for Issue #4
HOMEBREWER #4 - CONTENTS
IQ-VFO ... a High-Performance DDS-based VFO Craig Johnson, AA0ZZ
Back in 1997, radio frequency homebrewers really began taking advantage of the conveniences that DDS technology offered: 1-chip simplicity, DC-to-30 MHz signal generation ability and relatively decent signal purity. Since then, AA0ZZ and others have been creating and refining signal generators using this technology. The author began working with one of the latest DDS chips from Analog Devices, with an end goal of designing a 0-60 mHz VFO for use with the recently introduced KK7B high-performance R2PRO receiver. This the AA0ZZ story of taming the AD9854 dual-output (I-Q) DDS chip and creating a PCB in the process that others can also use. Additionally, your friendly Homebrewer editor has documented his enclosure for the project, creating a modular high-end VFO component for use on the bench. AA0ZZ and the NJQRP are also making his pc board and PICs available to help others construct this high-performance HF VFO.
Harnessing Harmonics in the IQ-VFO -- Craig Johnson, AA0ZZ, Jim Kortge, K8IQY
The spectral purity of a DDS-based VFO has been the subject of great debate in the technical community. Much of the discussion is related to earlier generations of DDS parts which feature Digital to Analog Converters (DACs) that are not as good as that on the AD9854 used in the currently popular IQ-VFO design. Designer AA0ZZ, along with noted QRP Hall of Fame member K8IQY give this topic some serious study.
Nuts & Bolts of RF Design - Part 2 -- Wayne McFee, NB6M
This homebrew transceiver was the subject of a presentation made during the QRP Symposium at Pacificon 2003. I focused on the process of designing and building this transceiver from scratch by selecting portions of proven circuits and stringing them together in order to achieve the desired result. In the previous issue, I presented a step-by-step approach to designing and building this rig using some simple "nuts and bolts" techniques. This time I’ll take you through the detailed circuit analysis, measurement and tuning procedures.
RF Power Meter Cookbook - Part 3 Joe Everhart, N2CX
This installment outlines test methods and simple circuits used to test RF power meters when you don't have access to expensive lab-grade equipment. N2CX focuses on testing below 30 MHz to demonstrate principles without resorting to special techniques.
Build the PicWx APRS Weather Station - Part 6 Dave Ek, NK0E
NK0E started this series with a simple PIC16F84A design and has since been adding various hardware and software pieces to create a functional weather station that connects via serial port to your PC or ARPS system. This time Dave adds an atmospheric pressure sensor to this ongoing fun and educational project.
A Homebrew PAC-12 Antenna -- Richard Meiss, WB9PLU
WB9LPU takes the basic design of the very popular KA5DVS "PAC-12" portable multi-band vertical antenna and makes it sturdier and more easily assembled in the field.
Etching PC Boards at Home -- Robert "RC" Conley, KC5WA
Here's how RC followed the lead of AB5XQ, and improvised a little along the way, to homebrew a pc board for the Pixie 2 QRP Transmitter. With just a handful of parts from some local suppliers, you too can make a great-looking pcb for that next project!
"Slap, Click, Twang" ... Morse Code the Old Way -- Mark Spencer, WA8SME
A simple interface that will allow you to use a telegraph sounder to copy code like they did in yester-year
SPICE Modeling Tutorial -- Chuck Adams, K7QO
SPICE, an acronym for Simulation Program with Integrated Circuit Emphasis, is a computer program developed at the
at Universityof California . Since it was developed with public funding, the program became public domain and is readily available from several sources over the Internet. I will give you pointers to sources that I know of at the end of this tutorial and hopefully you will not procrastinate before they disappear. Berkeley
Photo Documenting Construction of the NorCal BLT Tuner Kit -- Robert "RC" Conley, KC5WA
When RC asked if we wanted to see a few photos of how he constructed his original copperclad-enclosed BLT Tuner Kit, we of course said "Sure!". But when he sent over his photo-journalism work, we nearly fell off our work stool ... we think you'll be equally impressed!
TTAM: Test Topics And More - "Good Enough Q" Joe Everhart, N2CX
This time N2CXl describes how to connect some basic building blocks to measure Q and how to use almost the same methods to measure Q with some test gear you may already have.
QRP Operating: “Joys of the Classic Regen Receiver” Richard Fisher, KI6SN
Radio To Go: “QRP Events” James Bennett, KA5DVS/6
Coming Back to QRP Richard Arland, K7SZ
QRP Contesting "January 2005" Ken Newman, N2CQ
Farewell to a Friend -- Doug Hendricks, KI6DS
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Page last updated: January 3, 2005