[AMRadio] Side band power with increased carrier/was clipperton on AM

[Geoff Edmonson]

On 04/13/2011 02:22 PM, Gary Schafer wrote:

> This is why I was saying that the 375 watt carrier power is the best power
> to run a linear amp at. Reversing the audio phase to put highest peaks on
> the negative side causes you to increase the carrier so as not to over
> modulate on the negative side but at the same time overall modulation must
> be reduced.
>
> Probably clear as mud.

This is true, Gary.  And it is clear as spring water.  Everything is 
right on the money, as long as you're modulating with a single tone.

A Quote from John's page says:

______________________________________

*Here's the math:
PEP = ((peak-to-peak modulated RF voltage / un-modulated carrier 
voltage) squared) * un-modulated carrier power *

*    This large PEP can occur without negative over modulation, if the 
modulating audio is acquired by a voice from a microphone. Microphone 
audio is generally asymmetrical. *

*    To help me understand and explain the relationship between audio 
and purity of modulation, I've defined a function, which I call Symmetry 
Ratio (SR). *

*Symmetry Ratio (SR) defined: *

*SR = (Peak-to-Peak audio voltage) / (lesser of the two Peak Audio 
Voltages above or below the quiescent line)
SR = 2 if the signal is a Pure Sine Wave
SR cannot be less than 2 *
_______________________________________

This, as a result of John's discovery that his natural voice, as viewed 
on a scope, is asymmetrical, by an SR of 3.

Voice patterns are complex waveforms, very dissimilar to a single tone.

An analogy could be drawn from watching the ripples in a pond of water, 
after a rock is thrown into the center of it.  Further away from the 
point of impact, the waves are symmetrical.  However, at the point of 
impact, the water is -very- asymmetrical.  Quite disturbed.  Voice waves 
hitting a microphone diaphragm act the same way.

The whole explanation, with drawings and diagrams, is available at 
http://www.qsl.net/wa5bxo/asyam/aam3.html

73 = Best Regards,
-Geoff/W5OMR