THE XS-801 Crystal Radio Kit


Welcome fellow crystal set and kit builders. The XS-801 was summarized in the May 2008 XSS Newsletter. The purpose of this web page is to give you a bit of a flavor for the kit and its manual.

The radio is an ideal transition for those who’ve finished an Oat-Box or other starter crystal radio and desire to learn more and hear more stations. In building this radio you’ll learn about antenna matching, winding an advanced coil, coil and system Q, and accommodating an ear piece or headphones. The radio's features include antenna matching, dividing the AM band into 2-sections, variable capacitor station tuning, a circuit for reducing audio distortion of strong signals, and a large 4.2 inch by 3.7 inch #18 wire coil. Parts include two air variable capacitors, a spool of #18 insulated stranded wire, 2 diodes, an ear piece, and a number of passive components. The chassis, panel and coil form are pre-drilled and ready for assembly. The manual covers the assembly, installation, and operation of the kit, and includes suggestions for further adaptations/experimentation.

excerpt from the assembly section

panel picture

___Step #2 Place the wood trim legs under the 8 by 10 hardboard chassis and mark them with a pencil through predrilled holes 1-4 in the chassis board, as noted in the reduced chassis drawing, Figure 1. Use a small nail to make starter holes in the wood trim where marked. Then secure the chassis by installing a wood screw at each hole. Align front and outside of rails with the board and tighten screws. A copy of the chassis drawing is available on the article-index page.

___Step #28 Attach a 50 nF disc capacitor (503) across the Q and R leads of the pot, R2, on the front panel. See Figure 6, at right. Solder terminal Q at this time.

excerpt from operations section

Referring to the front panel, the antenna is matched to the radio's tuned circuit - C1 and L1 - by adjusting the antenna matching capacitor, Ca. Rather than resonating the antenna, the matching capacitor is placed in series with the antenna. The affect is that the resistance of the antenna in series with that cap appear as a large resistance across the tuned circuit. The match has the same effect as if you had used a step-up transformer. For more details on this method, see the article "Equivalent Series and Parallel Circuits," on our web site: article1.html .

So there you have it. It's a good one-weekender kit. The only tools and supplies you'll need are: a good antenna and ground, small cutters, small pliers, soldering iron & solder, Phillips & regular screwdrivers, a bit of hookup wire, some masking tape, some model glue and a well lighted workbench. If you live in the midwest, you're just a weekend away from listening to WGN in Chicago, KMOX in St. Louis, or KOA in Denver! =:) To order, click on the "to order kits" link below.