author: cgroen
author_rank: Unknown
timestamp: November 22, 2019, 04:43:58 pm
content: I'm not (yet) able to feel if there is a lot of noise or not, right now I'm trying to figure out the basicsAnyway, it seems that the 1.045 and 1.5 GHz spikes are to be expected, page 12 herehttp://download.dl2sba.com/vnaj/manuals/Driver/DriverGuide_miniVNAtiny.pdfmentions it. There is a "peak suppresion" setting which is on by default, in my case it seems not to have much to say....On the other hand, in the PDF the example with and without the setting only have a small difference, in my case it is much much more dominant....Not really sure whats going on....

author: Emo
author_rank: Regular Contributor
timestamp: November 22, 2019, 04:54:50 pm
content: Hi,I did experience the same when using VNA tiny 3.3.2 in combination with java OpenJDK 12.0.1. Using VNA tiny 3.2.10 is working perfectlyEricEdit; typo in version nr

author: cgroen
author_rank: Unknown
timestamp: November 22, 2019, 05:01:26 pm
content: Quote from: Emo on November 22, 2019, 04:54:50 pmWow, interesting!Where did you fint version 320 ?I'm not able to find it here:http://download.dl2sba.com/vnaj/

author: cgroen
author_rank: Unknown
timestamp: November 22, 2019, 05:11:57 pm
content: Using version 3.2.10 instead of 3.3.2, I get a different result!The spikes are gone when "peak suppresion" is enabled in the "info menu", if I uncheck the "peak suppresion" they are there again.