Thanks for all the information !   now just to find a 100 watt metal halide ballast!

I can't find a MH ballast kit on the bay for you without it being extremely overpriced. Maybe you can find a distributor locally of if that fails, have a tranny shop rewind it. Of course, if the rewinding part fails, you'll have to have the NEMA bracket cut from ye olde ballast and welded to the replacement.

I'm going to see if I can find a transformer rewinding shop either here or somewhere where I can mail it to them. Medved on the forum told me that if it was rewound then it would have to be tuned again. I'll have to keep that in mind and ask whether a rewinding show could do that.

For the rewinding: The only option you have to try it out and then measure the lamp current and hope for it to match. Otherwise the rewinding just failed...

If rewinding without breaking the core (pull the entire wire length through the existing hole all the 200ish times), then i think matching the N of turns will be sufficient. And that is what i would try. Take care not to scratch the wire



Besides, what about using "any" higher wattage autotransformer ballast as step up transformer, then ballasting from its output with a combination of Fluorescent chokes ?

For a much bigger autotransformer ballast (ie where its own part of ballasting is small), I guess 3P of 240V 50Hz 36W, 2P of 240V 50Hz 58W, or 3P2S of 120V 60Hz 15/20W all will sorta work. For a closer matching ballast the external added impedance would be less

Get one of these and disconnect the white wire from the ballast that connects to the cylinder with 3 wires: Red, white and blue. Then you will be able to use a 125w merc as much as you want, and it is would probably be cheaper than having the ballast rewound.

Why not leave the ignitor out completely ?

Why not leave the ignitor out completely ?

To be ready for an eventual future conversion back to MH100W...