I received a Google Alert about this regenerative receiver schematic being posted to the RegenRX Yahoo Group (you may have to be logged on the view it). It’s quite complex for a regenerative receiver – the average regen set has just a few transistors. But its Achilles Heel is the front end.
When I was young I had a Tennelec Memoryscan scanner receiver that was quite an advanced design for its day. I had it connected to a small discone antenna on the roof. But after a thunderstorm it quit working.
I found that it had a 2N3904 or 2N3906, I forget which, for the antenna front end, and that had burned out. The receiver started working again after I replaced it. The simple conclusion was that it was a faulty design. Putting the transistor right at the antenna input, with no protection against lightning, is not only a faulty design but it’s a safety hazard. A component could catch on fire and burn down the dwelling.
A receiver that has an external antenna jack should have a filter at the antenna input with a very low resistance to ground. If any fault currents appear on the antenna input, they will then be shunted to ground through the filter, which would have an RF choke with a low resistance coil of wire, for example.
One other point that I believe needs improvement is the use of a shunt regulator. This wastes a constant amount of power, which shortens the battery life if it’s powered by a battery. I think a low dropout regulator chip would be a better choice. The voltage would be more accurate, too.
