Erik, if I understand correctly, the purpose of the 1:9 balun is to reduce impedance by a factor of 9. So, presuming that I have a 450 ohm load at the end of the ladder line (which might not necessarily be true, under the circumstances), by connecting the VNA to the 1:9 balun, the VNA should report an impedance of 50 ohms, correct? Any deviation from 450 ohms at the end of the ladder line would show up as a deviation from 50 ohms on the VNA, at 1/9th the deviation at the end of the ladder line, correct? For example, if the actual impedance at the end of the ladder line were 900 ohms, the VNA would report an impedance of 100 ohms.
Yes, the ladder line is (nominally) 450 ohms, and the coax (nominally) 50 ohms. I am working to understand the use of a balanced matching network, the intended purpose of which is to transform the impedance of the ladder line to an impedance appropriate for the coax, but that is for another day.
I will have to study up on "TDR" mode - I get the general idea (impedance as a function of the distance from the measuring device to a specific location in the network), but I am not at all certain I understand it well enough to derive any significant information from its use in the present circumstances.
For the time being, I prefer to measure impedance at the location of each connection. I'd measure at the end of the ladder line, then at the coax side of the 1:1 balun, then at the end of the coax that would be connected to the ground buss, then at the other side of the buss, then at the end of the coax that would be connected to my tuner, then at the other side of the tuner, and finally, at the end of the coax that will connect the tuner to my radio... Whew!
