I am trying to set up lab equipment to measure my soon-to-come sample, but I couldn't get my mind around one thing, impedance termination. I will tell you what I have, what I want to get, and my concerns. My probes are already connected to coaxial wires that are terminated by trixial connectors. However, my oscilloscope/function generator/etc all have BNC connectors. So i need to get a triaxial to BNC adapter. my concern is, do I get a 50 ohm or 75 ohm adapter. What is it based on? The function generator? The coaxial wires I already have? how do I know if it is terminated by a 50 ohm or 75 ohm? (I cannot get in contact with the person who ordered them, nor i have their datasheets, they are just there and I have to figure it out with what I have).
I understand that they nature of my measurements are also important. But I am not asking if I have to change the wires I already have, I want to work with them, and then maybe change them latter to what better fits my measurements. Most of my measurements are DC. so does it matter at this point? I do measure a square wave of about 300 MHz, is this considered high frequency?