One Tube Regen Receiver
This is a project I saw in an Elementary Electronics magazine back in 1967. I still have that magazine somewhere and actually remember buying it one Saturday morning at Price Pharmacy (still in business) in my home town. The radio in that article was called “The Neophyte 1.” As soon as I saw the article, I knew I had to build it. Eight years later, in 1975, I finally did. The first version I built had a 6V6 output tube that drove a speaker loudly. The chassis was made from a cookie sheet that I got at the dime store. I wish I still had that radio. The most recent version was built very much like the one in the original magazine article. It is shown in the pictures below. The orginal magazine project used a plastic pill container for the coil form. A capacitor was switched into and out of the tuning circuit to allow for dual shortwave band coverage. Shortwave was kind of fun to listen to back in the ‘70’s. It is pretty dull now. Late night AM radio where the entertainment is today with all of the alien abductions, big foot hunters, and paranormal investigations. This latest Neophyte 1 has a plug in coil form made from a piece of thin wall PVC pipe and a 4-pin plug. It all epoxied right together and took a coat of brown paint to make it look vintage and cool. It is about 1 inch in diameter with, as I remember, 95 turns of 32 gauge enameled wire on the main tuning coil. It pretty much tunes the entire US AM broadcast band with an old 365 pF tuning capacitor salvaged from an old Globe transmitter. The tickler has about 8 to 10 turns, I think. I need to look at the coil again. Regeneration control is by a 50K potentiometer and works very well. The 6U8 tube is one of the most versitile tubes I have ever run across. You can use it to make a great oscillator and buffer or an oscillator and mixer. The triode section can be used to drive the pentode output section, making a decent audio amplifier that will drive a speaker. I do not think anyone is making the 6U8 anymore. The good news is that so many were made that you can still find NOS and used ones all over the internet. I probably have a dozen of them lying around. The performance of this simple receiver is impressive. I remember the evening I finally got my first version working. It worked the first time I tried it. The latest version that is shown in the photographs is used occasionally. The volume (there is no volume control) is pretty loud. It works with either low or high impedance phones. The little ear buds that are used with smartphones work fine. From the southeastern US I listen to KMOX in St. Louis, WBAP in Dallas, WBBM in Chicago, WHAS in Louisville, WLAC in Nashville, and WTAM in Cleveland. A wire about 50 feet long is strung from my bedroom window to a tree. With no powerful AM stations nearby, the regeneration can be adjusted to give near superheterodyne selectivity. It is a useful radio.