Philips Mastercolour CDM-E 70W / 83
In the Autumn of 1994 Philips unveiled a radically new kind of light source, and announced the first successful design of metal halide lamp employing a ceramic arc tube. The first products to market were the 35W and 70W single ended types, joined shortly afterwards by a 150W rating. Double ended types were soon also made available. For the American market, where the newer metal halide lamps of compact dimensions had not yet become popular, it was required to offer this retrofit lamp having a large ellipsoidal outer jacket.

The arc tube inside is substantially the same as for the European quartz jacketed types, modified slightly to account for the different temperature profile in this outer jacket. A major difference however, is the lack of the mildly radioactive Krypton-85 component in the gas filling of the arc tube, due to its prohibition in the American market. Without this ingredient it is very much more difficult to strike the arc tube.

An auxiliary starting device is therefore employed, this taking the form of a UV-enhancer glowbottle. This single electrode device is situated alongside one end of the arc tube, its internal electrode being connected to the opposite end of the arc tube. When energised, before the arc tube strikes, the electric field around the UV-enhancer is sufficient to cause it's own gas filling to break down. A brief pulse of ultraviolet radiation is generated, which is transmitted through the adjacent ceramic discharge tube, and the high energy photons facilitate ionisation of the higher pressure argon filling in the main arc tube. Ignition can thus be successfully accomplished on standard circuits without the need for very high voltage external ignition aids.
Manufacturer: Philips Lighting
Lamp Power: 70 Watts
Lamp Current: 0.98 Amps
Lamp Voltage: 85 Volts 5 kV ignition pulse
Cap: E26s/25 Brass with vitrite insulator
Bulb Finish: Yttrium phosphate vanadate
Bulb Type: ED-54 lead borosilicate ED-17 in eighths/inch
Overall Length: 138 mm 5 7/8 inches
Light Centre Length: 87 mm 3 7/8 inches
Electrodes: Tungsten single coil 9mm arc gap
Inner/Outer Atmosphere: Ar|Dy-Ho-Tm-Tl-Na-Ix Outer: Hard Vacuum
Luminous Flux: 6000 lm @ 100 hours 4,800 lm average thro' life
Luminous Efficacy: 85.7 lm/W @ 100 hours 68.6lm/W average thro' life
Colour Temperature & CRI: CCT: 3000K CRI: 82
Chromaticity Co-ordinates: CCx: 0.435 CCy: 0.400
Burning Position: Universal
Rated Life: 6,000 hours to 50% survival
Warm Up / Re-strike Time 3 minutes 15 minutes
Factory: Bath, NY U.S.A.
Date of Manufacture: October 1994
Original / Present Value: