I limit my quick peaks in the mike preamp, and include negative
cycle loading in all RF decks, but don't push things much.
I don't use negative cycle loading or ultramodulation, but I do take
advantage of the natural asymmetry of the human voice. Mine tends to run
about 135% positive when I limit the negative to 100%. The ratio would be
more like 2:1 if I clipped off a few excessive negative peaks. I usually run
about 640 watts DC input to the final. Considering the losses in the PA
tank circuit, the matching network at the transmitter output, the feedline
between the shack and the tower site, and the remote antenna tuner at the
base of the tower, I'd be surprised if I'm getting as much as 400 watts
carrier output to the antenna. When I talk, the modulatior plate meters
just barely wiggle beyond static plate current, unless I whistle or make a
sustained tone. With a sinewave signal from a generator I can make each
modulator tube draw up to 400 ma! The only "processing" I use is the
Universal Audio/Urei Model BL-40 Modulimiter (the only solid-state device in
the station except for the homebrew cw keyer).
There are people on the band who run/can run excessive positive
modulation, but you need a special detector I guess, because they sound
bad in my shack when they do.
I just make sure there is no flat-topping on positive peaks or bright spots
on the baseline in the negative direction. I once tried ultramodulation,
but I think I gained much more distortion than talk power. Most reports
indicated the audio was no louder, but had a scratchy sound. The most
effective thing I ever tried for "talk power" was high level symmetrical
speech clipping back in the 60's, but it added audible distortion, and I
went through about half a dozen modulation transformers in about as many
months, ranging in ratings from 500 to 2000 watts. After I abandoned the
high level clipping, I havn't lost a single modulation transformer since.
Don K4KYV
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