This radio utilizes a single 1625 tube that was made during WWII and was commonly found in jeeps in every theatre of that war. It was rugged, dependable and operated on the vehicles 12 volt systems in a pentode grid configuration. I like them because of that as well since filament a nd separate plate voltages (often high dangerous ones) are not required…. A simple 12vdc wall wart is all that is needed. And they are big, attractive and imposing tubes to be sure. The schematic used was devised by Dave Schmarder and has proved to be excellent.
Since it is a regenerative radio a 5k potentiometer is used as a gain control and a 1,000uF capacitor was implemented to suppress noise from the transformer. A tap off of the 175/46 Litz coil with a 10µH inductance value goes straight to pin #6 which eliminates the need for a tickler coil and the issues that entails. A 365pF variable capacitor along with the Litz coil completes the tank and a 31pF trimmer capacitor couples the antenna to it. This radio includes a small amp and speaker with a maple speaker grill meticulously crafted using a metal lathe and a vertical mill.
Flamed maple (fiddle back) was steamed and carefully bent to shape, thoroughly dried and mounted on it’s frame work. I then inlaid two strips of Gaboon ebony as a frame for the brass binding posts. All brass fixtures were 'brushed' and treated. After extensive sanding the body was stained and shaded with a beautiful orange lacquer that I tint here in my shop. Everything was then finished with multiple coats of satin nitro cellulose lacquer.