I just love regenerative receivers. I guess it's the simplicity of these gadgets that can do a lot of what much more complicated receivers can do. I had occasionally tried unsuccessfully to build a regen, but when Charles Kitchen's article in Ham Radio appeared I got really inspired and built my first working regen. That was in 1995, and since then I have built a number of interesting radios and learned quite a bit about what makes these things tick. I have only built solid-state regens, and have only built what I think of as "Armstrong" circuits, where regenerative amplification and detection occur in the same stage. I have concentrated on making receivers which can be used for amateur communication - these are not just toys. I find that about 90 percent of the operating that I do can be done with a simple regen as the receiver.
One thing I like about regens is their lack of spurious responses. I know this might seem a little crazy to those with limited experience with regens, but think about it. There is no IF to create spurs due to IF feedthrough or poor image suppression. The regeneration raises the Q of the resonator at the operating frequency, and this is the first thing the signal sees, so harmonic mixer responses are attenuated. The radios I have built use very loose coupling of the antenna to the detector (at least when I use an audio amplifier) so the traditionally mentioned problems that regens have with hand capacitance effects and radiation are minimized.
The regens I have built have all used old-fashioned high impedance headphones. They are easy to drive, provide some audio selectivity, and I like the way they sound. Besides that, they just seem to fit with the obsolete circuit.
Anthony Felino (AF) WN6Q
PO Box 2702, Santa Barbara, CA 93120
(805) 216 5287