Smith Chart impedance incorrect

[Charles]

I have noted on numerous occasions where the impedance shown on the Smith chart does not agree with the reference Zo entered in the main screen. I have not been successful in isolating a sequence of events or keystrokes that causes this to occur. If I perform a scan at one impedance, say 50 ohms, then change to a different impedance for another scan, the Smith chart impedance will not always follow. Sometimes it does, but more often than not it will be incorrect. I am using the latest version of the program. Most of the scans I perform are either 50 ohm or 580 or 600 ohm scans. I would expect the Smith chart reference impedance would always agree with the main screen. I have reinstalled the software, but that doesn't seem to help.
Am I missing something, or is this a software bug?
Thanks, Charlie, K4ZRJ

[w0qe]

Charlie,

I don't what you could be doing wrong. The reference impedance has nothing to do with making scans and is only used when making plots. It is changed in the main window under the setup tab and then displays in the right side of the main window anytime there is a vertical blue cursor in the main window. Likewise the reference Zo is always displayed in the upper left corner of the Smith Chart.

Are you saying that the SWR reference as shown on the right side of the main window does NOT match the SWR reference shown in the upper left corner of the Smith Chart window?

I tried in ver. 6.84 and 6.85 (not yet released) and could not get the reference impedances to be out of sync. Have you isolated what sequence of operations produces the problem?

73, Larry, W0QE

[Bob]

I was not able to reproduce this condition but I've added a bit of code to make it stop doing that. Charlie reports that it fixed the problem. That will be included in the next program release.
--73/Bob

[n7zo]

I just got my AIM4170C. Wow, what an instrument! I am very impressed and have all sorts of measurements I want to make.

But back to the subject at hand: I am running program version 684A (the latest) and my Smith chart was initially also calibrated to a different impedance. By default, the Smith chart was at 600 ohms and the rest of the program was at 50 ohms. I changed the Z0 a few times and the Smith chart remained at 600 ohms until I also set Z0 to 600 ohms. After that the Smith chart seems to track Z0 correctly. This is now only a small annoyance now that I have a work-around, but thought Bob would want to know.

Again, a great instrument. And I have found many valuable suggestions on this forum.

73, Bob Wright

[Bob]

The Smith chart reference impedance has been fixed in the latest version, I will upload that in a few days.

It also fixes the situation where message boxes sometimes pop up behind windows.

-- 73/Bob