FET, presumably? Should avoid needing the welding cable to connect it to the
PSU. Are there such high voltage RF power FETS available? You could see the
day coming when 'hollow state' finally succumbs.
Yes, FET. The actual point of the exercise is to avoid bulky magnetics
altogether. I am
using a (self-designed) buck converter for a PS and not isolating the RF deck
from the mains.
I will get isolation by transformer coupling the RF in and out. The lowest
frequency magnetics
are in the buck converter which runs at 150Khz. This is just a 2.5inch ID type
77 torroid, so it
does not weigh very much. Even with the required heat spreader and heat sink,
the overall weight
of the amplifier with power supply should beat anything out there on a watt per
pound basis. Also
the systemic (plug) efficiency of the amplifier should be considerably higher
then any currently available
because energy conversion losses are minimal.
Apart from the pie in the sky stuff above, the broadband matching problems are
interesting. I have done
a couple of single frequency implementations, class C, but broadbanding a class
AB implementation has
been explosively challenging. My little bag of dead soldiers is growing.
The parts are available from www.directedenergy.com, www.apt.com and from
Semelab.
The Directed Energy parts have very nice thermal properties and very low
package parasitic
inductance, but are designed for high energy, high frequency, pulsed DC
applications. They
have very high Ciss. The APT parts have better Ciss, but suffer from the poor
thermal characteristics
and poor package parasitics of TO220 cases. They are way cheaper, though.
73,
K0IW
George
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