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Kirkby calibration kit alternatives?

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G0HZU:
To demonstrate this I dug out an old library file of a 1000R 0805 chip resistor and this was measured with my DIY cal kit up to 3GHz.

Note the scale for resistance is 5 ohm/div and it is measuring parallel Rp and Cp (not series Rs and Rs).
So this should look like 1000 ohm in parallel with about 0.08pF up to about 1GHz before the parasitics begin to change things. This is with a cal kit that does not have Lx corrections for the SHORT so I had to optimise the SHORT by other means.


How would this compare to others on here? Have you ever tried to measure a chip resistor like this? You need a very good VNA and an accurate cal kit and SMD test fixture to do this and get data as smooth as this over a wide bandwidth :)

G0HZU:
Here's an old plot of a precision 32.4k chip resistor. I'm pushing the VNA to its limits here so the data is noisy and there will be a fair bit of uncertainty in the setup. But it managed to measure 32k4 with a flat response up to 100MHz. With a 100k resistor it gets really noisy but it does still manage to give a reasonable measurement.

This is with a DIY SMA cal kit made from scrap parts but with careful manufacture and a decent USER cal file.

Mechatrommer:

--- Quote from: G0HZU on February 22, 2018, 07:45:30 pm ---The results for the short aren't as good because there aren't any Lx corrections in the data. But it is still good considering it is using SMA based connectors in the SHORT. It would be easy to correct this for VNAs that support Lx coefficients and if a VNA supports this feature then I guess these would be included in the data?

--- End quote ---
i cant see any inductance effect for SHORT in any kirkby calibration data including the master file from where everything else are derived. so i guess his measurement setup is not supporting that, or consider the effect negligible. albeit not perfect, i can say ±0.5 degree error is good enough for me i guess (my VNA systematic error will be much worse from what i figured out so far). thanks for all your reports and findings..

G0HZU:
That's OK. Note that I had some free time today and had a look at your male OPEN and SHORT data in your custom correction file and the bundled S1p files. The male SHORT doesn't look as good as the female SHORT in your kit. There's a bit more phase shift in the male SHORT and although it's going to be better than an uncorrected kit, I'm not so impressed with it.

I generally prefer to use female cal kits because this is good for calibrating for non insertable devices that have SMA female connectors. But for insertable devices it's common to use both kits for a calibration. So I kind of ignored the male standards in your kit until today. There may be a way to improve this performance but I'd have to have one of these kits here to play with it.

hendorog:
This is a bit left field, but bear with me as it could be a simple method to get a better characterised cal kit ...

I have an SDR kits cal kit which is only supplied with electrical delay values. It has no fringing capacitance coefficents.
The open standard in the kit is just a dust cap. It has no effect on the measurement, at least not significant enough to matter.
Therefore the open standard is just the open female SMA adapter which I have on the port of my test set.

Taking a punt here and assuming that the female SMA adapter (which came with the Rosenberger SDR kit) I have is very similar to someone elses.

Therefore, could someone with a nice cal kit (G0HZU?) do me a big favour and sweep an open female SMA, and post the S1P file?

Then I'll take the file, try and run it through the script and see what C0,C1,C2,C3 values come out. Then put them into the VNA and try it out.

The short and load are already covered - there are no L0,L1,L2,L3 fields in the old VNA's for shorts, so I can't input those anyway.
Since I already have the delay for the short, so that is the best I can do for now.

I already have the SDR Kits load, as well as several non-precision 18GHz Inmet loads from eBay, out of which I have selected a few which measure quite close to 50 ohms at DC. The best I can do here is hope that they are still close enough to 50 ohms up to 6 GHz. At least they all compare sensibly with each other and with the SDR Kits load.

Anyone still with me? :)

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