The R5559 is a low noise triode designed for wideband amplification. The mutual conductance is 25 mA/V and like many low noise valves the anode current is substantial.
This exhibit is labelled Marconi and has plain pins. Our other exhibit carries the professional brand of M-OV (GEC) and has gold plated pins.
The construction features a frame grid and the straps defining the grid width appear top and bottom of the winding. The supports have to be tied together as the wire is wound to 50% of the breaking strain of the material.
The Marconi brand label.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 59 mm tall.
