Slow progress on the Radiola. For me, the difficulty is trying to restore the Radiola 28 for DC operation when this one, and most of the other thousands of Radiola 28 battery sets, have had the AC conversion package installed.
As I puttered around the set I noticed several circuits seemed to have the wiring "wrong." I didn't appreciate the extent of the modifications for AC operation until I read the RCA radio repair course chapter on the Radiola 28 conversion package. I've put the chassis wiring back to the original DC state, including replacing the AC resistor strip with a DC connection strip. For the DC connection strip (DC bus bar) this is the only picture I found:
I puzzled over the RCA's circuit and continuity diagrams for several weeks before I realized that this highlighted section represents the DC connection strip on the back of the catacomb:
This is what I ended up making for a DC connection strip:
It fits, and I really hope I did it right. I thought it would take a couple of hours, but it turned into a 4-day project for me. Other than this, there are only a few other parts that need to be replaced, but so far I haven't been able to find values for any of the components in the original DC set.