The Seductive Sexy Sizzler Set #11
This is my coolest crystal set yet! Too bad you won't be able to reproduce this one as the capacitors aren't made anymore. However, they can be found. Ain't those tuning condensers sexy?
My goals in making this radio are 1) the use of those beautiful tuning capacitors that someone sold me. 2) to make this radio on a breadboard just as in the old days. 3) to hide the new components, and 4) have a set that I can vary the L to C ratio.
The board is red oak that I bought on ebay. My neighbor with all those nice power tools cut the board to one foot long and used his shaper to put a little bevel on the edges. I brought it home, sanded and stained it with Minwax Red Oak Stain. The board is just over 7 inches wide. I am using a 12x6 inch by 1/8 inch black Garolite®, just as I do in most of my radio projects. The hole cutting was near perfect on this one. I drilled a hole in a bar knob and placed it over the variometer shaft. I then cut two holes and put flat head machine screws with nuts through the panel, to keep the variometer shaft from turning around a lot. That way the wire coming out the back doesn't wind up. I also put a couple of brass knurled nuts on the coil form to improve the looks of the set.
There are 3 hidden components hidden under a plastic bottle cap. My friend Dan, W7OIL showed me this technique. I painted the cap with black gloss lacquer. Then I drilled the 4 holes and mounted 3 machine screws with washers, solder lugs, nuts and knurled nuts. As you can see I used a lot of brass hardware on this crystal set.
Looking at the circuit, there are 4 variable elements. First is the antenna tuning capacitor, next is the antenna tap screws. Then the variometer part of the coil and lastly the detector tuning capacitor.
I tapped the coil in 4 places. These taps connect to the binding screws that are on the back of the set. The taps are on the fixed portion of the coil and will allow the user to closely match the antenna to the radio. The capacitor is in series with this coil.
The L to C ratio is important in the design of a crystal set. You can find some very fine articles about this written by Ben Tongue. By making the L/C ratio correct, the selectivity is improved and the efficiency is the best.
I was going to use the fahnstock clips on this radio but after looking over the beautiful features of this set, I felt that special treatment was needed. I had some 3/16 inch Garolite® that I wasn't using. I cut a 1-1/4 inch wide piece, drilled and mounted everything. I used some Z-brackets that are made my Keystone Electronics. This piece turned out very well.
I wrote a piece on the variometer that I am using.
The wiring was done with that heavy 14 gauge Belden tinned copper wire. It doesn't have to be wired that way, but it sure looks nice.
This radio works very well! I picked up a half dozen stations late last night before going to bed. Perhaps the AM band was in good condition too. I haven't compared one set to another yet.