On 5/3/22 06:03, Miro, N9LR via groups.io wrote:
Based on my very limited knowledge of this technology, calibration does "only" two things - accounts for t-line losses, and compensates for the effect of the t-line electrical length ("unrotates the complex impedance vector"). If I'm willing to accept lack of compensation for losses in the t-line, and also only need S11[dB]/SWR, and don't "care" about accurate (or even indicative) values of complex Z. If differences between individual nano's are minimal, and that does not significantly drives the need for calibration, I'd really like to have a single button somewhere in the menu saying "click here to SOL at S11" :)
Your requirement appears to be incoherent. Initially you said:
what is the quickest way to get calibration that will get me going quickly, without the need for SOL?
Now you're saying:
I'd really like to have a single button somewhere in the menu saying "click here to SOL at S11" :)
The answer to your initial requirement is to perform the calibration at your device ports as usual and save it into slot 0. That way, when you turn your device on, it's calibrated in a rational default which also happens to be what you've asked for and is about as quick an answer as you're going to get.
Your revised requirement no longer seeks "the quickest", but instead "single button". Presumably this is because you want the power-on default configuration to be for some other setup (you've mentioned other purposes without identifying them) and you want this "at the terminals" configuration to be available not by default at power-on, but readily accessible.
Is that a correct expression of your requirement? If so, presumably storing the at-the-ports calibration in any slot other than 0 is precisely what you're asking for. Then when you want to use it, you simply load the calibration from whichever slot you chose for this purpose. Does this address your requirement? Are you perhaps suggesting that the few seconds that it takes to get to a numbered calibration slot and retrieve it is a material inconvenience?
More broadly:
I see that as a perfectly realistic request, if (IF!) there are no known variations between individual devices when it comes to SOL at S11.
Well, yes, of course there are variations between individual devices, both at manufacture and throughout their service life. Whether you care about them depends upon your application of course. e.g. For most amateur radio uses, it is not necessary to recalibrate a digital multimeter throughout its service life, but that's not true for a lot of commercial/industrial lab uses. Whether the variations in your particular NanoVNA concern you will depend very much upon what you're doing. It's not even enough to say "for amateur use" as while for HF antenna evaluation it's probably negligible, for tuning a duplexer (as for an amateur band 2 m repeater) some precision is required.
- Roland 9V1RT
