Roy, W7EL wrote:
"But source reflections have no effect on SWR."

That`s right. The load is going to take a fixed percentage of energy
imposed on it and reflect the rest regardless of the actual magnitudes.

All the source impedance can do is to affect the magnitude imposed on
the load.

SWR is based only upon percentage of energy reflected regardless of its
actual magnitude, not how big or small the energy making the ratio. 1/2,
2/4, and 4/8 are all the same ratio.

Cecil has a valid point. If Roy had a properly tuned tuner between his
transmitter and his feedline, the SWR seen by the transmitter would be
1:1, and that means no reflected energy reaching the transmitter.
Reflections reaching the tuner are either wasted in the tuner or
re-reflected by it if the tuner is properly adjusted and no reflections
make it to the transmitter.

Best regards, Richard Harrison, KB5WZI