[AMRadio] Side band power with increased carrier/was clippertononAM

[Geoff Edmonson]

On 04/13/2011 08:22 PM, Gary Schafer wrote:
> Further you can look at the number of divisions on the scope that the audio
> occupies. The more divisions the greater the audio power on the signal. If
> you raise the carrier above the 375 watt level you will not hit the 100%
> mark on negative peaks as soon but you will sooner hit the 1500 watt PEP
> mark and you will have less total divisions of audio on the scope. This
> means less audio power transmitted.

What that means is, you don't have enough audio power available to fully 
modulate the carrier.

As the carrier level increases, the need for enough audio voltage to 
properly modulate the carrier increases exponentially.

25w out of a typical solid state transceiver, modulated to 100 percent 
with a sine-wave, produces 100w PEP.
If you increase the carrier level to 40w you'll only see 60w PEP and 
it'll be severely distorted, because there's simply not enough 
dissipation in the device.  Of course, we're talking low-level 
modulation levels, but amplify that with a linear on the output of a 
solid state transceiver, and the problem still exists, only on a much 
amplified scale.  A linear that only produces 1,000w PEP output, is only 
good for 250w -max- carrier, and -should- be dropped to 150~200w to 
ensure enough dissipation available for 100% non-distorted, non 
flat-topped audio.