It would seem we are overlooking the ability of the final ampifier (in AM) to
develop the RF necessary for such high peak values mentioned on this thread.
In the 60's there was a trend in AM broadcasting to allow the positive peaks to
get greater and greater. Gates developed a BC-5HA which essentialy had a 10 kw
RF stage, set to 5 kw and a 10 kw modulator fed with a separate power supply.
As I recall one station was able to achive close to 200% positive modulation.
Of course the negative peaks were compressed, clipped and otherwise processed.
At that point the FCC decided to establish a rule of +125% positive modulation
peaks. This was so as many stations trying to emulate this overdrove the
transmitter with resulting splatter and interference.
Now for ham radio, I don't think any of the commonly commercially sold, or
built rigs had RF stages great enough to achieve 300% positive modulation. When
the jug runs out of steam, it flat tops. Pretty nasty stuff ...
So while it was possible, I doubt many achieved such a feat.
Also the FCC enforcement was stiffer back in the dark days. I recall a guy
getting cited for adding reverb. This was another AM trick to increase "hang
power" on the RF current meter. Not sure what the ticket said but I know the
guy only had a Glode King, or 500 watt AM.
ed K0KL
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