Tesla SHC 250W (Deluxe) in operation

Although there was a close technical co-operation between these two companies, the development of high-pressure sodium lamps was more advanced and effective at Tesla in Czechoslovakia than at Narva in East Germany. The Czechs managed to implement Philips's superior monolithic arc tube design in 1973 while Narva kept on using outdated cap end seals for their burners (see there). Moreover, the quality of materials and processing involved in arc tube production improved so much at Tesla that they even managed to build and test a viable color-improved variant of their SHC 250W in the mid 1980s, shown here in operation (see there for the full details). Interestingly, it seems that both companies followed the same strategy as far as the initial lamp voltage is concerned. That SHC 250W Deluxe has electrical characteristics that are similar to those of Narva's NA250, with the exact same 90 V lamp voltage. The motivation for that was undoubtedly to achieve a sufficiently long lamp life given the limited material quality and processing possible in the Eastern Bloc, which prevented the realization of the performance and durability that characterized Western lamps at that time.