cheap power MOSFETS used for RF amps

[wannabetech]

Does anyone know of any MOSFETS that are similar to the ERF7530 but are cheap switching devices. It would be ok, in fact, good if I could find some that would do 300-400 watts for a pair EVEN if they required 200 to 400 volts or even more.

Thank you

 

[Shockwave]

The guys on 75 meter AM do this all the time. Cheap switching transistors used in the final of their class E transmitters. The problem is the excessive gate capacitance as frequency increases. This makes them very difficult to drive above 14 MHz. If you want a few hundred watts or more above this frequency you'll need to buy a real RF MOSFET designed for higher frequency applications. This will indeed remove the "cheap" out of the equation unless you can find some used surplus on eBay. Sometimes there are good boards sold there that are loaded with transistors like the MRF151. They were used in things like RF generators, plasma generators and MRI machines.