Don, I have heard the term, "class BC". Is this what you are referring to?
Jim --- Donald Chester <[EMAIL PROTECTED]> wrote: > > >I have an SB200 linear and on AM it is equivalent > to a DX100. > >I increased the bias on it so to the point just > beyond cutoff for AM so > >that > >it requires a little more to drive and it reaches > negative 100% modulation > >slightly before the driver does. But this seemed > to help the modulation > >linearity and efficiency just a little. > > That's an old trick that I first read about in a > 1930's RADIO article. > Overbias the AM linear to increase the negative peak > modulation percentage. > > It also can have a distortion advantage, especially > if the modulator driver > stage uses grid modulation. Most grid modulated > finals become nonlinear > near 100% negative modulation, or are simply > incapable of cutting the > carrier off completely, so to maintain good > modulation linearity, limit the > modulation to 90% or less in the negative direction, > then overbias the > linear output stage until the negative peaks in the > output reach near 100%. > This will retain modulationr linearaty on negative > peaks and reduce overall > distortion levels. > > > ______________________________________________________________ > AMRadio mailing list > Home: > http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami >
