Sylvania Sy-Lynx D 13W Compact Fluorescent

In 1984 Sylvania achieved a huge miniaturisation of compact fluorescent lamps by mounting a pair of U-tubes side-by-side, to create the 'double' design illustrated here. From the single-tube range of 5, 7, 9 and 13W a double-tube family of 10, 13, 18 and 26W was created. There was no 22W double created from the 11W single, because its length and high voltage would preclude operation even on 220-240V mains.

This early example in fact employs two individual discharge tubes, electrically connected in series and each with its own glowbottle starter in the cap. As such, when energised one tube lights momentarily before its neighbour. This design was produced for less than a year, being quickly superseded by a single four-limb discharge vessel. It was not practical to apply three U-bends, so a Philips-style glass bridge was adopted to join the pair of U-tubes just above the cap. Osram introduced such a design in 1985, and it is not known whether Osram or Sylvania was first with that concept. It allowed a small increase in efficacy by eliminating two of the four original electrodes. In 1986, Philips followed with its PLC lamp, with all tubes being joined by glass bridges.

Double-tube lamps immediately became popular due to the great reduction in length, and improved light distribution uniformity. It was this development that suddenly made CFL's much more attractive for the rapidly growing market of low energy downlight luminaires. Incidentally the efficacy of these lamps is slightly reduced, owing to light absorption losses between the adjacent tubes - note the increased core brightness in the lighted photo. They also tend to run hotter, the increase in mercury vapour pressure from its optimum being limited by a small hole in the cap to provide cooling.
Manufacturer: GTE Sylvania
Lamp Power: 13 Watts
Lamp Current: 0.175 Amps
Lamp Voltage: 90 Volts
Cap Type: G24d-1 PolyButylTeraphthalate
Bulb Type: T-12.5 T-4 in eighths/inch
Bulb Finish: Y2O3:Eu3+, CeMgAl11O19:Tb3+ Soda-lime glass
Electrodes: Triple Coil Tungsten Triple carbonate emitter
Atmosphere: Argon + Hg
Luminous Flux: 900 lm @ 100h
Luminous Efficacy: 69 lm/W @ 100h
Colour Temperature & CRI: CCT: 2700K CRI: Ra 85
Chromaticity Co-ordinates: CCx: 0.464 CCy: 0.411
Lifetime: 5000 hours
Warm-up & Re-strike Time: 2 minutes Instant
Burning Position: Universal
Overall Length: 150mm 6 inches
Length to Cap Plane: 127mm 5 inches
Factory: Charlestown England
Date of Manufacture: 1984 March Date Code: H39
Original Value: GB £6.30 (1989)
References: 1) Sylvania Catalogue 1986/87 UK p.Fluo-3
2) Sylvania Pricelist 1989 UK p.41