The January/February issue of QEX is out, and it is full of theoretical and practical technical articles that you don't want to miss.

In this issue, Thomas Alldread, VA7TA, introduces his "NimbleSig III" dual output DDS RF generator. This circuit provides signals over a range from 100 kHz to 200 MHz, with 1 Hz resolution. Professor Dr Thomas Baier, DG8SAQ, designed "A Small, Simple, USB-Powered Vector Network Analyzer Covering 1 kHz to 1.3 GHz." This article describes the circuit and its operation, and Jim Kocsis, WA9PYH, describes "A 2256 MHz PLL Local Oscillator."

Rudy Severns, N6LF, presents some research he has conducted in "Experimental Determination of Ground System Performance for HF Verticals." Part 1 describes the experimental setup, including the test equipment used and the antenna configurations tested. Part 2 -- also in this issue -- describes an experiment to verify the NEC-predicted "Excessive Loss in Sparse Radial Screens." If you use vertical antennas on HF, or have thought about using vertical antennas on HF, you will want to read all the articles in this series.

Maynard Wright, W6PAP, brings us more tricks for using Octave in his latest article, "Octave for SWR." Learn how to type equations from the Octave Command Line, and then use the Command Line Editor feature to scroll back, modify the expressions, and try it again. Vance Hawley, WA7FDR, taught an RF class at Idaho State University, and his students conducted some experiments into "Unusual Terrain Influence on VHF/UHF Propagation"; their report describes their findings. Nick Luther, K9NL, presents "A Protocol for Multicast Weather Data Distribution Over AX.25." This article is reprinted with the author's permission from The 27th ARRL and TAPR Digital Communications Conference Proceedings.

Ray Mack, W5IFS, begins a new column about software defined radio for those who want to learn more about this hot topic. In "SDR: Simplified," Ray will lead us through some experiments using digital signal processing (DSP) and other tools. Scotty Cowling, WA2DFI, brings us an announcement from TAPR about the new Mercury board for the high performance software defined radio (HPSDR) project.

Acting on a suggestion from Gary Johnson, WB9JPS, we are introducing a section called "Reader's Page" in this issue. Readers are encouraged to submit photos of their projects to show off their handiwork. To start things off, Gary submitted photos of projects that combine two of his hobbies -- woodworking and Amateur Radio.

QEX is edited by Larry Wolfgang, WR1B, and is published six times a year. 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.