The manufacture date is o the lower corner of the labels on Westinghouse early ballasts. this compensator was made in December 1939, the ballast in 1940! My "glow auxiliary" 15 watt ballast with a GB-1 glow bulb glow switch starter in the end of it was made in January 1939, and the familiar 2 pin metal can "FS" type starers came along in mid-1939, all from Westinghouse! The first starters of this type were either Westinghouse or their subsidiary, Bryant brand. Any other manufacturer that bought into the patent and was making these starters in those early days HAD to have text on the can stating that they are manufactured under Westinghouse Electric Co. patents! I have a few with text, like an early Ideal, and a couple others. They did make some of these Tulamp separate starting compensator ballasts in earlier 1939, just as the 40 watt 4 foot lamps came out (around April) with a GB-2 glow bulb starter in the ballast end plate in a socket actually TWO, one on each end for each lamp! GE's first 4 foot ballast were indeed the Thermal auxiliary, and Magnetic Auxiliary types, and YES a 2 lamp version existed, and I BELIEVE they were all 199-236 volt so basically 230 volt, and used a separate step up auto transformer. There was also a separate starting comp. as usual in these early units. I have one of the vert=y earliest, definitely pre-cartridge glow starter era 2 lamp 4 foot units, it is here on my gallery, and is an about April-May 1939 Hygrade/Sylvania HF-100 with a step up auto-transformer from 115-236 volts, and 2, 236 volt (240 volt actually) simple choke ballasts for the lamps, one connected lag straight to the lamp like, for example the choke in an F-15 preheat fixture, and the other with a GE Pyranol, good old PCB oil filled capacitor (oval metal can type) in series between the second choke and the lamp for both power factor and stroboscopic correction, as is in any TULAMP ballast, and that lamp has a skeleton core, non potted starting compensator in the starter loop. the chokes are potted, the step up is also skeleton non potted. The starters are 2 octal vacuum tube based, metal can, with internal glass bulb enclosed (unlike actual tubes for electronics that have a vacuum in the steel can itself!) thermal switch starters. One was missing the can, so I found a clear plastic container, old pill bottle or something, and attached it with silicone to the base, so the thermal switch is protected, and you can see the works! No light is emitted when it works, and no spark is seen because either a vacuum or quenching gas fill is used to eliminate arcing at the contacts, as well as capacitors across the tube sockets for the same reason. This unit is serial number 8108! I have 2 slightly newer ones and one is serial number 12,371, the other 15,997. Those have special adapters that take refular 2 pin FS-4 type cartridge starters, and these plug into the octal sockets to adapt over! These fixtures are what made me realize when these starters came along, and what preceded them. I would LOVE to have one of these Westy "Tub" style units with the original gear with labels in it! Can I afford one? Depends. But would love to have one nonetheless! My email is iwantQ7@yahoo.com
"just in case"! Also, I prefer one with ballast or comp or both made with 1939 dates on the label, but '40 is fine. These are awesome!!!!!!!