On Sun, 2007-09-30 at 17:37 -0400, wa3fiy@radioadv.com wrote:
> Jerry did answer the question very well but let's try another approach.
>
> Using a 100 watt max power rig as our base, no SWR foldback, no circuit
> breaker tripping,
> the rig can produce a max of 100 watts to a 50 load. That is 70.7 volts of
> RF to the 50 ohms.
> That's (70.7 X 70.7) / 50 or 500/50 or 100 watts. On CW that's fine but
> what about AM? On
> AM we must reduce the carrier to 1/2 voltage or 35.35 volts. Using
> P=E(squared) divided by
> R, that is 35.35 X35.35 = 1,250. 1,250 divided by 50 ohms = 25 watts. So
> the carrier power
> is as Jerry stated, 25% of the max power available. On AM modulation, the
> carrier voltage
> swings from the 35.35 volts with no modulation to 0 to 70.7 volts under full
> modulation.
> Hence, the instantaneous power varies from 0 watts to 100 watts under
> modulation. I have
> noted some of the import rigs rate AM carrier at 40 watts out. Don't know
> how they do that
> without creating clipping under full modulation. I guess maybe they do not
> allow 100%
> modulation. Anyone know for sure?
>
>
> 73,
>
> -Lee-
> WA3FIY
>
Probably they clip and splatter or ALC backs off the transmitter gain
backing off carrier and audio together. Or they run undermodulated like
a CB.
73, Jerry, K0CQ
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