Hm. Ok. So the audio voltage is summed with the supply voltage at the collector, thanks to the transformer, which boosts the output beyond just what you'd expect from the 13.8v supply voltage alone.
But -- and please forgive me if I'm being dense here -- that still doesn't answer my original question: can you actually push the output of a single 2SC1969 up to 75 watts on a positive peak?
With 100% modulation, the power at positive peaks reaches the four times the carrier power: with a 4 watt carrier, you'd get 16 watts at positive modulation peaks. With 8 watts of carrier, you'd get 32 watts at peaks, and so on. NPC would change this a bit since it would give you greater than 100% modulation.
But 75 watts sounds like you'd be pushing the 2SC1969 past its design limits. I decided to download the datasheet for it, and based on the curves that it shows, it looks like power output starts to level off at around 25 watts.
Now, maybe you can push it higher, but then I have to ask again: if you do that, will it stay linear? My guess is that it wouldn't. If you were to test with a sine wave then, I would expect the positive peaks to be a little attenuated compared to the original audio input.
-Bill
