Building a Binaural Weekender From the Schematic
Special to The ARS Sojourner
I started out building projects with perfboard, then began etching my own boards. I enjoyed it, but the designing process was a lot of work for just one board. Plus, doing modifications, troubleshooting, and correcting errors was a pain in the neck.
When Wes Hayward came out with his Micromountaineer in the July 2000 issue of QST, I decided to build a thirty meter version. Since he promotes ugly construction, and because I'd never built anything but VFOs using that method, I decided this was the time to try building a complete project with it. The experience made me a believer! The speed, ease of using components on hand, and ease of troubleshooting convinced me that this is the way I want to build from now on. And with a little effort, it doesn't have to actually look ugly. (Although I think Wes would say that excessive time spent trying to make the inside of a radio look nice is not time spent wisely!)
A short time later, and with the help of my elmer, Jim, NC9H, I built a fifteen meter version, complete with VFO. With that finished, I began to look for another project. Ah! Rick Campbell's Binaural Weekender! It sounds really fascinating, Ed Hare loves it, and Wes recommends it. And it won the 1999 Doug Demaw, W1FB, Technical Excellence Award. Why haven't I built it yet??
The first thing I did was email Rick. "Did any errors creep into the article?" Those things can really throw me. I then checked the material lists and saw I didn't have some of the capacitor types and a couple of the inductors he called for, so I fired off an order to Digi-Key.
I had everything I needed to build the VFO though, so I got started. First, I found a piece of PC board material that was large enough for the project and lightly scribed a _" grid on it. The grid helps me build things squarely and I always know how much room I'm taking up.
Next I decided how big of a box the VFO would require and cut out the pieces. Then I mounted three of the sides to the board material and mounted the tuning capacitor. After building the VFO and testing it, I added the fourth side and the top. My only deviation from Rick's schematic was that I added a trimmer capacitor so I could precisely set the frequency. The VFO worked as he said - exceptionally well.
With the Digi-Key order now in, I kept going. I decided to build one of the audio chains next and started from the headphone end. To save space and time, I held the IC in an "extra hand" (RS #64-2063) and soldered all of its associated components to it. Then I mounted it as an assembly near the front of the VFO enclosure. I finished the chain, building backwards towards the rear of the board, and a brief test indicated it was working fine. I might mention, I try to build with most of the components a resistor's height above the board so I can easily drop a resistor or capacitor to ground where I need to, and if I need to stick in a high-ohm resistor for a stand-off, it fits right in. I didn't need any on this project though.
After building the second audio chain beside the first one, I mounted the gain control pot & on/off switch. Since the things it was controlling were in the rear, I decided to mount it there and extend the shaft to the front. It was easy to drill a 1/8" hole in the end of the shaft, since it was one of those knurled types with a slot in it, made for push-on knobs. Then I put some super glue on the end of a 1/8" rod and stuck it in the hole. To mount the pot where I wanted it, I stood a small piece of board material on end and soldered it to the main board, then soldered the pot to small pads I'd cut on the end of it. To support the other end of the shaft, I wrapped a piece of bare #18 wire (thermostat wire) around it and formed two legs, then soldered them to the front of the board. I also used the wire to make little posts to secure the reduction drive.
I calculated and wound the toroids, then built the front end and demodulators. And after making some temporary connections for the power, headphones, and antenna, I was ready to fire it up. Wow! What a pleasant surprise! A first class receiver, and instead of hearing everything in the center of my head, I could hear it from ear to ear. It sounded better than I expected. This thing could spoil a guy!
Thinking it would be getting a lot of use, I decided to install it inside a durable plastic enclosure. And instead of making a frequency dial, I decided to install a UniCounter - the single segment display that was in the December 2000 QST. I'd purchased one, building a little portable frequency counter inside an Altoids box and really liked it. It would compliment this receiver nicely.
There was plenty of room for the circuitry on the right side of the VFO and by the end of an evening I had digital readout on my Binaural Weekender. And after a little more time spent painting and lettering the end panels, I was done.
If you're looking for a new project, and want to build something from scratch, I'd highly recommend a Binaural Weekender. If you aren't a QST subscriber, the article is available on the ARRL’s website at http://www.arrl.org/tis/info/pdf/9903044.pdf . (You'll need Acrobat Reader.) If you're also interested in the UniCounter display, the UniCounter website is at http://homestead.juno.com/rsstone/Unicounter.html .
Photographs:
- The VFO
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Dennis Payton, N9JXY, has become an accomplished builder of ham radio eqipment, working directly from shematics. He lives in Auburn, IN and loves ham radio and fishing.