Keith Dysart wrote:
Could you better describe how you determine that the source has a Z0
equal to the line Z0? I can guess that you use a Thévenin equivalent
circuit and set the series resistor to Z0.

This will do it.

We have a black box. We use a 12vdc battery and a current
meter to measure the impedance of the black box. The
current meter reads zero when we connect the 12vdc battery
to the black box terminals. What is the impedance inside
the black box since test V/I = infinity?

What is actually in the black box is a very low source
impedance battery in series with a 50 ohm resistor.

This is what you are up against when reflections arrive
at your source. The ideal voltage source does *NOT* exhibit
zero ohms. Gary Coffman once likened it to spitting down
a fire hose.

If the reflections are in phase with the source voltage,
the source exhibits infinite ohms to the reflections and
of course, 100% re-reflection results. The reflection
coefficient encountered by the reflected waves is variable
and depends upon the relative phase between the source and
the reflections. The series resistor has very little effect
on the reflection coefficient.
--
73, Cecil http://www.w5dxp.com