I am building a monochromatic lamp with the use of a low pressure sodium (LPS) lamp. Through research I understood I need a specific ballast for such a bulb.
The examples I found on the net feature a LPS bulb but only the 35W one. The ballast recommended for the 35W bulb was the Fulham Lighting WH3-120-L Workhorse 3 Adaptable Electronic Fluorescent Lamp Ballast, 120V, 64W max.
Unfortunately I require the 90W bulb for the project, as apparently it is possible to mount the bulb horizontally. I tried to look for a ballast for a 90W LPS, but often found products that are five times the price of the first mentioned ballast or that are unavailable in my area (I was only looking with those specific keywords.)
My question to you is: what kind of ballast should I be looking for for a low pressure sodium lamp of 90 watts?