Meda Mercury Side Reflector HML250PR

This most unusual side reflector mercury lamp is believed to date from the 1960s, and was possibly intended as an improved light source for streetlighting. It was manufactured by the small Swiss lamp company MEDA, about which very little is known. At one time Meda appears to have been associated with the German firm Julius Pintsch - early Pintsch marketing literature of the 1940s refers to its discharge lamps being handled by the MEDA-Department of the company, with the lamps themselves being branded Pintsch-Meda. Prior to WW2 the Pintsch company was absorbed into Osram - the German operations subsequently being lost to the group of companies that became Narva following the Soviet occupation. The British arm of Pintsch was absorbed into Thorn, and it is suspected that there may also have been a Swiss division that may have continued independently under the Meda name.

This lamp and others of Meda are built around high pressure mercury arc tubes that are of typical German design of the 1950s, very similar to earlier Osram and Radium constructions. The outer bulb has a most unusual flattened shape, and bears an internal aluminised reflector on one side. The entire bulb and reflector section are coated with a phosphor that appears to be magnesium fluoro-germanate, which would indicate that this lamp was made in the 1960s or earlier. The bulb is made in hardglass, which would imply that it was intended for outdoor operation. The lamp projects a wide beam in the direction perpendicular to the lamp axis, and narrow parallel to the axis - this would make it particularly suitable for streetlighting. The design is similar to that later developed by the Russian firm Reflux around the high pressure sodium arc tube for a similar application.
Manufacturer: Meda
Lamp Power: 250 Watts
Lamp Current: 2.13 Amps
Lamp Voltage: 135 Volts
Cap Type: E40s/45 Ni plated brass + porcelain
Bulb Type: X- X- in eighths/inch
Bulb Finish: Mg4(F)Ge06:Mn phosphor Side Aluminised
Electrodes: Backwound Tungsten BCT emitter
Atmosphere: Inner: Na,|Ar Outer: Nitrogen
Luminous Flux:
Luminous Efficacy:
Luminous Intensity: cd (@ 100h)
Beam Distribution: Approx 150° to 50% peak intensity
Colour Temperature & CRI: CCT: 3800K CRI: Ra 35
Chromaticity Co-ordinates: CCx: 0.395 CCy: 0.400
Rated Lifetime:
Warm-up & Re-strike time:
Burning Position: Universal
Overall Length:
Factory: Switzerland
Date of Manufacture: Approx. 1960s Date Code: 368
Original Value: Unknown