Thorn Alpha 5

Lantern acquired in February 2004.

I nearly have the entire Alpha range now; however, this one has been the closest so far to being scrapped! It was discovered in a skip amongst a pile of old brackets and damaged columns, and was incredibly lucky to be salvaged as the skip it was in was removed later on that day. The box has suffered some damage, but fortunately the lantern is still in a good condition; the only sign of its age being that the springy steel used to support the lampholders has rusted slightly, but this could be painted to make it look new again. A few derelict and heavily-vandalised SLI/H Alpha 5s survived at part of Derby's Raynesway Refuse Centre until 2008, when all were removed, and passed on to other Collectors.

From this angle, the box looks relatively clean and undamaged, however...

...a section of cardboard has been lost in this corner.

The label shows clear signs of moisture, but two other things are visible here as well: firstly, the lantern is actually meant to run a 200 Watt SLI/H lamp as opposed to 140 Watt. Both lamps are of the same physical size, so either can be used provided the correct gear is also fitted. Secondly, the delivery date looks to be the 22nd Nov 1979, so this lantern is older than all of the Alpha 6s are. This also indicates that this must be one of the final Alpha 5s produced, as the design did not feature in the catalogue for that year; its place being taken by a new Alpha 4 instead.

On one side of the box, the word 'B HAM' is scrawled. I assume that this stands for 'Birmingham' but why, then, was the lantern in Derby?

The lantern could be fitted with a NEMA socket, however this one isn't - you can see on the canopy where it is meant to be fitted. The lantern has two refractor panels per side instead of one complete refractor like the Z9554M has. The bowl clips are similar to the GEC ones, as used on such lanterns as the Z9454.

The lantern is tapered, so care has to be taken to ensure that the bowl is fitted correctly. There is a reflector in the middle of the lantern, which is odd as I would have expected it to run along the entire length of the lantern. In the background is the 200 Watt geared Alpha 6. To look at both lanterns, you would never think that they were made by the same manufacturer!

The lantern was fitted to an AC Ford AC 872 bracket on Thursday, 9th February 2006. It was then powered up using a 1980s' Thorn 90 Watt SOX / 140 Watt SLI/H ballast - a little more modern than the lantern, but probably produced around the time when SLI/H lamp production was drawing to an end.

The edges of the 90 Watt Alpha 4 and 8 can be seen to the left of the lantern - again, unless you knew, you would probably never guess that all three designs were made by the same manufacturer!

With the flash on, the detail on the bowl disappeared somewhat.

Finally, a view looking up from underneath the lantern - proving that a SLI/H lamp has indeed been fitted!

Lantern warm-up video:

Testing with my energy monitoring device revealed the following results:

Test Voltage (V) Current being drawn at full power (A) Measured wattage (W) Apparent Power (VA) Frequency (Hz) Power Factor True Power (W) Difference to rated wattage Percentage Difference
238.5 0.8 154 191 49.9 0.8 152.64 12.64 9%

Urbis ZX1 | Thorn Gamma 6




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