John KD5YI wrote:


Transmitters don't have a clearly defined output impedance and, whatever
output impedance is there, doesn't necessarily mean anything.

Your main concern is to provide a 50 ohm load for the transmitter to see.

actually, to provide an *acceptable* load for the transmitter that
maximizes radiated RF power. That might not be 50 ohms.. and I don't
know that we actually care what it is, unless we're designing amplifiers.

50 ohms is basically a "standard test condition" so that you can compare
amplifiers, and it happens to be convenient that everything is made with
the same standard impedance. That way, your test load (which will
dissipate a fair amount of power in some tests) can be located somewhere
different, and connected by a length of transmission line with the same
impedance, so the test at the amplifier output reference plane is still
valid.