Manufacturer: Philips
Model: Master Colour CDM-R 35W/830 E27 PAR30L 10
Application: Specialist, display and architectural lighting
Wattage: 35W
Diameter (max): 95mm
Length: 120mm
Tube Length: Unknown
Bulb/Tube material: Discharge vessel: Polycrystalline alumina, inner: UV-stop quartz, Outer: Hard glass
Colour Temperature: 3000K
Peak output wavelength: N/A
Total light output: 3300Lm
Rated lifetime: 12000 Hours
Cap: E27
Operating voltage: 90V (5kV starting pulse)
Operating current: 0.85A (On Philips MHC 035 S/50 ballast)
Warmup/restrike time: 3 minutes/15 minutes (maximum)
Cost (original): Unknown
Value (now): Unknown
Place of manufacture: Belgium
Date of manufacture: December 2004 - Date code M4
Lamp Status: Working
Notes: The ceramic metal halide lamp was first launched by Philips in 1994, and despite some technical challenges in the design of such a lamp (not least how to seal metal lead wires into the ceramic tube), it proved to be a huge success.  Ceramic arc tubes have a number of advantages over quartz, most notably that they are more resistant to chemical attack from the halide salts present inside the tube.  This in turn allows the vapour pressure in the lamp to be raised, increasing both colour rendering abilities, and luminous efficacy.  Colour stability from one lamp to the next can also be better controlled due to the more consistent shape of the individual arc tubes.

A compact single ended 35W lamp was the first of this series of lamp to be marketed, but following its success, the same technology was then built in to a number of other lamp styles - such as this.  This is essentially one of those single ended lamps, built into a huge great hard glass reflector (with a couple of tweaks).

The main problem with the reflector style lamps is due to the fact that the mirror surface is a simple metallic coating, rather than a dichroic coating.  This reflects forward both the visible light from the arc, and the heat as well - bouncing a good amount of it back towards it source - this can cause overheating of the arc tube.  Philips countered this by altering the amount of mercury that the arc tube was dosed with, meaning that the tube would still operate at the correct pressure despite the slightly higher wall temperature.

While the single-ended lamp at the heart of this lamp is only suitable for use in enclosed fixtures, the outer of this lamp is manufactured of (heavy!) hard glass, which negates this requirement, making it suitable for operation in open fixtures.  It's interesting to see a lamp which effectively has three envelopes - I can only assume that this was a cheaper or more reliable way of manufacturing this lamp - I imagine possibly because it negates the requirement to use a larger amount of UV stop glass in the outer, and that it is quicker to exhaust the smaller tube in the centre - the outer envelope of this lamp is at atmospheric pressure.

As with most of Philips products in this line, the workmanship is superb, resulting in a very clean, uniform beam.

I am curious to know the purpose of the small black plastic ring just above the cap which appears to be present on all of the CDM-R series lamps, can anyone shed any light on this?

Click Thumbnails for full size images.

This lamp added to the Virtual Display Shelf on the 23rd January 2007 at 23:45.

References: Manufacturers datasheets.

Acknowledgements: Many thanks to the website reader who donated this lamp for display!


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