A regen operates at the hairy transition of self-oscillation where
positive feedback yields a tremendous increase in gain. Doesn't
matter whether it is vacuum tube or transistor. The only difference
between remote-cutoff and sharp cutoff characteristics (transistors
of the bipolar junction type are very sharp cutoff equivalents to
tubes) would be on the amount of spurious garbage created when
the regen jumps into full oscillation.

But it does matter. In the heirarchy of regen devices tubes provide
the "smoothest" regeneration, followed by FETs, with bipolar
transistors generally taking a distant third. I am not asking because
I have never built a regen. I have built DOZENS of them, and I sell a
simple version on my website...but I'm always looking for a new
approach.

I know of no solid state equivalent (without some sort of AGC feedback
loop) for the remote cutoff pentode. Does anyone know if there is?

"AGC in a regen?"

Here, I was speaking in more general terms and not referring to
regenerative circuits.



Experiment with it.

I plan on it.


For experimentation purposes, a high gain-bandwidth product op-amp
IC might produce some interesting results. The gain-bandwidth (or
0 db open-loop gain frequency) of some op-amp ICs is up at 30 to
70 MHz now and the DC open-loop gain is enormous in comparison
to vacuum tubes. I sense possibilities of an op-am regen or even a
superregen on up through HF. Just a thought... :-)

The voltage gain of an effective regenerative stage is can be as high
as 100,000 as reported by Charles Kitchin. That's 100dB...not many op
amps have that kind of gain at say 10MHz.

Thanks for your comments. I always appreciate hearing from folks with
lots of valuable radio experience to share.

Bruce kk7zz
www.elmerdude.com