I read in sci.electronics.design that Ken Smith
wrote (in )
about '1/4 vs 1/2 wavelength antenna', on Wed, 2 Mar 2005:
In article , gwhite wrote:
[...]
You entirely missed the point. You don't know the output impedance because you
don't have a way of determining it by swinging the output full-scale.

You don't have to swing the output full-scale to measure the impedance.
Any change in the load, no matter how small, will cause a change in the
output voltage and the output current. From these you can calculate the
output impedance at the current operating point.

When a transistor is operating under large signal conditions into a tuned
load, there is still an output impedance and this impedance still
discribes what will happen for small changes in the load.


This incremental impedance is one of several different impedances that
can be defined for a non-linear source. No one is more valid
conceptually than another, but some are of more practical significance
than others.

The point is that if you want to talk/write about one of these
impedances, you need, to prevent misunderstanding, use a precise term,
such as 'incremental output source impedance' and define it.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk