Question for a formula related to electrical power?

[samy555]

Hi
When I read the page on the link:
https://www.electronics-tutorials.com/amplifiers/negative-feedback.htm
I found this formula for calculating the output power of RF amplifier:

2 * Po = [Vcc - Ve]² / R

Also found the same formula in the book: ‎ARRL - Experimental Methods in RF Design, where:
Po: the output power
VCC: the battery voltage
Ve: the emitter voltage
R: the load resistance
I think that number 2 came from a conversion of the Vp to rms

My question is: Why [Vcc - Ve]² and not simply Vc² ; the ac collector voltage??
Thank you

 

[Borber]

Calculations on your page are simplified for process of experimental designing by Ian C. Purdie.
From his articles you will not get theoretical knowledge but you may put together some pieces
of electronics of his design.

 

[chuckey]

Ve is actually Vce, which is the minimum (most negative) RF voltage. When the transistor is OFF, the collector is at Vcc, when the transistor is switched hard on the collector falls down to Ve +.2V (to be accurate). This means that if the emitter is biassed to +6V, then the transistor cannot deliver as much power as if the emitter is earthed (0V).
Frank