The BY2020 is a directly heated general purpose triode on a B4 base.
The filament is a single inverted V that is tensioned by a thin top spring. An interesting point is that in addition to the two notched grid support rods, two other rods can be seen to pass vertically through the anode and within the grid. These rods are not connected either electrically or mechanically and their function is not clear.
The balloon envelope is 46 mm in diameter, and excluding the B4 base pins is 88 mm tall.
Reference: 1043. Type BY2020 was first introduced in 1931.
Absolute Maximum Operating Conditions¶
Updated January 23, 2013.