On Fri, Mar 4, 2022 at 03:34 PM, Colin McDonald wrote:
It's a specific tool. One must use that tool as intended or it is no longer
useful.
I think we all agree with that :). My question is how to make it more useful (or easier to use) without breaking the bank. I hope the answer is to have a feature request for one of future releases that will "hardcode" SOL at S11 port, so I get Slot 0 back for other use :) 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.
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" :)
It takes seconds to perform a SOL calibration at the S11 port.
Not always true :) I sometimes need a quick measure when S11 port SOL is not an easy thing to do, and I forget to do it ahead of time :)
I've found the 3 measurements that hams need, SWR, Z impedance and capacitive
reactance to have very little variation between using a wide spectrum
calibration and a narrow calibration that is frequency specific.
I agree! The key problem I have is doing that calibration :) You are right, it's me, not the tool, but if that tool can make me better, or compensate for my shortcomings, why not :)
At HF frequencies, the coax is generally a factor in the antenna system so you
want to measure it along with the antenna for tuning purposes. You don't
necessarily want to calibrate each individual coax as you are trying to
calibrate a portion of the antenna itself at that point which doesn't give a
clear picture of what the radio is seeing at the shack end of the coax.
In general I do agree, but it's not that simple - sometimes I need SWR scan at the side of my RIG, sometimes I want to understand my antenna itself and then I'm willing to do proper calibration wherever needed.
For another thread - attaching a coaxial cable to my new antenna usually changes "everything" - complex Z, radiation pattern, ... That's why all my measurements at the antenna feed point have fairly good "balun" (current balun = CM suppression) that significantly limits the impact of the t-line to antenna "geometry". That's also why measuring at the RIG becomes necessity to understand (measure) potential impact of the t-line and to see what my TX is actually going to see
