The 866 is a half wave mercury vapour rectifier on a UX4 bayonet base. The mercury on the inside of the glass obscures the electrodes.
Here the supports for the cathode can be seen. An image of the inside was not possible, however, looking inside revealed a circular corrugated cathode supported at the ends and the centre. Above the cathode was a gap and the anode, supported only from the top cap, is a flat disc.The classic envelope is 60 mm in diameter and, excluding the UX4 base pins, is 143 mm tall.Reference: Data-sheet. Type 866 was first introduced in 1938. See also 1938 adverts. |
