DE, I Took it out and put it back in earlier, turned it on it flickered for a bit and went out. I was thinking maybe the ballast, but I've only had it for a year and a couple months.
what ballast do you have it on. I've heard too many cases to count over the years of the 150w radium having compatibility issues with the sunpark ballast used in current usa metal halide fixtures but it seems hit or miss. you could always test another bulb in the fixture or take the bulb to someone/where who runs 150w DE to see if it works fine in theirs.