"Jeff" wrote in
.com:

If you used a TDR, for example, to look at the set-up you would see 2
points of discontinuity, firstly at the 100 ohm source to 50 ohm cable
interface, and secondly at the cable to 200 ohm load. BOTH of these
discontinuities add to the overall mismatch as seen by the 100 ohm
load.

Your TDR does not work in the steady state frequency domain space, and is
misleading you.

In the steady state, the (complex) ratio of forward voltage to reflected
voltage is determined solely by the load impedance and characteristic
impedance of the line.

In crude terms, during establishement of steady state, you can view that
a load end reflected wave which is then partially reflected at a
mismatched source end, will reach the load end and be reflected in the
same ratio as the earlier passes. The subsequent round trips as steady
state is approached do not change the (complex) ratio of forward voltage
to reflected voltage in the steady state.

I know you have support here for the assertion that source end mismatch
affects VSWR in the steady state, but you won't find it in reputable text
books.

Owen