Reg Edwards wrote:
If the source is not what the meter expects then it gives the wrong answers.
And its faithful worshippers believe it!

If reflections are not allowed to reach the source (typical of
most ham installations) the source impedance cannot have any
effect on the SWR meter readings. Most ham installations are
Z0-matched to 50 ohms thus eliminating reflections between the
Z0-match point and the source.

You are describing systems where reflections are allowed
to reach the source which is atypical of ham installations.
--
73, Cecil, W5DXP