I've never had a chance to do much experimenting with tubes and RF, and I never got to build a regenerative receiver as a kid, so I thought I'd take a break from messing with headphone amps and try to design one using 12 volt tubes:
I think I may put a tap on the coil to switch between the AM broadcast band and the lower end of the SW band; I don't really want to get into using plug-in coil forms. The values of turns for the coil are to be determined when I decide what I'm going to use for the form. These low voltage tubes have a very aesthetically appealing heater glow, and are extremely cheap!