All,
I am on a quest to 'analyze' the original 104 G board. This was replaced
by the 104a that was completely redesigned. This board has a bad rep as
being a poor performer, I would like to figure out why. At the end is
the question: was it more the result of 'system' level selections such
as parts or filter design, or was it more the result of detail level
design.
This leads to the questions:
1. How can the impedance of an amplifier stage be estimated? For
example, if the collector of a 2N5109 is biased at 1000 Ohms and the
emitter is DC biased at 500 Ohms and RF biased with a .005 uf is it
reasonable to assume the output impedance is somewhere near 1000 Ohms?
2. If the base of the same stage is DC biased by 8200 Ohms to +12 and
3300 Ohms to ground how can the input impedance be evaluated? Is it very
low due to the RF bipass?
3. How can the effective input impedance of G1 and G2 on a 40673 be
estimated? The inputs are DC biased by values of 10k to 100k.
Sorry for the basic questions, thanks in advance.
Dan - kb0qil
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