What's the date, the yellow horizontal MH socket is usually only in newer fixture but the ballast label looks like a older design.

I can't find a date on it anywhere, I get the feeling it's not too old.

nice! the cap should have a date. the week followed by the year like 18-12 for 18th week of 2012. BTw, why is the socket yellow? i know they make pink open rated sockets but i've never seen yellow sockets... at first i thought it was a yellowed plastic socket.

Good point, I'll have to check it later, I just put it back together. As for the socket, I have no idea why it's yellow.

Yeah either the cap or the ballast should have some sort of date or date code on it. The yellow sockets are for the horizontal MH lamps-the ones that have the arctube curved upwards.

so a horizontal MH lamp will only screw into a yellow socket? or does the socket prevent another type of lamp from being screwed into it? what if you use a MV lamp or universal burn lamp?

The MH lamp that came with it is your standard Philips lamp, I'll have to take a closer look at the socket...

Yeah here's the same type of socket. They have a hook at the start of the thread which catches on to a pin that sticks out of a /HOR MH lamp.

You're right, it is position oriented, the lamp is too! Oh and I found the date of manufacture on the lamp... June 1995! It's slightly older than I thought.