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class-e HF amplifier driven by short pulses, output power capability

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neazoi

neazoi

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Hello, here is a typical HF class-e amplifier, using three 2n7000 in series to improve the on/off switching (I think).
Such an amplifier can output power in the range of 2W at 50R.

I was wondering what will happen if I drive the mosfet with short pulses, instead of morse code and at the same time increase the vcc voltage to much more?

As far as I know, semiconductors are capable of greater output powers if they operate for a few mS instead of a few hundrends or thousands of seconds. Can I increase the output power considerably, if I shorten the "ON" timing?

Class-E was an initial consideration, but I consider any other class as well.
 

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FvM said:
No schematic.
Click to expand...

I have just uploaded it.
As said, class-E is the initial consideration but I am not limited to it.

All needed is an amplifier switched ON/OFF with a short ON duration (in contrast to the morse code). Then I could extract much more power out of it (by using higher voltage?), since it won't be heated too much because of the short ON duration.
 

Class-E amplifiers are generally used for high efficiency, not only pulsed mode operation.But their design and implementation is quite difficult, needs quite deep RF design and optimization knowledge and technique.They are also quite dirty amplifiers in term of harmonic content.Class-E amplifier can also be used no doubt but the question is here, is it worthy or not for Morse code transmission ??
Maybe..
 
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    neazoi

    neazoi

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BigBoss said:
Class-E amplifiers are generally used for high efficiency, not only pulsed mode operation.But their design and implementation is quite difficult, needs quite deep RF design and optimization knowledge and technique.They are also quite dirty amplifiers in term of harmonic content.Class-E amplifier can also be used no doubt but the question is here, is it worthy or not for Morse code transmission ??
Maybe..
Click to expand...

In fact I should correct myself. I refer mostly to pulsed mode (on/off keying with short ON pulses), not in class-E. Whether durring the ON period the TX will operate in class-E or C, that is another story.
The question is if the shortening of the operation time of the TX, can allow higher voltage/current to be switched/amplified that otherwise could destroy the transistor in continuous operating mode.
 

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