Dr. William J. Schmidt, II wrote:
> Check these out... I just uploaded them to my website. They make fine CW
> amps... need a little work for SSB... but not much!
>
> http://www.wjschmidt.com/ham/apt9502.pdf
>
> http://www.wjschmidt.com/ham/apt9701.pdf
The notes don't discuss protective circuitry, if needed. You might want to
protect it from high SWR, overdrive, high temperature, and overcurrent.
Every time I talk to anyone 'in the business' about producing amateur
amplifiers
of this type, they say that the price point for a 1.5 KW amp would be over $3K,
by the time you add the power supply, protection, filter, autotuner, control
circuits, etc. As a homebrew project, it's not too easy because of the lack
of
a complete, tested design and the need to make a PCB.
I believe that a 'people's amplifier' could be developed using the APT MOSFETs
that would incorporate the power supply, protection, biasing, and filtering
that's needed for a practical unit that could be built by a reasonably careful
ham for less than $1K. By using relay-switched filters, the amplifier could be
entirely no-tune.
Although I think the inherent linearity of these transistors is not that great,
possibly some kind of negative feedback could be employed to improve it (I'm a
CW operator and would be happy with class C, but I understand that others have
different needs).
Who needs an Alpha 87 at $6K when this is possible?
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|