DIY VNA Electronic Calibration Tool with in-built Test Fixture

RE: DIY VNA Electronic Calibration Tool with in-built Test Fixture

Fred27 — Sat, 11 Sep 2021 08:51:42 GMT

Ah - if the switch remains between the VNA and DUT after you've calibrated then that makes perfect sense. Well, as much sense as RF witchcraft ever makes!

RE: DIY VNA Electronic Calibration Tool with in-built Test Fixture

Fred27 — Fri, 10 Sep 2021 21:02:12 GMT

Awesome board and a nice explanation of it's use. I see how useful this board would be for switching between your open, short and load outputs for calibration. Much cheaper than a ZN-Z103 too!

I hope you don' t mind me asking a very basic question. I have a limited understanding of RF so have probably missed something, but as far as I understand this is so you can calibrate the VNA and take into account any effects from the cable to your DUT. However, doesn't this RF switching unit have a significant impact on the measurement? When you remove the RF switching board, doesn't that invalidate your calibration? I'm sure even a very professionally made board like yours can't be a perfect transmission line, and I have even wondered in the past whether the similar off-the-shelf Peregrine PE42441-EK I've used for a previous project made a difference.

RE: DIY VNA Electronic Calibration Tool with in-built Test Fixture

geralds — Fri, 10 Sep 2021 16:25:33 GMT

Hi [mention:b0bc65b9ecdc4307bd967592f00e340a:e9ed411860ed4f2ba0265705b8793d05] ,

Thank you very much!

Your video was very informative for me.

Do you remember about my road test? I built an DIY SMA-calibrator?

FPC1500 Spectrum Analyzer - Review | element14 | RoadTests & Reviews

The Texas type is very useful; I'll buy it.

And,,, is this true? - the distances of the SMA's you made on the RF-switch where because the Texas VNA-calibrator. [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-3b6d255c-74c0-495a-bc4c-5131f0d3caee/contentimage_5F00_3.png:16:16]

Because every time I thought about "why made shabaz this distances on the board? I can surely put them a bit together closer?" [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-3b6d255c-74c0-495a-bc4c-5131f0d3caee/contentimage_5F00_1.png:16:16]

Best Regards

Gerald

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RE: DIY VNA Electronic Calibration Tool with in-built Test Fixture

baldengineer — Fri, 10 Sep 2021 15:24:10 GMT

Excellent post, as always. I looked at making my own calibrator for the FPC1500 a couple of years ago. I got stuck at the InstrumentView step. I wasn't sure of a good way to determine the values for the calibration file.

Eventually, I abandoned the idea because I found a fantastic deal on a used electronic calibrator, which is what I use on my FPC now. I would like to come back to making a OSL fixture at some point though.

I always thought it was comical that R&S recommended the FSH-29FSH-29, which costs 700 USD. While the FPC1500 FPC1500 (Complete) is 5000 USD. The OSL is almost 15% the price of a budget VNA!

RE: DIY VNA Electronic Calibration Tool with in-built Test Fixture

genebren — Fri, 10 Sep 2021 15:08:39 GMT

Awesome post! I really like your design, especially the control circuits, very clean and simple and requires no programming.

Well done!

RE: DIY VNA Electronic Calibration Tool with in-built Test Fixture

neuromodulator — Fri, 10 Sep 2021 14:37:02 GMT

Great post! Do you have any link to TI's board?