SON-T Deco - High Colour Rendering Lamp

The SON Deco was a short-lived lamp from Philips, offered as an upgrade to traditional SON lamps in areas where a high colour rendering index was desired, for example in city beautification projects. Its introduction was prompted by the popularity of the equivalent 'Specialux' lamp which Iwasaki of Japan had recently begun marketing in Europe.

Philips' lamp was marketed as a slightly lower cost alternative to Iwasaki's product but it was not successful, and customers continued to specify the Japanese original despite its higher price. The Iwasaki lamp manages to achieve an extremely tight tolerance in the spread of lamp colour temperatures, and the Philips lamp was simply unable to attain such good performance. Not only did it require several hundred hours burning-in for the colour to stabilise, the lamp life was shorter and the colour spread throughout life unacceptably large in the applications it was developed for. It was discontinued within a year of its launch.

Essentially it is a sodium lamp operating at much higher pressure than is normal for either standard SON or the intermediate SON Comfort / SON Deluxe lamps which have moderately improved colour rendering properties. Thermal insulation at the ends of the arc tube is provided by a pair of small metal cups, these being inferior to the large ceramic end caps found on Japanese lamps. Two zirconium / aluminium type getters are provided in this lamp, the getter beside the centre of the arc tube being positioned so that at its higher operating temperature it will effectively sorb hydrogen impurities during lamp life. The second larger getter at the top of the lamp serves mainly to remove oxygen and nitrogen during the lamp manufacturing stage.
Manufacturer: Philips Lighting
Lamp Power: 150 Watts
Lamp Current: 1.6 Amps 3.4A Starting current
Lamp Voltage: 91 Volts 3.5-4.5kV Ignition
Cap Type: E40s/45 Ni plated brass + vitrite
Bulb Finish: Clear Borosilicate glass
Bulb Type: T-46 T-14½ in eighths/inch
Overall Length: 211 mm 8¼ inches
Light Centre Length: 137 mm 5 3/8 inches
Arc Length: 34 mm 1 3/8 inch
Electrodes: Single wound coil No emitter
Atmosphere: Na,Hg | Xe Outer: Nitrogen
Luminous Flux: 7,000 lm @ 100 hrs
Luminous Efficacy: 46.7 lm/W @ 100 hrs
Colour Temperature & CRI: CCT: 2500K CRI: Ra >80
Chromaticity Co-ordinates: CCx: CCy:
Burning Position: Universal
Rated Lifetime: 8,000 hours to 50% survival
Warm-up & Re-strike Time: 10 mins (80% lumens) 15 minutes max.
Factory: Turnhout Belgium
Date of Manufacture: August 1995 Date Code 5H
Original & Present Value: £76.78 (1995) £98.88 (2005)
References: 1) Philips SON-T Deco Leaflet, April 1995.
2) Philips UK Price List, December 1995.