||This lamp is representative of a relatively early high pressure sodium model produced in Ukraine, by that country's former state-run lampmaker, PZGRL. Dating to 1985, its design bears many similarities to HPS lamps produced by General Electric of America. GE formed an early technical agreement with Tungsram of Hungary, and many features of its designs were subsequently adopted by the other East-European lampmakers. It is not known whether the arc tubes were also produced in Ukraine, or sourced in from another soviet manufacturer and simply processed into outer jackets. The reason for the suffix -4 after the name is not known - perhaps the 4th generation of this particular model.
The arc tube is manufactured from a notably opaque grade of polycrystalline alumina, whose optical transmission is somewhat inferior to other HPS lamps of the mid-1980s. One end is sealed to a niobium tube containing an external amalgam reservoir according to the GE style. The other end to a niobium wire with a PCA button hanging inside the arc tube, according to the Westinghouse style. A heat shield is provided around that end to provide thermal insulation and raise amalgam temperature, possibly to allow cap down operation - some lamps of this firm are specifically marked as such. There are pencil markings written on the arc tube.
The arc tube is mounted on a steel support frame, thermal expansion being accommodated by supporting the wire protruding from the cap end within a small ceramic bush. The outer bulb has been blown rather crudely in borosilicate glass, when examined in detail showing an unusually large quantity of striations and stones consisting of poorly homogenised glass from the melt.