The E.T. Crystal Radio

A real curvy number has been in my mind for some time now but just refused to come to the surface…until now. This one reminds me so much of the movie “ET” that it just had to carry that name. And while it won’t phone home it certainly performs well at receiving all those signals from outer space.

Another double tuned crystal radio was the order of the day and twin 365pF variable capacitors were chosen for the antenna tuning and main tuning duties. A compact HoneyComb coil was wound on a brand new coil winding former made just for this radio. And why the special treatment? Because I get so excited when I get close to finishing a radio that I am prone to forget all about the coil until the very last moment when available space is at a premium. This isn’t the first time I’ve done this but I learn more about these coils every time I have to try and make a smaller coil. This one has a ¾” core with only 22 pins and a winding pattern consists of crossing the outside of two pins and then skipping 4 pins on the inside as you progress around the former. The result is a very compact unit that is only 1” deep, 2” in diameter and yet still meters at 241uH using solid gray Tattoo wire. My standard HoneyComb coils have a 2 ¼” core, a 1” depth and 3 1/5” diameter.

To make listening easy and more enjoyable this radio includes a little audio amp and a small speaker both located in the upper half of the set. That speaker grill is fashioned out of curly maple as is the bezel that houses that 3 ¼” convex glass crystal covering the dial. The size of the amp in no way mirrors the volume that it puts out. It is LOUD! That’s why it has an on/off/volume knob out front. Of course there is a plug in on the back panel for those folks wanting to use headphones.

A 2:1 diameter ratio between pulleys allowed tuning to span 360 degrees on the dial and this one is a FADA RADIO beauty from 1937. All three knobs are ½” diameter solid brass polished to a brilliant shine as are all of the 30 brass screws mounted on the front panel. The outside of the cabinet and the front panel are made of curly maple and the outside is carefully bent to shape using techniques learned in guitar making. I hardly ever break one these days but there is a trail of shattered guitar sides from my early days of learning. I tone nitro cellulose lacquer here in my shop and then finish it off with several coats of clear.