|
GEC SuperSOX Miniature 18W |
The Philips 18W lamp required a new construction to deliver good performance at such low power. A close-fitting heat reflector was added to the periphery of the U-bend to minimise thermal gradients along the discharge tube, which would otherwise result in short life and low efficacy.
With the Osram-GEC design this feature is not present - the U-bend is insulated only by the same nickel plated steel flat disc as used on the larger SuperSOX lamps. Possibly this is owing to this company's application of a graded thickness IR coating to the outer bulb, which naturally ensures a more uniform temperature gradient along the discharge tube than in Philips lamps which have a constant IR coating thickness.
The GEC 18W lamp is filled with 1.5% argon in neon, higher than the 1% that is usually employed. This is needed to achieve a sufficiently long lamp life, but has the drawback of raising ignition voltage. That problem has been attacked with two small metal springs, which connect one of the lamp terminals to the electrically conductive IR coating, which itself serves as an auxiliary ignition electrode. Since the metal top support clip is in physical contact with the film and therefore also electrified, good electrical insulation of the discharge tube is required to avoid drawing sodium ions through the glass, and this has been achieved by reverting to the old 'bobbin' style ceramic insulators at the bend.
| Manufacturer: | The General Electric Company of England PLC | |
| Lamp Power: | 18 Watts | |
| Lamp Current: | 0.35 Amps | |
| Lamp Voltage: | 55 Volts | 280V Ignition |
| Cap Type: | BY22d | Mycalex Insulator |
| Bulb Type: | T-50 | T-16 in eighths/inch |
| Bulb Finish: | Indium-tin oxide film | Soda-lime glass |
| Electrodes: | CCC-4 Beehive | Black W + BCT emitter |
| Arc Length: | ||
| Atmosphere: | Na | 98.5% Ne, 1.5% Ar | Outer: Hard Vacuum |
| Luminous Flux: | 1,800 lm (@ 100 hrs) | 1,600 lm (@ 2000 hrs) |
| Luminous Efficacy: | 100 lm/W (@ 100 hrs) | |
| Colour Temperature & CRI: | CCT: 1700K | CRI: Ra -44 |
| Chromaticity Co-ordinates: | CCx: 0.574 | CCy: 0.425 |
| Rated Lifetime: | 10,000 hours | 70% survival |
| Warm-up & Re-strike time: | 8-12 minutes | Instantaneous |
| Burning Position: | Vertical Cap Up ± 110° | |
| Overall Length: | 210 mm | 8sup>1/4 inches |
| Light Centre Length: | 130 mm | 51/8 inches |
| Factory: | Shaw, Oldham | England |
| Date of Manufacture: | August 1981 | Date Code: NH |
| Original / Present Value: | GB £15.13 (1988) | GB £36.23 (2014) |
