I have that ballast! Just got it today* but no 35 watt High pressure sodium lamps. Too bad! I need to get some more diverse lamps.

I think one idea might be to use a 70W M98 pulse start metal halide HX ballast to run a pair of 35W S76 high pressure sodium lamps in series. Or another idea is to import lamps, ballasts, and fixtures from abroad if you can save up for them. I often do that to help me from not getting bored.

I have a few magnetic ballasts, but the problem is I am bored. Anything I can do that would be fun ( except watching lamps warm up) with these ballasts without hurting any lamps or equipment?

Not surprised unfortunately. It's just cheaper to do a full changeout especially considering the age of the installation as keeping any of the existing stuff would be a hassle down the line (in their eyes).

San Diego still had a few series circuits when I went down there and went to quite a few places a few years back, though what I saw was mainly HPS. Not sure if any of it is still around today. One of the segments from that same news channel also shows some series LPS if I recall correctly.

I can kind of understand replacing 100 year old cast iron, but the replicas don’t look too far from the originals🤔

What are everybody’s tips on effectively saving many  streetlight fixtures because I am starting a project doing just that for northern Virginia

Very interesting  , pretty much SOX converting in a HID fixture from Poland is something I have not seen YET. Though I did see a CDM Conversion from a Leda fixture as well, from a video which I watched half year ago, absolute a very fantastic design of a CDM optical refelctor was made for the CDM bulb.

With no leakage and no winding resistance it would definitely be the case - Both the line and the capacitor are low impedance sources, the rest is an autotransformer

It may however be designed such that the assymetry is small enough, and then the leakage and resistance become relatively significant factors. (In the limit case with exactly symmetrical windings, there won't be any apparent parallel capacitance, all capacitance will be only seen by the tube through the choke)

When i dig my ballast out i'll take a lamp current waveform

I got a replacement merc lamp today. The fixture is now fully working. Thanks for your help!

also should be noted SRS ballasts for 18W SOX lamps where quite common (as they officially require about 300V to strike, so an SRS ballast was seen as a good way to generate that in a compact low-loss-ish ignitor-less setup that also has the added benefit of inherent PFC correction)

https://www.lighting-gallery.net/gallery/displayimage.php?pos=-116224

(I was always a bit annoyed how they tied the coils together into a single terminal like that, so you cant use it with a regular 2ft tube or 18W-24W PL-L or 28W 2D if you wanted to LOL)

I actually think in the absence of the need to preheat the filaments, there is not necessary to have two parallel 'long' windings to the electrically hot tube end. And attached is a simple inductance with a tap circuitry actually inside the choke you pictured. Electrically, it is equivalent to the SRS circuit with asymmetrical windings, but with less copper as you throw away paralleled parts of the windings.

BTW it seems that SRS and like circuits still inflict a fraction of its capacitor value parallel to the tube. Slightly dampened by winding resistance, and leak inductance, but still here. As we all know discharge lamps do not like pure capacitor ballast or large parallel capacitors, this probably leads to high current crest, shortened life and like ailments... May be one of the reasons SRS circuits lost their popularity (in addition to high copper costs).