On Mon, 15 Dec 2008 23:29:35 -0500, "NoSPAM"
wrote:

"Telstar Electronics" wrote in message
...

You mean to tell me that you take a clean sine wave... pass it
through... say a single-ended class A amp... and you can put a tank on
the output of that amplifier... and tune for a harmonic? You will get
nothing.

Of course you will. No active device is perfect.

I decided to illustrate the fact that a single ended triode operated in
Class A can produce harmonics. For a tube, I used a 6C4 (1/2 of a 12AU7)
operated with 300 volts on the plate, a grid bias voltage of -7 volts,
driven with a pure sine wave of 14 volts peak-to-peak. The high driving
voltage was chosen to illustrate my earlier points, but the stage _IS_
operated Class A with the plate current between cutoff and saturation.

Did you bypass the cathode resistor or not ?

All active elements are more or less nonlinear, so if you need more or
less linear amplification, you need to use feedback/feedforward.

A non-bypassed cathode/emitter resistor will greatly improve the
linearity of a single stage.

Paul OH3LWR