Crystal Clear! Radio #53
Here is a simple one, gang! My Crystal Clear radio is built around a coil that was made for me by Master Woodworker Tom Kipgen. Most of my designer radios are built around one central component. The rest of the radio follows along. This beautiful coil is wound on a clear form. Since the coil is space wound (small distance between the windings), the visual effect is greater, not to mention the coil Q being greater.
The schematic is shown below. The circuit is much like several of my other sets. One difference is the use of a link switch to add capacitance to the main tuning capacitor. I had two look alike capacitors but the capacitance was only 280 pf. Not enough to tune the entire band. So I added 250 pf to the main capacitor that can be switched in to tune the bottom of the band. The capacitor happened to already be attached to the capacitor. No doubt that this was a grid leak capacitor for an old tube radio.
I used two pieces of plexiglas 9 x 7 inches (23,9 x 17,75 cm) separated by four ceramic insulators. As you might have guessed, all this is from my junk box. Having the two pieces of plexiglas gives the radio a more rigid construction. If I had omitted the bottom piece, the plexiglas might someday break. The second piece does add nice visual interest too.
Since I first built this radio, I felt it was missing something. Most of the parts are old time or could have been. (Not sure if they had plexiglas back in the old days). The germanium diode came around during World War II, so that had to go. In it's place there is a galena rock and a "catwhisker" probe. I left the original hardware on the detector area, so one could switch back to a diode.
This is not a performance radio. No litz, old type capacitors with phenolic insulators and no audio transformer. It still sounds good and I can pick up several stations during the daytime and lots at night. This is a fun radio and something that will look nice on my shelf (and maybe your shelf).
73 and good crystal DX. Dave - N2DS