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QEX -- the May/June 2010 Issue

04/22/2010

The May/June issue of QEX is coming soon, 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.

David Bern, W2LNX, describes his effort to learn how to program a PIC microcontroller to create a useful project, resulting in “A PS/2 Keyer: Using a Keyer Paddle to Emulate a PS/2 Keyboard and Mouse.” Replace the keyboard and mouse with a keyer paddle to control your computer or take a paddle, NUE-PSK modem and radio on your next outing for even more portability. Bern’s program is available on the Downloadable Files section of the QEX Web site.

Rubens Ramos Fernandes, ex-PY2QE, shows his “Frequency Counter for the Experimenter.” This handy piece of test equipment uses a PIC 16F876A microcontroller and the prescalar in a National Semiconductor LMX 2326 RF synthesizer to create a frequency counter that covers 30 Hz to 55 MHz in one range, and 55 MHz to 2.8 GHz in the second range. Byron Blanchard, N1KEV, explains the process of “Adjusting Bipolar Junction Transistor Crystal Oscillator Amplitude” output in his article. With a series of graphs and dc measurements, Blanchard shows us how to set the output amplitude of a basic oscillator circuit, and then explains why this technique works.

Mark Spencer, WA8SME, uses small 433 MHz transceiver modules to demonstrate remote telemetry techniques in The ARRL Education & Technology Program. These modules have no squelch function, which limits their usefulness for a data link. Mark added a squelch function as a way of “Solving Random Noise Issues n TRM-433-LT Data.” Gary Steinbaugh, AF8L, presents “An Inexpensive Laboratory-Quality RF Wattmeter.” This calorimetric design uses a thermistor temperature sensor inside an oil-filled dummy load and foam insulation to isolate the system from outside temperature fluctuations. Because the system is not frequency sensitive, it can be calibrated using low frequency ac or even dc power sources.

Jon Wallace and Richard Flagg, AH6NM, bring us another “Amateur Radio Astronomy Project.” This time we learn how to listen for “Radio Signals from Jupiter.” You may have already heard these signals around 18 to 28 MHz. There is even computer software to help you display the signals and share them in real time with other amateur astronomers on the Internet. Dr Sam Green, W0PCE, solves the problem of taking photos of an oscilloscope display with “An Oscilloscope Camera Mount.” His camera mount ensures that the camera lens is centered in front of the oscilloscope screen and properly aligned for the best pictures. Using digital photo editing software, he is able to convert the images into negative format and create gray scale images that are ideal for publication.

Bob Kopski, K3NHI, presents a short “Tech Notes” item about the characterization of Analog Devices 8307 logarithmic amplifier ICs. Kopski’s “Simple RF Power Calibrator” circuit (Jan/Feb 2004 QEX) used this amplifier, and was easily calibrated using a 10 MHz square wave signal. Recent performance changes in these ICs requires a revised circuit and calibration method, which he describes in this Note. Ray Mack, W5IFS, is back with another installment of his software defined radio column. In this installment of “SDR: Simplified,” Mack describes the steps required to set up a Linux computer to run the Analog Devices Blackfin BF537 DSP IC and Stamp evaluation board software. We are getting close to running some actual DSP experiments on the Blackfin board.

Would you like to write for QEX? It pays $50/printed page. Get more information and an Author’s Guide here. 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.

 



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