Bruce Kizerian wrote:

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 built my first regenerative receiver in 1947 with an A415
direct filament tube, followed by one with a steel DC11 - 1,5 V
direct filament tube - both excellent ones for the purpose. (Does
anyone remember them?). Bruce says there are three types of regen
receivers: the tube ones, the ones with a FET, and the ones with bipolar
transistors. However, there is also a fourth one: the negative
resistance reganerative receiver, known also as a Lambda receiver . The
oscillator is a transistor immitation of the tunnel diode, and the
negative resistance substitutes the feedback coil. It is my own
construction. You can find its schematic in the British QRP Club
magazine SPRAT No. 111, page 4 (with a correction in No. 112, page 25).
The whole construction with a PCB has been published in SPRAT No. 113,
page 17 (with a correction in SPRAT 114, page 24). The RX does not have
a feedback coil, and the regeneration is very smooth and rather even
over the whole band. So, that problem has been solved for good. It is
not stable enough for CW or SSB, but it is excellent for AM
broadcast stations from 500 kHz up to 30 MHz (with corresponding coils,
of course). So, according to my opinion, it is excellent for beginners
because they do not have to bother with the feedback coils.

If anyone would care to duplicate it, I would appreciate it
very much if I could hear about his experiences with it (on this group
or by e-mail: ). The whole project is still
open for experimentation. Best wishes,

Bozidar, 9A2HL