Manfacturer: Ken-Rad/Westinghouse
The Ken-Rad 100 watt mercury vapor lamp shown here has a less than common phoshor finish, it is called High-Output White. Most phoshor coated mercury lamps use either the color improved with the /C suffix or the deluxe white with the /DX suffix. Back in the old days mercury vapor lamps were made in several finishes and High Output White was one of them. These lamps used the /W suffix. Hi-Output White was as efficent as the current deluxe white lamps in that it adds a few lumens, but high output white has a higher color temperature, which causes a bluer appearance and the CRI is lower than DX lamps, thus the reds are still very weak. Also present is the clear tubular end, commonly called "cleartops" among lighting enthuiasts, which was common on all BT (bulge-tubular) shaped mercury lamps in the old days. The cleartop design was mostly abandoned by US manfacturers in the mid 1970s in favor of fully phoshored ends. Duro-Test manfactured cleartops well into the 1980s, although it is not clear if they ever went to fully phoshored lamps.
The lamp here was manfactured in 1966 and the arc tube still shows little or no end blackening, and it still lights wonderfully! It is branded as Ken-Rad but was actually manfactured by Westinghouse, as Ken-Rad was part of Westinghouse.
Lamp: Mercury Vapor
Wattage: 100
Starting Voltage: 240 volts
Operating Voltage: 130 volts
Ballast Type: H-39
Color Temperature: unknown
CRI: unknown
Light Output: 4400 Lumens
Bulb: BT-25 Hard Glass
Finish: Hi-Output White
Base: E-39s Brass Mogul Base
Class: -
Filament: -
Lamp Life: 24,000 hours
Manf. Date: July 1966
Country of
Orgin: USA
