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Sunday, April 11, 2010

AF Amplifier Selected: From the Ugly Weekender

We went to ZooMarine yesterday. It is a kind of aquatic amusement park west of Rome. I knew that there would be a certain amount of waiting around while the kids defied gravity. A couple of SPRATs might not have been enough for this job, so, just to be safe, I also took with me the ARRL compendium "QRP Power." This turned out to be a very good move, because while seated on a bench close to the entrance of the aptly named "Vertigo" ride, I found the AF amplifier circuit that I've been looking for (for my WSPR direct conversion receiver). It comes from a June 1992 QST article by Roger Hayward, KA7EXM. The AF amp in his "Ugly Weekender" DC receiver had just what I was looking for: discrete components (no IC's), an input impedance suitable for a diode ring mixer, and an output impedance suitable for a computer sound card. Thanks Roger! I built the first stage and the active decoupler this morning. They are working fine.

I wanted to find a photo to go along with this article. While doing a Google image search, the cover of one of my favorite books unexpectedly popped up (see above). VE7BPO's site explains why:

"A great reference for Ugly Constructing is The "Ugly Weekender" by Roger Hayward, KA7EXM and Wes Hayward, W7ZOI published in the August 1981 issue of QST. In fact, it was Wes and Roger who coined the term "Ugly Construction" when preparing this QST article. Wes was asked about this in 2009. The term was a takeoff from the 1958 book entitled The Ugly American by William Lederer and Eugene Burdick. "

I didn't know there was a connection between our construction technique and the book. I find it very appropriate. The good guy in the book is the "ugly" American. He is a practical, technically-oriented guy who puts his skills to use to help people.

For more background on ugliness see VE7BPO's (beautiful) site:
http://www.qrp.pops.net/ugly.asp

1 comment:

  1. Bill, you might also consider adding a diplexer after the mixer. Only 4 additional components, you can lift the circuit from Lewallen's 'Optimized QRP Transceiver'.

    73.......Steve Smith WB6TNL
    The Ugly Rosin Snorter

    ReplyDelete

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