The September/October issue of QEX is coming soon, and it is full of theoretical and practical technical articles that you don't want to miss.

Richard Chapman, KC4IFB, shows how to use the Arduino prototyping board to design a project, and then gives us a lesson in programming the microprocessor to "Build a Low-Cost Iambic Keyer Using Open-Source Hardware." W. G. Moneysmith, W4NFR, was a new repeater trustee needing a duplexer for a 70 cm repeater. He presents his solution in "A Homecrafted Duplexer for the 70 Centimeter Band."

Robert Zimmerman, VE3RKZ, describes one of his recent antenna experiments in "An Easily Erected 20 Meter Antenna for Emergency Use." Mike Hamel, WO1U, discusses "Phase Controlled Differential Drive for EER Amplifiers" in this presentation about envelope elimination and restoration as a way to achieve linear operation with high efficiency (such as Class E) amplifiers.

Gary Steinbaugh, AF8L, presents Part 4 of "A Cybernetic Sinusoidal Synthesizer." In this installment, Gary describes an RF power level control module for the synthesizer, and concludes with a 53.3 MHz low phase noise synthesizer using the 10 MHz reference signal. Bob Miller, KE6F, explains how you can use a surplus rubidium oscillator to build an "Atomic Frequency Reference for Your Shack." He presents information about the stability and accuracy of rubidium oscillators, as well as a number of practical applications for such a reference.

Would you like to write for QEX? It pays $50/printed page. Get more information and an Author's Guide. If you prefer postal mail, send a business-size self-addressed, stamped envelope to QEX Author's Guide, c/o Maty Weinberg, ARRL, 225 Main St, Newington, CT 06111-1494. QEX is edited by Larry Wolfgang, WR1B, and is published bimonthly. The subscription rate (6 issues) for ARRL members in the US is $24. For First Class US delivery, it's $37; in Canada and internationally by airmail it's $31. Nonmembers add $12 to these rates. Subscribe to QEX today.