> >That's why you need to measure SWR, and do it while the
> >envelope is rising....
>
>
>
> How do you plan on doing that on a wideband transformer output amplifier?
>
> Since the Impedance of the collector is equal to Collector voltage squared
> / twice the power output and the transformation ratio is equal to the
> sqaure of the turns on the transformer, the swr would be changing as the
> power output ramped up.
SWR is totally dependent on the load impedance, not the source
impedance. That's why you can change radio's or sources or tune
the source all you like and SWR will remain the same.
> >unless you use transistors that have a voltage
> >rating of several times the working voltage or use a hard clamp that is
> >very fast.
>
> Motorola rates their Bipolars at 30 to 1 swr over all phase angles, if
> operated within spec.
That works with a load Q>1, but try and do that some time with a
high-Q load. You'll send the transistors on a permanent vacation
long before 30:1 SWR is reached.
73, Tom W8JI
w8ji@contesting.com
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