How to Build the
Twinplex Regenerative Receiver

In 1934 a fascinating single-tube kit-form shortwave receiver was advertised in radio magazines. It was called the Doerle Twinplex because it used the brand new 19 vacuum tube which contained two triodes in one glass envelope.

An illustration of the front of the radio appears on the front cover of our "1934 Shortwave Manual" while the rear of the radio appears on Rock's "Secrets of Homebuilt Regenerative Receivers." If you have either of these two valuable books, you know what receiver I'm talking about.

I have to be honest. I wanted to build the Doerle 19 Twinplex simply because of its appearance. It "certainly" couldn't be much of a receiver. Not a single tube regenerative powered by batteries. It was too simple. Too old.

Oh, but was I wrong! When I attached the batteries, brought up the filament, and increased the regeneration, the signals came popping in! Foreign broadcasts, ships at sea, amateur cw and ssb signals, spy stations, WWV and more! More than once signals were so loud I had to rip off the headphones to relieve the pain! There were signals everywhere!

Of the many regenerative receives I've built, this is the most impressive. Simple. Stable. Sensitive. Inexpensive. It's far more than I ever expected.

Next, I built a version using the more modern 6SL7 twin triode vacuum tube. It was even hotter!

And then I built a solid state version using three transistors that tunes the region around 10 mHz to provide shortwave broadcasts, WWV and the 30 meter amateur band. It, too, really performs well.

You get three different receiver projects in this one book. In a hurry? Build the solid state version while you scrounge the fleamarkets and dealers catalogs for old time components so that you can build the original Twinplex. Or build a version out of whatever you have on hand. It's easy.

This is a project book intended to be used in conjunction with "Secrets of Homebuilt Regenerative Receiver" and "Building Your First Vacuum-Tube Regenerative Receiver" described in this catalog. This is a project book. You won't get much help with the basics. The other two books do that.

Great receiver! Sharp looking. Something you'll be proud to show your mystified friends and relatives. Get a copy and get building! 5 1/2 x 8 1/2 softcover 63 pages

No. 22148 ... $7.95

Building Your First Vacuum Regenerative Receiver

Dave Gingery Drools All Over the Radio...
As soon as the Twinplex book arrived from the printing plant, I sent Dave Gingery a copy. And I soon got a letter back...

Wow! The Twinplex Regen book is a gem. "Twinplex" along with your earlier regen book exactly fills the bill. We all drooled over the Twinplex and there is no telling how many regenerative radios were built with that look even if we could not afford a "19" twin triode tube. That technology was already obsolete in the mid 1940's when I began to build simple radios but it was right up a poor boy's alley because we could not afford the extra components or quite grasp Super-het technology. I built an autodyne just a few years ago and it was just as exciting as it was a half century ago. I'll build the solid state version one of these days and I might even play with some varactor diodes for tuning although I still like to see a tube glow and puzzle over just how the intermeshing plates of a variable condenser tune a circuit.
Dave...