[600MRG] Fwd: Class E Keying

[Hans Summers]

Hi Jim

Class-E is inherently non-linear by design. Attempts to modulate the input
> remove it from Class-E.
>
> Although certainly not perfect RC shaping is better than no shaping at
> all. More sophisticated PWM modulation can no doubt be accomplished to
> achieve different PA waveforms.
>

Yes agreed, RC shaping is better than nothing...

The following papers by NA5N are very informative on Class-E:

http://www.nrao.edu/~pharden/hobby/_ClassDEF1.pdf
http://www.nrao.edu/~pharden/hobby/_ClassDEF2.pdf

According to that, the best way to control the power output is by varying
the duty cycle of the input square wave. Messing with the bias on the
driver is a not unreasonable way to achieve something similar.

Oh Class-E seems such a delicate thing - everything has to be just right -
it seems to me that pretty much anything causes it to drop out of Class-E!
I wouldn't be at all surprised if dropping the PA voltage will cause it to
escape from Class-E operation. On the other hand maybe that doesn't matter
too much for a few milliseconds during key-down/key-up.

73 Hans G0UPL
http://www/qrp-labs.com
http://www.hanssummers.com