I used a Tridonic 118 electronic ballast (with resistors in place of tube heaters) and it started and ran, but under-powered (circuit 17W and lamp slow to run up)
Nice and flicker-free though!!

I've been using the fluro choke method for ages. The fluro choke hase been used professionally, ferguson listed a choke for 18W SOX and it requres a starter to work. From now on I use a proper ballast that has been custom made for me which set me back like $50 but was well worth it, this is the ballast here: https://www.lighting-gallery.net/gallery/displayimage.php?album=5374&pos=0&pid=163958

If you don't want to buy Sox standard lighting components. So I suggest you have two options without considering the lamp life.

1. Direct use of 36W fluorescent lamp electronic ballast (lamp heating process is a little slow)

2. Combination of 36W fluorescent lamp inductive ballast and high pressure sodium lamp electronic trigger cd-2a

This method is only applicable to 18W, 26W and 35W