Here's one of two 100W Sylvania HPS lamp I also got with the 100W mercury lamps I recently won on eBay. Both of them ignited on a S55 ballast and warmed up all the way. I assume they don't cycle, but I'd need to run them on a S54 ballast for a while to confirm it.
I have the same lamp - from 1983 - it was my first HID lamp. I stole it out of a streetlight that had been knocked down by a car when I was a kid, and only in 2003 was I able to fire it up for the first time.
Actually Michael, The ED took over only 150 watt and below (the 150 watt for HPS and 100 watt for MV) in 1980. But by around 1988 it went to ET-23.5 shape for all the sources until around 2000ish Sylvania only put all MV in ED shape because they were sourced from on.
175 and 250W MV lamps are made in ED shape today. So are the 400W lamps. I thought Sylvania was the only one who used the ET-23.5 lamps since GE and Phillips HPS lamps are ED-shaped like the one above.
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