Ron, K5BDJ, asks
>So, is there a strong case for ALC, when the capability is there?
I'll stick my neck out a bit here. ALC as it is usually implemented is a
bit like shutting the stable door after the horse has bolted. It can be done
(but usually isn't) by looking at the plate swing and putting a suitable
voltage delay on the rectifier so you limit the plate voltage swing before
it gets too big, but you have to worry about the bandwidth of the resulting
control loop. Generally, ALC loops have a pretty slow response time, and so
can't catch much other than gross overdrive. Having said that, the ALC in
some Yaesu tube transmitters is very sensitive to a few microamps of grid
current, and so works fairly well, but ALC from amplifiers doesn't seem to
buy you much, if anything, in my experience.
I put the capabiltiy into my amp when I built it............and disconnected
it. If the monitor scope shows nice sharp voice peaks, that's far more to
the point.
73
Peter G3RZP
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