Two Questions
 

Reg this has to be a troll question. I am sure you
know the impedance of a
transmitter can be almost anything. Usually an ohm
or so for transistor
transmitters and a couple of thousand for a tube .
It is then matched to
whatever load is hooked to it.

I have no wish to be unkind but I'm sorry to say it is
your response which is likely to be considered a troll.

In any case, the question was "Is the internal
resistance of a transmitter 50 ohms or is it not 50
ohms?". The correct answer is "It is not 50 ohms." Now
let's get on with Q2. ;o)
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Reg, G4FGQ