I love these stop sign boxes! They are just crappy basswood, but look at the way they stain. As long as I started on the stain, here is what I did. I lightly sanded the boxes, then applied a coat of Min-Wax wood conditioner. This allows the stain to evenly soak into the softer woods. I then applied a coat of Min-Wax Red Oak stain. After drying I lightly sanded it with some fine steel wool. I then added another coat of stain, and a very light steel wool sanding. Then I used some gloss Deft. After about 3 coats, this is shinier than my bald head after I get out of the shower. (I do this at least once a week. I cut back due to the high water prices and the time I waste that I could use building more sets).
The top is Garolite® that covers the entire top of the box. Since the variometer coil is nearly as deep as the cabinet would allow, putting the top covering the entire top of the boxes allows me to use the 3 inch coil form.
Perhaps I should explain why I am building these things. Mainly because I wanted to and I am in between crystal set and tube set ideas. That aside, several times I needed just a variable cap or inductor to test a circuit or idea. I thought it would be cool to have some nice looking stuff, just in case a girl or two stopped by. Those that know me know about how likely that would happen.
The capacitor is a triple gang type with a maximum capacitance of 440 pf per section. I decided to make this a three terminal device. One is the ground or frame of the capacitor. One is a single gang hooked for 440 pf. The third terminal is connected to two gangs of this capacitor. If I need lots of capacitance, I can then parallel the two connections for a total of 1320 pf. You can build yours any way that you see fit and with what you have.
The Octocoil is made with a variometer coil. As shown on another page, the variometer is a two terminal variable inductor. I wound the big coil with a total of 40 turns of my famous 40 wire/ 44 gauge rf litz wire. The number of turns you need will depend on the gauge of wire that you use. Litz isn't necessary, but it is very nice for the rotatable coil as the wire is super flexable. The inside coil has 24 turns of the same litz wire. The outside coil is just over 3 inches in diameter and the inside coil is just over 2 inches. These are common mailing tubes found everywhere.