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Because these are not linear RF devices, their input gate capacitance is higher. This is one of the most important specifications for RF and every other MOSFET datasheet publishes it except Palomar. Because it's high, the gain gets very low at 27 MHz. and they require a lot of drive to overcome this gate capacitance which, causes more heat. Real circuit gain is about 9db, where 5 watts drive only produces about 40 watts output per stage. So, one stage is usually not enough and two stages are usually overkill that needs to be cut back.

[QUOTE="Shockwave, post: 695511, member: 10882"] Because these are not linear RF devices, their input gate capacitance is higher. This is one of the most important specifications for RF and every other MOSFET datasheet publishes it except Palomar. Because it's high, the gain gets very low at 27 MHz. and they require a lot of drive to overcome this gate capacitance which, causes more heat. Real circuit gain is about 9db, where 5 watts drive only produces about 40 watts output per stage. So, one stage is usually not enough and two stages are usually overkill that needs to be cut back. [/QUOTE]

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