Basics of FET design help request...willing to do the work

[R O Tiree]

Thanks for that, Paul.

> Read my process...Possibly not the bias you want, though

Got my head around that, thanks, and tried it out with several NJFETs over the last few days.

> Way-out example...

I hadn't got around to one as way-out as that example, but I found subbing even a 2N5485 into a "properly" biased simple circuit like this was awkward to do.  I found that dropping the current as you hinted at earlier in this thread gave me better results.

> _Without_NFB_, yes, this is true.

Next on my list.  Waiting on that book you referenced above.  In its simplest form that would be feeding half the drain swing back to the gate, right?  A cap (to strip out the DC component) in series with a resistor matching the one you already have from gate to GND?

> Inerresting expression.

It's fairly common over here and is used to describe something quite noticeable... it seemed quite aposite given the Olympics are on TV constantly in the background as I write and we're doing stunningly well.  Often used in a slightly disparaging sense, such as, "He had a vindaloo curry last night and he's been f@rting for Britain all day!"

[PRR]

The most direct NFB on a single JFET is to not-bypass the source resistor. As a first approximation: doubles input overload, cuts gain and THD in half.

Most other NFB schemes spoil the high input impedance, the main reason to use a JFET in audio.