hehe what i tried to demonstrate....
opamp1 output is benchmark signal.
opamp2 output should = opamp1 output if no significant loading.
my question... why we got bigger signal when probing after the yellow wire? compared to opamp1 (benchmark signal). i've proved that probing before the yellow wire ie at opamp2 output is equal to opamp1 output, not bigger.
so this should rule out my measurement setup (i think) and the suspect is in the yellow wire. what i tried to demonstrate is as Janne's statement said that i have to diagnose each stage, each output step by step to pinpoint where the problem is. since i cannot see any woobling respond in any output sma 1,2 and 3... so it must be in the yellow wire (sma 4). with this test setup, i am certain that the problem is in the wire, hence i'm asking standing wave question, not impedance control question. and my mind also buggered with why "1/10X wavelength rule" didnt work. ie if the cable length is less than 1/10X of the frequency wavelength, then we can neglect reflection? but not in my case here.
maybe you still dont get the point of the circuit that i've built. it a "highly evolved highly thought" "scientific instrumentation" test
, kinda like impedance analyzer, bode plotter circuit etc, except its simple, diy, and my own idea and way. this picture may help you to get to the idea. i beg you to give it some thought.
it is much like the internal components (i guess, conceptually) of the device that you have used to test the green aligator clips... the Agilent Technology "Stimulus Respond - Two Port Insertion Loss" test, except my circuit is way way cheap. you connect the aligator clips to the "Two Port" of your device... but for my device below, i need to solder the DUT to the "Two Port" as you can see at the bottom most of the pcb.