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The recipe for success

2017-09-08 17:15  
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Dave's 32nd crystal set

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Did you ever do something and it turned outright? This is one of those rare cases with me. This one turned out perfect!

My #32 radio is based on my favorite single coil circuit that I have used in several of my sets, including my #8. The major difference with this one is the really nice oval shaped spider coil. I bought this box over a year ago, just waiting for the moon, sun and stars to be in the right position. Recently I made some large spider coil forms out of 1/16 inch thick styrene with great success. I wanted a decent coil for my radio and one that would look presentable. Now that the ducks and planets were in a row, it was time to construct.

I wrote a page on spider coils that might be of interest. I use 1/16 inch styrene sheets because they have low rf losses and it is easy to work with. I made the coil and chassis for my radio with this stuff. One thing to be careful is not to heat this plastic. It will melt. Make sure to do your solder lug soldering before you attach the lug to the panel.

The coil has 33 turns of 40/44 litz wire. The hub of the form is 4 inches long and one inch wide. I used a compass to draw the circles. All the cuts were made with a scroll saw and carefully sanded with a 1 inch belt sander. I made the slots a little wider by letting the 1 inch belt sander do it's work. Please be gentle using the sander on the styrene. The total size of the form is 6 inches by 3 inches. The diode tap is at around 25 turns from the grounded end. Please refer to the circuit diagram in my #12 set. Only the coil is different.

Otherwise everything else is pretty straight forward with this little radio. Guess I will shut up and listen to the AM stations.

73 and good crystal DX. Dave - N2DS

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