Mike Coslo wrote:
"More it is about a tuner`s habit of showing a higher VSWR as the power
level is increased."

Standing wave ratio (SWR) is often called "voltage standing wave ratio
to distinguish it from the standing-wave ratio expressed as a power
ratio which is (Emax / Emin)squared' (From Terman`s 1955 edition
footnote on page 97).

SWR is a measure of the amplitude ratio of the reflected to incident
waves at the load. It`s a means of expressing the reflection
coefficient.

SWR is independent of power level or of transmission line length on an
ideal line. Just as a speedometer doesn`t require driving a mile or for
an hour for a valid mph reading, an SWR meter doesn`t require any
particular line length to present a valid mismatch reading at the
transmission line load, despite reasonable objections by Reg Edwards.
The degree of mismatch can be indicated by an SWR meter in the usual
case.

Power level is not an SWR factor but often plays a role in the
indication of SWR as well reported by Mike Coslo and his respondents.

Best regards, Richard Harrison, KB5WZI