Charlie's crystal set

New Photo and Text information

After reading the other entrys I think that I need course in technical writing. The set is complete now and the new photos are up. Some things that I need to add to the text is that the dials are a construction of my own . A scanned protractor provides the tunning dials. the other dial faces where done with a image software that I have on my computer named PSP. The dial frames are normal wood paneling with a facing that I didn't like so I used the back and applyed three coats of polyurethane. The frames where drawn with the same software as the dials , printed in paper then cut out and layed on the wood panels to be traced on . Then cut with a coping saw hand saw. It took some time but was the effect that I wanted.

As you can see there are two headphones on the set one is a pair of Balwin C, the other is a set of Brush crystal headphones . This works well. Thought in my mind the Brush are by far the best headphones that I own.This allows myself and one other person to hear the set at the same time.

The set DX's well, not as good as some of the other in the contest . I have to this point got 38 stations with the set . the longest distance is San Antonio Tx WOAI, over 1000 miles from Covington Kentucky, stations from Cannada , New Orleans, New York, and the Nations capital in fact most of the East coast. It may not be the best for DX but I'll call it good enough for my needs.

Like the rest of the you I wish the the rest the best of luck. It been fun building and operating this set, an experince that I'm glad I haven't missed.

Since everyone is naming their set I'll call this one Why-too-Cay.

Charles A. McGinnis
AKA: vulcan_41015

Photo and Text information

The radio that I have built, was designed by going to several web sites of the members of this and several other clubs. The antenna tuner / trimmer is a Tuggle design. The main tuning coil came from a design that I have seen on both Owen Pools and Al Klase pages. I made the decision to put a switch in so that I could tap the detector to the top of the tank as well as the center of the tank coil ( a sensitivity / selectivity switch ).

Being a dual tuned set I hoped for a little more selectivity which has been the case. I have a 6 pole, 2 throw switch, to allow me to switch out antenna and main tuning coils for both BC and SW coils ( Switch 2 ). There is also a 2 pole 6 throw switch which controls which tap the antenna is connected to the antenna coil ( Switch 1 ).

The coils are inductively coupled and are on a slide bar. Something that I have seem on sets designed by Mike Peebles.

The detector circuit came from two sources

The first source was from the The Xtal Set Society Newsletter Volume 6 and 7, A project contributed by Ron Pierce using dual diodes as the detector.

The second source came from web site named Learn about The Crystal set. In this site there was a circuit with a cap across the detector diode. The cap provides a small charge to supply additional current for the diode. ( This increased the current to the head phones by 2 uA. on my set for the strongest station. )

The head phones

When working with the head phones I at first went with a a magnet set of phones. I now have a High impedance set of crystal head phones. the set is designed to use either Crystal or Magnetic head phones. There is a audio transformer in the circuit. This allows the primary of the transformer to supply inductance for the crystal head phones , and allows for impedance matching for a magnetic set of head phones on the secondary of the transformer. The ideal for the transformer was from an article on Ben Tongue web site.

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