Peter wrote:
> >No, it's application of tube technology. A tube that will do push-pull
> >AB2 audio will do parallel or push pull AB2 RF. There's nothing magic in
> >parallel v. push-pull when tuned tank circuits are used.
Bill says:
> I'll have to disagree here. A single tube neat cut off. This is still
> the
> case when
> they are in parallel. However, in push-pull class AB this non-linearity
> can be reduced at crossover (near zero-crossing). As one tube is turning
> off the other is beginning to conduct. There are lots of examples in
> articles about Push-Pull amplifiers in the older books and in hi-fi
books.
Peter is correct. In RF applications with a tank push pull makes no
difference in linearity.
The linearity we are concerned with at radio frequencies is
amplitude linearity in the envelope, not fractional cycle linearity.
Imagine driving the PA with 1 mW, and then increasing drive power
gradually increasing it to 100 watts. It is the power gain, as drive
level changes, that we are concerned with. This has nothing to do
with push-pull or parallel operation.
73, Tom W8JI
w8ji@contesting.com
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