How can PSMH work on a probe start MH ballast? Wouldn't that make the lamp probe start? lol If there's no starting probe there must be an external igniter unless there's a coil around the arc tube like with HPS retrofit lamps.

Electronic ignitor of some kind in the base, which is why they are base down burn

Interesting. I heard GE had come out with some pretty unique Mh lamps in the 70s and 80s but I had never seen any. I wonder how reliable these were. I doubt they made very many so you have some pretty unique/rare lamps.

To answer your question it does indeed fire up on a MV balllast!

Sweet! I can't even get a regular 175W MH lamp to fire up on a 175W MV ballast. I tried and the lamp wouldn't light. It did once but after that it doesn't do anything, though the electrode closest to the base flashes blue right when power is shut off.

I've heard of small towns using MH lamps on 175-400W MV fixtures so why is is that it doesn't work for me? does it only work on certain voltages or ballast types? (I was using the 120/240V CWA ballast that's in my GE M-250R1)

As far as I know 1KW MV ballasts have the same OCV as a MH version 450V so they are interchangeable

I heard that 400W MH work pretty well on 400W MV but I couldn't get a MH to light up in my M-400 split door either. It too has a 120/240V CWA GE ballast. All the MH lamps I've tried have been Sylvania. I was able to get a MH lamp to light up in my 175W MV yardblaster back when I had that but I can't seem to get them to light. I need some real MH ballasts.