Thorn EMI Alpha 3

Lantern acquired in May 2005.

This is my second Alpha 3, and my second lantern with the EMI suffix in the manufacturer's name - just a couple of observations there! The lantern was removed due to a failed ballast, and was replaced with a second-hand SGS 204.

There are several differences between this lantern and my first Atlas Alpha 3; the most obvious being the longer shoe to accommodate the lamp control gear. The bowl is also different - instead of having a white spot to diffuse the light, prismatic refractors are used. Other minor differences include the bowl and clip hinges now being part of the bowl itself, rather than being made of separate strips of metal. Also, the back two clips have been removed from the design - I assume that such changes were all made to cut costs.

Even though the two back clips are not fitted, the indentation in the canopy where one of them would go can be seen quite easily - clearly, the press was never updated to omit these rear indentations from the canopy.

The gasket on the lantern is loose, but the mark in the dip of the bowl was not completely caused by rainwater seeping in and then evaporating under the heat of the lamp - it is (mainly) a swarm of some rather cooked wasps!

The gear tray is hinged, and is opened by removing two screws; however, it will not fully open unless the operator presses the two 'arms' of a V-shaped strip of metal together - shown at the top of the photograph.

Remember how I said that the lantern was removed due to a faulty ballast in the description? Well it, certainly, looks as if this is the most likely culprit for the lantern to have stopped working - this black mark doesn't look healthy at all! The ballast carries the code '32 8D', which may be a date code - the '32' could represent August 1986 (using the Thorn Enfield dating system), although '8D' is similar to a Philips-style code, and could represent April 1988. Although the capacitor cases are both rather corroded, one of them appears to have the date code '0987', which would represent 23rd February - 1st March 1987. With this being a Thorn EMI-branded lantern, I am inclined to think that it would have been produced in 1987 too, as by 1988, the EMI suffix began to disappear from Thorn Lighting products.

The two prongs to the left of the bracket entry are what hold the V shaped metal strip in place.

The lantern was restored on the 25th May 2005. The bowl and metallic components were all cleaned, but I decided to paint the canopy as some of the marks on it could not be removed despite a variety of substances being tried on them.

The inside of the canopy was also repainted. Originally, I had thought that this area was left unpainted, as with the Atlas version; however, the white started to show through as I cleaned the individual ridges with a soapy sponge.

A new ballast and ignitor were obtained and were, duly, fitted. The original ignitor probably still worked, but I swapped it as the casing was quite rough from corrosion.

The lantern was mounted to an AC Ford AC872 wall bracket on Tuesday, 9th August 2005. It was then wired up and switched on. The lantern roared into life and was soon at full power - it was rather bright, to say the least!

Lantern warm-up videos:

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
236.6 2.5 419 592 49.8 0.71 419.97 19.97 5%

Alpha 3 Lanterns in the Collection

Atlas (Original Type)

Atlas (Modified Type)

Thorn EMI

Thorn Beta 5 | Designplan Concourse




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