"This tube contained three triodes with a series connected filament for all. The shelf carried the grid and plate connections for the 2nd and 3rd sections. The box listed the tube number as E.M.V.-3A. These tubes were made by the Cleartron Vacuum Tube Co. and the name came from Alfred E. Emerson, CEO of Cleartron. In 1928 Emerson sold the rights to the Multivalve to English interests for $95,000 plus royalties."

 These are very scarce and rarely show up for sale. Seeing one new in the box is almost unheard of.

The filament on this on is GOOD