400w BLV NAH-TSX "SON-L"

1 x 400w BLV double ended high pressure sodium lamp.

Interestingly, this lamp has R12.5s caps on it which seems to make it compatible with G.E.C's SON-L series of lamps.

The Osram-GEC SON-L range was introduced in 1974 and was the first double ended high pressure sodium lamp brought to market.
They employed a thin quartz outer envelope which would not melt when brought so close to the arc tube which enabled these lamps to be positioned right in the focal point of a compact reflector system for excellent optical control.

Other companies soon introduced their own versions with Thorn quickly becoming the market leader with the R7s capped SON-TD range.
Osram also introduced a range with Fc2 caps.
SON-L was discontinued in 1994 so it's interesting to see a BLV branded one. There must have been some demand for some time for another company to deep it worthwhile to produce them.