WinterDeere
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Would that be equivalent to enhancement mode versus depletion mode? Or n-channel versus p-channel?I wonder how many know the difference between a Pentode and a Triode vacume tube.
In my world, there are tube guys and FET guys, and I was always a FET guy. The microprocessor guys still use MOSFETs, I assume with shorter and shorter gate lengths, but the high frequency stuff I work on is all HEMT (High Electron-Mobility Transistors)... just another special type of FET. In simplest terms, FETs are classified by channel type (positive versus negative conduction layer) and enhancement mode versus depletion mode (i.e. whether you apply a gate voltage to turn it "on" or "off".
The trouble with tubes, at least when talking high power amplifiers, is the voltages. If you like to stick your fingers into circuits to tune or adjust, stay the hell away from high power tubes... high impedance = high voltages.