[Arran]

The sch is dismal, nothing can be discerned.

http://www.nostalgiaair.org/Resources/684/M0015684.htm


The wires going to CG's of the tubes are rubber-coated and had to go.
A long wire was hanging....I cigured it is the 77s grid going to the tuning cap....indeer one of the cap's lugs had solder on it and a hole half open. Also rubber coated.

Looking at the sch.....it is a TRF. 3-tube at that, 2 RF stages and the audio amp. Did not know AC /DC TRFs existed.

Now off to recap.

Mike;
  There are lots of AC/DC TRF circuit sets around, but I'm surprised that RCA would build and or market such a thing since they owned the superheterodyne patents. Most of the ones I have seen were cut rate off brand sets, like the ones the infamous "Plant A" used to churn out, as well as U.S Simplex. The original Transitone model TH-1 from 1939 was a TRF AC/DC set, which was built by U.S Simplex, for Philco, but unlike this RCA it was not a Philco designed set.
Regards
Arran