I've been busy getting back to college so to preface I apologize for not replying sooner. I will say I have found some information in the form of a book I got for Christmas. It's simply called Fluorescent Lighting and was published by Philips in 1952. It goes over all aspects of the stuff, but important to this topic it has a chapter on ballasts. There's a few calculations on how to make a choke for an FL lamp, so over this summer I shall have to try designing and making one. I'll probably start off with a 120v choke for a F20T12 lamp as that's what easiest to test for me.

I've found the lamp out now, so will light it tomorrow and do some measurements. Heading to bed now, it's been a long day and we actually have to get up in the morning   to let the council sparky in to have a look at some work we need doing.

If the currents right then you are likely to be all good with that ballast as it won't run as hot as mine. Will be interested to hear what the lamp voltage is when you measure it.

Thanks for the interesting post, Mark. We must be very lucky then, because the 50W SON ballast we use is pretty much spot on, certainly as far as lamp current goes, I don't recall the voltage, must get the lamp out and take some measurements, watch this space..!

This is an interesting topic for me too. I have been looking at suitable ballasts for a 60W SLI/H linear sodium lamp I have and it's proving a little trickier than I first thought. That said, I have a 65W fluorescent choke which is pretty close. The only problem is the ballast gets very hot with time so isn't suited as an ideal alternative.  The popular choice of 50w SON is ok but not perfect. Everything else is way out.  I did look at a 70w fluorescent ballast but it behaves more like an 80w MBF/U mercury ballast so isn't suitable. However, it may be possible to wind a small inductor and add it in series to this ballast to bring it in line with the proper lamp current. This may be an option for the best outcome.  The issue seems to be, there are two properties of inductors that influence the circuit current other than the lamp resistance.  Ballasts also have a resistance plus reactance.  Measuring the reactance and basing choice on this doesn't work the coil resistance also needs to be taken into account and this forms an impedance problem (although not too tricky).  I need to look at a few ballasts and see if this proves fruitful in finding a different ballast for my 60W SLI/H. As for the 200W SLI/H I think the general choice is the 150W SON ballast but if I remember correctly, it actually needs a second paralleled ballast to achieve a better match. Can't remember the additional ballast, might be a 35w SOX but would have to look into that more. I'm lucky enough to have an auto-leak ballast for the 200W SLI/H but it's trickier to work out its impedance being technically a transformer. When testing the suitability of a circuit, I keep a close eye on lamp current and keep that as close to the design as possible. The voltage seems less important so long as its not higher than the spec. as this is where electrode damage occurs.

If I have the chance to I definitely will.  I've been on that section of I-80 before as a passenger, but only during the daytime and I never noticed the LPS tucked under the bridges.

You'll have to go back as a passenger so that you can get pictures.!

Drove back to Indiana, not much to report other than I got stuck in Chicago traffic. However, right before I hit traffic while I was on the outskirts of Chicago, I caught the HPS lights still left on I-80 warming up. What surprised me was going under an underpass I saw SOX lights being used! I got to see them warm up piece by piece under each bridge I drove under. Couldn't get any photos of it as I was driving but it was a nice site. I don't think I've seen LPS in public use in America at all.

@wide-lite 1000 I'll let him know about that, they are the original drive train pieces to the car. I wasn't able to drive it yesterday as snow was in the area but I should get a chance to over winter break after he fixes the power steering and carb issues.

It arrived today, after we missed the delivery on Tuesday, and had to reschedule it. Pictures to follow.

 You should be able to sell the old engine/trans for decent money as 283's and powerglides are getting rather rare nowadays .