The type 226 is also known as type 26 and in this case as X-226. The Hygrade name is believed to have been used by Sylvania.
The 226 is an AC filament valve used for radio applications such as RF and IF where the mains hum was not important. It was not to be used where AF was present such as the detector or audio stages.
The anode is wide and narrow from front to back.
Seen from below the single inverted V filament has the grid to either side.
The baloon envelope is 44 mm in diameter, and excluding the UX4 base pins is 95 mm tall.
References: Data-sheet. Type 226 was first introduced in 1927. See also1927 adverts.
