During the month of December of 2012 I built a high performance crystal set receiver out of an old TRF (tuned radio frequency) radio chassis. In the summer of last year I acquired this chassis from one of Michigan's antique radio flea markets. Twenty dollars was the sum I paid for this dust covered electromagnetic apparatus. Bring it home, I quickly (like all things in my life) stored it away somewhere were it wouldn't obstruct anyone's working space. The warm weather months past by and the snow started to roll in. Finding myself bored one day in early December, I decisively started work on the crystal set.
First order of business was to construct the three spider web coils. With one hour of man work per coil (winding wire round and round, tying them all together and finally carefully removing them from the winding jig) took almost a half of a day, a lot of patience and surgical dexterity. I decided to employ a pulley mechanism to vary the space between the coils (mutual coupling). Thankfully I had a box of silver plated radio hardware that I bought at a electronics flea market here in Detroit. It was chock full of small pulleys, just what I need for this crystal set receiver project. After shaping my unique movable coil mounts, I commenced to string dial cord. But before I could do that, I had to machine my own dial chord drive pulleys. They're made out of poly-vinyl plastic which were mounted on reostat shafts. Disguarding the guts from those reostats, I maintained the natural front panel appearance of this antique radio.
The TRF chassis already came with tuning capacitors, so I didn't have to worry about those. The only thing left was to give the receiver a day of beauty. With a quick scrubbing of laundry soap I was ready to pimp out this ride with some boss looking graphics. I chose to use custom transfers (decals)to give this radio a genuine look. Using my own graphic of the ionosonde logo, I gave this piece the look of a big corporation rather then a lone home builder.