The 1926 ARRL Handbook Regenerative Receiver

This story started when my good friend Bruce, W1UJR, visited an antique store in Ellsworth, ME a few years ago, and made a deal with the proprietor for two old pieces of 1920s homebrew radio equipment. The regen receiver pictured above was one of them. The other was a smaller single-tube radio, which only had about half of its parts remaining: the main coil, and (I think, taking an educated guess) a variometer were no longer with the set. The set that is the current topic is pictured below in its as-found condition:

Bruce kindly gifted me both sets in April 2007, and I picked them up from him on my way home from a day trip up the coast with my XYL. The smaller set became the foundation for a short-wave XTAL set. The larger of the two was a three-tube set, a regenerative detector followed by two stages of transformer-coupled audio. Originally there was a (burnt-out) UX-199 in the detector socket, and a pair of Cunningham UX-301s in the audio amplifier stages. This is odd, since the 199 likes 3.0V on its filament, while the '01As want 5.0V, and all three filaments were wired in parallel. Maybe this was why the 199 filament was open? Or perhaps someone stuffed the 199 dud in there to fill an empty socket to make the unit look complete? Who knows? In any case, the bad 199 got replaced with a good '01A. Also, the bakelite chassis had been drilled for two identical cylindrical audio transformers, but one of them had been replaced with a non-original unit that was JuSt dangling by 2 or 3 connecting leads. One of the windings on this poor transformer was open, to boot, so it got replaced with another period unit from my stash. At this time I added an RF choke, I think originally salvaged from an old Majestic broadcast radio, in the plate lead between the transformer and tickler winding. I also had to spend some time freeing up the throttle (regeneration control) variable condenser so that it would turn freely. Finally, I had to replace the grid leak resistor, which was open. I found a suitable replacement that was labeled 5 megohms, but read about 7 megohms. Close enough. In my seemingly bottomless junkbox I had pair of 5V 3A regulated power supplies, so one of these became the filament supply, and I fed suitable plate supply voltage to the detector and audio stages, and the set came to life! The single Aero coil that was installed covered the 80-75M amateur band, plus a fair amount of space on either side. I tuned in an AM QSO on the 75M band, and heard Bruce in a round table with Dirk, WA2CYT, and some others. I quickly fired up my Ranger on frequency, told Bruce what I was using for a RX (in truth I had him guess, which he correctly did) and completed my first QSO with this receiver.

1926 ARRL Handbook regen, top view:

At this point in time I still had no idea of the history of this radio. Then, last spring, I was discussing the set with fellow antique radio enthusiast Carl, WA1 KPD, at the 1st NEARFEST hamfest in Deerfield, NH. Carl said it sounded like one featured in the 1926 (1st edition) ARRL Handbook. He offered to send me a copy of the article so I could verify it. The set is featured on pages 49-51. It turned out that indeed I was the owner of a fine example of the 1926 Handbook radio, with a somewhat different layout from the example pictured on page 49. Incidentally, Carl had himself built a beautiful reproduction from the Handbook article, and sent me some digital photos of his.

I was able to find additional Aero coils for the radio at the 2007 AWA Annual Conference flea market last August, including a broadcast band coil in its original box. In addition, my friend Lou, VE3AWA, had also bought some of the coils from the same seller and ended up giving me most of the ones he scored! I now have continuous coverage from about 3.0 Mc/s to about 15.0 Mc/s, as well as the AM broadcast band (gotta use the correct frequency units for the period, of course. Maybe I should have stated the frequency coverage in terms of meters of wavelength?).

I'm writing this on New Years Day, 2008. Earlier this afternoon I had a fine business SKN QSO with N1SZ, Dave, in Woodbury, CT, somewhere in the vicinity of 3.55 Mc/s. I was using this receiver, along with my push-pull '45 TNT transmitter. Life is good!

1926 ARRL Handbook regen, bottom view:

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