The September/October issue of QEX is already out, and it is full of theoretical and practical technical articles that you won't want to miss. QEX is the ARRL’s “Forum for Communications Experimenters.” Published bimonthly, it features technical articles, columns and other items of interest to radio amateurs and communications professionals. The mission of QEX is threefold: To provide a medium for the exchange of ideas and information among Amateur Radio experimenters; to document advanced technical work in the Amateur Radio field, and to support efforts to advance the state of the Amateur Radio art.

Here’s what you’ll find in the September/October issue of QEX:

• John Hansen, W2FS, describes “VSC-X: A Virtual Serial Cable” that uses a pair of X-Bee Pro modules, which transmit with an output power of about 60 mW on the 2.5 GHz band. These modules use the Zigbee IEEE 802.15.4 protocol to provide data transceivers. Hansen adds the necessary hardware to create a USB interface and a serial interface. Use a pair of these modules to remotely program your mobile transceiver, no wires required! How many other applications can you find for a virtual serial cable?
• Arch Doty, W7ACD, explains some results from his experiments with “The Effect of Soil Properties on the Performance of Antenna Radials.” When earlier research was interrupted by some heavy rains that changed the ground conductivity of his antenna test range, Doty turned his attention to the temporary effects caused by that change.
• Fred Franke, WB2FNO, introduces an electronic “component” many of have never heard of in “Playing with the Lambda Diode.” The lambda diode, built from two transistors, exhibits a negative resistance response that proves useful for a variety of circuits, including a signal generator, dip meter and crystal oscillator for checking crystal operation.
• Jukka Vermasvuori, OH2GF, describes a test circuit that he built for “Measuring Coil in Tuned Circuits.” He explains the importance of measuring coil Q at the frequency at which the coil will be used.
• Maynard Wright, W6PAP, presents the next in his series of articles about the Octave programming platform in “Octave for Curve Fitting.” Wright uses Octave for some antenna modeling calculations, and shows us how to use some of the program’s features to accomplish a least squares fit of the data.
• ARRL Lab Test Engineer, Bob Allison, WB1GCM, gives us his impressions of Receiver Design and Technology, a new book by QEX author Cornell Drentea, KW7CD. Allison explains why RF engineering students and those more casually interested in receiver design topics would benefit from a copy of this new book.
• Ray Mack, W5IFS, returns to our pages as an author, with a long-awaited addition to his “SDR: Simplified” series. In this installment, he introduces us to cascaded integrator comb (CIC) filters, and explains their operation in the signal processing chain.

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