When did RCA really cease production of tube-chassis TV's..?

[Whirled One]

From what I'd previously understood, RCA abruptly swtiched completely over to solid-state after the 1974 model year. I've seen a 1975 RCA product guide, and I don't think it listed any tube/tube-hybrid stuff at all. ...but here's a KCS-189 (a cute li'l 9-inch B&W portable) that I just found that plainly identifies itself as a 1975 model. Could it have been some sort of short-lived "holdover" just to get rid of leftover parts inventory? I don't think I've ever seen another 1975-marked RCA TV that wasn't solid-state.

BTW, the '74 RCA product reference describes the KCS-189 as a "hybrid" chassis, but that really seems like stretching things a bit. It looks like there's only *one* transistor on the chassis-- it's used as the 2nd video IF amp. On the tuner, the VHF mixer/oscillator and the UHF osciallator are transistors, but the RF amp is still a tube. Everything else is tube-based (aside from the usual handful of semiconductor diodes, of course).