I note the subject matter of this thread is "Insertion Loss"

Insertion loss is the ratio of power delivered to a load, to the power
delivered to the same load when a network is inserted between the load
and the same generator.

With insertion of a passive network, such as a tuner, the insertion
loss can even be a gain.

Calculation or measurement of insertion loss ALWAYS involves or
implies knowledge of the generator impedance. In the present context
the generator is the transmitter.

As nobody knows the internal impedance of the transmitter this thread
will rapidly degenerate into nonsensical argument if it hasn't already
done so.

You have been warned!
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Reg, G4FGQ