Nowhere-Man, for most folks who want to build a radio but have never built one before the starting point is usually a Xtal receiver or one step on...a Regenerative receiver (Regen.) a lot of designs for those two are for receivers to cover the MW band, trouble is the number of stations transmitting in that band seems to be getting less and less, shortwave bands are an alternative even though the number of stations is also in decline on those bands there's still plenty going on plus there's the Ham bands, Oceanic HF (aircraft) plus lot's of other stuff as well, almost all Ham transmissions are SSB or CW although there's a few that still transmit AM from time to time, SSB can be received and resolved on a regen receiver no problem but the design and physical layout are important, there's lots of regen designs on the web and in magazines etc, some good, some not so good, some Micky Mouse.
The key thing to remember if you were to design/build a regen is usability.....touchy tuning, hand proximity effects or a squealing regen with not a lot in between means it's time to re think or throw it in the bin, stability and ease of tuning are the main points to aim for, selectivity is very good to excellent with a properly working regen, you won't need a very long antenna either to receive lot's of stuff, to keep frequency pulling to a minimum use an RF amp, and for the regen detector tuned circuit use as low an LC ratio as you can get away with, that will help mask changes in the tuned circuit capacitor values and valve inter electrode capacitance values due to changes in temperature and operating conditions, a low LC ratio also means less copper expanding/contracting which equals less drift, keep the grid leak capacitor as low value as possible and the grid leak resistor high, that will help stability too, try and use a low gm valve for the detector rather than a high one.
Hope this is of some use....Good luck if you decide to build a receiver.
Lawrence.
The key thing to remember if you were to design/build a regen is usability.....touchy tuning, hand proximity effects or a squealing regen with not a lot in between means it's time to re think or throw it in the bin, stability and ease of tuning are the main points to aim for, selectivity is very good to excellent with a properly working regen, you won't need a very long antenna either to receive lot's of stuff, to keep frequency pulling to a minimum use an RF amp, and for the regen detector tuned circuit use as low an LC ratio as you can get away with, that will help mask changes in the tuned circuit capacitor values and valve inter electrode capacitance values due to changes in temperature and operating conditions, a low LC ratio also means less copper expanding/contracting which equals less drift, keep the grid leak capacitor as low value as possible and the grid leak resistor high, that will help stability too, try and use a low gm valve for the detector rather than a high one.
Hope this is of some use....Good luck if you decide to build a receiver.
Lawrence.
