[Arran]

A lot of the higher end sets, and some mid end set, used separate mixer and oscillator tubes to get around the noise created by a pentagrid converter. My CGE E-81 (same chassis as a an RCA T-7/T-8 did this, and they did not use a tuned RF stage. Though I should point out that Philco sets of the 40s often used another type called an octode converter, a type 7A8, what difference the extra grid made I don't know, but in a single band five tube set it doesn't really matter. RCA liked using another type called a 6J8, it was a triode-heptode converter, the triode was the oscillator section and the heptode was the mixer, this was what my Philco 40-180 used in the front end, in effect you are using two tubes but in one envelope.
Regards
Arran