The 3 knobs on the chassis and lack of a damper tube in the tube lineup makes me think it might use that infamous Muntz/Belmont chassis that had no damper, H afc or H Osc tube and instead was just a self oscillating output tube and HV rect.
Edit the tube layout looks similar to the Muntz.
https://earlytelevision.org/muntz_m21.html
Odds are they bought that cheap chassis to put in their cool custom cabinet.