The biggest challenge will be getting the correct MOS-FET. Common MOS-FET's have a very large amount of input capacitance making them impossible to use at radio frequencies, even AM.Then I can make an AM/FM receiver with a MOSFET(without BJT)?
Dual gate MOSFETs are pretty common in TV tuners and a fair number of Ham radio front ends, JFETs are not exactly rare in FM tuners - I've seen a number of projects for low SW transmitters with the common or garden IRF540 MOSFET as the transmitter PA stage.
Horses for courses - Power MOSFETs in TO220 or bigger have a few nF gate capacitance, RF DG MOSFETS like the BF991 etc have a few pF capacitance.As pointed out before - BJT's are cheapest - which drives most designs. They also typically offer more gain than a JFET. Gain of 100 is usually obtainable.
MOSFET's are pretty crappy for RF amplifiers because they have a input capacitance of a few 1000 pF.
Some Ham transmitter projects I've seen used MOSFETs like the IRF540 as the PA stage, but the driver stage to drive its gate capacitance wasn't trivial - good enough for a QRP transmitter in its own right.look up the ratings on the 3n200, or 2sk99, typical rf low level amp mosfets, no where near 1000 pf input capacitance. you are thinking of large signal power mosfets, some of which are used for rf power amplifiers, but the ones designed for rf power amp use have less input capacitance than power mosfets designed for pwm or motor driver use.
I can find the 3N200, but I can't find the 2Sk99, do you have any datasheet of 2sk99?look up the ratings on the 3n200, or 2sk99, typical rf low level amp mosfets, no where near 1000 pf input capacitance. you are thinking of large signal power mosfets, some of which are used for rf power amplifiers, but the ones designed for rf power amp use have less input capacitance than power mosfets designed for pwm or motor driver use.
AFAICR: the S.E. Asian manufacturers, at least at first - had numerical ranges of part numbers unique to one company.Hello,
I can also not find the 2SK99.
My databook jumps from 2SK97 to 2SK103.
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by Gary Elinoff