After getting a 1 lamp rapid start ballast to work as a preheat ballast, I thought of trying the next level up: to get a 2 lamp high power factor rapid start ballast to function as a tulamp preheat ballast. After many failed attempts at getting it to work, I finally did. See it in action here. Although it took a little longer than most preheat ballasts including real tulamps for the starters to kick in, eventually they did. What I discovered was that some high power factor 2 lamp rapid start F40T12 or F34T12 ballasts could do this while others had trouble doing it. In addition to that, some FS-4 starters worked with this combination, others had difficulty lighting the tubes. After experimenting around, I finally got it to work. In this video, you see a Sola ballast being used. The combination I used was to go from the red wire to the lamp 1, from lamp 1 to starter 1, from starter 1 to the other lampholder of lamp 1, from that lampholder to the first lampholder of lamp 2, from lamp 2 to the yellow wire, then go from the other yellow wire to starter 2, from starter 2 to the other lampholder of lamp 2 and from that lampholder to the blue wire. As stated before, this combination works with some 2 lamp HPF RS ballasts but not others, if it works, it will favor some FS-4 starters over others and it will take a little longer than most preheat circuits including tulamp F40 preheat ballasts for the starters to work when they do. All in all this was a fun experiment. The way I wired it was similar to a tulamp preheat ballast with the exception that the tubes are in series. I suppose if you can't find a tulamp preheat ballast right away, this is a good way to satisfy your tulamp preheat cravings, at least for the time being. With that said, enjoy!

I tried this experiment once again and tried a number of different ballast and starter combinations. It seems that the Magnetek watt reducer ballasts stay the coolest temperature and get the starters kicked into action the fastest. These ones have the light blue and yellow label with the words "watt reducer" in a futuristic looking font. The combo also works best with Chinese made Sylvania FS-4 starters, which seem to get working the fastest. The experiment was performed with 2 F40T12 lamps. I also decided to take a 2 lamp strip light with a HPF magnetic rapid start ballast and remove the ballast cover and run it for a few hours wired in standard rapid start mode, take the lamps out and check the temperature and then let it cool a little bit and run it again for a few more hours in series preheat mode and then take the lamps out and check the temperature. This was a slightly newer Magnetek watt reducer ballast, or maybe it was slightly older. Whatever the case was, the label was slightly different in that it had the words "watt reducer" in a more standard looking font but was otherwise similar. The ballast got hotter than my other Magnetek watt reducer did in both modes, but both times I checked the temperature they seemed to be about the same temperature. I checked the temperature by taking the lamps out and then grabbing the ballast with my hand. It was pretty hot, but cool enough that I could stand to touch it both times. All in all this was a fun experiment.

HPF ballasts use capacitor as ballasting impedance, what does not generate voltage kick when the starter contact open, so it will never have the cold/humid starting reliability the preheat system is credited for. It actually has the same starting limitation as the RS connection, might be even worse, as the RS heat electrodes at the same time when voltage is across the lamp, while preheater first heat and then apply the voltage, while during this time electrodes cool down...