Van Horne AC Tube

This rare tube was made by the Van Horne company of Franklin, Ohio in early 1927.  It was an attempt to make a tube whose filament could be operated on AC, rather than battery power, without introducing undue amounts of hum into the signal.  The filament required 0.8 volts at 2 amps.  It was very similar in function and characteristics to the Armor AC-100 tube.

There are no radios known that were designed to use this tube, and it disappeared from the market quickly.  The introduction of the UX-226 by RCA late in 1927 sealed its fate. 

A unique feature was the port at the center of the press (visible in the last picture) through which the air was exhausted during manufacture.  This method was unique to this tube, and was the subject of a Van Horne patent.

Many thanks to Jim Cross of Vacuum Tubes, Inc. who was able to identify this tube for me.