Sg246A........Oooooh a blast from the past....... its a Gate Controlled Switch
I may still have one or two left...Where abouts are you ?
Also there was an article in Television mag a few years back on modifying the Line stage, by removing said GCS and replacing with a conventional BU208 based driver stage......Interested?
I could dig it out and mebbe scan it for you....
Oh nostalgia......the number of Sony sets with blown GCS's 8) 8)