Raytheon A
Half Wave Rectifier
1927

Raytheon called the Type A a rectifying tube but it was actually a chemical device. It was rated for 2.5 amps with a max input of 9 volts and was intended as a filament supply rectifier. These "tubes" had a short life and tended to explode or catch on fire after some use and were withdrawn from the market after a brief period.