What a rare and interesting set. Stromberg Carlson sets are usually well built, in my limited experience. One peek at that dual chassis and you can tell this is not an RCA clone
Is a schematic available anywhere online?
I noticed that this page at the ETF website has a little more info about the purity & static convergence gizmos:
http://www.earlytelevision.org/strom..._brochure.html
Regards,
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html