The 14Y4 is an American full wave rectifier. This exhibit was made by Philco. The 7Y4 has a 6.3 V heater but is the same valve. The older octal based 6X5GT has the same ratings. The introduction of the Loctal base intended for rugged and mobile applications saw many older valves re-worked onto the new base.
The maximum reservoir capacitor is 40 µF and the minimum series resistance for current limiting is not given in the literature.
The lower anode. The pressed sheets forming the anode are stitched together. This anode attaches to the left support. The right hand support is used for the upper anode. The central cathode is common to both.
The profile shows a small central bulge for the active region. The blackened side fins are to dissipate the generated heat by radiation.
The identification is etched into the dome of the envelope.
The wide glass tube envelope is 29 mm in diameter and, excluding the B8B base pins, is 56 mm tall.
Reference: Data-sheet. Type 14Y4 was first introduced in 1952.