The Philips A141 is a bi-grid or space-charge tetrode and was made in the early to mid 1920s when such valves were thought to offer advantages over the normal triode. Triode development soon left the bi-grid behind.
Philips also made an A441 bi-grid and another with the Type of Q.
The side terminal connects to the inner grid.
The composite base pins in the standard B4 configuration.
The gettering covers the envelope and no observation of the internal structure is possible. Also there is no identification visible.
The balloon envelope is 41 mm in diameter and, excluding the B4 base pins, is 79 mm tall.
