Hi all. Me again. I have been looking all over for original wire wound magnetic ballasts and I can't seem to find anywhere, so I have decided to take the leap and make my own. Now this of course is no trivial task and requires a fair amount of enginerding. I'm busy crunching the numbers as we speak but to be sure I'm doing it right I just wanna ask you guys something. Are the spec sheets of the SOX lamps (this one in particular https://www.assets.lighting.philips.com/is/content/PhilipsLighting/fp928145700008-pss-global) given with RMS correction or not. It can be worked with either way but it's important to know so you can include it in calculations. Needless to say if I succeed I will post the results and schematics I've come up with for another brave soul to try if they so wish. I was also wondering if instead of using an ignitor coil using RF HV to energize the neon could be an option? It wouldn't serve any practical purpose for my project but it would be fun to try and I have always liked HV and RF HV is even more fun anyway I look forward to hearing from you guys and feel free to give me any suggestions

Oh and just for clarity's sake when I mention RF HV I mean radio frequency high voltage. Imagine a small low power high voltage high frequency circuit (akin to something like a tesla coil) where the electrode is wrapped helically around the SOX lamp to cause immediate ionization of the neon

I've found a listing on UK eBay for a genuine 26W SOX-E ballast, see here - it's not badly priced, but you will of course need an ignitor as well. Ideally an SX26 but an SX72 will work ok, see here.

Best of luck if you do try making one, though 

That does make my life a lot easier. So I will likely get it. I'll continue to design the ballast just as an extra project, who knows it might be useful to someone one day. Just a question on the ballast itself. Does it have a built in capacitor already? (as I am aware some do and just don't want to buy a cap unnecessarily)

By the looks of it, the ballast is just a plain series choke with no capacitor wired to it.

That was also my thought, however looking at the included circuit diagram for the ballast it appears to not need a capacitor.
Although there is a section of the diagram that's faded in picture that appears like it might be a capacitor. But I'll only be able to properly tell once I have received it

It's a simple choke ballast, so no series capacitor needed. A 5µF capacitor across the incoming supply for power factor correction is usually used, though. It's not essential, but my sense of completeness means I always include one.

Oh, what looks like a capacitor in that diagram is the N indicating neutral.