Richard Clark wrote:

W5DXP wrote:
So how do you get the reflections in a single source system to be
incoherent?

Two reflective interfaces with an aperiodic distance between.

That won't do it unless the distance between them is somehow
dynamically changing. For fixed distances, steady-state signals
will be coherent.

The example of the challenge serves to illuminate (pun intended) the
logical shortfall of those here who insist that a Transmitter exhibits
no Z, or that it is unknowable (to them, in other words), or that it
reflects all power that returns to it (to bolster their equally absurd
notion that the Transmitter does not absorb that power).

This is a convenient rule-of-thumb, nothing more. It solves the
problem of something being unknowable. A source obeys the rules
of the wave reflection model. Unfortunately, we don't usually
know the exact value of source impedance seen by the reflected
waves. Thus, the rule-of-thumb.

Engineers and scientists simply converse with the
tacit agreement that the source matches the line when going into the
discussion of SWR (and why Chapman plainly says this up front on the
page quoted earlier). This is so commonplace that literalists who
lack the background (and skim read) fall into a trap of asserting some
pretty absurd things. It follows that for these same literalists, any
evidence to the contrary is anathema, heresy, or insanity - people
start wanting to "help" you :-P

I agree with Chipman on that.

Now, be advised that when I say "accurately" that this is of concern
only to those who care for accuracy.

That's the part I don't understand. You can assume a whole range of
impedances for the source while the forward power and reflected power
remain the same. Is "accuracy" somehow involved with efficiency?
--
73, Cecil, W5DXP