I have a bunch of ferrite cores I've parted out from junk radios, but I'm not sure what the permeabilities are. Without a inductance meter, I'd pretty much be taking a stab in the dark as to how to wind them. I'm guessing most am ferrite bars are around 125 on the permeability scale,but you never can be sure. Also, every time I use a ferrite core, I get radio disney saturating my coil- it's the most god-awful station on earth.It bleeds through even when I decouple the antenna! Maybe a soup can would have less permeability,but just enough to help pull in the low SW stations. I suppose I could also try a tunable ferrite slug as well. Anyhow, I scrapped the "radio" this morning,except the tank(that took me abut 2 hours to make last night), and I rebuilt it with a better layout. Now there is no hum, but on a piezeoelecric earphone I can hear something,like intermittent crackles.I've built a couple AM regens, so I can tell there is a signal there, I'm just not getting it yet.I also only used 7 volts for the power supply, so before I make any changes I will try 12 volts and see what happens. I do have a question, though. Does anyone know what the output impedance of this circuit is? My earphone has a gazillion ohms of impedance,and I'll probably need to adjust my output. I know tht there is a WWV station on 2.5MHz, but not sure what else,but I aim to find out. I have a shortwave radio on my bench, but it's not the same as listening to your own,no matter how bad it might sound or how hard is is to tune.