Actually no, back in the days of plate modulated AM you needed 50% of the DC input to the FPA in modulator AF output to modulate 100%. Phase modulation was pioneered by RCA and Collins back in the 1950s eliminating the modulator and half of the audio chain thus saving a whole lot of electricity. Now with Class E MOSFET modular technology the savings are even greater and transmitters more compact and efficient than ever.
"Well the FCC didn't like this too much and changed the rules to limit the
"audio" power to both SSB & DSB transmitters. I don't remember the exact
specifications but it amounted to about 8 watts of maximum audio power."
Again no, 4W carrier is equal to 12W PEP* be it AM, DSB or SSB, a carrier has no peaks, no modulation and carries no intelligence. There is no such thing as "audio power" in this context, it's all RF on the air. "...8 watts of maximum audio power" is sufficient to modulate 16W DC input to the final 100% so it has never had any place in Part 95 equipment.
* FCC math is bizarre, before PEP output became the standard it was DC input which actually makes sense. Then at 100% modulation PEP was X2 the unmodulated value and with SSB the unmodulated output was (and is) zero. Along comes CB SSB and the FCC scrambles to find new output limits and decided on 4W carrier for AM and 12W PEP for sideband, somehow with Part 95 that comes out to a factor of three, not 2 as it once was. It only gets worse, now Amateur Radio being under Part 97 it comes out to a factor of 4, not 2, not 3 but 4??? It only goes to show how engineering got left in the dust of money making spectrum auctions and the like, they can't even read a 'scope anymore! Peak electrical AC power is measured from the zero center line to the tip of either a positive or negative peak, that's why the name PEAK power. Peak to peak is just that, the tip of a positive peak to the tip of a negative peak, PEAK TO PEAK. I'd just love to put the FCC on Are You Smarter Than a 5th Grader purely for the entertainment value.
As long as we're on the subject of toobz, there were always those power mad fools trying to squeeze every last drop out of a lemon battery. Yeah, it's real. There are limits to everything and while unlike solid state you won't likely let the magic smoke out the power supply does a little dance under modulation. If you put the RF outpoot on a monitor scope you'd see positive peaks flattened as if by an invisible hammer and so much carrier pinch you'd think you're looking at digital pulse modulation, SQUARE WAVES! (;->)
I love toobs, really big toobz.