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Homebrew Regenerative |
| Shortwave radio is what got me interested
in this radio stuff in the first place. Ever since I was a kid huddled in front of an old
console radio my grandmother gave me, I've been fascinated with the notion of listening
broadcasts originating half-way around the world. I even had one of those SWL
"callsigns" that a national SWL club used to issue.
Somehow over the years I had gotten away from SWLing. However, with the resurgence of interest in regenerative receivers in the QRP Community, my interest was peaked once again. I had some free time one weekend and decided to try my hand at building one from scratch. I raided my junk box and found that I had just about everything I needed to build one. Also, I decided that this would be a good project to build using techiques I had been reading about.
The receiver I built was the "Pipsqueak." This little gem is based on an earlier regen design by Charles Kitchen with an improved audio section designed by Paul Harden. This little receiver is almost as simple as they get. After a few hours of melting solder, I actually had a working receiver. The only problem I encountered was some oscillation when the volume was cranked all the way up. This was quickly resolved by added a .01 ufd capacitor across the output of the audio amp. Now it's rock-solid.
I mounted the circuit board on a small piece of pine and used a piece of copper-clad circuit board material for the front panel. The coil in the tuning section is wound with #22 hookup wire on a plastic 35mm film container. I also did a little fiddling with the tuning section to get the band coverage I was interested in. I wound up putting a .001 pF cap in series with the 140 pF poly variable tuning cap. It tunes from 4.9 - 10.3 MHz, covering 2 or 3 of the more popular shortwave broadcast bands.
The performance is surprisingly good for such a simple receiver. With a 20-foot wire antenna strung through the ceiling joists of my basement shack, I'm able to pull in the major shortwave stations with plenty of volume in the headphones. With a longer wire antenna, even more station from all over the world can be heard. Morse Code and Sideband reception is done by advancing the regeneration control just below the point of oscillation. This rig is a lot more stable than a tube regenerative, because in a tube design , heavy metal chassis is needed, and you get a "ringing" when hit, or you tap the tube. :) but, they were wonderful cheap devices to make. Although I no longer chase QSL cards from the stations I hear, I still like to fire up this little radio and listen to the news from BBC. What makes it even better is knowing that I'm listening to it on a radio I built from scratch. The magic is back!
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