Fifty years ago this month, the March 1968 issue of Electronics Illustrated showed how to put together this transmitter for 40 and 80 meters. As the photo makes clear, it’s about as simple as can be.

It uses a 50C5 (or 50L6) tube, with the filament powered directly off the AC line with a 400 ohm resistor. Two silicon rectifiers are used as a voltage doubler to provide about 350 volts for th plate.

All components are mounted on a wooden board, with connections soldered to finishing nails on the board.

The neon lamp in the schematic is there as a safety precaution. Since one side of the key is connected directly to the power cord, the lamp comes on to show that it’s plugged in the wrong way–with the hot side on the key. If you plug it in and the light comes on, then you should reverse the plug. (And you’ll probably have the added complication of blowing the ground fault interrupter of modern house wiring.)

Also, since there’s no filtering of the output, this transmitter probably doesn’t meet modern spectral purity requirements.