I must confess, my curiosity got the best of me from Jose Carlos'
measurements. The question however still remains. I wonder what
the NF of a Norton amp does with real other impedances than the
regular 50 ohms used for evaluation. The curiosity of a Norton circles
around the fact that there is virtually no feedback when the input is
unterminated. I have studied K8ZOA and the original patent papers.
Again I confess I am not mathematician enough to solve the answer
theoretically. There are too many variables. The other curiosity of the
Norton is the fact that its input impedance assumes the value of the
driving impedance per the original patent paper.
One thing obvious from Jose Carlos' measurements
is that the noise goes way up when the amp is unterminated. This
would lead me to believe the noise would be greater with a larger
input impedance simply because of the Johnson noise of the larger
impedance.
This one is definitely on the list now as something to look at in
spare time.
Lee K7TJR
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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