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.

My first regen RX was in 1947 with an A415 direct filament triode. (Does
anyone remember it?) It was followed by DC11 - a steel 1.5 V filament
tube - both excellent ones for regen receivers. (We used to call them
Audions.) Bruce says there are three types of regens : with tubes, with
FETs and with bipolar transistors. There is also a forth type: a
negative resistance reganeration receiver, an invention of mine (also
known as Lambda receiver). You can find its scematic in the British QRP
Club's magazine SPRAT: number 111, page 4 - with a correction in number
112, page 25, and a complete construction in SPRAT 113, page 17 - with a
correction in SPRAT 114, page 24. The schematic is a simulation of a
tunnel diode and works in the negative part of the U/I characteristic.
It does not have a feedback coil, and the regeneration is very soft - so
the worst problem has been solved. Its stability is not convenient for
CW or SSB, but it is excellent for broadcast stations from 500 kHz to 30
MHz; a real project for beginners. If someone duplicates it, I will be
happy to hear about his experience - by e-mail
. hr) or on this group. Best wishes,
Bozidar, 9A2HL