I bought a S51 coil ballast from atlantalightbulbs:SO400-71C-211K , and had a question.

I originally designed the box to have the eballast mounted on the outside, so there is very little room inside to mount the coil ballast that is replacing it. The only spot for it is to sit directly underneath the Ushio bulb (which is sitting at a 45 degree angle). At one point, the ballast will only be 2" from the bulb. Is this recommended?

Also, with the ballast this close, I am afraid a heat shield over it would do more harm than good, as this would restrict valuable airflow over the coil.

I looked at others plogs, but everyone else has more room inside, and therefore much more space between the ballast and bulb. I am trying to avoid mounting the ugly ballast outside, or making a seperate external "ballast box".

Here is a picture from my PLOG. Although the bulb is not in the box in this picture you can see the bulb is really close to the ballast. I have had mine running for 6 months and havent had any problems with the ballast. I did have my bulb go out but I doubt that it was the ballast's fault. To keep it cool I just made sure that there was air that moves past it.

I connected the coil ballast to the projector last night and had the ballast outside the box for testing purposes. WOW...that thing gets hot! It burns when touched! I can't imagine how hot it would get directly under the bulb inside the enclosure.

Mine is mounted outside the box. It's a look only it's creator could love But it was my first build and it works.