No one talks about the nasty distortion you get in most receivers when you get much over 100% modulation.
Most people sound MUCH nicer if they run the audio under 100% modulation. My transmitter might like doing 15 watts of carrier and 1500 watts pep, but no one is going to think it sounds good... Brett N2DTS > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of ne1s > Sent: Tuesday, December 12, 2006 2:55 PM > To: [EMAIL PROTECTED]; Discussion of AM Radio in the Amateur Service > Subject: [AMRadio] Re: Screen Modulated 813 > > Bry Carling writes: > > > Lary - I was talking about the kind of set-up with the 6DE7 > > that produces a SMALL carrier of say 6 or 8 watts > > and then does 90 watts p.e.p. on the voice peaks. > > > Right - that is the question I addressed. > > > I may be nuts, but my empirical sense tells me that is > > far more impressive sounding in the receiver n the other > > end than the signal from the typical "novice rig" that runs > > 75 watts carrier input with Heising mod. OR even a plate > > modulated class C rig with 22.5 watts carrier input and > > 90 watts p.e.p. > > > I think by "impressive" you mean the ratio of power in the > sidebands to > unmodulated carrier power - if so, I'd agree. > > > The power is turned DOWN during the inefficient phase > > of the transmission in other words. > > > We need to be careful here, because this created a > misunderstanding about a > year ago. With efficiency modulation (be it a linear > amplifier stage, or > screen suppressor, or control-grid modulated amplifier) PLATE > EFFICIENCY (RF > power output/DC plate power input) is lowest when the > instantateous output > is lowest. Therefore, the lower the output of the unmodulated > carrier, the > lower the PLATE EFFICIENCY. If we think of efficiency in > terms of power in > the sidebands/total power consumed (integrated over time), > your statement is > correct. > > > WIth less and less quiescent signal the transmitter appraoches > > the efficiency level of a DSB rig. > > > > Yes - in the limit, as the carrier level is reduced to zero, > that's exactly > what your left with: DSB w/o carrier. But the above comments > on efficency > still hold - plate efficiency in this case will be zero when > no modulation > is present, because there is no RF output, with finite DC plate power > consumed. But, integrated over time, I believe less power > will be consumed > to convey the intelligence, so in this sense, "efficiency" is better. > > 73, > -Larry/NE1S > ______________________________________________________________ > AMRadio mailing list > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Partner Website: http://www.amfone.net > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > ______________________________________________________________ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
