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Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Noise from a Class C Amplifier Posted: Fri
Jan 27, 2006 10:37 am
This might be a simple question,
but I need some assistance. I am looking at the noise generated by a
Class C amplifier (to keep things simple, lets assume it is has a 10
watt amplifier) and how to measure it.
Also I would like to
know if anyone has some suggestions about how to analyze the noise (instead
of measuring it, can I perform some calculations and get an approximate
Finally, has anyone tried to simulate the noise from
a Class C amplifier?
Any information will be appreciated - websites,
magazine articles, books, etc.
Post subject: Posted: Sun Jan 29, 2006 11:54
Joined: Mon Jun 27, 2005 2:02 pm
You can measure
the output noise of the PA by using Spectrum Analyzer. You first have
to measure the output noise when the PA is off, this result will be
used as reference point, you have to know the temperature at which it
was measured. Then turn on the PA and notice that the noise floor is
increased. Make these measurements at the same RBW.
between the noise floors at both cases is the gain of the noise + PA´s
Noise Figure. Of course that the noise is also dependent on the BW of
operation (RBW of the SA in this case) and the temperature according
After this calculation, you can deduce the self-contribution
of the PA to the noise measured.