Lee,
Not class E.? Its class D and MOSfets or Bipolar transistors can do that.
Class-D requires a on state (saturated) that Mosfets do well.? ?Its not device
speed as IRF510 is more than good enough to amplify at 70mhz.
Both E and D both reply on devices that properly used behave
like switches.? The larger difference is E will be single ended and D
is typically push-pull.? Both offer the ability to deliver greater than
75% efficiency.
Switching is a non-linear action and most of what is applied for RF
power is very different
The desirable feature is low? input capacitance as that makes it
easy to drive (lower source and sink currents required from the driver).
Along with low gate capacitance a low value of gate to drain capacitance?
is needed as that behaves as Miller feedback and slows down switching.
That capacitance directly opposes the driving signal requiring more power
from the driver device.
The next feature is low gate saturation voltage.? Keep in mind we have
no more than 5V and under heavy loading the ACT00 can barely do that.
Most mosfets want higher voltages to switch to achieve saturation.
Currently BS170 and 2n7002 are closest to ideal short of GaN FETs
and those while good (closer to ideal) are difficult to use as they exist
only as die, not leaded devices.
Hint: if you understand how a switching power supply works you
have a start on how a switch mode RF amplifier works.? There
are more than a few papers and tutorials on the web.
--
Allison
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Post online only,?
direct email will go to a bit bucket.
Lee