"Jim" wrote in message
...
Most power MosFets have a large Gate to Source capacitance which makes
it
difficult to use them at radio frequencies.

It can be done, but the higher the desired operating frequency the
greater effect the parasitic capacitance has, so most designs I have seen
were up to 7 MHz and that was about the upper limit.

A German ham radio magazine just published a project for a 400W MOSFET PA
covering the 80...20m bands:
http://www.vth.de/FUNK/funk/09_05/28.asp

Markus HB9BRJ